In-car oil pan R&R and bearing replacement?

Blazer406

Mechanical Engineer
Joined
May 2, 2002
Chasing a hot idle oil pressure issue... I'm looking into pulling the pan and plastigauge some bearings..... possibly rolling in some .001 bearings where needed. (Engine is a fresh build....only 1 hour or so of run time). Crank was used...std-std from a junkyard engine that I had polished...then new std bearings installed.

If the rods/mains clearance turned out to be .003... I could slide some .001 bearings in there with the engine still in car..

Anybody have any words of wisdom should I go that route?
 
could it be an oil filter housing to gear clearance issue ? much easier to check and correct. I believe it will give you the same symptoms
 
could it be an oil filter housing to gear clearance issue ? much easier to check and correct. I believe it will give you the same symptoms

I don't think so....it is a new melling HV kit with new plate...and gears....and spacer....with the end play set up....

I will do some checking.

I am going to put some 20W50 in it tonight to see what that does...

Hopefully I can get the hot idle oil pressure above 10 psi. Currently it is at 5 psi or so..... touch the throttle... and by 2000 RPM it is nearly 60 psi.... but the idle pressure stinks.

I guess I should add... cold idle pressure is 50-60 psi
 
?

Do you have a girdle on the eng? Do you have roller rockers? I have some coated STD. good for about.0005 tighter.
 
Really loose main and rod clearence's are not ideal but usually won't hurt idle pressure that bad when running a HV pump, I would look at cam bearing and lifter clearence for troubles if pump and crank check out adequate.

Kevin.
 
Do you have a girdle on the eng? Do you have roller rockers? I have some coated STD. good for about.0005 tighter.

No girdle.... only installed the billet mains (2 center).

T&D Roller rockers....

Tought about restricted pushrods.... might give some more volume available elsewhere....
 
Really loose main and rod clearence's are not ideal but usually won't hurt idle pressure that bad when running a HV pump, I would look at cam bearing and lifter clearence for troubles if pump and crank check out adequate.

Kevin.


Lifters are used stock 60 deg Chevy V6 hyd roller lifters.... bodies looked great...
 
Did you mic the journals before it was assembled? I'm assuming no. I've done what you are asking about and it can be done so if you are gonna pull the rod caps and mains to mic them not slapping in a new set of bearings would be foolish if you think the ones in there are suspect/too loose.
 
Did you mic the journals before it was assembled? I'm assuming no. I've done what you are asking about and it can be done so if you are gonna pull the rod caps and mains to mic them not slapping in a new set of bearings would be foolish if you think the ones in there are suspect/too loose.

I was talking about checking clearance with plastigauge from the bottom side... and see what it said. Then decide whether to install .001 undersize bearings or not.... or mix std and .001 bearings.

They were checked when the crank was polished....but I can't remember what they came to..... (was nearly a year ago.... just now got engine back in car) Seems like it (the rod and main bearing clearance) was supposed to be around .002 or slightly under when the engine was assembled.

FWIW I wouldn't ever install undersize bearings of any sort in an engine without checking clearance.
 
Sound like you did a nice build there, If it were me I would pull the intake and use a priming tool with clean oil, spin the pump to get a "birds eye" view of oiling, I realise you can't see everything but you may "hear"where the leak is coming from for further inspection taking note of pressures as you work the pump and maybe even heating the oil somehow to duplicate running viscosity, unless a good sized leak is found, the pump/cover may have crack in a passage that leaks when hot(expansion problem). Good luck.

Kevin.
 
To clarify what I meant: If you are going to drop the pan to plasticgauge the rods and mains it would be foolish to not have the .001 bearings right there waiting to go in if you find that any of the clearances iare to loose.

I never thought that you'd pop in tighter bearings without checking the clearances. I have changed rod bearings with the engine still in the car on more occassions than I care to remember. I had a crank with a slight score on two rod journals. Every time I'd go racing I'd have to drop the pan and pop in two new rod bearings afterward so that I could daily drive the car. The scoring on the crank was so minor that the normal stresses of daily driving wouldn't wear the bearing BUT the more extreme pressures of racing would somethimes get down to the copper.
 
I have not had experince with building turbo buick engines but I have had problems with mellings pumps in small block chevy engines, that caused low oil pressure. me and my dad quit using mellings pumps because of that.
 
To clarify what I meant: If you are going to drop the pan to plasticgauge the rods and mains it would be foolish to not have the .001 bearings right there waiting to go in if you find that any of the clearances iare to loose.

I never thought that you'd pop in tighter bearings without checking the clearances. I have changed rod bearings with the engine still in the car on more occassions than I care to remember. I had a crank with a slight score on two rod journals. Every time I'd go racing I'd have to drop the pan and pop in two new rod bearings afterward so that I could daily drive the car. The scoring on the crank was so minor that the normal stresses of daily driving wouldn't wear the bearing BUT the more extreme pressures of racing would somethimes get down to the copper.

No harm done.... just didn't want anyone to think I might do such a thing..... :)

It might be a mute point.....I'm going to try the 20W50 oil this evening... if it gives decent oil pressure idling.... I will drive is and break it in and keep a close watch.

Someone else on a PM pointed out my fans aren't coming on like they should (they don't turn on until 205 deg).... even thought DS shows they should be on...... once I track that down.... the "hot" oil pressure might be at 170 deg.... which might still be 20 psi. Seems the oil is much thinner at 205 deg than it is at 170...... might be my imagination.....
 
do you have an oil cooler on the car???

No...

The plan is to eventually after a few thousand miles.... and the rings get seated... to transition over to full synthetic. I don't want to risk any oil coke on the turbo bearings.... or worse... oil breakdown from extreme temps. Also... IMHO.... oil viscosities for full synthetic oils are much more stable at various engine temperatures.... as compared to regular dino oil....

As an update.... the 20W50 oil went in last night... and I got the fans to cut on via the ECM signal (relay connector had come loose)..... and now the hot idle oil pressure is around 20 psi.... or slightly less......and the engine maintained 175 deg or less... definately headed in the right direction.

I am going to try the mods Lee suggested (looking back it was in another thread) about jbwelding up the oil hole in the rockers and re-drilling out to .030" ..... to restrict some of the top end oil.....
 
cant hurt to throw a cooler on it real quick i know plenty do not run one but i have always run one...
 
You can drop the pan, replace the mains and rods with the engine in the car. Plastigage isn't the best way to measure bearing clearance, but in the car, it is your only alterative.

FM or Clevite makes .001 OS rod and main bearings. I like FM for the main brgs.

Tip: Do the mains first......and, when you plastigage the mains, support the crank on both ends with a jackstand or floorjack. If you overlook this step, the weight of the crank will distort the plastigage readings.

Take your time and measure carefully. You can probably fix the low pressure problem this way. You really should have done this before you ever installed the engine, but it can be corrected in the car.

Dave
 
No...

The plan is to eventually after a few thousand miles.... and the rings get seated... to transition over to full synthetic. I don't want to risk any oil coke on the turbo bearings.... or worse... oil breakdown from extreme temps. Also... IMHO.... oil viscosities for full synthetic oils are much more stable at various engine temperatures.... as compared to regular dino oil....

As an update.... the 20W50 oil went in last night... and I got the fans to cut on via the ECM signal (relay connector had come loose)..... and now the hot idle oil pressure is around 20 psi.... or slightly less......and the engine maintained 175 deg or less... definately headed in the right direction.

I am going to try the mods Lee suggested (looking back it was in another thread) about jbwelding up the oil hole in the rockers and re-drilling out to .030" ..... to restrict some of the top end oil.....

Sounds like its fine for now. Remember to seat rings you need some boost! Not a lot but 5lbs in quick blasts & the rings are seated in the first 50 miles but they need that boost so dont baby it! Worst thing you can do.
 
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