sillbeer

Ok, I have been battling a cooling problem on my 83 since I have bought it. It used to run hot all the time no matter what. So, I ordered a new thermostat. I also upgraded to late fans and I cleaned off a lot of crud built up on the front of the radiator. I drove it in the summer (No A/C) here in Phoenix and when it was about 90-100 degrees outside it would run right in the middle, to the 3 rd line in heavy traffic- fans blazing. So, now we are in the wintertime, it runs hot as hell!! It was 50degrees yesterday, Im driving 80mph and the needle climbs past the 3rd line is halfway between the 3rd line and the hot zone. I usually have to run the heat full blast just to keep the temps below the halfway mark when I drive home at night. Also, it takes forever for it to warm up in the wintertime. My best guess estimate is the Tstat froze at partial open or something. OK, so I got a new wahler T stat and I tested it this time. It didnt crack open till about 190 F and wasnt completely open till abut 200-210F!! it was usually fully closed by 180F So, why do these things have such problems with thermostats?? Should I order a low temp thermostat and just hope it opens by 180F? this would explain my hot running. According to clarks garage, the 3rd line in an early car is 97C, which is about 206F. If the thermostat installed in the car now is acting the same as my replacement one, then its not even fully opening until the temps are in the 200's and it closes off at about 180F lol....Any advice? keep ordering Tstats until I get one that works?

heavy fuel

sounds like it's working just the way it's supposed to, regulating the output temp to right around 190F. The thermostat doesn't really open all the way unless there is some other problem, but it is constantly modulating to keep the water temp up. the car runs the best that way, and the cooling system is most efficient. You might look for other problems like radiator blockage, water pump corrosion, whatever might keep the water from circulating properly.

Lizard944

This saga sounds familiar. I think I may have given my $.02 in a thread awhile ago on this. I had similar issues after putting in a new TS after a coolant change. Old one was good but I changed it "while I was in there." Always ran hot just below the third line after putting in the new one. Tested new TS in boiling water with a thermometer and it wouldn't open until ~200F. Should open around 180F (83C). Long story short, I put the old one back in (which opened right at 180F) and all is well again. Runs just above second line. This is one part I'd only buy at the dealership, since it will come with a two year warranty, or buy from a company that will exchange it, but I only paid $18 at the dealership.
--Lizard

sillbeer

Thanks guys for the input. Lizard, I bought this Tstat from pelican parts..Im sure I could exchange it, but I mean, if the one I got from them the 1st time runs hot, and now this new one from them doesnt fully open till 200F+, then this could be an endless chain of buying and exchanging Tstats. Is the Tstat from the dealer any different? still a wahler or is it Porsche specific?

joes

I'm afraid your radiator is trash. You could try and get it boiled out but I would choke up the money and get a new one. Also when you install a new t'stat drill 5 or 6 3/32 holes just below the center hole where there is some meat. Install with holes up. This allows air to bleed when you fill up the system.

sillbeer

you guys are sure the radiator is junked? I mean, the car runs cooler in the summer!! Is the T-stat supposed to not open until it reaches 20F over what it's rated at?

951jamie

I got a 71* thermostat from 944online and now my 1984 runs between the first and second marks.However I did find out that on the early cars they need to be bleed very well.My mechanic bleeds them and also pours coolant into that small hole on the water neck.

Calmchaos

i have kind of the same problem.
I just put in a new Tstat because my old new one was stuck open and the car never warmed up.
Now it warms up to the third line and just about stays there even when it's below freezing outside.
I'm thinking my radiator sucks (have thought this for a while).
But I want to switch my transmission in the summer so I wanted to wait until then so I can put in a radiator without those inlets for the transmission fluid cooling hoses.

I'll probably try bleeding it again first though.

sillbeer

yea, I have bled the crap out of this thing. I spent about an hour or so when I filled the coolant. I had the front jacked up, heat on and I did a variety of methods. I blew into the overflow tank, and then I ran the engine and used the coolant bleed port on the filler neck. I also drove it around and everytime I drove it, I would open the bleeder until all I would get was coolant.

Lizard944

Ok, do this experiment. Start up the car and let it idle until the fans come on. If the temp comes down to around the second line and cools off enough that the the fans kick off within a minute or so, then you know the radiator is ok as water is circulating through it. If the rad was clogged, the fans wouldn't cool the engine down much because of the constricted water flow and the fact that the water pump isn't circulating a lot of water at idle speed. "Heavy Fuel" had it correct when stating that the TS "modulates" in order to maintain a certain engine temperature. 200F is way too late for your TS to open and 180F is way too early for it to be fully closed. What's happening is that when you reach legal highway speed, with a lot of air passing over your radiator, it cools the engine below 180F, thus making your TS want to close or partially close. If your TS is "fully closed" at 180F, then it's probably partially closed at
~190F. This is what's responsible for your higher running temps.
You can confirm all of this by removing the TS. If the temp runs normal to subnormal, then the TS is the culprit, and you've also confirmed that your temp sender/instrument gauge is working properly.
Incidentally, my dealership TS is a Wahler. The bottom # are 83o, 04 05.
Temp rating and date of mfg.? Maybe they had a bad batch? I bought this in
March 07. If "05" means production date 2005, perhaps they had a problem back then that slipped by and were sold to the public. Just a theory. Seeing that Porsche was so good about recalling our water pumps or cruise control computers, I'm not sure how this could've happened.

--Lizard