Oil pump instal

[Grego]

Hello, great looking board! I am a new member.
I started instaling a new melling oil pump onto a 1994 Cherokee 4.0 block this morning. During a dry fit I noticed a wobble in the machining surfaces and got out my feeler gauges to measure. Checked the mounting surface of the pump with a machinist staight edge and this was nice and flat. The block on the other hand had a high spot center of the mounting bolt holes. Feeler gauge shows a .010 gap with the pump pressed down on one side, so a .005 high point in the center. The gasket that came with the pump is pretty thin around .0145, a felpro that I have is much thicker at .0275.
Has anyone else noticed this discrepancy on these blocks? With all the post on these boards about wacky oil pressure on the 4.0 I'm wondering if this could be a partial cause if the torque on these bolts is not correct. It appears that the oil discharge hole in the pump is centered on the high side of the block. I'm thinking about adding a .005" shim to the block surface at the bolt locations. Any thoughts?
Thanks, Greg.

[GoMopar440]

I believe that a member here reported a similar issue with the oil pump mounting surface. SilverXJ posted about it if I remember correctly. There was a machined ridge that interfered with the oil pump being able to sit flat against the block. I'll see if I can find the thread.

[GoMopar440]

Check this thread out. Particularly the 10th post down on page 25.
http://www.jeepstrokers.com/forum/viewt ... &start=360

Is this the problem you're running into?

[SilverXJ]

Yes, I have found this on a few different blocks, all 00-01s though. Both with the HV and non HV Melling. Don't bother messing with shims, just modify the little bit of the pump. See here: http://www.jeepstrokers.com/forum/viewt ... =34&t=2671

[Grego]

Good job on the right up Silverxj!
You are probably right about being a overlooked part of the job. I did find that bit of interference because that lip kept my bolt holes from perfectly lining up. I do however still have a high point in the block surface. I will try some plastic gauge around various points with the pump torques down to the block tomorrow, and really see what I have to work with.
Again, Great job!
Thanks, Greg.

[SilverXJ]

Is the high point in the spot I reference or someplace else?

[Grego]

It's someplace else. It is between the two threaded mounting pump holes, tapering back over the oil flow inlet hole. Hope this makes sense.
Greg.

[Grego]

One more question Silverxj,
I drew a file over the high area on the block to nock it down flush for the pump mounting. With the new screen mounted to the new pump I compared the new pump to the old with the screen still attached. The new is 1/8" higher than the old. The screen shaft is in as far as it will go. The pan is now not sitting flush. I do not want to try to tweak the screen at all to make fit in fear of loosing that seal, I would rather slightly modify the pan. As far as min and max clearance between the screen and pan is this measurement taken from the bottom of the screen tube or the screen itself? Right there is a 5/16" difference. Hope this makes sense.
Thanks for your time!
Greg

[SilverXJ]

You need to install/adjust the screen so you have clearance with the pan.

[Grego]

Thank you.
Greg.

[Retlaw01XJ]

I used blue Loklite on the pipe/pump junction as a sealer. Then checked pan fit- no good. I just rotated the pickup assembly in the pump a little which did the trick.

[Grego]

Thanks Walt!
Greg