Have cash, need help. Too much oil pressure - PeachParts Mercedes-Benz Forum

jasonleefreeman · #1 05-02-2006, 01:49 AM

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Please, anyone, I'm desperate. 8 weeks and I still aint got it figured out. 79 240d with way too much oil pressure. So much oil pressure that it keeps popping the o-ring out the side of the filter canister. I have changed the o ring, the filter, even changed the filter canister, all to no avail. Dropped the pan and checked the oil pressure relief valve, it's tweaked to the side (see picture), apperantly too much clearance between piston and cylinder. I put it back in it's place and it worked for a day, took the pan down again and i've got the same problem. If that valve sticks where the piston will not go back into the cylinder, is that too much or too little oil pressure? Is that likely the problem or is it a symptom of the problem? If that is the problem, does anyone know where I can buy just the valve or do I need a whole new pump? Anyone have valve or pump for sale? Got money that I'm ready to spend to get the car working again.

Thanks,

Jason

tram · #2 05-02-2006, 01:54 AM

Is there a possibility that your oil cooler or cooler lines are plugged/ kinked/ blocked? I'd look at this really closely.
I'd replace the entire pump with a new one. Cheap insurance!

thorsen · #3 05-02-2006, 08:45 AM

Did you replace the pressure relief valve?

Pete Burton · #4 05-02-2006, 08:59 AM

Start by replacing that valve with a new one.

jasonleefreeman · #5 05-02-2006, 11:13 AM

I have not yet changed the pressure relief valve, that is my next move, as soon as I get one. Does anyone know the mechanics of that valve? With it stuck in that position (see pic above) would it allow unlimited pressure? Someone has got to know how that valve operates. Everyones help is sure appreciated.

Thanks,
Jason

Pete Burton · #6 05-02-2006, 11:21 AM

Oil pressure overcomes the force of the spring, allowing oil flow through the valve, modulating pressure. When it's bent like yours, it doesn't do that anymore.

jasonleefreeman · #7 05-02-2006, 01:26 PM

Quote:

Originally Posted by Pete Burton

Oil pressure overcomes the force of the spring, allowing oil flow through the valve, modulating pressure. When it's bent like yours, it doesn't do that anymore.

so it allows unlimited flow by the oil pump, creating more pressure than the o-ring can handle?

P.E.Haiges · #8 05-02-2006, 03:42 PM

Jason,

The oil pump is a constant flow device proportional to speed so the oil pressure is determined by the resistance to the flow of the oil and the viscosity of the oil. If the resistance is very high such as a stuck relief valve the pressure will be very high.

U don't have to replace the oil pump, it ain't broken. Just replace the relief valve. This will fix your problem.

P E H

Hirnbeiss · #9 05-04-2006, 10:16 PM

And did it fix the problem?

barry123400 · #10 05-05-2006, 12:05 AM

It would pretty well have had to fix his problem other than the actual passage to the relief valve in the oil pump being obstructed somehow I believe.

Hirnbeiss · #11 05-05-2006, 07:15 AM

But perusing the archives shows that to be a fairly common problem with them. When cold, pressures can exceed 100 psi, which is beyond the normal trigger pressure of the relief valve. So if his managed to fail shut, a significant design failure - more typical of something designed by Yugo - then he could see downstream overpressure during routine operation (i.e.,cold startup).
Summary: I expect a new valve to solve his problem

jasonleefreeman · #12 02-14-2009, 07:27 PM

I know it's been forever since I had this problem, however, I notice that I never posted the end result. So that people reading this don't have to wonder, the new pressure relief valve fixed the problem. Again, thanks for all the help I got over two years ago.

Brian Carlton · #13 02-14-2009, 09:03 PM

Quote:

Originally Posted by jasonleefreeman

I know it's been forever since I had this problem, however, I notice that I never posted the end result. So that people reading this don't have to wonder, the new pressure relief valve fixed the problem. Again, thanks for all the help I got over two years ago.

Thanks for following up with the thread. All too often, folks fix their issue but do not return to the thread and let others know what transpired.

Charlie20 · #14 02-15-2009, 12:38 AM

That's really good advice you took. I drove for years with the oil pressure pretty much pegged during normal operation. Now I am overhauling the engine and discover that the intermediate gear set (that drives the oil pump, $$$) has the gear teeth chewed up pretty badly. I theorize that this is due to higher torque caused by delivering higher pressure.

captainmonk · #15 02-15-2009, 05:14 AM

oil pressure is always pegged when car is moving