theiceman

You also may want to consider putting a mechanical oil pressure gage in and see what it reads.
Obviously not to many guys chiming in here. May want to try pelican

Ed Hughes

I'd replace t-stat, check oil lines, etc, to make sure you have good flow. The pressure, is still the big concern.

Ed Hughes

One other thing-make sure the oil cooler and cylinder fins aren't all plugged. Seems you mentioned it's been sitting, maybe pull the fan to see if rodents didn't build a nest in there or something. The heat could be accounting for some of the low pressure.

The other question I have, is are you driving it and seeing that temp? If it idles for an extended period, it's gonna get a bit warm.

rusnak

If the T-stat is bad, that might shut oil pressure back away from the cooler. I think it's worth looking at now that the oil is at baseline. What kind of oil filter are you using?

joes911s

Mann filter. Where is tstat in the motors with internal oil cooler? js

rusnak

the thermostat is on the top of the block, on the right hand side, next to the oil breather hose for the crankcase. The thermostat is designed to not let oil circulate in the engine oil cooler until the oil is warm. It opens up, allowing oil to flow to the cooler. But even cold oil will show much higher pressure than you have.


When you start it up, what pressure do you see?

rusnak

ok, I see 3.5 bar at cold start up. That's normal. Then it drops as the oil gets hot. You might only have a bad thermostat. To check it, you can use a calibrated pot of oil on a stove with a thermostat in it. You should see it open by 180F and fully open at 210~240F.

I don't know if you need to drop the engine to get to the thermostat on your car.

rusnak

Here's a nice article written by Chuck Moreland, owner of Elephant Racing.

It explains the function of motor oil, and the relation of temperature to viscosity, and the effect on engine life.

http://www.elephantracing.com/techto...emperature.htm

theiceman

Check both parts 28 and 34
If you have a broken spring you will have low oil pressure as it will all bypass.

ron mcatee

I suggest you install a Carrera oil cooler with a fan. If you do go to a Carrera cooler, you will need to install a switch. I suggest the following procedures I found on www.rennlist.com several years ago. They reduced the oil temps on my 88 Carrera by almost 35 degrees. The 99 degree celcius thermostat keeps the oil at 210 degrees even running the engine hard.

"1988 Carrera oil cooler 244 F thermo-switch replacement with a lower temp one"

The factory thermo-switch mounted on the Carrera oil cooler on my 88 Carrera was rated at 244 F. I obtained the info on putting a lower temp unit in from a Rennlister. It was about using a BMW radiator auxiliary fan switch that worked very well for him. I bought one from Pelican and put it in the car. The factory wiring harness has a single wire with a round spade type connector going to the single pole thermo-switch. I cut the factory wiring with a single pole end and soldered on a flat spade connector. The BMW auxiliary fan switch is for E-30 series cars from 1984- August 1987, specifically 325e/es//i/es/iC cars. It is a two prong, Red Top, 99 degree Celsius switch (equates to 210.8 F) made by FAE, P/N 61-31-1-364-273-M323 and costs $13.75 from Pelican. Your local BMW dealer may have one, but cost may be higher. Autozone has them listed as P/N SW572 and cost $16.99. It is a special order item at both places. www.Pelicanparts.com usually has them in stock.

You have to remove the flex lines attached to the oil cooler and the hard lines. Be careful when loosening the mounting bolts on the oil cooler. There is a lot of oil in there and any movement will cause it to spill on you. Once you have enough oil out of the cooler to remove it, carefully lower the cooler to the ground and dump the rest of the oil out of the cooler into a drain pan. Then remove the factory switch from the cooler. Cut and install a flat spade female connector because the BMW part has two male connectors on it . Install the BMW switch with a new gasket and tighten. It doesn’t matter which male connector you plug the wire onto. You then need to make a ground wire that will connect to the other male spade on the switch. I used brown wire just like the factory so there is no doubt as to what it is for. I made my ground wire about 8” long and put a female connector on one end and a connector with an eyelet on the other end. How long you make the ground wire is up to you. Make sure the eyelet is big enough to have a 10mm head bolt go through it, because on top of the oil cooler beside the new switch there is a 10mm head bolt you can use to mount the ground wire. Once all the electrical is done, replace the foam rubber seal (P/N 930-207-353-00) that mounts to the protective stone guard. Remount the cooler, reinstall the flex lines, and start the car and let it come up to operating temperature. Once the hard lines get hot, check for any leaks at the flex and hard lines. If you need to change the flex lines, now’s the time to do it. If no leaks are detected, let the engine run and monitor the heat gauge in the car. Make note of the temperature when the oil cooler fan motor comes on. Depending on gauge calibrations, it should come on at about 210-215 F. I wanted my hook-up to be automatic so that’s why I did mine this way. Hope this helps explain what I did.

race911

Guess my post #12 was invisible.......... Only had my hands in 100+ 2.7s that failed in various ways back in the '80s and '90s, plus the engines we managed to keep running as the owners kicked the can down the road.

Again, it's normal at 250F to be near zero at idle, coming up to barely adequate at 2500-3000 RPM going-down-the-road speeds. 30 minutes of freeway driving at 80F will get you into that range. Now if you're up in the Frozen Tundra with this happening, yeah look at the engine mounted thermostat and oil cooler.

So yeah, a front cooler is a necessity. And that's just the beginning of the expenses for even elementary track-worthy preparation.

theiceman

i think we read your post Ken, but what wasnt clear was if they were coming through your shop because they were frapped out and needed fixing, or if they were going out that way because it was normal

MrBonus

I can't see the post above theiceman's or #12. Strange.

theiceman

post 12 for Ian....

Pretty typical of what used to come through the shop for cars of that era.

And you want to run a 2.7L car on track????? Planning on having as much tied up in it as you've got in the 997?

joes911s

Ken, thank you for your input. By "track?" I meant a few DE's a year and thats iffy it is going to explode. I thought you may have understood my intentions as real racing and therefore ceritifiable nuts for starting with a 76 model.

Based on your experience I can accept the low pressure as being a function of high temp but all the oil engineeering reports seem to warn of exceeding 230 F. I am in Alabama thus am projecting trouble for the upcoming summer months. AC belt removed long ago and I think I can guess why.

Is there an alternative opening temp for the internal oil tstats? I don't see a posted deg f on the parts catalogs but if I could see it openings at 9 o'clock in lieue of 10:30 I'd sure feel better.

Your description of the oil pressure being "just barely enough" at highway speerd/rpm is accurate.

Anyway, I want to be proactive in improving my chances of not becoming another "engine rebuild in progress" thread any sooner than I must. js