oil pump problem

CLC85TA

CLC85TA

Forum Member
Well, the rear main of my 1 pc rear mained 350 popped out during break in, and oil was pissing out of the block. I'm running a melling high volume pump, it may or may not have the high pressure spring in it, but I have the other.

Just as a check before I pull the motor, I put a drill motor on it and spun the shaft at about 100-200 rpm, and it pegged my oil pressure gauge in the car (60psi). Isn't this like developing full oil pressure with the engine runnin at 400rpm?

I'm about to embark on pullin the engine tonight. Any thoughts on why the oil pressure builds so quick????

I was told by my uncle the relief piston in the pump may be in backwards, not causing it to open.
 
gauge was pegged as soon as the motor was running.... I'm using the same transducer and gauge that was in the car on the original motor, which worked a-ok when i yanked the 305 in november.

If this helps, with the coil wire off, it'll hold over 30 lbs while cranking on the starter.

While pulling the motor out, oil poured out of the rear of the engine when it tilted up. Time for a new r.m.s.
 
Where did u get the motor? I would check for blockages in the oil galleys..

Check all mains and see if one is dry compared to the rest, same with the rods. If you dont find anything then check the pump relief like you mentioned or change out the pump...

Whats the reason your running a high volume pump? If your not spinning the motor into th 8k range or have you bearing tolerances set really loose I'd just run a stock volume low pressure pump.. You only need about 60-65 psi on a street motor the might see 7 k here and there..

If you make move more volume than is need to keep the rotating parts suspended on then you end up loosing power due the huge load from the oil pump try to stuff all kinds of oil thru the galleys and bearings that it doest want to take..
 
Use a stock pump. It will be more than adequate. Think about the abuse that stock engines get & mileage with stock pumps. I have three chevy v8's with over 300k all using stock pump.
 
Ok, we (me and CLC85TA) swapped out the oil pump, pickup, oil, and filter this afternoon and the exact same shit is happening. Even with a drill the gauge is pegging out at over 60psi.

Right now it has a new pump, pickup, fresh oil, new oil filter, the bypass is working just fine, and the pressure sensor is working alright too.

It isn't a fauly sensor either because before when it happened it actually blew out the oil pan gasket.

Any ideas? We are thinking last fall when we build the motor a mud wasp plugged up an oil passage....

Thanks
Tom
 
100_0900.jpg

100_0902.jpg
 
Have the main bearings on right? the slotted ones go on the top? other way around would block all the oil passages.
 
I'd assume so. Victory Racing or Victory Engines did the maching and cam bearings. I'd fucking hope so from a place like that.
 
IS there not supposed to be some sort of check ball under the rear main cap that goes into a oil galley?? What kind of chevy v8 is it??
 
The block is a 86-88 casting GM 350 bored .030 over.

After clearing the head and getting away from it a while, it looks like the crank or rod throws hit the oil pan gasket and tore them clean off. There's no marks on the skirts of the block, and it sounded fine when running.

I'm going to hook a better pressure gauge to the motor some time this week and spin the pump again, hopefully it'll be in the 80psi range.

Anyone have access to an oil flow diagram for a gen 1, 1 piece rear main 350's oil flow paths? I'm wondering if I get flow to all the lifters, then would the main passages be clear?
 
When a gasket blows like that its usually due to high pressure. Not Oil pressure but crankcase pressure. oil pressure will feed, mains, cam, pushrods, etc. but will never feed to the pan. 1 of 2 things.

A) Your PCV system isnt sufficient enough (you're holding pressure in the crankcase)

or

B) You have major blow-by. What did you gap your rings at?

The first thing I would do is a Cylinder Leakdown test. That will show how much cylinder pressure is being vented into the crankcase. Do you have anymore pics of the setup while in the engine bay?
 
Slo_240sx said:
B) You have major blow-by. What did you gap your rings at?

The first thing I would do is a Cylinder Leakdown test. That will show how much cylinder pressure is being vented into the crankcase. Do you have anymore pics of the setup while in the engine bay?
Click to expand...

Right now in Ryan's car it's just a PCV valve plugging the hole in the valve cover. I don't have any pics of the set up but he might. I'm not sure of the piston/ring combo he has but the block is .030 over with .030 pistons and rings for the pistons.
 
You must log in or register to reply here.
Back
Top