engine siezed, any thoughts on why

helped a man with a 340 breakin. fired right up & I held it to 2200-2500. oil psi was 80. water temp climbed to 160 fairly fast. no leaks & sounding good & all of a sudden after about 3-4 minutes it suddenly started to slow down somewhat noticeably & I was manning the throttle & I thought I had with my hand just relaxed/backed off a bit so I moved the throttle up a bit but it stayed the same then 2 seconds later I heard a barely noticeable possibly but not sure metallic "hit" then it died 1 second later. we put a socket on the crank & it is locked solid. No info on clearances. thank you for your time.

Possibly a rod bearing piggy backed.

Something I could never comprehend,if you have a crank that is the correct diameter and a rod that has the correct bore and correct bearings with proper clearance,how could one possibly end up on top of the other ?

But,I guess it was thrown together anything is possible !

I don't know, but somehow they do. It defies the laws of physics

he's a busy guy but he will get back to me when he opens it up. I was not involved in the build but his OCD matches mine (& then some!). he said the shop assured him that P/V collision was not possible with his dimentions (lift/piston amt in the hole). he said the ring gapping was the norm & bearings iirc between 2-3 tho plastigauged. all the final prep we did was standard procedure AFAIK but I feel bad like maybe I missed something. well I guess it is somewhat conjecture for now but I will post how it turns out

Sounds like some trash got washed into a bearing, maybe a main or rod Let us know what you find out

I definitely will Cab

Hmmmm.

I would not consider someone OCD if he relies on the shop for PV clearances and his use of plastigauge for checking bearing clearances........

What was the temp and oil pressure when it "slowed down"?

BSB67, point taken. Morty, same no waver which you would expect on the water temp. it happened FAST, out of the clear blue/no warning, with one or two seconds total from first hiccup to dieing & closer to less than 1 second

We're any of these sand or bead blasted?
Intake manifold
Valve covers
Oil pan
Timing cover

I ask because I've seen this done on many occasions, and when the post blasting cleaning procedure isn't 100%, you often end up with a situation like what was described.

I will add that to my list of questions

The only thing I glass bead blast in a engine is iron rods and crank to be able to check for cracks and that's it.

Definitely never aluminum anything, especially not a intake manifold.

I learned this on my own the hard way when I was about 19-20 years old and did my own 340 rebuild and used my bosses bead blaster cabinet.

Now I use a steam pressure washer to prep my rebuilds.

Sounds like it spun a bearing...

it's gonna be interesting what it ends up being

Main bearing clearance too tight. Possible rod, but I like main. You did not suggest hearing knock as engine slowly slowed down. Just sayin.

I heard a very slight what sounded like a metallic contact of some sort & it starting to slow down (both at the same time) & I looked over at the tach cuz I thought I had let up on the throttle & I started to throttle it back up & it died. all this took place in about 2 seconds from start to finish & I was thinking later I shoulda killed it on that first contact however slight I heard but it died in about the time it would have taken me to reach the kill switch cuz I was not sure where exactly the switch was (he fired it up/I twisted the dist/pointed the light/kept the throttle open/checked for leaks). EDIT SXR I reread your post & there was the one slight contact rather than a continual interference (if that helps)

A friend of mine had somebody else build a 440 for him a number of years ago. They put the wrong bearing shells in the block (no oil holes)...I think his wife was about 20 miles from home when the motor seized...\

how tight was piston to cylinder wall clearance?? the time frame would be about right for the pistons to seize in the cylinders if the clearance was too tight..

One can surmise all day long but the correct answer will come when you take it apart!

Once the engine cooled to ambient, is it still locked up? My thought would be insufficient piston/wall clearance. I've been involved in a case with a tight bearing. The bearing wiped but didn't lock the engine up.

He said it might be a month till he can get back on it (wife/kids/job, the usual unimportant life distractions). I'm gonna call & leave him a msg & I will ask him if he will try & turn it, that'd only take 3 minutes. EDIT we talked & he had already retried the breaker bar when it cooled & it is still locked up as tight as a drum

Rod bearing. You'll see when he opens it up. That's my "Fearless Prediction".

R.

Dog, noted!. He said he likely wont have time to get back on it till Nov but for sure I will post the outcome.

If I were a betting man I would say something to do with the pistons. Either wall clearance or wrist pins.

I spoke with him last night & he has a week off straight in early Nov & likely he will be on it hot and heavy but right now he sure ain't a happy man

Any sign of coolant in oil? Remove spark plugs and attempt to turn engine,,,yes I am thinking about hydrolock. Remote chance, worth a thought. Although doubt that engine would merely slow before seizing. Still like tight mains, but thoughts on tight pistons and pins and rod bearings are too worthy. Broken rod. Any oil in the engine?

Boroscope thru oil pan drain hole. Any metal in filter or oil?

Will engine turn backward with socket on breaker bar or prying flywheel teeth.

I assume transmission is in neutral or clutch is in if manual. Naw,,,if slowdown was detected before stall.

Dropped a valve?

Starter not locked to flywheel teeth?

Throwing sh*t against wall to see what might stick.

Just lying here, listening to Mark Levine and chewing my cud waiting for the debate.

This happened in the car? Any chance the front pump piled up?

Kevin

I called him last night at work & he picked up & we talked for a spell. he drained the oil & said it looked OK, he cut open the filter & said there was some "fine" metallic particles, nothing disturbing. when I was there he turned the crank CW & it was stuck. On the phone he said that he had already retried to turn it when it was cold & used a longer extension on the breaker bar & it was still stuck solid (I'm assuming he went CW). it is installed in the car all buttoned up & ready to go just needing the breakin. its an auto (not sure if it was a 904 or a 727). he was thinking it might be a trans front pump issue, but I told him that I did not think it was that. I offered my borescope that is over at racing partners shop for him to use. I told him that just me I would just go ahead & pull the heads and intake/pistons/rods but I think he wants to see what the borescope shows & possibly any pherifical (sp) issues such as the trans before completely tearing into it

Cam bearing seize up cam if incorrectly replaced on rebuild. Will breaker bar on engine allow any rocking movement at all resulting from timing chain slop?

On big block, removing pan really fast,,,,if not all gooped with silicone sealer. I understand that small block can be a bit more challenging. Easier than removing heads.

Borescoping could explain enough to suggest if to remove heads or pan first.

tight the first time & he put an extension on it the 2nd time (when cooled) & still unbudgeable. I queried him a bit on the ring gaps and who did the machining etc and he put it together by himself so I dont have much knowledge on anything other than what happened on the breakin. I think for now it's dead in the water till he can get to it. if he makes it over sometime to borrow the scope then something may show up on the cyl walls. For sure with all the interest I will post the outcome when the time comes

I'm betting on pistons seized to cylinder walls, sorry

The rapidly rising water temps, then more throttle to keep it running, then a quick seize, sure sounds like pistons melting to the bores...
It could be main bearings too but either way it's probably going to have to come back out

Definitely interesting to see the teardown results. Now I'm even more nervous since I'll be firing up my new 451 as soon as the cam/lifters get back from the grinder!

You sure it is the engine that locked? I had a torque converter do that and the engine would not turn until I disconnected the trans then it turned fine...

He was thinking torque converter/pump/trans issue & wanted to seperate em. I told him that he would not be able to get to the 4 small bolts to free it. I'm gonna get back at him in a week & see if there is any new developments

yes that would be a challenge

No challenge, just unbolt the trans and pull it off the converter.

If you can't get it to separate, you just found your problem.

If it does separate without a fight I vote for a piston stuck from too little clearance.

Kevin

Alright, I will pass it on

No need to unbolt the trans, remove the dust cover and then the four converter bolts and see if the starter spins the converter or not If it won't turn enough by the crankshaft to remove those bolts you may need to remove the tranny to be able remove them If it won't turn over it is probally the tranny or converter, if it spins the converter try rotating the motor with a socket on the balancer bolt and see if it will turn or not either way, in fact do that first

I'll pay admission to see that.

Robert

Converter bolt wedged at the back of the block. Been there.
Doug

Cab, I can see him getting to two bolts if he's lucky. With the engine or whatever is stuck how would he get to the others?

Incorrect ring gaps? KB Hypereutectic pistons, for example, require larger clearances than cast or forged, IIRC.

I have heard of a 383 sb chevy engine running for miles with a spun main bearing. Noisy, but still started and ran.

Spun, or misaligned, cam bearing will break the camshaft in half at that journal (brittle material). That happened to my dad's old 400M Ford.

he said he thought he gapped the rings a bit too large & they are forged pistons. I wont be involved in the teardown (I barely know the guy) but I am gonna call him soon & see what he has to say & I will find out if early Nov is still the plan to get something done on it

If he could turn it to get it apart, it should still run.

Its a spun Main, and nothing else.

A seized piston, crank can still move abit, clearances n bearings.

A siezed cam bearing, crank can still move with chain slop.

A vert bolt stuck to block, crank should still be able to move backwards, at least with a breaker bar. Besides the described sounds weren't right.

A bad vert, no way. You would still be able to get some kind of crank movement.

A spun rod bearing, crank can still move there too, clearances.

A spun Main,Yep, Locked up Tight.

So , there is my Out on the limb, Big Fat limb opinion.

Good news though, is there wont be a lot of carnage.

Could be bearings but I would expect more shrapnel in the filter.

I have seen a front pump seized up solid. Thought it was the crank until they tried to separate the engine from the trans. Took a 6 foot bar to get it apart.

If the trans is good my bet is still pistons.

Kevin

A guy I knew locked up a freshly rebuilt 383 one time. He said it ran about 30 seconds, and just quit running. pulled the heads, and all 8 pistons were locked in the cylinders. The machine shop he had do the bore, and who sold him the pistons did too small of a bore, cast pistons to forged pistons. The shop refused to help him, said he should have caught that in the build process! I told him they should have caught it before it ever got to him.

The new machine shop had to destroy all the pistons when removing them. They did a larger overbore, and sold him a set of pistons that matched the bore. The crank had absolutely no movement.

My guess is its piston related. Gene

IMO, That's a He said guy I knew, Story. IMO, No way, are All 8 pistons going to seize up at the same time. Less then a minute to boot too , come on.

I just got off the phone with him, he pulled the rockers & no change, still locked solid. He's gonna pull the heads & I suggested when he pulls the pan to undo the rods that are angled right & with a wooden dowel see if the pistons can be driven up. he may have a little time here and there before his Nov vacation week rolls around and I will update with any tidbit that he uncovers. thanks all, the extensive and I do mean extensive interest has made my day!

I edited my first post later to say you may need to remove the tranny if it won't spin over backwards or forwards with a breaker bar on the crank bolt

Ive got to go with a locked up rod, maybe main.

Pistons/rings should loosen when cooled off, but the crank welds itself.

Who knows.... should be interesting, but unfortunate it happened.

I had a BB dart lock the crank up at 40 mph (stick car) and it stayed welded. Chased a miss that morning but it was a tossed lifter...then lockup.

Likely a coincidence of all coincidences to have converter/transmission cause seize up if neither had been modified simultaneous with engine build,,,unless some quirk occurred at installation of engine time.

Like we forgot to fill the trans up or the trans had an issue.

My ex had a new 82 Camaro with a 2.8 that had a noise in it that the dealer was ignoring. I forget what the noise was but I figured about 20 miles in second gear at 5 grand would sort it out. 10 miles out and 5 miles back it did. It labored for about 5 seconds and seized solid with a bang.

Had it towed to the dealer and they assumed as did I that the engine was pooched. Big surprise when they couldn't get the engine and converter to separate. Front pump was what the problem was.

Kevin

A buddy had a similar engine issue with an 85 IROC - after about 10 miles red-lined in first gear the cat converter over-heated and set the car on fire. It took the dealer and his insurance 4 months to figure out who was liable.

Mains, still still my odds on bet,,,many other good possibilities on deck so would not bet the ranch.

I'm betting a piston seized due to heat. I would suspect the slight changes in RPM you noticed was due to the piston starting to scuff the wall, then ultimately seizing. Pull the heads and looked for a scuffed bore.

Did he fill the both the block and radiator with coolant before break in? Rapid temperature raise points to a low coolant level.

When mine jammed the converter bolt, the motor would not budge in either direction with a breaker bar and a pipe. Didn't really hurt anything except the bolt and the threads in that hole in the converter. Still has same flex plate, converter, no block damage,only very slight scratch.
Doug

I didn't check the coolant but I know he did & now that you mentioned it the temp did come up fairly fast (was at 160) and that was at the end of the ~4 minutes. I'll probably get back at him in a week or 10 days & if I hear from him first I will for sure post. He knows from my last ph call that I am concerned about it & anxious to help (find the cause & the solution).

I just spoke with him & he reports that it will turn now but very hard. He said the weekend after next he might have it out & possibly opened up. EDIT two converter bolts were clocked to where they could be removed then he turned the crank to get at the other two. He plans to pull the eng from the top. After talking last night I am going to be in on the diagnosis & I will post what develops. I probably should have waited for something more definitive before posting but I am bored & kinda anxious to see some progress

I had a rod bearing seize in a 400. Locked the crank tight. Was just thinking how bad that sucked getting out compared to normal. So i know a spun rod will lock one up.

My vote for piston.

spun main. did it twice

He forgot to use sealant on the oil pickup tube. Can't trust that connection without sealer. LOL. Let us know what you find in there when he opens it.

For sure, with all the love I've gotten on this deal I will garner all the details

On small block make sure all the galley plugs are in it. The machine shop might have remove all and not replace/advised him they were removed. Cur open the filter if it is clean a galley plug is missing. If I remembef righ the plug straight down from the oil pressure guage port will bypass the filter and show oil pressure just the mains wont get enough. Seen It before

The plug may be missing, good point. This engine defies all odds

He cut the filter open & said it was clean. I'll get back after him next week

In the small block tech archive the is a post about changing oil pumps. About halfway down it talks about how to check to see if the plug is in there through the oil sending port using a small rod. It has the dimensions for how far the in the rod should slide in. The plug diverts oil to the filter. That plug is the DEVIL! Can you image pulling it apart and never finding any reason why it ate itself, because there would have been nothing wrong in the bearing assembly, it would show pressure, you would finally chalk it up to that mystery "issue" putting it back in and if does it AGAIN!!!

My last circle track eng iirc the rod stopped 7&1/4" down from flush with the NPT oil sender port at the rear top of the block after I drove it in down visually halfway between the 2 horizontle ports. with no plug yes with alot of debris that could easily cause an immediate problem or if there is no significant debris the eng will wear out years before its time with the owner having no clue what is actually happening, all the while doing religious oil/filter changes & thinking he is golden! I will call the guy again soon. EDIT I could see where a non Mopar shop could easily miss that detail.

Update?

Seems like there needs to be time limit on a question like this. All of us motor heads need conclusion. 😃

I think this thread is just a joke to see how long he can keep a bunch of gear heads in suspense.

Tease us with the possibility of engine carnage pictures, and then leave us hanging....:)

Fastmark I'm going as fast as I can (& I got 2 calls in to him). Wingman, I do not operate like that, everything I have posted regarding this (& any of my posts) has been straight up). I posted the question & I sure was not expecting it to take off like it did but the guy has a wife and kids and a full time demanding job (& from what I understand a schedule that changes shifts) so there is not much I can do except keep in touch which tells him that I am interested in resolving this. I'm looking forward to a resolution too & in fact I was a little reluctant to put his business out here (not sure if he is on here or not) but my intent was honorable & I figured I needed to hear what the Mopar brain trust has to say for possibilities (& I sure got em!)

RR has been nothing but a straight up guy who has contributed a lot to this site. I feel it is out of line for the two of you to question his integrity. If you don't like the post, don't open it, No need to attack him

X2

I (very much) appreciate the backup guys, & you know as much time as I spend on here I've noticed that some people tend to wake up more foul on the weekend (I ain't sure why!) but I have seen it. When the time comes not sure If I can take pics or even if pics will be needed/applicable as it will depend on what it ends up being but when I know you will know

I agree with TJP, no games here, a guy with a busy life. Sit back and relax, the answer will arrive.

X3

Didn't anybody see wingman's little smiley at the end of his post?

I can relate to the guy taking his time not pulling his motor right away. About 15 years ago when I built my Dart on the first drive it slung the frive shaft out. Ruined a brand new drive shaft, a new rear end yoke and beat the pi$$ out of the exhaust. I didn't touch it for three weeks after that ordeal.

I did miss that!

I'm sure Robert & the guy that owns this engine want to know the problem as soon as possible.
Sure, the rest of us want to know too, but the answer will come when time allows.

Hold on here guys. I'm the one who put the 😀 on the post. That's why I did it. I'm not being rude. I understand that guy is not like me. I would have ripped it apart the next day. But that's me. I can't leave something unresolved and still sleep at night. My brain works all night. I really like the fact that their are people with a lot of knowledge on this board and I glean from them as well. I have had to solve some complex problems for people and all that knowledge get filed in my memory banks. This mystery is just waiting and we all want to help 😀😀😀😀. See I'm still smiling.

Everyone on the forum knows RapidRobert is a very good guy. A little sarcasm/ribbing got taken wrong. PLEASE lets get back to the subject. LOTS of us are chomping at the bit to see what the cause of this catastrophe was...

thanks guys! Yeah I've only met the guy 3 times (fireup was #3) & he said he has been putting this together for 1&1/2 to 2 years (wife/kids/job are such a distraction!) and he was pretty bent out of shape when it locked up. That Challenger looks like the day it rolled off the showroom floor. before fireup I chided him that he looked more nervous than an expectant papa would be! & he did not think that was very funny (he was sweatin bullets which I don't blame him). I did not have the timing advanced as much as he thought it should be (he was right), probably coulda used another 10 deg & he was thinking that that was the cause but it did not get over 160 in a mech gauge plumbed to a bypass line at the WP and this was with 3 or 4 minutes of run time (thoughts on that?). when I posted this I expected to get a few replies especially since the eng ain't undone yet to find what did happen and I certainly did not expect it to morph into what it did. I will put another call into him tonight. we're all good here (for now!). RR

I just spoke with him & no (real) progress except he said a valve stem he observed, was blued. I went over prior stuff & he reinterated that the oil and the filter were clean and that he undid the rocker arms before he put the breaker bar on the crank & he got it to turn ~ 1/2 turn to get the other (2) TC bolts off & it was real hard to turn. His schedule has worsened & he wont be able to do anything (more) until Nov 17th at the earliest.

Well if you have only met the guy three times, then you are a good Sumaritan. Since your not close buds he may be embarrassed that his motor failed in front of you. That man pride thing. I had a bud who had a bad habit of letting his cars sit in the driveway at idle for 30 minutes to "circulated " the oil. One 55 Ford pickup he had seized up AFTER he put it back into the shop. It would not turn over the next time he started it. It stuck the valves. Even with manganese guides. I know the shop that built the heads and they were right. He used Av gas and it does not really lube as well and at idle, the motor would not get enough oil. Just a thought. Good luck. I'm thinking very serious about building a run stand for just such an occasion.

Yep, only met the guy 3 times. he had heard of me & had called several times for advice over a several year period & on the last call he said he was getting ready to fire it & I volunteered to be there to help if I could. I did not have the dist advanced enough & he is thinking that my mistake was what caused it to lockup. Agreed I did not have it advanced enough but there was a mech temp gauge plumbed into a pump bypass & it reached 160 & was at that point for awhile before it hiccuped & died & that was at ~3.5-4 minutes. I really don't consider myself a good samaritan as it took me years to get people on here to leave me be and I deliberately do things out here in this apt complex to make people fear me and leave me alone (I like my privacy), everybody wants mechanical help & I dont know anything about modern cars which non mechanic people have a hard time grasping. I'm on disability for mental health issues & I spend most of my time watching TV, jogging and of course Moparts (the worse one of all!). he caught me at a good time on a rare good day & since breakin is so critical I wanted him to be sucessful. when the time comes if it is bearing related then that would elim the timing/heat issue.

He undid the rockers and then he is trying to turn the engine over ??
And he is surprised the engine is hard to turn over ???

I doubt if your timing caused the problem

correct, I think I heard him correctly, he unbolted the rockers thinking that maybe there was a top end binding then he turned the crank to get to the other two TC mini bolts as he is going to pull the eng when he has time. that was about all he had to offer as far as new info & I just went over the prior stuff previously mentioned like the oil/filter etc so that maybe something he forgot to add would come to him during that conversation last night so I would have something new/relevant to post. Oh I think he also said the pushrods were not bent or if he did not then he would have mentioned that for sure if they were bent but I think I did ask him. EDIT & he did mention that a valve stem looked blued MORE EDIT that is a relief that I am off the hook for the timing (I think I had it at ~25 & it was ~2200 RPM). MORE EDIT John Oh OK now I grasp what you are saying as keeping (all of the valves closedtrapping the compression in all cyls would for sure make it way harder to turn! Now that I think about it I ain't sure if he did that before the turning but I think maybe he turned the crank later on that same day then his next day off he undid the rockers & pulled the manifolds as it was last night when he mentioned the blued stem.

I know of a BBC that didn't get any prelube on the pin to pistons. Seized up tight as a drum on the dyno. May have been mentioned above, but I skipped over most of it.

I think he means...... If you unbolt the rockers...... And don't remove the spark plugs......they turn over pretty hard.

Hopefully the guy was smart enough to pull the plugs.

This thread has been one long, drawn out, speculation fest ... there could be a number of reason it locked up ....

(1) I originally thought he tried to turn it later on that evening & I was long gone or maybe he said the next day (I've kinda got lost in the details myself). (2) yes it has drawn out & I have felt the love & you have even contributed to that (2 posts!), much appreciated! (2B) on the cause, I'm thinking pistons/rings or bearings but that is an edumacated guess & there are several more potentials for sure & all have been mentioned!. when I know I will post the same day & it will be anticlimactic for sure. Likely I wont be there when he discovers it but I'm sure I will be involved in the fixing

It's like an accident on the highway, on the other side of the median, one can't help but look ...

But it is increasing my post count blathering on about nothing ...

After posting this morning I went & ran some errands & on the way there I was thinking that absolutely there was no love coming from you (your reasons for posting) but it was adding to your post count (I had a good laugh to myself on that!) and you are (mainly) looking for an opening to jab. for example, You said "blathering on about nothing" well yes your post is a prime example of that. One thing that you are good for double R is that you teach a person tolerance. Maybe one of these days I will meet you at the Nationals and & I will introduce myself & thank you for the edumacation. I have yet to fully grasp why me and you got off on the wrong foot way way back & have stayed that way in spite of my occaisional efforts to be nice (most of the time!). I guess that is life. To your credit your tech is pretty knowledgeable & I respect that. Have a good day brother. RR

Here we go !!

Agreed, I shoulda known better than to take the bait. Wont happen again (cross my heart & hope to die)

Oh RR, = Relax Robert :-} I'm sure the other RR means no harm, just stating things are dragging..


The latest update I saw, is the engine is no longer Siezed up. It actually turns. That opens the possibilities of the cause even Further. Greattttt....

I guess I'm no Longerr locked on my Main bearing siezed up blathering. :-)

Do look forward to the actual cause as do many of us. I know the balls not in your court. Like your posts as well, especially that distributer phase thread. I learned from it, so did others and some did not. Keep us posted.

(1) best advice I've heard all month (not the first time tho!) (2) yeah his schedule sounds demanding, I barely know the guy but he said they flew him out of state for a work seminar then switched his shifts & did some changing to his vacation schedule (way more than I could deal with). (3) Oh the second I get some (relevant) news I will for sure post it!

You know you are lying to yourself, you will take the bait, you always do ...

Thank you, another post ... ding ...

Now if he only learns how to take the cheeze without springing the trap...

I have to much time invested in this thread to see it fade away :-)

Any resolution on why this happened yet??

Robert posts 20 times a day, when he knows the answer he will tell us.

Only 20?

Any updates?

I left him a message 3 or 4 days ago but I ain't heard back from him yet. the last time we spoke roughly a month or so back he said something about working on the interior & some other non engine related areas which was dissappointing cuz we need to get to the bottom of this but since it ain't my deal I gotta just go with what is presented to me but he does know that from me being involved in this deal that I also want resolution to this & that I am willing to help him achieve that & he has expressed appreciation for that interest/concern. I will post the outcome.

I spoke with him this evening. the shop that did the machining tore it down and ALL bearings are wiped smooth & clean (rods & mains) including thrust surfaces on #3 main halves EXCEPT the #4 main had spun. He (the owner) saw the bearings but did not take off the cap on the spun #4 main. this shop polished the crank (std), owner ordered std clevite bearings from Summitt. he recollected to the best of his ability that he plastigaged em at 2&1/2 tho. Assembly lube used. it was showing 80 lbs when we broke it in till it locked 4 minutes later. I told him either (1) wrong machining (2) oil psi or (3) debris & I wouldn't think debris cuz he said they were all smooth & it had 80 lbs at the sender but bearings can get starved especially the #4 main & rods on either side of it that feed from that main, but this was a 2200 RPM breakin, not high RPM & I said my money is on improper clearances. that's the latest guys, any thoughts? Oh & the #4 main cap was blued & he is going to source another cap & have another shop line bore it then the same (1st) shop that originally did the machining, put the short block together (not what I would do). I offered to put it together for him for free. EDIT He said the shop called in some other machinists to check it out & they are at a loss (I suspect they ain't miked anything yet, just visual.

No ideas on the cuprit, glad to see you are still engaged on this and thanks for the update!!!!

it is too challenging to let go especially with all the interest you guys have shown me on this and the puzzling development on the visual. I'm looking forward to eyeballing it in person as this is second hand info.

Since you mentioned blued cap and clearances checked: any chance the bearing saddle of either the cap or block had an edge ding.
Motor ran fine until heat built to the point of bearing failure.
I'm coming in late and I'd be suspect of foreign material in the bearing interface, or dome sort of block or cap defect displacing bearing.
Be interesting to find out how difficult assembly rotation was prior to start-up.

I ain't sure if startup rotation was mentioned priorly. He took some some pics that he is going to send & I'd like to be there in person before it goes together, I will for sure post any new info. EDIT what sounds strange to me & to them (& the people they called in) is that all the bearings are wiped smooth

IMO the bearing clearance was to tight. You don't wipe or spin main bearings with .0025" clearance on a new engine with 80# of oil pressure. If it didn't have oil pressure the top end would've been very noisy.

Id like to see the bearing pics, almost sounds like a machining error. I recently used PG to check for consistency but on the real measurement it was nearly .0015 off.

Interesting. Based on the autopsy it sounds to me like #4 was too tight due to the wrong bearing (undersize bearing in a standard bearing box) or there was insufficient oil supply to the #4 bearing. If the builder did indeed plastigauge all the bearings or the engine turned over at assembly, then I would guess an oil problem. 50 years ago I was working on one of the old babbit pounder 216 Chevys that have the oil dippers on the rods for rod lubrication. The engine was in the car and I got disoriented and got one dipper on backwards. The engine ran for about two minutes and locked up. The rod I had assembled incorrectly had fused itself to the crank and the rod was a pretty deep blue color. This sounds similar.

I think the tight or lack of clearance is why he had 80 PSI.

Robert

I think this is a good example of what can happen when someone lacking engine building experience is left to do it by themselves.

Unless there was no assembly lube, or a plugged feed hole to the #4 main, there is no way the crank would have passed the "feel" test for how it turned over.

I've seen where main journals on the crank or the main line itself is out if whack, to the point where the clearances measured fine, but the crank didn't feel "right" when turning it over........ And on a couple of occasions it actually locked up when all the caps were torqued.
I've had this happen twice. Once the problem was the block, once it was the crank.

good call on the psi & even tho it was a hi vol pump (not sure what spring), that number sure kinda points to minimal overall leakage. Evidently they did not mock it up/mike clearances after they did their work as he ended up plastigaugeing it himself (that had been bothering me from early on). I'm gonna see if I can drive up to the machine shop & take a look at the carnage.

With a 1st time engine builder, I have to wonder if the #4 main that spun was incorrectly installed. If the lock tabs were not in the grooves, the clearance at the bottom may have been OK, but the sides could have been very tight, causing the shells to spin as soon as the heat came up. The bearing shells could have begun spinning on start up, and it took 4 minutes to create enough heat to lock the motor. You are all assuming the new builder had the bearings correctly located.

If the #4 main bearing spun bad enough to lock the motor and turn the cap blue, and the other bearings look OK, how are you ever going to determine the real cause other then to point to #4 spun bearing and its blue cap? Gene

Was the number 4 main cap installed backward?
Doug

i replaced the crankshaft on a 302 ford pickup once that was low mileage although i dont remember how many miles as this was in the mid 80's,the center main bearing was installed wrong,the half with the hole in it was installed from the factory in the cap and not the block,never did figure out how it ran as long as it did,bearing didnt spin in the block?

This is why to use a good engine builder with an engine test stand. The shop can run up the engine , do the break-in and check for problems.
This way, anything happens; it's on them.

Sounds like the thickest bearing wound up in the smallest main bore and the crank was on the high side. Seems like clevite bearings for mopars, are always close to max wall thickness, but on chevys .0003 under max wall.

And 80 psi is normal on melling pumps standard or high volume, sb or bb mopar.

I have cranks reground to .011, .021, or .031 on chryslers. Usually gets clr. close to .0025. Got tired of telling them low side only to get them back on the high side, and having .001 or less clearance.

Did he ever check to see if the plug is in the block? If not it's going to eat itself again.

This is why I invested in good micrometers and dial bore gauges and meticulous assemble my own engines. Checking others work is important but checking final clearances is mandatory. I have caught several mistakes by even good machine shops that would have had bad results if gone undetected. I have found many mistakes on motors assembled by others and repaired their mistakes. Good luck with the next attempt.

the problem is is I was never involved with the build until I offered to come over for the breakin which locked up within 4 minutes. I barely knew the guy & we had only spoken on the ph several times prior (way way back) about cam & some parts selections. I offered to do it for him this time as he is turning out to be a nice guy & whatever the cause it was a horrendous deal (& I feel for him) but he says he is having shop do it (same shop I'm thinking but not sure), I'm assuming they are gonna make it right). I will get all the details as I get em & I want to go up there & have a look see sometime (& take some pics) which he did & is going to send to me. He has a real demanding work schedule (I ain't never spoken with anyone who got on "salary" who was not full of complaints about it). I will note all Q's you guys have posted & get back to you when I have something.

I would make sure to check all the oil galley ways. I had a motor built and there was a blockage that the builder thought was clean but when he measured it against the others with a welding rod it was plugged and felt like he was hitting the block with the welding rod. I had some bent push rods and some bluing on other push rods and it ate the #4 main. It was just debris from machining possibly from bushing the lifter bores. i heard the valve noise. This was after about 100 miles on motor.

I'm gonna give him a call tonight & see if there is any news & request permission to visit the shop (& take pics hopefully) if it ain't too far away.