Oil Cooler Bypass Valve- Cause of low oil pressure when car is warm?

[2Mitsus]

Well I just got back from taking it out for a drive (heavy abuse).

My oil pressure at very hot idle at 1k rpm is now about ~1.6, 1.7 bar, compared with 1/2 bar I was dealing with last week, at ~800 rpm (idiot oil light was flickering). When the oil pressure was that low last week, I immediately dropped the pan. No obstruction to oil pickup, other than a very small amount of permatex gasket shit on the screen, presumably from when i hammered out my oil pan last. Checked rod bearing clearances at that time, and all were well within spec, actually they were very well (#1 & #2 between .001 (.025) and .0015 (.038), and #3, #4, #5, and #6 were all exactly .001 (.025)). Mains werent plastigaged, they still all had the dull coating on them with very very little obvious wear. Thrusts looked great as well. My shortblock is about 1.5 - 2 years old, along with my oil pump. Great oil pressure when cold, which (to me at least anyway) rules out my oil pump. I put 2 tiny shims in my relief spring assembly, which helped oil pressure while cruising, especially when cold. But I was still getting low oil pressure at idle (barely 1 bar), after a spirited run. I use 15W50 Mobil1, so I felt my pressure should be better- my hot idle pressure has been slowly decreasing for approximately the past 6 months.

My oil cooler seems hotter to the touch now after driving it, then it was before.

Chris- you'd be surprised. On the valve itself, the lower portion (that expands and retracts), I could see discoloration on certain spots, like it hasn't been moving in a while. And the valve IS a simple design. A c-clip on top, the upper sealing portion, a spring, and the lower portion that expands and retracts. I removed all that crap, its now just the bolt itself with the main rod (which I may cut off).

Not saying this is everyones problem, but living in a place with 100 degree heat daily, this has helped me a little bit.

[TurboBob]

I was hoping someone would do this.

Keep us informed of how it works for you....

I wonder if a BAOC (Big Ass Oil Cooler) would help instead of the stocker (thinking the stocker might be getting restrictive in its old age......

Bob

[AdamVR4]

Andrew -- wow! That's great news. Would you suggest I try exactly what you have done thus far? Do you still feel as though you want to replace the valve? It sounds like removing the valve all together helped a LOT.

Good luck bro,
Adam

[2Mitsus]

Originally Posted by Multiades

The mechanism seemed pretty simple and fool-proof (if anything more foolproof than a coolant thermostat -- fewer parts).

you wouldn't even think of leaving a 10+ year old t stat in your car now, would you?

[bertz]

thats awesome andrew i'll be doing my valve later on today

[Dakken]

I just pulled the C-clip and removed the spring and other stuff on my bypass valve as well. It was a lot easier than I expected. I just have to remove the driver's front wheel, one splash panel, the acc. belt tentioner and then put a 1-1/16" deepwell socket on it to get the valve out.

Immediately it idled about 2 ticks higher while cold. I let the car idle with the AC on until my data logger showed 195 F. I looked at my oil guage and it was one full tick above where it was idling previously. I took the car for a spin. Unfortunately, I could not tell a difference in the oil pressure while cruising. It appeared to be at the same position as previously. My idle oil pressure stayed 1 tick higher than previously even after I did a 1-2 gear pull and then let it idle.

Sorry for just using my stock guage. I don't have an oil pressure guage and I don't plan on buying one. I just wanted to post my results to let you know that it did work for me. I have already ordered a new valve that will be going into my car with a new oil pump and rod bearings next month.

[doctorstupid]

ok, now i have removed and replaced my filter adaptor thingy, and i have absolutely no recollection of any such valve thingy. if we could get someone to post pics, this thread would be a lot more informative. i figure it's worth a shot

[Dakken]

It is #6 in the pic.

[doctorstupid]

ah, i see. now that i think about it, i remember. thanks

now this thread could be made even better with a somewhat stupid proof explanation of what exactly needs to be done.

if it can improve oil pressure (which it has shown it can), it's a totaly worthwhile thing to try.

[2Mitsus]

if anyone knows the readout on the GReddy oil pressure gauge, they can see my oil pressure now- gauge is the middle one on the center cluster. for anyone's information that might not know, 6 bar is straight up...
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