87 over heating

[schulr]

I have noticed over the last month or so that the temp has been slightly above half way on the scale. Previously it was always say 1/3 up the scale.

The belts are fine, but the aux heater fan in the engine compartment is no longer running. Previously, this fan was always on once the ignition was turn on. The fan still works when you actuate the heater controls but only then.

Today, it was 90 in Atlanta and on the way home, smoke was coming from the exhaust for about the last mile and it smelled like something was burning but the engine was running fine.

Question, should the aux heater fan in the engine compartment always be on or is it temperature sensitive?

If the vale guides fail or start to pass too much oil, would this have an effect?

Need to get this under control soon as we are having a contours on 7/9 at Flashback

Bob

[don911]

Do you have auto heat? The heater blower in my car only comes on when the heat is on and is controlled by the auto head temperature.
I don't know the cause of the overhead issue but I think if it's a valve guide issue, it would happen gradually.

[schulr]

Don, the heater is manual and I have replaced the heater fan relay in the past. These relays are not too reliable but since it works with the heater control, the relay should be fine. Some have said that the aux fan was temp controled for added cooling. If this is the case, that could be one of the reasons? However, still does not explain the sudden smoking while over heated.

Bob

[don911]

The aux fan on the front oil cooler is temp controlled for cooling. I don't think the heater fan is going to help much to keep a motor from overheating.
Could you have a plugged up cat?

[kqw]

The temps. rising just above the 9:00 position should be normal with those outside temps.

The aux. heater fan should activate as Don said, automatically if high temps are reached. When I lived in Phoenix, there were many hot 100+ deg. days and when I arrived home the aux. heater motor was running.

Make sure your oil is up to standard levels and your oil cooler fan is activating.

Where exactly was smoke coming from? Out of the tail pipe or out from under the car?

[schulr]

Good point on the oil cooler fan, will check that over the weekend. I had assumed the smoke was coming from the exhaust but maybe not. No oil on the ground and the engine compartment is clean.

As for the aux fan in the engine compartment, are you saying it is temp sensitive and should come on when hot?

Bob

[kqw]

Originally posted by schulr
As for the aux fan in the engine compartment, are you saying it is temp sensitive and should come on when hot?

Bob

Yes....

If your oil cooler fan is activating, your oil levels are where they should be and the temps rise just above the 9:00 mark when the outside temps are high...you're running normal.

[schulr]

Thanks, will do some more testing over the weekend and post the results

Bob

[kqw]

For example...

This past weekend I rallied to Hershey and back in about 90 deg. weather.

I had the A/C blasting and I ran about 85mph on average for about 1.5 hours. The temps reached just above the 9:00 position on the temp gauge. Car ran fine.....

[88911coupe]

Could someone confirm this about the engine heater fan coming on? We are seeing near 100 degrees here in NE Oklahoma but my car has only approached the 9 o'clock position sitting in traffice with the a/c running full blast. At what point is the aux heater fan supposed to come on? I guess this would be a reason NOT to backdate the heater in my car...

[schulr]

Going to try and read the Bently over the weekend and see what it says, from many other post while searching, most have said the fan is just for heating and cooling of the mortor.

Bob

[kqw]

With the carrera front oil cooler and cooler fan running, it's going to be a bit of a challenge to get the car hot enough to activate that aux heater motor.

Maybe someone from Texas/Arizona with an '84 - '86 carrera can chime in on the temp that activates the heater motor. Those years did not have the cooler fan attached to the front oil cooler.

[derkpitt]

Drove mine yesterday in ATL. Temp gauge was at half way.
Mine will also smoke for no apparent reason in both hot and cold weather. But it's not using enough oil for me to be concern about right now.
You mitt want to check the micro switches on the heater control levers, they control the heater fan in the engine compartment. If the switch are not adjusted correctly a small movement of the lever mitt turn on the fan.

[ZOA NOM]

Check the top of your motor (behind the fan) for a layer of dirt and grime that severely hinders the cooling effect of the fan. I discovered this when I did an engine drop, and noticed a cooler running motor.

[rds356]

Another for example:

Drove round trip (320 miles) from NJ to Hershey (Porsche Parade) in 90 plus heat with a turbo motor. Car ran a constant 210 degrees at 80 mph. Got stuck in a monster traffic jam on RT.78 while driving home for 40 minutes. Temps rose to 230.
My Mechanic said 210 is perfect for burning off oil impurities. To cold creates sludge build up. He also drove out and back in a 56 356 speedster. He saw a constant 250 oil temp with no apparent harm.

[schulr]

Read Bentley and found the following on the operation of hte aux heater fan in the engine compartment

According to the Bentley manual, the fan is also activated when the engine compartment temperature reaches 260 degrees, the vehicle is stationary and the ignition is on. It says that it is switched by a temperature switch in the crankcase vent cover at the rear of the engine

Since my aux fan no longer comes on without activating the heater control levers, assume my temp switch is bad. Does anyone no where it is exactly? I have looked and searched archives but can't find any reference.

This also clears up any question as respects back dating a 3.2, looks like this fan is required for proper cooling.

Bob

[kqw]

The aux. heater blower should not activate unless the levers ARE pulled. The levers activate the blower and close the heater boxes directing heat into the cabin.

In contrast: When the blower motor activates because of high running temps., the levers are down (heater boxes are open) and that heat is being directed out through those open heater boxes.

I don't think you have a problem....

[wente]

Has anyone else out there wired the fan to a switch for additional heat removal? I'm moving to the bay area in a few months and I want to do everything possible to keep my car cool in the traffic. If porsche designed it to kick the blower on at 260, I would think it would help to dump the heat out all the time when in a traffic jam. I've added an aux oil cooler switch, so I'd like to just add the engine blower to that circuit if there's an advantage. I'll give it a try in the next few days and give you guys a report if it helps. My 87 hit 10 o'clock today in 90 degree ambient with the ac on and oil cooler fan running moving at 75mph @4000 rpm.

[schulr]

kqw, what I have boiled this down to is my aux fan is not working unless I use the heater controls. According to Bentley, the fan should come on with the ignition key turned on, my no longer does. I plan on checking the temp switch once I find it. The bentley shows this to be in the center rear behind the aux fan.

Let you know the outcome once I test this switch.

Bob

[kqw]

OK...that's fine...

Let me just ask...Are you saying that your Heat blower motor in the engine compartment always came on when you turned on the ignition. I.E., that motor ran 100% of the time?