Oil pump question.

[FSJunkie]

A feeler gauge for the gear side clearance to the housing will tell you if you need to replace the cover or not.

Buick V8s and V6s use this exact same oil pump design, only their oil pumps are smaller. The AMC oil pump actually has pretty high capacity compared to the Buicks. The AMC 258's starting in the early 1980s switched to an aluminum oil pump housing too. They were cast iron before that.


Aluminum oil pump housings with steel gears don't actually wear out that fast so long as the oil is clean. The steel gears are not what wears the housing. The steel gears grinding dirt and contamination into the aluminum housing is what destroys the housing. They just are not as durable.

[Full Size Jeeper]

Thanks Ristow and babywag, I'am going to try and finish it tonight.

[babywag]

When I re-did my cover it wasn't flat either.
Lapping it made it much better, it takes a while but made a HUGE difference in hot oil pressure on mine.
I used a really long file and after a few swipes it was ready for lapping.

[Ristow]

lap the cover till the tolerance is nil,but the gears turn freely. it will increase as it heats up. i just do mine feel. if it's off the engine,yes i would work till i can;t feel any clearance but the gears turn freely.

[Full Size Jeeper]

So, should I lap the timing cover side to try and tighten up the clearance a little. The TSM say 2 to 8 thousands is spec, but .002 is preferred. Also I will never be able to get rid of the .002 difference between the gears.

[Full Size Jeeper]

So to my thinking, the timing cover mating surface is not flat or the top surface where the gears sit is worn, the drive gear side is more worn than the driven gear side by .002. Also the gears to cover has some grooving, but the thickest feeler gauge I can insert is .003 on either side. So with that said, do I have A usable cover? Thanks in advance.

[Full Size Jeeper]

Driven gear is at .004

[Full Size Jeeper]

Here is the plastigage. Drive gear is at .006

[Full Size Jeeper]

After.

[Full Size Jeeper]

Before.

[Full Size Jeeper]

Took about an hour and a half to get it good enough for me.

[Full Size Jeeper]

Okay, worked on the oil pump end cover, used a piece of glass and valve lapping compound.

[Ristow]

never silicone. i use aerosol copper coat there if at all.

[Full Size Jeeper]

Thanks for the reply's. I will skip the mid plate, some sort of sealer was used on the gasket. I will check the clearance and ask a few more question later. Also had no oil pressure problems the year and a half I drove it.

[440sixpack]

I've seen worse. whatever you do don't try to smooth it up all that does is increase the tolerances.

The mid plate can be replaced, or don't use it if your adapter plate is in good shape.


Hard tell how bad your cover is by a picture but if it's decent I'd rather use it than a Chinese reproduction.