machine shop question 3.1 gm

I've got a 96 Monte Carlo with a 3.1 v6.
I just replaced the crankshaft and bearings and now have little to no oil presssure. It wasn't like that before i did the crankshaft.
I primed the pump and filter and still nothing.
Valve train very loud and after a minute the oil light comes on.

In the rear main seal kit, there was an o'ring that i never found a place for.
Could this be my problem??

Probably not. Change the oil filter again before going any further.

Was the oil pump replaced?

It's hard to tell what your problem is, but I would suspect loose clearances with your new crankshaft and bearings. Did you (or whoever assembled your engine) check the bearing clearance with plastigauge?

What other work was done with the new crankshaft?

And why did you replace the crank+bearings in the first place? What was your origional problem?

It's not a new pump. Should have replaced it but I didn't.

I bought the car from a guy that replaced his own intake gaskets. After he was done, the motor had a slight rod knock on start up. So the car sat for 4 years and then I bought the problem .

I figured throwing in a reman. crank and bearings would have solved my problem. Guess Not!

I asked the part store about plasticgage and they told me it wasn't needed. Everything is machined to spec.

Anyways; after completing the job the first time,
I removed the oil pan and the oil pump again to check and see what I missed. Nothing, everything looks fine. Just wasn't sure about that O'ring.

Is there a recessed hole where an O ring can go? Maybe above the top half of the bearing in the block side? Or oil pump drive ? but why now?

Off the top of my head, an O-ring would be for either a crank sensor in the block, or the oil pump drive at the back of the motor (where there would be a distributor on older engines). Depends how big the o-ring is. The O-ring is not your oil pressure problem, unless it's stuck in the pump. For $50, i would have replaced the pump, but that is probably not your problem.

Remove the oil pump drive at the rear of the engine and inspect it. Make sure the gear is good, and also with a flashlight look down the hole and make sure the gear on the cam is good.

Thanks a lot
I'll remove the oil pump drive tomarrow and let you know what I find.

I forgot to mention
that the O ring is one half an inch in diam.

Injector o-ring maybe?

Is this an extra o-ring from a gasket kit? If so, then forget about it - they always have extra's.

How much main clearance is there? Even an old pump should do fine unless it was worn/shot from the water in it. It does seem like the original problem that made the rod knock is still present. It could be many things, wear, blockage,internal leak,missing plug, wide clearance, ect.

Pulled the oil pan today and replaced the oilpump.
Nothing changed.

I also pulled out the oil pump drive and spun the oil shaft to prime pump.
Had lots of oil pressure there, but still none at the cam or rocker arms.

Has to be the wrong crank. going to try to pull the motor tomarrow.
I guess before I pull out the crank I should plastigage it ?

Or maybe I should just take it back to the part store and do some bitchen.
I might get my money back. Then I can get my crank done and get bearings to match.

I'd take one cap off, verify the upper main bearing is in the correct spot and plastigage that cap.

I agree. Before you pull the CRANKSHAFT (you keep calling it crack lol), go ahead and pull one main cap off and use the plastigage to determine if your bearing tolerances are good or not.

If they are within spec, then your problem lies elsewhere. If they are too loose, then you can return your crank and start bitchin.

Sorry, don't know why I'm on crack. Brain fart I guess.

I think it's possible, that they could have boxed the wrong crankshaft.

The car only has 51,000 miles on it. And the old bearings weren't spun out.
Just a little worn .

Pulled the motor out today. removed the crank and everything is just the way it should be. Plastigaged all 4 mains and all 6 rods. There all within spec.
I first blew out the oil passages with compressed air and they were good. then I used the oil gun and shot oil through them. Oil came through the front cam bearing.
I guess I won't know anything until I get it back in the car.

It is best to trace out the flow of oil before r&r engine again. It seems that unless it is found/fixed then it is bound to repeat the trouble.

As long as the engine is out try to spin pump with drill, if there's resistance then we can assume there's oil pressure. From there try to trace out the path from mains, rods, passages,camshaft,oil pressure port, top end,ect.

Many times the pressure can be checked in a different spot and when engine is out with a drill spinning the pump the problem can be heard or seen much easier than when in car running. I'm not sure how this engine is laid out , but some popular things may be front galley plugs, no groove in upper main shells, bearing hole in wrong spot, cam bearing hole not lined up, head gasket installed wrong or wrong gasket if oil goes thru the gasket, rocker shafts on backwards, ect.

Thanks 534bc, But too late.Engine back in the car .

This time cam and lifters are nice and quiet. But still , I've only got 15 psi @ idle with cooling fans on and in gear. Oil light flashes dimmly.

Bearings are definately in correct. One thing I question; is there some kind of sealant on the main cap that supports the oil pump? Between the cap and the block : for the oil passage.

Car runs great. Maybe it just needs a sending unit?

I use rtv on all oil sealed surfaces such as that cap. Many do not use anything.