Mike Murphy

All 4 oil lines should be HOT (you could burn your fingers) when your gauges indicates anything much over 200-210 or so. If not, then replace the plunger guts or entire thermostat.

JackOlsen

250 is abslutely too hot. It has less to do with oil as much as engine seals and other components.

I'd want to see if your external thermostat is opening fully (you can test it in boiling water, once it's removed). Before you do that, though, check for pinches or kinks in the lines that run to and from the fender cooler. Some shops will put the car on a lift and damage those lines.

Peter Zimmermann

tone: The front lines, above/behind the front tire, should get hot enough to quickly cause pain! If not, the thermostat that allows oil to flow forward isn't opening properly...

Edward

I did the cheap-but-effective DIY method: I went to Home Depot and got sheet metal and dense closed-cell foam (for pipes). I did a quick rough cut of the area in cardboard to "fit" the areas that I needed to block (outer side of the cooler and the bottom). Then traced that out onto the tin and cut with a cheap set of tinsnips. A few sheetmetal screws later and the pieces I installed are solid as a rock. Did a final "seal" by squishing the foam between the gaps of sheet metal and bodywork. The whole process took maybe an hour or a bit more, but the seal is suberb: the air has NO way to go except right through the cooler.

FWIW, a couple of years later and all the sheetmetal is still solid and the temps are still where they should be. Even on 95+ degree trackdays, the oil might just barely scooch up above 9:00 to maybe 9:30 (say about 230-40?), but then on the cooldown lap, she's back down to about 8:30 ...and remember that's on really hot days with track usage.

I also cut an opening into the valance that's a bit larger than the Carrera-sized foglight opening to aid cool-air intake. Unfortunatley I did both these mods at the same time so can't tell you what the sole effect of the extra intake is. But I will bet that sealing the cooer will address the lion's share of your high temps.

Oh, and if memory serves me, 8:00 is about 210degrees, 10:00 is about 250 ...someone here posted a pic long ago ...perhaps someone still has that? Hope this helps you.

Edward

BlackPearl

Personally, I've heard 250-degrees is the breaking point for lubricants, and certain metal parts. If you don't have a numeric oil temp gauge, either get the replacement from performance (around $100 - I installed mine in 10 minutes with a small screw driver set) or follow the "2nd tick" rule: if the gauge gets to the 2nd tick on the face (around 2/3rds), get off the track or road, and shut down the engine for about 15 to 20 minutes. Turn it off, since the engine, oil lines and cooler can act as heat-sump and hold the heat better than the engine fan and ambient heat loss can cool. If it means one less lap at the AX or DE, so be it. If you miss the first 2 innings, so what? You still have a Porsche that runs.

I have an '83 SC with a Euro brass 19-line oil cooler (replaces the "Trombone" cooler). It helps cool the engine oil, but "stuck in traffic/no air movement" can be a problem.

I installed a Spal 6.5" fan in front of the oil cooler, and rigged it to a switch on my dash (the headlight-washer switch was R&R'ed for the fan switch. Who needs to wash the headlights in SoCal?). The fan pushes 300CFM of cool air through the oil cooler when speeds are low or I'm stopped. Even on SoCal hot days (85-Degrees to 95-degrees F.) my oil temp rarely exceeds 210-degrees. If I'm going faster than 40 MPH, I turn the fan off, since the ambient air flows higher. If I'm in stop and go, downtown, or sitting in line at the AX's, my fan is on. Also, I run 20-50 Mobile-1 or 10-60 Liqui-Moly synthetic oil.

The technical specs on the fan required I use a standard Bosch 30-amp relay, to avoid power issues and popping the 15-amp fuse.

So: here's the set-up:

1) Built a pair of 12-gauge wires to and from the dash for the switch. First wire ties to the fuse panel above the left front fender and goes to dash switch witha 15-amp fuse link tied in to the wire (power source). Second wire runs to the relay from the dash switch (these are the longest wires of the group, about 4' long).
2) Ran a wire from the fuse panel to the relay hot side.
3) Mounted relay next to fuse panel. Grounded the 30-amp relay to the fender bolt next to fuse panel. Grounded Spal fan to horn-mount bolt under right-front fender.
4) Ran a line from the relay to the fan hot side.

When the ignition switch is off, no power is delivered to the fuse panel, and no power goes to the switch or the relay. No issues with killing the battery.

The fan is mounted directly to the cooler with metal wire straps ... nut and bolt style (I thought about zipties, but at 200-degrees, I didn't want them to flex or melt under heat and lose the fan to the street). The fit allows air to flow freely through the oil coller and over the front tire.

Costs; Fan = ~$70 with shipping; wires = $0.49 ( I have a lot from work); 30-amp relay = $1.50 at dismantlers; wire ties = $1.49 for a pack of 4.

Tme to install entire unit; from jacking up the car and removing the front tire to driving down to get a beer after I was done: 2.45 hours.

Savings? My 171K miles engine should make it to 300K even with tracking it.

These are my experiences. Yours may differ.

Good luck!

tone40

I tried to open the thermostatic plunger end cap on the oil cooler relief valve. I tried several different methods to get the cap off- including a flat insert into the cap slot and dykes for grabbing, heat to loosen the cap, pipe wrench around the circumference of the cap. All to no avail. There must be a special tool. That baby is on there real tight. Unless someone has another suggestion, I am going to have to take it to the local indy for replacement of the plunger. =$$

I did not get a chance to drive it for a oil line heat check. But, I did inspect the oil cooler. I wanted to pull the cooler out for a check on the fan. I could rotate the fan by reaching around the valance (bearings still smooth). But the fan blades are hitting the shroud.

I could not loosen the oil lines to pull out the cooler. Another real tight assembly. Since I have to take off the front bumper in the near future, I will check out the fan & shroud situation plus the fan electric operation through the front side.

I did not see any kinks or leaks in the oil line routings. But there is a large gap between the cooler and fender. Later I will upgrade the air routing similar to Edward's suggestion.

In the mean time, I am limiting my routes to cool environments. I will concentrate on getting the thermostat replaced. Any advice is greatly appreciated.

Mike Murphy

I think you'll find that the replaced thermostat will make a big difference. The fan, by the way, is set to come on at 244F, so Porsche really only intended for that fan to come on in an emergency situation.

tone40

Well, it appears that the rubber mallet banging and torch heat loosened up the thermostat in it's bore.

I took it for an aggressive test drive Sunday eve, after the check up. Cool temps. but a lot of high rpm twisty road conditions. I noticed that the temp rose, but then started to drop. When I got back I tocuhed the front fender oil lines. They were hot to the touch. I have driven in stop and go driving since then and the temp gets no hotter than ~218.

I still need to close up the air flow gap and correct the fan functioning. I feel much better about the oil temps now.


Thanks everyone. The basic problem appears solved.

Mike Murphy

Excellent! You used my favorite tool, the BFH.

sig_a

It's nearly 95 and humid in Cincinnati today. So I let my 1987 911 3.2 sit in the garage with engine running at 850 rpm idle. I have a Fluke with a temperature probe made of stiff brown wire. With engine running, I inserted the wire probe into the dip stick tube to about 20 inches into oil tank. Readings in F were no higher than 205 F and seem to fluctuate down to 200F with oil circulating from the engine to the cooler to the tank. This was lower than I had imagined judging by the non numeric gauge reading exactly horizontal or 9 oclock, which is roughly 1/3rd of the way to the second white mark or +/- 212 F. For those unaware, the first white mark up from the bottom of the gauge represents 90 C or 194 F; second white mark up represents 120 C or 248 F; last red marking represents 150 C or 302 F. Then I moved the probe to the left front wheel well and measured both supply and return lines where one was 201 F max and the other was 186 F max. Oil cooler fan was not running. For what it's worth, my car has gotten close but never touched the second (120 C/248 F) white mark. Someone on an earlier post said the thermostat is set on the oil cooler fan to switch on at 244 F. Makes sense since 250 F is hot.

Jascha-M

The attached oil-circuit diagram (applies to Carrera models) is quite helpful for understanding the role of the two thermostatic valves and intervening oil pump. As you can see, the auxiliary oil cooler is indeed on a separate circuit (scavenger side of the oil pump) from that of the high pressure side that directs the oil to the engine cooler through an internal thermostatic valve. The thermostatic valve located in the wheel well opens @ 83 deg C (~182 deg F) and the engine opens @ 80 deg C (176 deg F) –not shown is the added fender cooler fan that is triggered to go on by a thermo-switch set to ~ 244 deg F

UberXY

Simple fix: if the temp is above 85 and there is a remote chance of getting stuck in traffic, air cooled cars stay home. OTOH, when I had a 996, no problem at any temp under any circumstances.

Steve
84 Carrera
64 356C
02 G500
00 M5

Mike Murphy

One reason why they changed from air to liquid.

Mike Murphy

Jascha K., this diagram explains why "sig_a" temperature readings were lower when taken from the tank than the readings on the temp gauge. Nice diagram.

Mike Murphy

What do you mean "hold the rpms?" What does your temp gauge read when the engine is hot?