I installed my new Devek radiator yesterday and there is no change in the temperature gauge reading. I'm still showing between 200 and 210 degrees at 105 ambient and I'm noticing some significant pinging on acceleration.
I'm running about 60/40 water/coolant with Water Wetter, a thermostat that has been fully tested, a new rear thermostat seal and a new tank cap. The timing is correct to factory specs.

 

Burped right? Lower hose collapsing? Heater valve stuck open?

 

Burped right, new lower hose, stuck heater valve would make it run cooler. AC works fine.

 

A stuck heater valve will make it run hotter if you're not running the heater and blowing cool air over the heater core.

 

From your previous posts: Pieces of the rear thermostat seal were lodged in the radiator trying to come out of the ends of some of the water channels. THESE were responsible for the reduction in flow.

Do you suppose there are some pieces stuck in the cooling channels in the block? Maybe a compressed air/water flush of the block is in order. I have no idea how you would do that, but you seem pretty creative. :-)

There is not that much that can go wrong with the cooling system. New radiator, new thermostat.... are you sure the water pump is moving enough liquid through the system? Puzzling.

 

Hi Ernest,

My 90 S4 runs just like yours. I don't know if it's significant pinging but I do hear some knocking under acceleration. I have to have the radio off and I do have to listen for it but it's there. My temperature gauge pretty much reads the same as yours. It gets real high when the outside temperatures get over 100 F.

I've had both the pinging and the temperature checked out and I've been told it's normal.

I think I've convinced myself that this is normal behavior for my car but I still don't like driving it in really hot weather. I get too many butterflies in the tummy when I see that needle getting close to the red zone. I've avoided taking my car on several trips after I've gone to "weather.com" and found out the temperatures along my route were predicted to be over 100 F.

I'm wondering if Porsche ever got complaints from their customers when these cars were still new and under warranty. I wonder if there was ever a bulletin put out by the factory saying that the gauge reads high but that this is normal and nothing to worry about. It would be a real relief to me to hear from the factory that this is indeed, normal behavior.

Jim

 

Glen,
Please help me understand the heater valve's function and how it might be a problem with overheating.

 

Still, others do not have these problems, so I suspect something must be wrong.
People with S2, s4, etc, drive in hot areas with their temp running at normal levels.

I'd double check the water pump.

I had one that had damage, and it would be turning with the belt,
but the plastic fins were broken, or detached, so it would be spinning,
but not pumping much water.

I also agree with the plan to pump water through the block.
I'd pump it in the opposite direction of normal flow, so any chunks
or obstructions will come out in reverse, not get wedged any deeper.

I'd also be sure that the guage is not faulty.
The pinging my be from something else.

But if the temp is really higher than normal, there must be something wrong.

Did you get a lower temp thermostat from Devek at the same time?
That might help a bit...

 

Ernest,

I feel bad for you. Thats an expensive item and it didn't solve your problem. All you can do now is throw your hands and in the air and scream "God why have you forsaken me?"

 

It sounds like you have checked everything except the fans... Try hooking them straight to a power supply. Make sure that they are both running at full blast. Take it for a spin and see how it goes. I have found that 90% of overheating problems come from bad air flow.

 

The water pump is from 928 Specialists and is about two months old. A lower temp thermostat will make it take longer for the engine to reach full operating temperature, but the heat load doesn't change.
Weissach, that sounds like a plan. It would, at least, answer the question of air flow for once and for all.

 

Ran the car with the fans on full and found no difference.

 

Ernest:

Trying to find things you haven't fixed.

The heater in normally open on these cars at that is safest. Wouldn't want to get caught in the Alps without your defroster.

The coolant path for the heater core does not include the main radiator. So that fluid would be returned to the engine at the same temp. Worse it robs the radiator circuit of a bit of flow.

On my old Buick, the heater valve is shot. I zip-tie it open in the fall and cut it in the spring. I'm better about it now as I did have overheating problems as I'd set the climate system to cool vent in the summer (no A/C). The heater core just got hot, but no air was moving. That was enough to send it into a boil at shut-down.

I have run the heater to help cool a hot engine. I wonder if that itself isn't a bit of a wives tale.

I was looking at Weissach's post and thinking "90% oif my overheating problems are (suddenly) bad hoses." The other 10% have been how I tune the engine. Usually too ambitious with the spark advance. I see you've chipped your engine. I'd consider trying it with the stock parts.

 

KHAN!

 

Ernie - I know it's better to have belly pans than not. But, I don't have one and my S4 runs cool, midway between the two white lines - even in stop and go with the 100+ outside temps we've had lately. I would be interested to see if yours runs cooler without the belly pan, just as an experiment. It's about the only thing you haven't tried.