son and I were wondering how hard it would be to change oil pump in a 1995 Z28. He is on leave for 20 days. We both heard you can change it from underneith without removing the engine just wondering if this is true also.

 

If you support the motor from above and drop the k-member, you could get to the pump that way.

 

Oil pumps VERY VERY rarely go bad, why do you want to change it??

 

That's one way..but all you need to do is jack the engine off the mounts to get the pan off...and the oil pump is right there...

 

I'm pretty sure that you can only do this with the 6-speeds, the auto's don't have the room to slide the pan out even with the motor jacked up all the way.

 

its the other way around A4 is easier then M6
although nearly impossible it can still be done on a M6

 

Just did this on my Z a couple months ago. LT1/A4. Support engine, take motor mount through bolts out. oil pan will come out. Will be easier if you support the engine from the top (cherry picker, hoist) so you can rotate the crankshaft to move the counterbalances out of the way. its a tight squeeze, but it is doable. Use some pb blaster or a good penetrant on the exhaust bolts a day or two before you attempt this if you have the time, it'll help get the y-pipe out of your way. Changed oil pump because the car had sat and the relief valve froze up resulting in about 100 psi oil pressure. Acutally a lot of room once you get under there and get things jacked up. Remove your oil level sensor before you attempt to drop the pan or it will break off. I swapped to a vortec truck pan I had layin around and did away with the sensor. Same pan, just no hole for the sensor. I ditched it because the sensors like to leak, and I check my oil, watch my gauges constantly.

 

On an A4, you remove the oilpan and the 2 motor mount bolts. Then hoist the motor up as high as it will go and remove the pan.

 

Could you explain a bit better, please? Remove the oil pan bolts? Then the motor mount bolts? What about the y-pipe? I have an off-road y-pipe, if that matters.
IDK, and I need to do this soon. Thanks.

 

Remove the starter, the Y-pipe, and the convertor cover.
Remove the oil pan bolts and nuts and the oil level sensor.
Remove the bolt attaching the oil level dip stick and pull the dip stick out and pull the tube up about 6 inches.
Remove the motor mount through bolts. and lift engine up off the mounts. Turn the crank arrow to the 12 o'clock position and wrestle the pan out....

It's as easy as that.....chuckle....and it's not all that easy.

 

Just get in there and it'll be obvious what all needs to come off. Don't forget to remove that low oil sensor, or you might break it. It takes some time but it's really not that bad.

The worst part by far is knowing that no matter what you do it's still going to leak oil for no apparent reason.

 

We think it needs to be changed because when the car warms up the oil pressure drops to zero but when you step on the gas it goes back up.

 

It is doubtful the oil pump is the problem. You are likely looking at something more.

How many miles on the engine?

 

I agree...it most likely isn't the oil pump. As you probably know, the cam bearing clearances 'set' the oil pressure. Low oil pressure at idle is probably a sign of a worn engine.

The rule of thumb for oil pressure in a Chev small block is 10 psi per 1,000 rpm. It's pretty common to see oil pressures of 5 psi at idle (dangerously close to the red zone) but it shouldn't fall to zero at any time.

If you have a lot of miles on the engine you might want to consider a rebuild