jeremyhurt

I have a 1996 Z with a LT1-350 6 speed.

I just pulled the engine this weekend after working about 8 hours trying to get the oil pan off. I probably could have pulled the transmission alone, but I went ahead and pulled the engine. I figure I can at least put the engine on a stand and clean it up.

Just thinking through the remainder of my project and curious of what I should probably do. Should I change anything else other than the oil pump now that I am inside the engine? I really don't want to spend ALOT of money, but what do you folks recommend since I got the engine out?

Rings? Bearings?

Any tips or advise is appreciated...

96capricemgr

Why would you change the oilpump?

The oilpump does not wear out and the stock oilpump is very reliable and definitely sufficient.

jeremyhurt

I had no oil pressure.

I had a local mechanic look at the car and he said it could be:

Oil Filter...
Oil Pump...

If its not one of these, may need a rebuild.


What are you thinking it could be?

Mystery Bird

Was that no oil pressure verified with mechanical pressure gauge or just going of the electric pressure switch and gauge in the car?

jeremyhurt

When the car pulled up at the garage, they made a comment by listening to it, that it sounded like it had no oil pressure. I'm not sure if they used a mechanical gauge or not. My brother had them look at it. They looked over the car and checked a few things and said what it could be.

Its not getting oil to the valves, the roller rockers are screaming. Maybe they are wrong, but either way the motor is out of the car lol. Assuming there is no oil pressure. I am going check the pickup tube and put a new pump on it. Id like to fix anything that I can without doing a rebuild while the engine is out. What worries me is that I have only had the car for about 160 of the 120,000 miles it has on it, therefore I don't know what kind of torture it has been subject to.

96capricemgr

Even if the pickup falls off they generally still have pressure at idle.

true no pressure is almost always either bearings so far gone they don't restrict flow enough to build pressure, or the oilpump drive got damaged/eaten up. The oilpump drive issues are usually caused by either buying a cam from a second rate hack that didn't get one with the right gear and was incompatible or someone putting a HV pump in stressing it too much and wearing it out.

If a mechanic told you the oilpump went out you probably need to stop trusting him. The oilpumps do not fail, on rare occasions a pickup tube will fall out and it will cause some low oil pressure conditions under acceleration/braking or high rpms but even this is rare and is not the pump itself failing.
If the engine was run long enough like this for things to get noisy I would expect substantial damage beyond whatever the initial problem was.

jeremyhurt

Ok... cool

Oil Pump = Pull Engine
Oil Pump Pickup= Pull Engine
Oil Pump Drive = Pull Engine


Might as well change main bearings, rod bearings, and rings since the engine is out. Wouldn't you think?

96capricemgr

Actually the oilpump drive is in the lifter valley so it just requires the intake to be pulled.

I would advise more diagnosis before anything else.

Mystery Bird

If the engine truley had no oil pressure it's toast and frankly suprised it didn't sieze up. I would have verified oil pressure with a mechanical gauge before tearing the engine out. Those pressure switches that control the gauge inside the car have diaphrams in them that wear out over time and can cause no oil pressure to register. 120,000 miles isnt' much for an LT1.

96capricemgr

mileage is not bad but people do such stupid things to cars and who knows what was done wrong before he bought it.

jeremyhurt

maybe its not the oil pump...

I just feel like i should change all the parts I can easily get to while the motor is out.

96capricemgr

The thing is the cheaper aftermarket oilpumps have had some cracking problems starting a few years ago. So when folks blindly have to replace perfectly good stock stuff they often put JUNK in it's place.

Stock stuff in meant for long warranties and 200k+mile service life, aftermarket stuff is not always designed to do anything more than take your money.

bw_hunter

If you do this also change the cam bearings. You're talking a total tear down to do this. If the bore looks and measures good and the piston ring lands and skirts look good, put a set of stock rings back in.....

rat's nest Z-28

I had the same problem at about the same mileage (no oil pressure at idle). except I had no noises. When I disassembled my engine & inspected the bearings they were worn out. I ended up changing all the bearings (main, rod & cam). I also honed the cylinders & re-ringed the pistons. Don't forget to replace the rear main seal & damper seal. You won't want to re-install your engine only to have it leak...

jeremyhurt

Just to follow up....

It wasn't the oil pump but it was the oil pump drive gear. P/N 1103868, that cost $93.00 LOL.. The Oil pump and shaft both appear to be relatively new. Anyone know where you can buy that drive gear for cheaper than straight from GM?