Hi,
I got a question about thermal health of LA small blocks.
I currently have a 344 on the dyno. Nothing serious, 9.5cr, 302 heads, comp 264HR cam, headers.

Currently it has no oil cooler, just stock pan. The water temp is set at 176°F at the water neck and the dyno system cools it down so it stays there in any condition, no problem at all.

When holding it steady at 3000 rpm and 25% throttle opening I easily get oil temps of 260°F + . Did not even attempt to run close to full throttle. Is this normal?!? I will add an oil cooler before going any further, but just wanted to ask if there is something wrong with the motor! How would they ever hold up if I hold them wide open on the road for a a couple of minutes. Maybe this is a very German question (Autobahn), but I am just shocked about the rise in oil temperature. Thought the water jacket would cool it down with no block fill.

Thanks
Flo

If temp probe on dyno is accurate something is wrong with the engine, it's either burning up pushrods or bearings etc.

Oil temps should never be over 220ish on a dyno unless intentionally doing it for circle track style endurance testing.

My stuff usually stabilizes around 195 oil temp on break in, then during pulls will be in the 160-190 range never higher. Only time I have ever seen over 210 was burning up valvetrain or had hard block in it.

I assume it built oil temp very quickly as well?

We usually break them in around 25% servo load & 3000 RPM. Should take about 7-8 minutes to build 160* oil temp. If does it quicker then I know something is up....

The one filled block I did on gas got to 220 temp pretty quick during break in, but after it stabilized we ran it all day & oil temps never came anywhere near 220 again, stayed in 190's all day during pulls.

Like I said if you trust the temp probe the engine should be coming off for disassembly/inspection. Put a temp gun on the pan if you have one....

I calibrated the probe with -well no ides for the vocabulary here- but 100% equipment. Probe is correct!

Block is not filled

I had the valve cover off once in between, looked fine.

Lifters are factory roller lifters from the late 80s 318 blocks, so it cannot really burn the cam. Are the pushrods ends critical?

It actually takes quite some time to get up to 160 / 170. I heat the coolant to 170 before starting the engine, so oil is warmed up (gets to around 120). And I can run it all day at 2000 rpm and some load on it.

At 2500 and low load no problem either. As soon as I start opening the throttle and get more than 100lbs I can watch the gauge coming up. Takes some minutes, but will climb to 260, then I pull it back down.

Guess I need to get the oil out and see what is going on :-(((

I must admit before I had the probe working (had trouble with the I/O card, did not want the Ni/Cr-Ni-probes) I had it running at 3000rpm and some load (150lbs) for quite some time and everything seemed fine- Coolant temp dead on, oil pressure was OK, but did not have an oil temp gauge! hope not too much is dying in there...

Well you know the excess oil temp has to be coming from somewhere.... usually unwanted friction. If it runs 260 actual oil temp with 170 water temp there is something drastically wrong inside the engine. Another thought could be the engine is running way hotter than you think it is, Just because the cooling tower is showing 170's water temp does not mean the engine might not have a cooling issue, hot spot in heads etc. You're not running a Thermostat in the engine are you?

I have seen one burned up pushrod add 15-20 degrees of oil temp... so yeah pushrods are kind of important, although I doubt that is your problem if you had the VC's off & looked at everything there. I was also going to ask about possibility it was wiping a cam lobe but I see it is a hyd roller.

BTW I shut our motors off if they hit 220... I can't imagine running one at 260 for any period of time. What oil are you running?

there is no thermostat and the motor water pump is shut off... I am using the coolant conditioning and water pump of the dyno. that stuff is way over dimensioned. I am measuring the coolant temp in the stock location at the manifold and also using this as input for the temp control of the dyno.

One thing coming to my mind: I do have the oil filter in stock location and some ancient C-body-small block headers where three primary tubes are essentially wrapped around the oil filter (less than 2 inches distance). And I have no real cold air ventilation in that area. Is it possible I am frying my oil there? Especially as I was running a very late spark to show the effects of different COHR in the cylinder pressure trace, NOx emissions and exhaust temp. I had over 1300F exhaust temp in the header tube close to the port.

will post pics on MOnday when I am back at work...

I am currently using a 10W40 Diesel truck oil we are also using on our turbo charger test stand. I know from personal experience (air cooled motorcycles) that these oils in the right motor can handle 140C measured oil temp (about 284F) for short time under heavy load. But it should be no where up there for my understanding in this tame motor!

I have this thing running for a couple of hours now (overall maybe 5), I was thinking if a bearing is making that much heat it would have melted by now...

Do you have an idea how much drag torque these motors should have? Like when you shut off ignition, hold the throttle wide open and spin it with the dyno? That should tell me if there is something so severely wrong...

I cannot really take it apart as I still have to do two classes next week with that motor. Then I can rebuilding it if necessary...

Thanks for sharing your experience! I really appreciate it!
Flo

It's not the headers being too close to filter etc. I've ran them touching the filter/pan & never seen any difference in oil temp.

1300 EGT's on gas is fine & normal.


I would not be relying on the dyno water pump to be pumping the water through the engine, we always run the water pump... the pump itself will be a MAJOR water restriction to the water circulation when it is not turning. I think that could be your problem..... It is why motor will run fine until you put it under load.

I know Air cooled motorcycle engines like a Suzuki GSXR motor etc do run very high oil temps, but they are also designed that way..... ie. very tight bearing clearances etc.

I can't give you a # on how much TQ it will take to turn over the motor, every one is different, there are too many factors (ring pack, valvesprings, rocker geometery, compression etc) that effect that.

All I can tell you is that 260* oil temp on a SB Chrysler is way way beyond normal, especially on a mild one like that.

I would run it with the water pump on & see what that does.

I agree with everything Ryan has said, did you say you are running that motor with over 100 lbs of oil pressure? If so that is way to much, take the oil pump off and inspect the oil pump bypass valve to see if it has the right bypass valve in it. It should have several holes in the side of the valve. I have had three oil pump from Melling in twenty years that had B-RB oil pump bypass valves in them, which makes the pump not able to bypass correctly like it should. That may be why your oil temps are way high like your getting. The first motor that I saw this on would blow the oil filter adapter gaskets out as soon as I rev the motor up and peg the 100 lb. gauge One of the motors was on a DTS engine dyno and it recorded 140 lbs of pressure at or around 1500 rpm to break the cam in, we shut it off after the second time of trying it and found the 440 bypass valve in that pump also Let us know what you find and do

We had high oil temp on the first small block w headed engine we built , 250f oil 150f water ,on breakin - we found the oil was dark and smelled burnt after the first few min at 3000 to 3500 no load , it turned out to be that all the holes in the rocker shafts were not drilled all the way thru ,almost trashed a new set of offset rockers, changed shafts and oil temp stayed under 200

the oil has absolutely perfect honey color! that and the nice water temp is why I was not too worried about the non-working oil temp probe during the first runs... which I heavily regret now!

we saw up to 90psi oil pressure with warm oil at 2500rpm... first oil adapter gasket blew when priming the motor. Thought I messed up, used another one, torqued it down a little harder, seals fine. Pump is a regular Melling

With the oil (I guess) over 300F, oil pressure at idle dropped down to 18 psi which I thought- not knowing the real oil temp- was still fine .

I will get back there on Monday, drain the oil and cut the oil filter open. If something is disintegrating in there there should be traces of bearing material or so...

Will check on the water flow too! We are aqctually measuring it, will monitor that flow too. The dyno cooling system can move up to 4000gallons / hour against >30psi backpressure.

if it is clean it has to survive another two of low load passes (up to 2500rpm, under 70lbft) before I tear in it. Thursday classes are done. I am monitoring oil now. Set up an auto shut off at 130C (266F). Hope I will not have a rod looking at me...

The rocker shafts are the hardchromed MP ones. deburred the oil holes (there were metal chips in there which annoyed me considering the price). One part I am worried about are my cheapo Ebay roller rockers. But as I said they seemed fine when I had the valve covers off.

Thanks for the knowhow. Any other ideas what to look for are very welcome.

I am a total rooky when it comes to American iron.

Pull th oil pump apart and check the bypass valve as I already suggested. I drill a smallhole in the little cup and use a sheet metal screw to thread into the drilled hole and then pull the cup out with a set of pleairs, claw hammer, anything that will pry the little cup out. Make sure and remove the cotter pin first. You can tig weld or braze the hole up and reuse the same cup if and when needed, the cotter pin will hold the cup in place. Most standard non high volume and or high pressure small block Mopar oil pumps struggle to make 55 lbs revved up with cold oil, check the bypass valve

thanks for the advise.
I definitely saw over 6bar ( 90psi) oil pressure sevral times at 2500. Thought that was fine. Will look for that on Monday!

Just wanted to give feedback!

The oil pump seemed the ticket here. Put in a new Melling (old one was a new Melling too..) and oil pressure is much lower, but stays stable at 4.8 bar (round 70psi).

Oil seemed slightly used, but no metal traces at all, also after letting it sit overnight. Oil filter the same, very clean. Much cleaner than I expected for a brand new rebuilt motor.

Oil temp seems much lower now. But need to get another probe tomorrow. Will report!
Did not disassemble the old oil pump yet... no time, just lot to do...

Just for info. Drag torque at WOT and 1500rpm is about 8Nm with warm oil and coolant... cast pistons with stock replacement type rings, 344 with 9.8 compression.

Thanks to all for the info. This was very helpful!