ulrichd

Noticed slightly higher oil temps on my drive this evening (usually the needle is pretty steady at 8-9 o'clock but was screeping toward 10 o'clock). The oil lines under the rockers were warm but the trombone lines were not. That seems odd - any suggestions?

autobonrun

If the oil lines under the rockers are warm but the oil line to the trombone and the trombone itself are not, my first thought would be the thermostat is not opening. You should be able to feel hot lines on both sides when it opens up.

Jay Laifman

But note, after I had the same concern, I remember learning at some point that the thermostat on the trombone coolers opens at a much higher temperature than I thought. I don't remember the exact temp. But, I do remember that it was higher than my car normally gets, even on hot days.

Porsche Newbie

Thermostat.

autobonrun

After your post I went back to my Bentley Manual. Let's see if I can explain this right. There are two thermostats in the lubrication system. The one on the outlet of the oil pressure pump regulates the lubricating oil temperature to 176 degF. If it is not to that point, it completely bypasses the engine oil cooler. Assuming it is over 176 degF, it will start sending oil to the engine oil cooler which is mounted on the engine.

The thermostat we're talking about is the one under the rocker panel. What is different with this thermostat is that it is looking at the temperature of the oil that is returning to the reservoir, not the pressurized oil. It is set to divert the returning oil through the Aux Oil Cooler (trombone) at a temperature of 113 degF.

What I just learned from reading (and I've only had my car 22 years) is that this return oil thermostat is actually a combination thermostat/pressure relief valve. If the oil pressure is excessive it will also divert oil away from the front cooler.

So, the reason oil is not reaching the front cooler could be from the thermostat portion or the pressure relief portion of this unit not working correctly. Bottom line, he should probably check this unit.

ulrichd

Thanks for your responses. I will start with the thermostat insert (replace it) and go from there.

Jay Laifman

That's certainly lower than I recall. I'm going to have to check mine all over again! Thanks for the great info, and for bothering to get it.

carnick

Is the front oil cooler bad? I suspect mine could be - at higher temps, I don't hear the cooler fan running!! Shouldn't I be able to hear it?

theiceman

Well first of all what kind of car do you have ? what kind of oil cooler ? does it have a fan ? what is higher temps ? higher engine temps or ambient temps ?

ie a little info would help.

carnick

I have an '88 911 Targa, 3.2 engine. Not sure what kind of oil cooler?? It's original to the car - is it fan cooled?

Thanks -

theiceman

Well I have a 78 so I am not sure , lot of guys here would know but try having a look under your front right fender and see what is there..

ron mcatee

Carnick, The 87-89 Carrera's had a fan installed on the oil cooler from the factory. The factory thermnal switch will not come on until oil temps reach 244 degrees F (too damn hot). Also, in your case, if no hot oil is reaching the cooler, it will never come on. I tested my fan by going inside the trunk down on the passenger side and disconnected the oil cooler wires from the harness. I then made a couple of 6-8 foot leads with alligator clips. I attached the alligator clips to each side of the wiring and then to the battery for power. If the fan works, you'll know it when it comes on. I wanted to keep my temps at no higher than 210 degrees F. As someone in a previous thread had suggested, I ordered a BMW radiator temperature sensor (rated at 99 degrees Celcius) from pelican for about $12 and put it in. I modified the wiring slightly at the thermal switch (did not cut the factory single pole wire to the temp sensor on the oil cooler) by making an adapter to fit the single pole and put a spade connector on the other end. I think the wire was about 3 inches long. On the other side of the dual pole sensor (BMW) I made a ground wire about 6 inches long with a spade connector on one end and an eyelet on the other big enough for the 10mm head bolt to go through it and used that as the ground. Of course all this was done after the oil cooler was removed from the right fender well. My car now runs at or below 210 F most of the time. When it goes over that temp, the fan comes on and runs until the temp drops to about 205 F. I thought about putting a 91 degree C sensor in the car, but that would have the fan coming on most of the time and cause premature failure of the fan. Some recommend putting in a separate switch to turn the fan off/on. I opted to do it automatically with the current wiring mod.