Mrmerlin

Yep, in the Pet it shows the rear seal started in 83 after a certain VIN

WallyP

Make sure that the metal sleeve is properly located in the upper radiator hose connection. This spreads the incoming coolant and improves radiator performance.

Brad W

Wally, the sleave was in the correct position. I went ahead and sent the rad out for overhaul. If that does nothing then I am not sure what to do next.

H2

"metal sleeve"? Is this on the S4 radiator too? I guess I'm not acquainted with this part. I should check this. Where is it?

H2

jpitman2

Its in the top right water inlet to the rad tank. 37mm (1.5") Cylinder with 90 degrees cut out to send hot incoming down before it goes across the tubes. looking into radiator inlet, the cut out is from 3 o'clock to 6 o'clock. The inlet moulding should have a ridge to engage a cut out in the tube so its correctly oriented.
jp 83 Euro S AT 52k

Richard S

Do you have an air compressor? If so, now is the time to blow out all the crap from the AC condensor. Since you have the radiator out, use an air hose with an air nozzle, blow from the back to the front of the condensor....watch as a huge cloud of dead bugs, dirt and crud blow out the front. This should help with the airflow to the radiator. It certainly helped mine after I did it.

Rich

David L. Lutz

Still not clear if it is on the S4 Rad's too?

hacker-pschorr

The only reason why your car ran better with the one piece aluminum radiator is because it's new and clean.

20 year old radiators are clogged on even on cars with the best maintenance schedules. Porsche didn't have any issues testing these cars in 120+ degree heat, so unless you live in the Sahara a stock car (with everything working 100%) shouldn't have any problems either.

I vote check the fans out really good. I can run with my stock 81 radiator (with the supercharger) without my fans on as long as I'm moving at least 20mph on a 95 degree July day.

Is there an easy way to test the mechanical fan other than trying to stop it with your hands when the engine is hot?

928nut

Anybody has a picture of what this "thing" looks like ? I don't recall seeing it when I had the gasket/side tank replaced on my '79 few years ago.

Jan

Brad W

I can get a pic when it comes back unless someone has a pic already.

928nut

Brad, I would appreciate that, if it isn't too much trouble.

As to your overheating problems, I can relate very well. I noticed my '79 suffered from the same issue the very first summer after I bought it 15 years ago. Slow, stop and go traffic on a hot, humid day would push the system near its limits.

I did a number of things, like you're doing, all without noticeable improvement.
My rad was clean as a whistle, inside & outside, installed lower temp. thermostat and fan switch, replaced my viscous clutch assy. with one from an '85 that looked as close to being brand new as any you'll find, rewired the electric fan so it would run after engine's shut off, tried the "water wetter", etc. All these measures provided barely noticeable improvement.

It wasn't until I decided to ditch my A/C, two-three years ago, and removed the condenser, compressor and everything else associated with the A/C, that I saw a dramatic improvement in my engine cooling. Ever since, I haven't had ANY overheating problems at all. It all points to airflow problem, having the condenser and rad sandwiched together limits the air flow and I've also come to believe, that the viscous fan just isn't quite up to the job, in this configuration.

At slow RPM, there isn't all that much air being drawn trough the rad by it and the electric fan being a "pusher" fan isn't isn't all that efficient at getting air to flow trough the condensor and rad. Lot of air gets scattered/deflected from the front of the condenser. Perhaps an electric-puller fan setup, same or similar to the S4 setup, is the answer.

While I'm OK now, I realize my fix isn't a viable option for you, living in Texas. I'll be reading with interest on your progress and how you'll eventually solve your problem.

Jan

dprantl

My former '86 with R134A converted A/C never had any problems for the 8 years I owned it, even in 100 deg F Atlanta humid temps in stop/go traffic. It had the original viscous fan and a working auxillary fan. IMO the viscous fan is more than adequate to cool the car with A/C. It sure pulled more air through it at over 2k RPM than the S4+ electric fans. I could blow up a sandstorm on people standing beside the car when revving it up without the belly pan.

Dan
'91 928GT S/C 475hp/460lb.ft

928nut

Well, it just goes to show that we should end all our posts with "YMMV".

By the way, I forgot to mention that a new water pump didn't help my overheating either - YMMV ;-)

Jan