Has anyone seen this oil pump failure? (Pressure relief spring)

[nickanicus]

Background is that I purchased this M52 for a swap in my 88' and have been disassembling it in order to check components and make sure that I'll have a problem free engine once in the car. I was pulling the pan off to swap on the E34 replacement, and I was surprised to find that the oil pump pressure relief spring sticking out of the side of the pump. Obviously, this caused a low pressure scenario.



Has anyone seen this failure before? The retaining "cap" that puts pressure on the spring decided to break and the spring was just hanging out the side. Any thoughts on why this might have happened? This motor has 83k. I would have thought that BMW would make such a critical part out of metal... I'm baffled.

I ordered replacement parts and have plastigaged the rod/main bearings. Tolerances look good (.0015"), and the crank shows no wear. The bearings do show wear and are being replaced.



Any advice/comments?

[dirty30]

When I put my brothers S52 together we got all new parts for the relief valve and pump.

Here are the numbers:

07119934625 circlip
11411722836 cap
11411722837 o-ring
11411706809 spring
11411719937 piston
11411748100 outer rotor
11411748098 inner rotor
07119905857 reverse thread nut

I'd say as long as there isn't any obvious signs of wear or shavings in the oil pump body then just replace the guts and you should be fine. My brothers S52 made great pressure at idle/ high RPM. Just my 2 cents.