Thermostat issues

[MadKiwi]

Greetings 44ers,
My '84 944 started running hot, with the bottom rad hose staying cold, so I gave it my standard running-hot first-defense tune up:
- New coolant cap
- New Thermostat
- New bottom rad hose (just in case it is collapsing under pump suction -- now an area of personal paranoia after this solved a problem on another car).

So, now things are worse.
I appears that the thermostat never opens. Temp climbs steadily all the way to the other side of the guage. Bottom hose stays cool. I have bled the system ad nauseam. Hot, cold, running, with & without rad cap, heater on etc.
So, here's my idea:
What is the plastic elbow on the front of the thermostat housing? Looks like it is for a hose connection, but it is blocked off.
What if I drill this thing out and connect a hose to it. The other end would go to a T-junction on a hot hose at the other end of the motor (e.g just before the heater valve). This should dump a bunch of hot water on the T-stat.
Ideas?
Is there a classic 944 solution to this that I don't know about?
Thanks for any help.

[AA_Ezra]

Hey,
First of all that Cap on the watter pump ( white or yellow from age ) its a cap For the Turbo waterpump So it has a updated turbo water pump and the turbo has and extra hose that connect's to that piece that is blocked off and goes who knows where but it doesent matter.
I had the same problem this is what i did.
1st when you drain the Radiator and you need to fill it up again you have to make sure you get all the air out. This is what i do
1. Refilll it with phosphorus free anti freeze. to the mix you need in youre climate
2. Open up Presure relife bolt witch is located At the top radiator hose ( some are on the hose itself, or on the thing the hose clamps on to ) just enuff where you can see the lil hole
3 Open up the Resivoir cap
4. Get you're garden hose and turn on the watter
heres the fun part.
5. Have you're cresent wrench handy. with the watter hose on kink it so the watter stops flowing and put the hose in the resivoir release the kin so the watter goes forced into the tank
6. once the watter startes flowing out of the bold you unscrewed and no more air is comming out reach over and tighten it.
7. Tigthing screw with wrench and not to tight put rad cap back on and you're done no more air

2nd you want to check and make sure that the ground cable that is on back of the manifold ( should be about 3-4 brown 12 guage wires bolted down) is tight and not lose b/c when its lose it makes you're temp guage to whakey and it goes really hot and sometimes jumps making you're gauge off and you think its over heating. for me i turned the car off turned it on ACC and it read sometimes normal temp but turn the car on for like 1 min an it jumped to hot.
When you start the car in the morning or whatever time of day it will take the car like 10 min for it to reach about half way point sometimes even longer so it's safe to say if the car overheat's that fast then you got's probly a lose ground.
Hope this helps leme know if you can't find the ground i'll try to send a pic

[Britwrench]

The thermostat is not opening. There are a variety of reasons for that:



There is an air bubble in the system because it wasn't bled properly.
(more than likely)

The thermostat is faulty or installed the wrong way round. (pulling the lower hose will confirm that)

The water pump is not pumping (very unlikely)

The cooling fans won't come on due to low coolant temp in the radiator.
With no coolant circulation, the engine temp gauge will read into the "very hot" area of the gauge.

This assumes you used the correct parts, had the manual available and there were no outstanding problems before.
The block-off plate is for other 944 models. You don't need it

[MadKiwi]

Thanks for the responses. Sounds like the bleeding method involves a precise formula of chanting and sacrificial virgins. I'll drain the system and start again, or is there a reliable method of getting air out once the system has already been filled and run?

One thing I forgot to mention: on other cars (with the t-stat at the top of the motor), I have usually drilled a 1/8 hole at the top of the t-stat to aid in air-bubble removal. I did the same with the new Porsche t-stat. On the Porsche, the flow through the t-stat is in the opposite direction from "usual." Any chance that the tiny flow of coolant from the cold rad directly onto the back of the t-stat is enough to keep it from opening?

thanks,

[AA_Ezra]

Its Posible, to get the air out with the system already full. Just untightned that bold on the top radiator hose or the screw on the hose itself wichever you have. and force water into the resivoir tank w the garden hose and as soon as you dont hear any more bubbles coming out tighten it and then remove the garden hose.

[MadKiwi]

How do you "force" the water into the resevoir? Seal around the filler neck with hands as much as possible?!?

[AA_Ezra]

Yep, watter is going to flow out that's no biggie I Just put the hose inn and the thread's on the tip of the hose cover it as much as you can with hands it's kool if watter comes out, whats importand is that you keep enoug watter from coming out the resivoir so that that the bolt you untighten get's all the air then eventualy the water forced out so theres no more air in system, let go the hose so watter still flows out that screw tighten it and then go back n take out the hose. Presto chango you're done and hopefully heat prob is gone

[NKN84944]

Umm you don't need to force water into the reservoir! Refer to this thread where I posted the procedure from the garage shop manual. Basically you open the bleeder screw and fill the reservoir until coolant starts coming out of the bleeder screw. Then start your car with the heater on and watch the coolant coming out of the bleeder screw until air bubbles stop coming out. Then you close it up and away you go. You can force bleed it from the coolant reservoir, but this may not get all the air out as it doesn't circulate as well.

[Britwrench]

There's no need to "force" water into the system...follow the manual and all will be well.

[premius maximus]

I like to run my:

'92 968 MO30 cab 3.0L (w/ 97K miles) &

'83 944 (200K miles) WITHOUT A THERMOSTAT.

...THERMOSTAT DELETE OPTION!

...I always allow the engine to warm up in a starting idle, (watching the temp gauge) before rolling off of the paddock and whacking the throttle.

The instructions for burping the liquid coolant system in the Haynes manual are good. Also, if you haven't flushed or back-flushed (reverse-flow direction flushing) your radiator, that may be something to consider. A fresh air-tight gasket on the liquid coolant reservoir cap, or new cap, is important. Don't worry about connecting the turbo-coolant hose to your water pump. A good radiator without internal corrosion, and plenty of un- (thermostat) -obstructed water pump liquid coolant flow-rate should suffice. I live in Alabama. It gets very hot here.

I will never go back to using a thermostat, unless I move to Germany or Chicago with winter-time driving. I'm not sure about Kentucky. I know it gets plenty cold there in the winter, but when you summerize your liquid coolant system, you could seasonally delete the thermostat. Otherwise, for me, thermostats are not worth the risks of their inevitable and surreptitious failures.

Premius Maximus !!!!

[hpaulb]

Allong the same lines. Rebuilt the car last spring. Heat never got above the first bar and everything was hunky dorry. My wife takes it out yesterday and notices it in the red? Takes her two hours to get across town to park it in my brother house. Kept stopping to let it cool till is was ok to proceed. Now what in the world would cause a properely working car to do this. A friendly guy stopped and checked it out. Fluids were ok and no leaks. She said there was no heat. She remembered this as a little trick I'v used in the past with cars that overheat. Turn the heat on full to get you were you need to park. I'm thinking the thermostat was bad. Maybe that's why the car never got that worm. Always open. No it stuck closed and overheats? Anyone seen this before.
?

[MadKiwi]

Thanks to all who responded with advice. Here's an update:

Yesterday I bled the system per instructions (started motor with the bleed screw open, ran it this way until motor hot, fiddled around in ways I cannot recall). The thermostat would not open.

So I removed it. Takes longer to warm up, but it gets to half way quite nicely. In traffic this morning, it did not dip below 1/4 on the guage.
This is good enough for now. If one day I run out of things to do, I may revisit the 944 t-stat issue. But I may be dead by then.

[MadKiwi]

Opens fine on the stove at the indicated temperature.
When cobined with Ragu, the overall effect was Kraut flavored.