Cooling system mystery

[franks]

My cooling system is over heating. The hose going into the radiator is hot, however the hose leaving the radiator is cold. 45 deg F outside. The gauge is at 3/4 and rising. I replaced the T'stat last night thinking it would help. I also have a bleeding screw leaking which may or may not be relevent. What is going on? See photo.

[632 Regal]

air in the system
the bleeder lets in air when the car is not running and you have to bleed it all out every time you start it now.
dont sound fun at all man.

[Kalevera]

Is the TSTAT correctly installed? I had the same problem on my M30 last month....it was due to the fact that the rubber gasket was in on the wrong side of the tsat -- interestingly, the old one was installed the same way and worked fine. Apparently, my new one needed to have the O ring on the tstat housing side.

oh, ya, like jeff says...bleed that sucka.

best, whit

[632 Regal]

now theres a picture...looks like it correct in that the top big hose is hot. Is it hot where it goes into the radiator too?

[emw525E34]

Hi Franks, I see thats an M20 engine. common problem is : there may NOT be enough coolant in the system. Take off the TOP Hose from Radiation to engine. The Engine inlet part, loosen the clamp and remove that hose. Pour additional coolant mixture until it almost overflows!. Replace the hose and clamp tight. Bleed some more and it should not overheat.

Or else, your Tstat (either not installled correctly or not working: Arrow pointing UPwards on Tstat). Water pump may be a problem.

Common problem is that insufficient coolant in system means steam just heats up the upper part of the hoses while the lower hose are still cool. ie no coolant circulating!!!.

Very common problem for the M20 motor. The top hose fill trick works everytime for me!. Good luck.

[Mr. BILL]

I learned a lot from this board last summer when I had overheating issues. It sounds like you've got air in the system. Especially with a leaking bleeder, which I assume is the one on the t-stat housing. Right?

If it is, then I suggest the following. You're going to have to replace it. When you re-fill the system follow these directions to the letter.

1. If you can, get the front end of the car as high as you can. Ramps would be good.
2. Make sure the heater control is on hot.
3. Drill a small hole in the rim of the t-stat at the top, (arrow).
4. Close the bleeder on the radiator and open the one on the t-stat.
5. Pour in gallon of coolant. BMW is best, Peak is OK too.
6. Pour in distilled water, you'll begin to hear air escaping through the t-stat bleeder.
7. When you "think" all the air is out, evidenced by a continual flow of coolant without bubbles or spitting. Top off the radiator and actually blow into the radiator neck to force coolant thru, eliminating any air left in the system.
8. Close the t-stat bleeder. Snug will do.
9. Open the bleeder on the radiator and fill with distilled water until coolant and no air /bubbles are evident. Then, top off and blow into radiator neck, forcing any air left out. Replace radiator cap.
10. Start engine and when temp comes up, open bleeder screw, allowing air/bubbles to escape. When only a streem of coolant comes out, rev engine to about 2000 RPM's for 15-20 seconds close bleeder.
11. Take car for a spin around the block, open bleeder until no bubbles, then tighten.
12. Repeat 2-3 more times.

That should do it.

Note, I take a wide mouth funnel designed for radiators, line it with a paper towel with a hole in it to blow into the system. You look/feel stupid doing this, but it woks!

Also, be careful not to overtighten either bleeder screw, snug will do.

Good luck.

[franks]

The gasket is between the t'stat and the cover.

[franks]

Yes, but it is real cold leaving the radiator and the temp gauge is on 3/4, ouch.

[franks]

Do rou mean the hose from the t'stat cover to the top of radiator. Or, the hose from the engine, exhast side, to the t'stat cover. I am not sure which hose you are talking about. I was also thinking of the water pump, but it is not leaking or making noise. How can you tell if the flow is correct?

[franks]

It is not the one on the t'stat cover it is the one on the radiator. I belive I have fixed it. The female threads had a small crack and a little special super glue for plastic seems to have fixed it.