Overheating Problem-Not Solved
08-14-2003, 12:57 PM
#47
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ErnestSw,
Perhaps maybe we just except a design flaw Porsche made with the 928. Some run hot some don't, mine will skyrocket in temp if I use the AC and sit in bumper to bumper traffic. Well I'm in Phoenix which is nearly as hot as hell.
I think you pretty much replaced everything you need to cure your problem. The dirty word (head gasket) could be a problem but I'm sure you checked that. Overheating seems like a cancer you can't cure very easy.
I suggest if you can't get this behind you, than sell it and get another shark. It can save alot of headaches that I see you have with it.
Perhaps maybe we just except a design flaw Porsche made with the 928. Some run hot some don't, mine will skyrocket in temp if I use the AC and sit in bumper to bumper traffic. Well I'm in Phoenix which is nearly as hot as hell.
I think you pretty much replaced everything you need to cure your problem. The dirty word (head gasket) could be a problem but I'm sure you checked that. Overheating seems like a cancer you can't cure very easy.
I suggest if you can't get this behind you, than sell it and get another shark. It can save alot of headaches that I see you have with it.
08-14-2003, 01:17 PM
#48
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Red UFO,
These cars were tested in dessert conditions when they were designed and I'm convinced that they all came out of the factory with adequate heat management for even Phoenix conditions.
I've discovered that my control unit is not functioning correctly and I'm hoping that this solves the problem, not only for me, but for you and others as well.
Have you tested your control unit per the manual?
These cars were tested in dessert conditions when they were designed and I'm convinced that they all came out of the factory with adequate heat management for even Phoenix conditions.
I've discovered that my control unit is not functioning correctly and I'm hoping that this solves the problem, not only for me, but for you and others as well.
Have you tested your control unit per the manual?
08-14-2003, 01:56 PM
#49
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Hi Ernest,
Which control unit are you referring to? Is it the fan control unit that looks like a big heat sink?
Is the test procedure in the owner's manual or the 9 volume repair book?
Thanks
Jim
Which control unit are you referring to? Is it the fan control unit that looks like a big heat sink?
Is the test procedure in the owner's manual or the 9 volume repair book?
Thanks
Jim
08-14-2003, 02:05 PM
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Hi Jim,
It's the control unit that's under the hump between the passenger's seat and the door. The testing procedures are in chapter 19 of the shop manual.
It's the control unit that's under the hump between the passenger's seat and the door. The testing procedures are in chapter 19 of the shop manual.
08-15-2003, 01:12 AM
#52
I have read with interest the messages on the cooling problem.
With my 1990 S4 Auto, I have carried out a full operational check on my cooling flaps and they work as design and follow the curves published by Porshe, with and without A/C on.
I have regularly change out my cooling water and each time I have given it a good pressure back flush from my garden hose.
Recently I noted that my temperature gauge in the instrument cluster was registering lower than usual and last Sunday it started fluctuating at the start of relatively long drive.
On returning home I deemed it time to check my thermostat.
Unfortunately when removing it the upper set bolt sheered at the head which necessitated a long process to remove the stud which was finally done successfully.
Internals or the cooling passages were very clean with no corrosion evident of build up of water salts.
I removed the thermostat, cleaned it up, checked its operation.
Started to open at 83 degrees and full opened up at 98 degrees C. The opening distance was 9mm, so was of sufficient travel to seal when fully opened.
Checked the seal at the back of the thermostat and satisfactory, so replaced thermostat and reassembled unit.
Now car coolant sits on 89 degrees C on the gauge constantly.
My operational temperature ranges for 2 degrees to 45 degrees C in extremes and temperature has always remained constant around the 89 to 90 level even in stop start traffic in high summer conditions.
A simple way to check the temperature of the coolant is to get a mercury in glass thermometer and place it on the radiator outlet hose and ensure that the bulb is in contact and then bind it on with electrial tape to ensure good contact and heat transfer. This can also be done at other locations , that is adjacent to sender unit for temperature sensor etc.
I you get the temperature at the sender unit and then check the temperature gauge you may find your problem.
Hope this message helps.
Tails 1990 928 S4 Auto
With my 1990 S4 Auto, I have carried out a full operational check on my cooling flaps and they work as design and follow the curves published by Porshe, with and without A/C on.
I have regularly change out my cooling water and each time I have given it a good pressure back flush from my garden hose.
Recently I noted that my temperature gauge in the instrument cluster was registering lower than usual and last Sunday it started fluctuating at the start of relatively long drive.
On returning home I deemed it time to check my thermostat.
Unfortunately when removing it the upper set bolt sheered at the head which necessitated a long process to remove the stud which was finally done successfully.
Internals or the cooling passages were very clean with no corrosion evident of build up of water salts.
I removed the thermostat, cleaned it up, checked its operation.
Started to open at 83 degrees and full opened up at 98 degrees C. The opening distance was 9mm, so was of sufficient travel to seal when fully opened.
Checked the seal at the back of the thermostat and satisfactory, so replaced thermostat and reassembled unit.
Now car coolant sits on 89 degrees C on the gauge constantly.
My operational temperature ranges for 2 degrees to 45 degrees C in extremes and temperature has always remained constant around the 89 to 90 level even in stop start traffic in high summer conditions.
A simple way to check the temperature of the coolant is to get a mercury in glass thermometer and place it on the radiator outlet hose and ensure that the bulb is in contact and then bind it on with electrial tape to ensure good contact and heat transfer. This can also be done at other locations , that is adjacent to sender unit for temperature sensor etc.
I you get the temperature at the sender unit and then check the temperature gauge you may find your problem.
Hope this message helps.
Tails 1990 928 S4 Auto
08-15-2003, 01:20 AM
#53
Nordschleife Master
RED, here's something to try.
Used to be, when I slowed down, my car's temps would do the spikeing thing. They would rapidly rise till they were on top of the top white line. The fan clutch is good, hum...
They would realy spike when I had the a/c on.
I just figured out what my problem is.
About half way up the gap between the condenser, and the radater was filled with debrie. Basicly no air could flow through the lower half of it.
I ran the car today w/o the condenser, the extra electric fan, or the debrie. The temp guage is almost rock solid. Hum, intersting.
Might be worth a shot. The problem is that you almost have to break into the freon system to get it cleaned out. Not cool, unless your already doing it.
Used to be, when I slowed down, my car's temps would do the spikeing thing. They would rapidly rise till they were on top of the top white line. The fan clutch is good, hum...
They would realy spike when I had the a/c on.
I just figured out what my problem is.
About half way up the gap between the condenser, and the radater was filled with debrie. Basicly no air could flow through the lower half of it.
I ran the car today w/o the condenser, the extra electric fan, or the debrie. The temp guage is almost rock solid. Hum, intersting.
Might be worth a shot. The problem is that you almost have to break into the freon system to get it cleaned out. Not cool, unless your already doing it.
11-13-2006, 08:14 PM
#60
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Originally Posted by heinrich
WTF with all the thread resurrections 
Actually, I'm going to look at a 928 this week that has "an overheating issue" and thought I'd better bone up on what the cause could be before looking at it. I hope the issues haven't changed in 3 years. Gracias amigos.
Harvey