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

[doctorstupid]

tomorrow i'll take my valve apart (its just sitting on a shelf in the garage right now) and post some pics. 2mitsus gave me a pretty good idea of what i'm going for, so i think i can figure it out pretty quickly.

[Blue94VR4]

Can someone post intsructions on how to remove this valve? I saw one post where it was done by removing ac tensioner. Is there a way to do it w/o touching any belts?

Thanks

[erikgross]

I'm a little late on this thread, but...

I have both an aftermarket oil pressure gauge and an aftermarket oil temp gauge. I have both analog and digital readouts with peak hold and record/playback capabilities. I've recorded temps and pressures under various conditions and kept an eye on things. I have my low-pressure warning light set to come on at 1.09bar, and I've only seen it go off a couple times in the last year. Both times it was above 1.0bar, though.

As best as I can tell, my oil cooler bypass valve opens at 90C (194F) because once the oil temp rises above that number, it never falls below it. One exception is coasting down a looooong hill at 70mph while in gear (injectors off, engine just pumping air), I saw it get down to 88C. This is the same behavior I see for my coolant temperature, except that the thermostat for the coolant is set at 80C. Once warm, my coolant never drops below 80C by more than a couple degrees unless I turn the engine off.

My typical warm oil pressure is around 1.3-1.4bar at 90C at 800RPM, with it occasionally getting down to 1.1 or 1.2 when the temp is above 100C and my idle drops down toward 700 or so. The highest I've ever seen my oil temp is in the mid 130s (275F ish) and that was when I was driving between 4000 and 7000RPM in 2nd gear up Mt. St. Helens switchbacks for about 15 minutes straight. I put it in 3rd after that and things calmed down

For reference, my car is a '95 VR-4 with 76,xxx miles and it's on the original engine, oil pump, oil cooler, most of the other "big" engine stuff. My gauges are the Defi-Link variety. If there's any other information anybody would like as far as temp/pressure data, ask away and I'll try to get an answer. If it's of any use, you can see my typical/extreme temp and pressure data for a 20min road course session on my web page - look at the bottom of this URL:
http://www.team3s.com/~egross/Events...923/index.html

--Erik

[lethal_vr4]

Erik,
Care to take some number for us with the valve removed... sounds like it might pan out.

[erikgross]

Originally Posted by lethal_vr4

Erik,
Care to take some number for us with the valve removed... sounds like it might pan out.

From the diagram posted in this thread, is the valve #6? And when you mention removing the valve, won't this leave a hole that needs to be plugged? I haven't looked at the valve or housing in detail, so I'm not sure what exactly is entailed in removing the valve and then operating the car.

I probably won't have time to do any modifications to the car that take more than a half hour for the next 3 weeks. Rallycross this weekend, autocross next weekend, and road course day the following weekend If it's just a matter of driving the car and getting some readings at this point, I can do that easily pretty much any time.

--Erik

[Dakken]

Originally Posted by Blue94VR4

Can someone post intsructions on how to remove this valve? I saw one post where it was done by removing ac tensioner. Is there a way to do it w/o touching any belts?

Thanks

It may be possible to remove it with the tensioner on but it would be a major PITA. A 8" cressant wrench won't fit on the valve, I tried. It is 1-1/16" (I made a typo error when I said 11/16") which is pretty dang big. If you have a wrench that big, then you still will have very little room to turn the valve, maybe 30 degrees of rotation max. Even if you can loosen the valve up all the way, there may not be enough room to take it out. In that case you have to take the tensioner off anyway.

Trust me, taking the tensioner off is a peice of cake. Just loosen the pully, lower it down some, then take the pulley completely off. Then it just takes 3 12mm bolts and off it comes. Doing it any other way would take much too long.

[doctorstupid]

i didn't get a chance to crack my valve open today, worked from 1pm to just now (with a 2 hour break for a barbecue ) on my talon tsi (i'm really starting to loathe that car, this is the third time i've had to drop and work on the tranny in less than 2 months, and i swaer to god if it doesn't have second gear this time i will run at the nearest living thing and kill it ). and tomorrow i'm doing a tranny swap on some honda shit-box all day. if i have a chance once i get home i'll give that valve hell

[Blue94VR4]

Originally Posted by Dakken

Trust me, taking the tensioner off is a peice of cake. Just loosen the pully, lower it down some, then take the pulley completely off. Then it just takes 3 12mm bolts and off it comes. Doing it any other way would take much too long.

Thanks,

I know I can take it off, I just don't know how to put it back on How you you adjust the tension of the belt when you put it back on?

[Dakken]

Originally Posted by Blue94VR4

Thanks,

I know I can take it off, I just don't know how to put it back on How you you adjust the tension of the belt when you put it back on?

I know the service manual says to go by a specific pound of resistance in the belt. I don't have the special tool to measure it so I did it the old fashioned way.

I started with the belt loose but not slipping at idle. Then I turned on the AC and headlights. If it slipped then I turned off the engine and tightened it. Repeat until it stops slipping. Then I would turn on the AC, headlights and rev the engine. If the belt didn't slip then I had it just right. If it slipped, then I tightened it a little more. Repeat until it stops slipping. It is much quicker than it sounds. I can get the belt adjusted right in about 5 minutes.

[Toni]

wouldn't relocating the oil cooler help in oil pressures as well? IE removing from the heat soaked area behind the IC and in front of the plastic fender piece? I mean what if the valve is working fine, and it cools the oil, but it will only be to a certain point. Then when you stop there is no more fresh air coming in that area so it will be warmer at idle then at cruise. It would be nice to put a temp sensor in that general area and really see what the air temp is at certain points, heck stick it right on cooler and see when the oil does actually come into the cooler. Any thoughts?