amet

hi all,

I had a similar problem on my 84 and it took about two months to solve.

the car was running hot ,between third mark and red.

I think I have bled the system about 30 times. then i thought of checking the temperature on the block. Having just installed the new temp sensor(for the gauge) i measured the resistance and it was all OK.
Then i used clarks procedure to check the gauge and found it was way out.

I took the gauge to the VDO repair place and couple of bucks later they re-calibrated it. Now its doing fine.

I figure you could re-calibrate it your self with Clarks procedure but I wasn't too keen on it.

http://www.clarks-garage.com/shop-manual/elect-19.htm

Just my $0.02
zeljko

Lizard944

Hey Sillbeer, I wasn't really feeling "ignored," just being my usual sarcastic , ornery self..lol
I've just changed a lot of t-stats in my days, and have seen some weird stuff. Even changing the coolant specific gravity (diluting) can change the attitude of the t-stat in some vehicles. What was working well before a coolant change, might start giving you issues afterwards. You mentioned that you changed your ratio to 70/30? Theoretically, you should be running a little cooler, so maybe this new mixture is making an overly sensitive t-stat to start closing a bit, thus restricting flow. May not have reacted that way with your previous coolant mixture.
In my Exploder 5.0L , a lot of engine management problems and rough running has been narrowed down to the t-stat not holding the proper engine temp. Let everyone know how you end up resolving this once it's fixed!

ausgeflippt951

Lizard, it doesn't seem to me like installing a 170 degree thermostat (if there is such a thing) would make much of a difference on the DME, but I agree -- 160 does seem low.

Also, keep in mind it's around 110 daily Tucson/Phoenix, so I'd rather the car run a bit cool than a bit hot. What are my options for cooler-ranged thermostats?

sillbeer

exactly, its unusually hot here in Az than the rest of the country. it will only "cool off" to the 90's and sometimes it will stay in 100's at night and its regularly 100+ everyday during the summer with few exceptions...Thats why low temp thermostats arent such a bad idea. It's harder to dissipate heat the hotter it gets so keeping the coolant temps down early is a wise idea...

Got Me a Porsha

Here's the issue I have with lower temp thermostats...

Once you exceed the thermal efficiency threshold of the cooling system, ie it can no longer keep up with demand, the lower temp thermostat is rendered useless, as compared to a higher temp 'stat. For example, if it is 117 degrees outside, idling in traffic, a/c on, and the stat opened at 192 degrees, but the cooling system can only maintain 200 degrees, a 180 degree stat would make absolutely no difference. It would only open earlier. The entire cooling system must be able to support the thermostat.

In fact, I can debunk all of your "theories" on how to make a car run cooler, and I have the money pit to prove it!

sillbeer

Very true sir! It depends on your radiator and water pump at that point. But yea, if the low temp stat opened at 160 but the cooling system can only maintain 200, all the low temp stat did was open sooner than the stock one would have...I wonder if an external oil cooler would help things? this isnt a track car (yet) and I don't really beat on it....

944CS

If anyone wants one of these to combat the heat, pm me...bolts right on to all 8 valve cars (turbo included)

Will Feather

Hey guys, new member here. Ya im having the exact same problems as all you other guys. Im runnin a 84' 944 and it runs hot. At the 3rd line and above to be exact. If i run it in the driveway for like 20 mins it will get up to half way to red. When im driving it, it hovers about 3rd line unless i hit a stop light or sign. So, i put a new thermostat in it. And like someone said before me, it really dosnt matter if you put a low temp thermo in it, if the thermo is fully open (even if it opens quicker), the engine will still continue to heat up. I also need a fan relay, but like another user, i just have my a/c on to keep both fans spinning at high speed, thats not my biggest concern right now. So basically im down to just replacing the radiator. It has a new thermo, all the hoses flow freely, to my knowledge the water pump is fine, so this would be a good assumption? I mean it is a 23 year old radiator, sounds like a safe bet to me. Now the next question is, how do you remove the damn radiator, you cant even see it with the hood opened. So i assume you have to take the front nose spoiler off (the piece with the porsche emblem). Will this be sufficient to getting to the radiator?

sillbeer

nope, the radiator actually is pretty straight forward to remove. All you have to do is jack the front of the car up, drain the coolant, remove the under tray (if yours is there) remove the fan connectors, remove the radiator hoses (4), disconnect the fan switch, remove the upper clamps, and it drops out of the bottom.

Will Feather

Thanks alot man, thats exaclty the type of help i was lookin for.

sillbeer

Interesting update! So, the temp gauge finally reached into the red zone on my way to work the other day. It was probably 50 degrees outside, cruising about 65-70 on the freeway. I get to work and the needle is right on the edge of the hot zone. So, I pop the hood expecting to be able to fry eggs on the coolant overflow. Not so much. the coolant overflow wa sonly heated slightly by the engine bay radiant heat. no bubbling, no steam, no gurgling. upper rad hose was pretty warm, but I could hold onto it with my hand for about 5-7 seconds. lower rad hose was cold. So, i borrow my buddies' infared thermometer. I checked it out when I got home. The needle was just below the 3rd mark, but the fans were running just yet. I get out and started probing all over the place with the thermometer. I checked the header runners, I was getting over 500F on the rear and about 380F or so on the rest. The head surface temp was about 160-180. I checked both rad hoses, the upper one was about 150F and the lower one was about 125F. I checked the head right at the temp sensor, it was about 180F. I checked the coolant neck on top of the motor, 175F. So, I'm now leaning towards a bad gauge reading. When I had the dash out, I cleaned a bunch of grounds behind it. I'm thinking either the sender, or bad grounds. Do these gauges go bad? it does hop around sometimes but not very often.