Hi,
I know I have a lot of questions but you rennlist users are very helpfull in answering a lot of newbie questions !

With AC off, outside temp. 5 degrees and doing +/- 140km/h the engine temperature needle just tips the red area (97 degrees celcius ?) in my '90 S4.
I have no problems but I'm just curious if it's normal the engine gets so hot during fairly normal conditions. I'm wondering what happens when outside temperatures starts rising during summer... I also get the impression my coolingfans are running a lot.

If I slow down a bit (residential area) temperature drops to +/- 90 degree.

Do you experience the same ???

Thanks.

 

My 90 S4 runs at about 3/4 of the gauge. 190 I think. Check your cooling flaps for operation

 

That's on my spring to-do list, drill / tap the radiator cross-over for a real gauge that gives me a number.

 

Sounds a little warmer than my car runs...check to see if your three flaps in the grill are opening and closing properly. I believe there are three automatic settings, many have disconected this feature

 

Does sound like its too hot.

Check the cooling flaps and if they're not working we can set them wide open. If they're working how old is the anti-freeze/what type?............has the thermostat been changed?

 

Paul,

That reading sounds high. When I do 140/Kmh in 5 Deg C, the temp gauge is on the first white marker line.. More than 200/Kmh, then it will creep upwards to the mid marker..

My car also runs warmer in traffic, and can get to the upper ranges in summer. I also do not have the front spoiler attached, and have the vent flaps in the nose removed for full airflow at motorway speeds.

Have you done a coolant flush recently..? Is the water pump new? (When was it last changed..?) Are the flaps in the nose opening and closing properly..? Have you examined the radiator for blockage by leaves, dirt, road debris etc..?

The car is designed to run a bit warm, but that sounds much higher than mine. Then again, you have a 90S4, and mine is an 87, and maybe the gauge pod is different.

Hope it helps....

tot ziens,

 

Tot ziens ??? From Holland ?

Next Monday I have an appointment with a Porsche specialist to get a quote on a (hopefullt small) oil leakage. I'll bring up the temperature issue, maybe they can check some of the things you brought up in this topic. Since the car is new to me I'm not sure what components have been replaced (or flushed) recently. I'll let you know what they've found next week.

Thanks.

 

Some other possibilities: cooling system not air tight, old reservoir cap, old seal between water bridge and thermostat.

 

Or the gauge could be inaccurate. Put an infrared temperature probe on the thermostat housing and the engine side should be only a couple of degrees higher than the thermostat rating.

 

IIRC the usual rule is if it gets hot at low speeds and cools as speed lifts, its an airflow problem.
If it gets hotter as you go faster its a water flow problem - pump (impeller loose - plastic?), radiator core issue, clogged block passages etc. An airflow blockage due to the vanes mentioned above wouldnt help at all. I have also seen temps rise badly at speed if the ignition is retarded.

Recently I tested new electric fans in my S at 35C ambient, A/C on, and it held under second white mark while idling. At anything over 60kph the fans cycled in/out some.
jp 83 Euro S AT 52k

 

Hi Paul,

No, I am not Dutch, but had a former Dutch business partner. I spent some time in Holland, and a bit more in Belgium.. Schilde, near Antwerp....

I hope your oil leak is small....

'dag

 

On my 90 S4 there was a plastic panel/sheet that was between the radiator and oil cooler
on the backside of the bumper. It came loose once, and at speed would fold up and block
the air going to the radiator. So if it only happens at speed, this could be an issue, and
easy to fix if you know about it.

 

The last car I looked at that had temps approaching the redzone turned out to be the flaps mentioned by Calgary Ole. But before I remembered to check that we verified that the thermostat was good and installed properly (good seat in the water bridge and o-ring on the outside of the thermostat).

 

Paul,

My 90 S4 Auto runs at around 87 to 90 degrees C, and 97 degrees C is a little too warm. I would check the system temperature by infared temperature probe to confirm the accuracy of the gauge, or by attaching a thermometer to the return hose to the radiator.

I fully agree with jpitman 2, so something is slightly wrong with your cooling system.

With the ignition off the cooling flaps should be shut, on start up they should open to 30% and when the temperature climbs they should open to 100%. If A/C in on they should immediately go to 100% open. You can check this out in your garage.

Your car is fitted with 2 by 2 speed electric cooling fans that are interconnected with the air conditioning system, the cooling temperature and the engine temperatrure IIRC.

If you turn the A/C on the fans should immediately go to full speed and flaps will fully open. This cooling system is a relative complex system and Prosche discontinued the cooling flaps on the GTSs, however, mine work fine. Many S4 owners have disconnected the flaps, however, they were installed to bring the engine temperature up to operating temperature in the shortest possible time and improve the air flow around the car.

There is a full description of operation in the WSMs and if you have not got them I would suggest that you at least get Jim Moorehouses Technical CD. Jim is a member on Rennlist and I also believe Roger at 928sRus has them for sale. They are cheap and the contain nearly all the information released by Porsche on the 928, as well as the WSMs and many others manuals, specifications, electrical drawing and instruction manuals.

Your problem could also be the thermostat not working correctly, it should be cleaned and checked by immersing it in hot water with a thermometer and see what temperature it opens and by how much. Again the information is contained in the WSM. You may also need to change the "O" ring seat of the thermostat to ensure that there is no bypass.

A quick check on the cooling, switch the A/C on when you are driving and the fans will go to full speed and see whether the engine temperature drops. I appreciate it only 5 degrees, but if the engine temperature does not drop it could indicate the flaps are not working correctly and if this is the case you will have restricted air flow.

Also check the A/C condenser and the main radiator external cores for blockage, to ensure you have full air flow. You may also need a complete cooling passage clean through and new coolant added.

Tails 1990 928S4 Auto

 

Hi guys,
I just woke up and saw your input.
Quickly I rushed to my garage to theck the simple things about the cooling flaps.
First I checked the condition they were in, they were fully closed.
I started the engine and checked again. Still closed.
Then I put the AC on. The flaps were still closed and there was 1 fan spinning. The other one (on the right side seen from looking front to back) was doing nothing....

I now have set the colling flaps fully open by hand and this morning I'm gonna take her for a ride to see what happens.

I felt no resistance when opening the flaps so the're not stuck I presume. Also after putting the AC off the flaps were still in same open position even when I stopped the engine.

Any thoughts about the 2nd fan not working ? Normal ?

Thanks!