M42 oil pump...WHICH way does it go back in???

[MikeDE]

I had everything laid out as it came out of the motor, but that was a month ago and I have since moved some things.

The outer rotor has some little square marks on it, i'm pretty sure that they were facing out tomards the oil pump cover when I took it out of the timing case.
The inner rotor has a lip on one side and is totally flat on the other....which side faces 'out' towards the oil pump cover????

EDIT-I'm pretty sure that the marks were on the same side when I took them out, but then again....

Help, I can go no further till I figure this out.

[Simon S]

Man - I wish I could be of better help..
I was totally in your shoes - (apart for some time, cleaned, etc.) forgot how it went back together.

Here's a pic:


Honestly, I can't say for certain if it's correct in that picture even.

Bottom line: to my great relief - I found that it only went back together one way. Basically keep trying to assemble it until it works out.

(again - I wish I could be more helpful here..)

[MikeDE]

NM- I just looked at the old and new pump side-by-side...

The new 'e36' pump, p#1432096, is about 1-2mm thicker than the old pump.

This is where it's making my head hurt...I have(all things being equal) an M44 front timing case, with an M42 oil pump(1714611)??!! The M44 oil pump(1432096) is physically too large to fit iunder the cover no matter how I put it in.

Does anyone know if the Euro E30(non-a/c) M42 had a different timing case(slider v. idler gear) than the US or British models????

EDIT-Looking thru Realoem @ E36 early and late M42's, it appears as if thru the luck of the draw, some had the later case and some had the earlier case.

Off to the dealer to order the early pump...damnit.

[Simon S]

Is there wear on the original pump parts? How do they fail?

For as simple as the design is (two gears with practically unwearable 'teeth') - I don't understand how the m42 oil pump mechanism is a weak point.

[MikeDE]

Is there wear on the original pump parts? How do they fail?

For as simple as the design is (two gears with practically unwearable 'teeth') - I don't understand how the m42 oil pump mechanism is a weak point.

I have read a few times that it is not the best design and has failed on quite a few motors, so for the price of 30euro & the case being off already, I don't mind swapping it out.

I will be holding onto all of the old parts incase I come across another m42 that needs anything.

[Simon S]

ah.
10-4

[Dj Buttchug]

fwiw the oil pump is very well designed. The problems comes from clearance issues between gear teeth within the mechanism itself. I cannot remember the exact numbers for checking clearance but some m42 engines that have been neglected (not changing oil) can have issues.

Excessive clearance causes low oil pressures and then you get to rebuild it :)

always a good idea to check this shit with a feeler gauge before you put it back in. Op if you need numbers pm me

[MikeDE]

fwiw the oil pump is very well designed. The problems comes from clearance issues between gear teeth within the mechanism itself. I cannot remember the exact numbers for checking clearance but some m42 engines that have been neglected (not changing oil) can have issues.

Excessive clearance causes low oil pressures and then you get to rebuild it :)

always a good idea to check this shit with a feeler gauge before you put it back in. Op if you need numbers pm me

Thanks dude, but I went to the dealer the same day and ordered the correct pump. It looks like this engine was taken care of BUT I have spent too much money as it is, and cannot afford nor do I have the patience to do this whole thing again if the pump goes bad.