#6/#5 spun rod bearing ?

This thread came at a perfect time

Lost the oil pressure in my Hemi and it started to knock.. This is what I found when I opened it up. (Sorry for bad picture quality)

Its the # 6 Rod bearing (I think) that is sticking out... Havent removed the rods/pistons/crank yet.

Is the Hemi block oiling system the same, refeering to..

#5 main feeds #8 rod
#4 main feeds #7 and #6
#3 main feeds #5 and #4
#2 main feeds #3 and #2
#1 main feeds #1

and would the Hemi oil system also be better off with restricting the passage to the rocker shafts.

Oil system is a external Milodon Dual Line system with a Melling HV pump. No windage tray.

I guess in my case I think the spun bearing happened because of low oil volume in the pan.. Ive also been messing about trying to get the E85 carb to run right. Had to change the oil a couple of times because of carb running excessively rich in the beginning. Typical luck for me, the loss of oil pressure happened about the same time I managed to find a nice carb tune.. Though I think the bearing had been messed up longer than that, but it let go right then...

/Tom

Posted By: TomsCharger70

Re: #6/#5 spun rod bearing ? - 09/06/11 07:51 PM

Ive been thinking about the spun rod bearing. One thing that crossed my mind is that maybe the reason is that I used to thick oil, 15W20 and ran to much oil pressure in the engine. Cold the oil pressure was 100psi and once engine got warm it was about 60psi. Weirdly the oil pressure did not go up by much at high RPM, about 75psi @ ~7000rpm.

The clearances were/are quite loose in the engine, its an old Pro Stock engine. The bearing clearances for main and rod bearings were, if my memory serves me right, in the .0025 something (I cant find my rebuild memo). I left the clearances where they where when I put new bearings in it, clearances were/are a tad loose, but its an old race engine, and my plan was when I bought the engine, that Ill do a service and drive it as is for a season or two, then do a complete rebuild of the bottom end.

..Any ways... The thing that came to my mind is that was the oil to thick and the pressure to high when cold, could that have caused the bearing to spin??? So what do you think, did I

up???

/Tom

Posted By: 68LAR

Re: #6/#5 spun rod bearing ? - 09/06/11 07:53 PM

Quote:

Yes that and the excessively THICK 98 cold psi and 65 at idle doesn`t seem ideal to me personally. With fairly large bearing clearances in my motor I still run 5w30-10w30 oil and even though I have an 8-quart pan, I run bet 6-7 quarts and have about 70psi cold and 30-40 at idle/cruise.

Cool, you're entitled to your opinion, but tell me this, how many cases of rod bearing failure have you heard of, that was attributed to too high of oil pressure? I'm guessing that I'm allot older than you and I've NEVER heard of high oil pressure causing bearing failure. Granted it robs horsepower, but this is my choice to have higher pressure......... I've heard of many, many more failures due to too low of oil pressure, rather than too high.

Posted By: TomsCharger70

Re: #6/#5 spun rod bearing ? - 09/06/11 08:05 PM

I kinda think there is a possibility that high pressure and loose oil viscosity may cause a bearing to spin, it comes down to physics. IF the clearances are to loose, the thick oil circulating at high pressure, may cause such a "drag", no idea what to call it in English, but the forces at play get so high, that it rotates the bearing?

/Tom

Posted By: 68LAR

Re: #6/#5 spun rod bearing ? - 09/06/11 08:13 PM

Quote:

kinda think there is a possibility that high pressure and loose oil viscosity may cause a bearing to spin, it comes down to physics. IF the clearances are to loose, the thick oil circulating at high pressure, may cause such a "drag", no idea what to call it in English, but the forces at play get so high, that it rotates the bearing?

Bearings are "indexed" so they won't rotate. One reason of what causes a spun bearing is metal to metal contact, or, lose of oil pressure. Your theory may be valid, I'm no physisist, but I'd have to see documented proof.

My bearing clearances are .0025", which is in line for my type of engine usage. Nothing exotic, here.

Posted By: Moparnut426

Re: #6/#5 spun rod bearing ? - 09/06/11 08:15 PM

Quote:

Quote:

Yes that and the excessively THICK 98 cold psi and 65 at idle doesn`t seem ideal to me personally. With fairly large bearing clearances in my motor I still run 5w30-10w30 oil and even though I have an 8-quart pan, I run bet 6-7 quarts and have about 70psi cold and 30-40 at idle/cruise.

Cool, you're entitled to your opinion, but tell me this, how many cases of rod bearing failure have you heard of, that was attributed to too high of oil pressure? I'm guessing that I'm allot older than you and I've NEVER heard of high oil pressure causing bearing failure. Granted it robs horsepower, but this is my choice to have higher pressure......... I've heard of many, many more failures due to too low of oil pressure, rather than too high.

I have heard of it "washing" the bearings, That was in an 8500rpm dirt latemodel engine. It would accually just force the oil out of the bearing, I dont understand it for sure either, but the engine im talking about ran 20w50 with .003 rods, and mains, and he had 95+ psi oilpressure, and had a bearing failure on his small block, when he changed the pump to no more than 65psi at the same rpm the bearing issue went away.

so from that I honestly dont know why...

Kasey

Posted By: maximum entropy

Re: #6/#5 spun rod bearing ? - 09/06/11 08:41 PM

excess viscosity increases demand on the suction side of the lube system. bb mopars are borderline in this regard already, and if the pressure side demand is increased (bigger clearance, high rpm), the suction side demand will increase also. your viscosity is probably WAY too high with all that stp, and fairly thick oil to begin with. do you have a 1/2" or external pickup? and to the guy with the hemi with the rod bearing squirting out, DUDE, you have two different kinds of rod nuts. or am i hallucinating?

Posted By: Performance Only

Re: #6/#5 spun rod bearing ? - 09/06/11 08:44 PM

Quote:

Quote:

Are you oiling the rockers full time? If not don't restrict the oil to rockers The reason being that the stock oiling through the cam only allows oil to the rockers around 15 camshaft degrees....

Ya, my blocks are all stock oiling systems. So I have to live with what I got, and do the yearly tare down and inspection from now on.
Thanks to all for good info,
Larry

the reality is that the engine needs to come apart completely now anyway, so it's a good time to do the oiling mods and get it over with.
there's no reason a street/strip combo should have that much oil pressure. pressure is a result of restriction, keep that in mind.
when the engine was built, was each rod checked for size and roundness? oil clearance doesn't mean much if the bearing lacks themproper crush to hold it in place. those index tabs you speak of are just that, a way to locate the bearing. they're in not intended to keep one from spinning in the housing bore.
as far as restricting oil to the top end, hogwash. it's a driver, not an all out race car.
do the oiling mods in order to get the volume of oil to the places it needs to be. use due diligence in checking housing bore sizes and other standard engine building practices and move on. engine failures are costly, doing it any way but the right way the 2nd time around is even more costly. best of luck.

Posted By: Paul_Fancsali

Re: #6/#5 spun rod bearing ? - 09/06/11 08:47 PM

Hi Larry
Have you given the thought to all the power used to drive that kind of pressure I used to do the same thing lots of oil pressure until I realized how much power it cost me. Now I pretty much limit it to no more then 65-70 hot or lower. I also run thin oil when possible. With what you have it like karo syrup on a cold day. Not saying your wrong just a thought

Posted By: TomsCharger70

Re: #6/#5 spun rod bearing ? - 09/06/11 09:08 PM

Quote:

DUDE, you have two different kinds of rod nuts. or am i hallucinating?

Nope, you are correct. A rod nut is a rod nut... Loos weird, but does its job.. story is that previous owner of the engine did a service to it, changed out bearings. He lost two of the nuts, but being a race shop owner he just went into his shop and looked what he could find on his shelves...

/Tom

Posted By: 68LAR

Re: #6/#5 spun rod bearing ? - 09/06/11 09:51 PM

Quote:

the reality is that the engine needs to come apart completely now anyway, so it's a good time to do the oiling mods and get it over with.
there's no reason a street/strip combo should have that much oil pressure. pressure is a result of restriction, keep that in mind.
when the engine was built, was each rod checked for size and roundness? oil clearance doesn't mean much if the bearing lacks themproper crush to hold it in place. those index tabs you speak of are just that, a way to locate the bearing. they're in not intended to keep one from spinning in the housing bore.
as far as restricting oil to the top end, hogwash. it's a driver, not an all out race car.
do the oiling mods in order to get the volume of oil to the places it needs to be. use due diligence in checking housing bore sizes and other standard engine building practices and move on. engine failures are costly, doing it any way but the right way the 2nd time around is even more costly. best of luck.

My clearances were checked prior to the build in 2004, as stated, rods and mains WERE all at .0025".
The increase in oil pressure is done by me adjusting the pressure relief spring in the oil pump, up a tad. With the relief spring untouched, my pressure was at 65 psi cold and 45 hot. I wasn't comfortable with that.
Again, a question of what oil mods I should make, IF any, still has to be anwered. Remember, this is NOT a dedicated race engine. Most of the time it is street driven. DO I NEED TO MODIFY THE OILING SYSTEM????? Right now, to tell you the truth, I'm confused and getting mixed opinions as to IF I do need any mods at all.

Thanks for any input,

Posted By: 340Bird

Re: #6/#5 spun rod bearing ? - 09/06/11 10:17 PM

I drilled the feeds from the mains to the main feed on my small block. The hole had 3 steps if I remember right and got small(maybe .125) at the ends. I don't remember the drill size; just that it was the same as the size at the mains.
Bird...

Posted By: Performance Only

Re: #6/#5 spun rod bearing ? - 09/06/11 11:16 PM

Quote:

Quote:

the reality is that the engine needs to come apart completely now anyway, so it's a good time to do the oiling mods and get it over with.
there's no reason a street/strip combo should have that much oil pressure. pressure is a result of restriction, keep that in mind.
when the engine was built, was each rod checked for size and roundness? oil clearance doesn't mean much if the bearing lacks themproper crush to hold it in place. those index tabs you speak of are just that, a way to locate the bearing. they're in not intended to keep one from spinning in the housing bore.
as far as restricting oil to the top end, hogwash. it's a driver, not an all out race car.
do the oiling mods in order to get the volume of oil to the places it needs to be. use due diligence in checking housing bore sizes and other standard engine building practices and move on. engine failures are costly, doing it any way but the right way the 2nd time around is even more costly. best of luck.

My clearances were checked prior to the build in 2004, as stated, rods and mains WERE all at .0025".
The increase in oil pressure is done by me adjusting the pressure relief spring in the oil pump, up a tad. With the relief spring untouched, my pressure was at 65 psi cold and 45 hot. I wasn't comfortable with that.
Again, a question of what oil mods I should make, IF any, still has to be anwered. Remember, this is NOT a dedicated race engine. Most of the time it is street driven. DO I NEED TO MODIFY THE OILING SYSTEM????? Right now, to tell you the truth, I'm confused and getting mixed opinions as to IF I do need any mods at all.

Thanks for any input,

i'm just trying to help. did you ever check the housing bores for size and roundness? frankly, most home builders don't because they don't have the proper tools or experience to do it. 65 psi cold is a smidgen low on a cold motor, but not what i would be concerned about. what was the pressure hot at 6000 rpm? that's way more important in my book.
i'm just saying, IMO you should do the oiling mods. it's not voodoo, it helps. the basic mods are fine although i still prefer the 1/2" oil pickup.
are you running a std or high volume oil pump?

Posted By: ZIPPY

Re: #6/#5 spun rod bearing ? - 09/06/11 11:16 PM

I'd suggest get chuck senatore's old book, and ream + clean up the passages between the oil galley and the mains the way it's spelled out in there. Other books say it in one sentence, but that one explains exactly what to do.

If you've never checked out what a mess those particular oil passages are in a stock block you're in for a real treat. It would not surprise me if you found a couple holes that are 2/3 the size of the others, and that would do it.

For the type of use, I would not restrict the oil to the rocker shafts with an stock (other than above) system.

Considering the preference for high viscosity oil/additive, that stp adds a whole bunch of viscosity....but if you like it, go ahead and use it....I also think it's a good candiate for the old direct connection "hemi" 1/2" oil pickup, radius and blend the pickup passage modification. SAE 50 and 40 weight were commonly used back when the books detailing those mods came out.

All that will give you more flow (volume, not pressure) through the system......it should definitely help

Posted By: Thumperdart

Re: #6/#5 spun rod bearing ? - 09/06/11 11:36 PM

Quote:

Quote:

Yes that and the excessively THICK 98 cold psi and 65 at idle doesn`t seem ideal to me personally. With fairly large bearing clearances in my motor I still run 5w30-10w30 oil and even though I have an 8-quart pan, I run bet 6-7 quarts and have about 70psi cold and 30-40 at idle/cruise.

Cool, you're entitled to your opinion, but tell me this, how many cases of rod bearing failure have you heard of, that was attributed to too high of oil pressure? I'm guessing that I'm allot older than you and I've NEVER heard of high oil pressure causing bearing failure. Granted it robs horsepower, but this is my choice to have higher pressure......... I've heard of many, many more failures due to too low of oil pressure, rather than too high.

Settle down skippy...............wasn`t refering to the spun bearing just damn thick oil that`s all and another thing, older DOESN`T make you smarter. Now where were we?

Posted By: 68LAR

Re: #6/#5 spun rod bearing ? - 09/06/11 11:40 PM

Quote:

i'm just trying to help. did you ever check the housing bores for size and roundness? frankly, most home builders don't because they don't have the proper tools or experience to do it. 65 psi cold is a smidgen low on a cold motor, but not what i would be concerned about. what was the pressure hot at 6000 rpm? that's way more important in my book.
i'm just saying, IMO you should do the oiling mods. it's not voodoo, it helps. the basic mods are fine although i still prefer the 1/2" oil pickup.
are you running a std or high volume oil pump?

I know you are trying to help. It's hard to show feelings with a key board. I appreciate all of the replies so far, really!
I did not check bore size because of the reason you mentioned. 65 psi was cold idle. At 2200 rpm it was at 75 rpm. I didn't take it up higher than 3500 and it remained at 75. When I raced it with the engine at temp. my oil pressure sets, or sat at, 75-80 psi at 6500 rpm.
With that, what mod would you recommend? I'm leaning toward the one that blocks the oil from #4 to the cam bearing and drill and tap in a restrictor into the main oil galleies for rocker lubrication. If any mods, to me, this one as described in the "Power Adder" section, would work best on a street/strip engine like mine.

Quote:

Considering the preference for high viscosity oil/additive, that stp adds a whole bunch of viscosity....but if you like it, go ahead and use it....I also think it's a good candiate for the old direct connection "hemi" 1/2" oil pickup, radius and blend the pickup passage modification. SAE 50 and 40 weight were commonly used back when the books detailing those mods came out.

I guess that I forgot to mention. I already have a 1/2" pick up with a high volume pump.

Posted By: AndyF

Re: #6/#5 spun rod bearing ? - 09/06/11 11:43 PM

Checking the passages from the mains to the gallery is the most important step. I've learned this lesson the hard way on a couple of engines. If one of the passages is partially plugged then the engine will spin rod bearings every time you lean on it.

Posted By: 68LAR

Re: #6/#5 spun rod bearing ? - 09/06/11 11:51 PM

Quote:

Settle down skippy...............

I'm just a dumb old man, but I am settled.

Posted By: Thumperdart

Re: #6/#5 spun rod bearing ? - 09/07/11 12:04 AM

Good to know and I was just yankin your chain.

Posted By: Thumperdart

Re: #6/#5 spun rod bearing ? - 09/07/11 12:06 AM

Quote:

Checking the passages from the mains to the gallery is the most important step. I've learned this lesson the hard way on a couple of engines. If one of the passages is partially plugged then the engine will spin rod bearings every time you lean on it.

Agreed............when I started the big-block journey years ago, Pettis did the oiling mods to my block and I`ve ran 6-quarts of oil at 7000+ rpm`s for 11+ years w/out issues.

Posted By: justinp61

Re: #6/#5 spun rod bearing ? - 09/07/11 12:08 AM

Larry, I'm not trying to be a smart azz, but if you're supposed to use five quarts of oil to one bottle of STP, why use three bottles to nine quarts? I think in it's day STP was great stuff, but now there are better products out there. Yes, I ran STP for years, but only one bottle. I'd be curious to see what your oil viscosity is with you're mix. The oil may not have anything to do with your problem, but I've have never heard of anyone using that much STP.

My 408 has the oil passages drilled out, full grove mains, .0025 on the rods and .003 om the mains and a high volume pump. It runs about 60 psi hot at 2800 and around 40 at idle. I know the volume is there so the pressure doesn't bother me.

I hope you find and correct your problem and have no issues in the future

Posted By: Performance Only

Re: #6/#5 spun rod bearing ? - 09/07/11 12:50 AM

Quote:

I know you are trying to help. It's hard to show feelings with a key board. I appreciate all of the replies so far, really!
I did not check bore size because of the reason you mentioned. 65 psi was cold idle. At 2200 rpm it was at 75 rpm. I didn't take it up higher than 3500 and it remained at 75. When I raced it with the engine at temp. my oil pressure sets, or sat at, 75-80 psi at 6500 rpm.
With that, what mod would you recommend? I'm leaning toward the one that blocks the oil from #4 to the cam bearing and drill and tap in a restrictor into the main oil galleies for rocker lubrication. If any mods, to me, this one as described in the "Power Adder" section, would work best on a street/strip engine like mine.

i wouldn't block any oil to the top end. the pressures you listed above are fine. we run similar pressures on engines that regularly see 7000+ rpm at the track and get driven hard on the street. it's all about volume, not pressure. open up those main passages so the volume gets to the bearings. you'll be surprised how small some of them are as cast. having the 1/2" pickup is great, but by itself it doesn't help much. you need the other passages opened up for it to be effective. one other thing, replace the rod that spun the bearing, don't repair it. if the one next to it got hot, make sure it's checked out preperly or replace it too. hopefully the rest of the damage isn't too bad.

Posted By: MR_P_BODY

Re: #6/#5 spun rod bearing ? - 09/07/11 01:03 AM

Also you want the volume... its also removing heat...
like was said already, pressure is the by-product of
flow vs restriction... you would have plenty of flow
with what you have BUT with the thick oil and the restrictions
you have lots of pressure

Posted By: 68LAR

Re: #6/#5 spun rod bearing ? - 09/07/11 01:03 AM

Quote:

i wouldn't block any oil to the top end. the pressures you listed above are fine. we run similar pressures on engines that regularly see 7000+ rpm at the track and get driven hard on the street. it's all about volume, not pressure. open up those main passages so the volume gets to the bearings. you'll be surprised how small some of them are as cast. having the 1/2" pickup is great, but by itself it doesn't help much. you need the other passages opened up for it to be effective. one other thing, replace the rod that spun the bearing, don't repair it. if the one next to it got hot, make sure it's checked out preperly or replace it too. hopefully the rest of the damage isn't too bad.

Will do! I did ordered 2 new rods and a new piston for #6, as it hit the head. I also had to order another crank, mine showed a couple of cracks. I get carried away with things from time to time. The STP thing is one of those times. Maybe it contributed to the failure, maybe not, remember this engine was built in 2004.....
Thanks to ALL for your input, believe me, it is appreciated. Thanks again.

Larry

Posted By: Sport440

Re: #6/#5 spun rod bearing ? - 09/07/11 04:47 AM

Quote:

Quote:

I know you are trying to help. It's hard to show feelings with a key board. I appreciate all of the replies so far, really!
I did not check bore size because of the reason you mentioned. 65 psi was cold idle. At 2200 rpm it was at 75 rpm. I didn't take it up higher than 3500 and it remained at 75. When I raced it with the engine at temp. my oil pressure sets, or sat at, 75-80 psi at 6500 rpm.
With that, what mod would you recommend? I'm leaning toward the one that blocks the oil from #4 to the cam bearing and drill and tap in a restrictor into the main oil galleies for rocker lubrication. If any mods, to me, this one as described in the "Power Adder" section, would work best on a street/strip engine like mine.

i wouldn't block any oil to the top end. the pressures you listed above are fine. we run similar pressures on engines that regularly see 7000+ rpm at the track and get driven hard on the street. it's all about volume, not pressure. open up those main passages so the volume gets to the bearings. you'll be surprised how small some of them are as cast. having the 1/2" pickup is great, but by itself it doesn't help much. you need the other passages opened up for it to be effective. one other thing, replace the rod that spun the bearing, don't repair it. if the one next to it got hot, make sure it's checked out preperly or replace it too. hopefully the rest of the damage isn't too bad.

There are different reasons for restricting oil to the top end. The cam itself is a "Pulse oil restrictor" to the top end.

In a race engine, a additional restrictor will also help to prevent to much oil from pumping to the top end at high RPM draining a insufficient pan.

Some will groove the cam journal for a constant oil supply to the top end vs a Pulse cam supply. That would need a restrictor to the top end.

The Mod in the Power Adders section has a restriction too. As does All the above situations.

But, The Power Adders Mod addresses the #4 main Oil supply drain of the valvetrain that Robs the oil supply to #6 and #7 rod journals that get the First hit of a weak oil supply.

All the other mods wont! They will still pull/rob oil from the #6 and #7 rod bearings to feed the upper valvetrain.

At minimum while your block is apart drill the angled oil galley feeds from the mains to the oil galley to make sure they are clear "all the way through".

The "Power Adders Mod" is alittle extreme for your ride IMO. But, I would still consider a Jet restriction in the block or head for your ride. Lighten up on the STP too a little.

Your car is Mostly a street car. But with the 11.sec. trips down the 1/4 it still thinks its a race car. If and when any bearings run out of oil @ 6000 RPM, Does it care??

Posted By: Sport440

Re: #6/#5 spun rod bearing ? - 09/07/11 05:32 AM

Quote:

Rod bearing issues are very common with stock block engines. Most of the failures I've seen were caused because people didn't take the time to open up the passages from the main gallery to the mains. The factory did a poor job on those passages. What works for years in a street engine doesn't last very long in a drag motor.

#4 main usually causes the most problems because it also sends oil to the top end. So those rod bearings get smoked first if oil volume or pressure isn't up to par.

More simply put on the #4 main problem.

Posted By: HardcoreB

Re: #6/#5 spun rod bearing ? - 09/07/11 12:45 PM

I didn't see it mentioned here so, I think the excessive volume of oil in the pan caused aeration in the oil. The oil level is probably too high and gets whipped by the recip assy., especially under acceleration. Addressing this and the other things mentioned; radius all block passages accessable and opening the feeds to the mains, should fix your bearing issues.

Posted By: gregsdart

Re: #6/#5 spun rod bearing ? - 09/07/11 01:37 PM

Quote:

Quote:

I know you are trying to help. It's hard to show feelings with a key board. I appreciate all of the replies so far, really!
I did not check bore size because of the reason you mentioned. 65 psi was cold idle. At 2200 rpm it was at 75 rpm. I didn't take it up higher than 3500 and it remained at 75. When I raced it with the engine at temp. my oil pressure sets, or sat at, 75-80 psi at 6500 rpm.
With that, what mod would you recommend? I'm leaning toward the one that blocks the oil from #4 to the cam bearing and drill and tap in a restrictor into the main oil galleies for rocker lubrication. If any mods, to me, this one as described in the "Power Adder" section, would work best on a street/strip engine like mine.

i wouldn't block any oil to the top end. the pressures you listed above are fine. we run similar pressures on engines that regularly see 7000+ rpm at the track and get driven hard on the street. it's all about volume, not pressure. open up those main passages so the volume gets to the bearings. you'll be surprised how small some of them are as cast. having the 1/2" pickup is great, but by itself it doesn't help much. you need the other passages opened up for it to be effective. one other thing, replace the rod that spun the bearing, don't repair it. if the one next to it got hot, make sure it's checked out preperly or replace it too. hopefully the rest of the damage isn't too bad.

After rereading my post and the rest of them, PERFORMANCEONLY is spot on IMHO.

Also consider this. Too much viscosity can starve a bearing. I would never use an additive that increases viscosity because the oil engineers know what they are doing, and why. There is a constant loss of pressure as a liquid moves through a tube. Thicken the liquid, and the rate of pressure loss due to friction sky rockets. Sometimes a thinner oil is much better in certain circumstances than thinner oil. Given that a lighter oil will still support the load, you have more capacity (flows easier) and more cooling. But your motor should work just fine with 15w40 if the passages are ok and bearings etc are done right. The restriction I talked about also hurts you on the suction side. Then when the oil is trying to move through the motor there is more loss. Stack everything together and the answer to why the bearings failed is in there somewhere.
An extreme example of what I am talking about with pressure loss happened at the newspaper where I used to work. The ink we pump hundreds of feet to the press is thicker than 600w grease. The engineering study said to run huge (8 inch?) pipe to overcome the friction. Some genius said it cost too much, and reduced the size of the pipe in the plans. Guess what? The presses on the end of the line couldn't get enough ink when the first ones were running.
As far as pressure needed, I run 65 psi at idle cold. Never goes above 65 psi. .0025 rod/.0035 main clearances, 7200 to 7800 rpm at the stripe. No problems. I do run the motor hot, which keeps the viscosity down some.

Posted By: dodgeboy11

Re: #6/#5 spun rod bearing ? - 09/08/11 04:51 AM

Cold oil can and will cause a bearing to spin. When I was operating the dyno at the shop I worked at, I wouldn't make pulls on the engine until the oil was 200 degrees at a minimum. I try not to beat on any of my vehicles until I see the oil pressure running at its normal "warm" range.

Posted By: AutoEngineer

Re: #6/#5 spun rod bearing ? - 09/09/11 06:13 PM

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Quote:

One bottle of STP treats 5 qts. of oil. My system, 7 Qt. pan, windage tray =1 more qt. and an
HP oil filter = 1 more qt. That's 9 qts, and I just add another bottle for GP's. You can't have too much zinc.

I am not saying STP is bad, but remember that the oil in the STP bottle that carries the additives may not be the best oil.

As a matter of fact, you CAN also have too much zinc in the motor oil. Too much zinc increases the formation of sludge and pitting of metal surfaces.

STP is also containing additive called Viscosity Modifier and they are polymers. By using an additional STP bottle, you are also pouring more plastics to the crankcase. Certain aftermarket oil additives are also containing chlorinated paraffin that one type of an active chemical ingredient. It is causing bearing weight loss. The lubricant industry is using a bench test ASTM D5119 to evaluate an oil's ability to control copper/lead/tin corrosion of bearings. Using aftermarket additives you most often improve the chemical corrosion of the bearings. Read the attached pdf file copied from a lubricants professional journal a few years ago

The US Federal Trade Commission has had a few cases against aftermarket motor oil additive sellers

STP Engine Treatment
http://www.ftc.gov/opa/1995/12/stp.shtm

Valvoline Engine Treatment
http://www.ftc.gov/opa/1997/10/valve.shtm

Slick 50 Engine Treatment
http://www.ftc.gov/opa/1996/07/slick.shtm

Dura Lube Super Engine Treatment
http://www.ftc.gov/opa/1999/05/duralub2.shtm

Motor Up Engine Treatment
http://www.ftc.gov/opa/1999/04/motorup5.shtm

Prolong Super Lubricants
http://www.ftc.gov/opa/1999/09/prolong.shtm

Make your own conclusions from the above, but as a lubricants professional and formulator of lubes I would prefer to use high quality lubes instead of making own mixtures with aftermarket additives. You can't necessarily improve an oil by pouring in more additives from an expensive little bottle. As a matter of fact, you even can make things worse. Overdosing STP may not have been the one and only reason for the spun rod bearings, but sure it has had it's own negative reactions to the motor oil

Attached File

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Posted By: 68LAR

Re: #6/#5 spun rod bearing ? - 09/09/11 10:56 PM

Quote:

As a matter of fact, you CAN also have too much zinc in the motor oil. Too much zinc increases the formation of sludge and pitting of metal surfaces.

Not trying to start an argument here, but 2 things come to mind.
1. Why did the other bearings, rods and mains, look like new?
2. There ain't no sludge in my engine, or pitting, for that matter.

Thanks for your input though!

Posted By: AutoEngineer

Re: #6/#5 spun rod bearing ? - 09/10/11 07:26 PM

Quote:

One bottle of STP treats 5 qts. of oil. My system, 7 Qt. pan, windage tray =1 more qt. and an
HP oil filter = 1 more qt. That's 9 qts, and I just add another bottle for GP's. You can't have too much zinc.

Quote:

Quote:

As a matter of fact, you CAN also have too much zinc in the motor oil. Too much zinc increases the formation of sludge and pitting of metal surfaces.

Not trying to start an argument here, but 2 things come to mind.
1. Why did the other bearings, rods and mains, look like new?
2. There ain't no sludge in my engine, or pitting, for that matter.

Thanks for your input though!

I am not going either to start arguing here clear issues, but someone stated here that you can't have too much zinc in motor oil. That is NOT the truth and it has been a very long time well known issue among people who are working with the R&D of lubricants.

Like said, your bearing failure may not have been a direct result of overdosing STP, but statements here won't renew the basics of science like chemistry and tribology. Too much zinc in the oil causes problems. Period

This is the end of this discussion from my side.

Posted By: 68LAR

Re: #6/#5 spun rod bearing ? - 09/11/11 08:09 PM

Quote:

This is the end of this discussion from my side.

Me too!