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Mon Feb 23, 2004 1:31 pm

Ok, here is some more information on my oil pressure issue, and thanks everyone for so far helping out:

It is a 2 liter type IV in a 914, age unknown to me, it came out of a car I recently got rid of, ran great powerwise, didn't burn oil, and is now going to be put in another 914. Compresion tested hot was 120 psi, even on all four. valves kept there adjustment between 3000 mile checks very well. use Mobil One 15-50 oil. Also had all stock cooling tin and seals in place

Only problem I noticed was low oil pressure when driven hard on the freeway. I'd get the point of getting worried at 30 psi at 3500 rpm. also had a unmarked oil temp gage, the stock type that reads from the bottom of the sump.

It appears from reading past posts, that I was getting the oil too hot, thus causing the pressure loss. To check my temps, I took a calibrated (calibrated by a friend at a NASA lab) thermal coulpe, and after a run in the car, stuck the TC wire downt he dipstick hole, all the way into the oil (which is pretty close to my dash gage sender in the sump). I then marked my dash gage with the readings I picked up from the calibrated TC in the dipstick hole.

What i found was my oil was getting at least as hot as 250F!, and it was only when my dash gage approached this number, did my oil pressure drop. When my oil temp was near 203F, or even as high as 234F, I did not have an oil pressure problem.

So I guess my real problem is oil temperature, anyone agree / disagree?

My iron pump, as far as i can tell is the bigger gear Type I pump (ie 30 mm gears, and according to posters on the list, is a melling brand. I have no idea if it is O-ringed in place, but can tell that the .004 inch gear top to cover distance is at the limit Bentley calls out for stock pumps (not counting the thin .004 papaer gasket). thus the pump is probably not a probelm here, right?

at any rate I need to determine why my oil temp is so high.

i think I should just go ahead and put the cover on the pump, and install the engine, and then add a head temp gage and see if there is a probelm there.

Before re-installing I want to re-oring the pushrod tubes, as they dripped a bit on the heat exhangers, and replace the crank seals, and oil cooler seals, just for good measure as engine is out of the car now. When i pulled the tin, I did find a small amount of leaves on some of the fins, and a little junk on the oil cooler, but it was very little, I cleaned that up, but do not think is was bad enought to cause oil temp problems (guessing less than 5% of oil cooler was blocked).

I have no idea of the engines compression ratio, but guess it is not way to high, as the compression test showed only 120 psi, and I do not have blowby, but this is not an absolute confirmation of that. (if compression test was 190 psi, I would figure it is a high compression engine)

also note that I have the stock distributor,(with a pertronix) and vacuum adv/retard works, and timing is set with a strobe as per factory, I believe it is 28 degress at 4000 rpm. Note I also once did try reducing the advance to about 24 degrees at 4000 rpm to see if it made a difference, and it did not change the oil temp gage reading. I also am running california 91 octane gas.

Maybe I will find a clog in the oil cooler gasket?
or maybe I will find once the engine is back in the car, a high head temp, indicating a problem, although I would be at loss to know what is causing it.

I assume if head temps are resonable, and oil temp is still to high (and pressure low when hot) I should add an auxilary cooler, but the question would remain, why is the stock cooler not enough?

any rate if anyone has some ideas, or suggestions, or thinks I am going about this right, or just plain going about it dead wrong, please let me know.

thanks in advance.

dave

Mon Feb 23, 2004 7:12 pm

The stock cooling system should be more than adequate on a stock engine, the temp you quote is equivilent to 120 deg Centigrade, this does seem a little high but not excessively high to me (the last type 4 engine I had ran at temps of 110 - 115 deg C - although I wouldn't vouch for the accuracy of the guage). It would touch 120 if I was pushing the engine hard.

My earlier quote on viscocity was incorrect, its the lower figure that is the viscocity for operating temperature :oops:

I would say that the alignment of the oil galleys as previously mentioned is probably ok as you have good pressure normally.

The operating temp range for mobil 1 is up to 400 deg C but I cant find at what temperature it reaches its thinnest viscocity, however I do know that Porsche, the same as VW only reccomend SAE 30 oil for the 914.

As timing doesnt seem to be the issue and the cooling system is in good order I'm still inclined to think that it may be due to the oil as I have experienced this problem before. The problem wasn't on a VW admittedly, it was on my Triumph, the engine was freshly built to a fairly high state of tune and wanting to use the best oil after all the hard work I'd put in I used Mobil 1 0-50 (the only grade that was available at the time) but it suffered exactly the same problem, in the end I had to switch back to mineral based oil to solve the problem.

It wont hurt to test this by running a fixed grade oil and seeing if it cures the problem, if only to eliminate it as not being the cause, if it does turn out to be the cause and you want to stick with running the thinner oil then I would say you need to change the oil pump for one with closer tolerances, extra cooling would help but its not really addressing the cause of the problem just the effect.

Have you tried posting this problem on shoptalkforums.com? they have a type 4 forum there, I think theres a few guys there running 914's they may be able to come up with a different angle.

Hope this is of some help.

Regards. Mick.

Thu Feb 26, 2004 8:13 am

Dave, had you had any more input into this problem? I'd be interrested to find out what solution you found.

Thu Feb 26, 2004 11:26 am

Mick, no new progress yet, but I will try to keep this list posted, thanks for your advice on this. engine is out fo the car right now, so it will be a while before I can re-test it.

I have a hand injury, so have been going slow, having friends help with this project. (difficult to even turn a wrench!) Hopefully not too much longer, and I'll get results.

dave

Thu Feb 26, 2004 5:29 pm

A thought that might help. A similar sort of temp thing came up on the bus line. Kind of out of my area of know how....

http://www.thesamba.com/vw/forum/viewtopic.php?t=63996

Is it possible that the vac retard on your distributor is not functioning correctly?

Fri Feb 27, 2004 11:27 am

Hope your hand gets better soon Dave.