yet another oil pump / relief valve question

[Rigmaster]

So, I bought a '71 2002 ITB race car a couple of months ago. Haven't been able to get it on track yet, but I've been tinkering with it a bit.

Went out to start it up this afternoon, just to keep things working. Car starts fine, but since it has no choke plates (Weber 32/36) you have to feather the throttle when it first starts to keep it from stalling out. I was doing this today and the oil light came on, I quickly shut it down and looked under the hood to see a flood of oil on the floor!

I'm planning to change the filter and refill the oil and run the car again tomorrow. I've heard about the infamous "sticking pressure relief piston" for years and years, but it's never happened to me. I know Metric Mechanic sells (or used to sell) a "blueprinted" oil pump for M10's which is basically a new stock oil pump with a bronze sleeve in the body of the pump where the steel pressure relief piston fits. Last I saw on their site, it was ~$250, which is expensive, but not as much as a new OEM pump.

Just looking for options/ opinions here- I know you guys won't let me down!

[jimk]

Take you oil filter off. Bet the oring has blown. Put on a new, high quality filter.

[srnoncom]

Having just gone through the same situation with a new pump, and LOTS of research.....start with jim's recommendation.

Let us know

[merlin]

RIG your alive!!!!!!!

With as cold it has been that can cause a problem with the valve. It could be ice or oil as thick as well 20/50 racing. It could be a simple the cold and an seal. The only sure way to know is to replace it but thats PITA and some coin. I would wait for it to warm up and with a new filter try it again.

Sam

[Rigmaster]

Thanks guys for the replies.

I wasnt' planning on replacing the pump just for the heck of it, just looking for feedback before tearing into it.

My plan right now is to replace the filter, top off the oil, then run it and see what it does. I think the PO installed a WIX filter on there, not sure if that is good, bad or neutral in terms of an internal relief valve in the filter.

It was maybe 40-45 degrees today when I started the car, but I did have to blip the throttle a couple of times to keep the car from stalling out.

I was planning to add an oil pressure gauge to the car sometime anyway, but with this development, it's just been moved up on the list a bit.

Thanks!

[carlkkreienkamp]

40 to 50 deg. should not be a problem unless you are running single grade 50 wt.or so. Up north I run 20-50 or 10-40 and start up in 15-20 deg or lower weather all winter without a problem. As stated above oil filter ring likely is the culprit.

[c.d.iesel]

don't rev it so much untill the oil/coolent temps start

coming up! get BMW oil filters and be gentle on ALL

cold starts-ups. Install a 0 - 150 psi oil presure gauge.

[allbim]

You can just buy a new pump housing for less than $60. That's what usually wears and makes the relief valve plunger stick.

http://www.bmwmobiletradition-online.com/bmw/showparts.do?model=ST12&mospid=47140&btnr=11_2582&hg=11&fg=30

Edit: You may have to buy the inner rotor with the housing. I'm not sure I'm reading the catalog correctly. Still a lot cheaper than a whole new pump.

[jimk]

Incidently, the filter internal relief valve has nothing to do with high oil pressure. It's there just to avoid bursting the paper element inside. Excessive oil pressure is maintained by the pump relief valve, unless the oil is too thick for the relief valve to handle.

[Rigmaster]

Pulled old filter and installed a new one today, mopped up the spilled oil and topped off the oil in the crankcase.

Car started right up and no leaks at all!!!

WOOT!!!!!

Looks like the o-ring/gasket on the Wix filter had blown out, probably due to thick oil and cold temps.