M50 w/ M42 Radiator = No Heat / No Temp Sensor?

[RobertK]

Alirghty, on to my new problem..

Now that the car starts I tried to bleed the cooling system today. First thing I noticed is that the temp gauge is not working, second is that heater is blowing cold air, and third is that I cannot tell for sure if the tstat is opening.

Now I have searched and just want to confirm with the M5x/S5x veterans on what I need to fix this. Here is what I have gathered, if you can please confirm.

1. Swap E30 coolant temp sensor into the M50? (Which one blue or brown?)
2. The spider hose should be connected to the upper heater core hose and the hose coming from the cylinder head should be connected to the bottom heater core hose for the heat to work?
3. The incorrectly installed spider hose might explain why there is an air bubble in the head no allowing the tstat to open correctly?

[318isbmw]

Alirghty, on to my new problem..

Now that the car starts I tried to bleed the cooling system today. First thing I noticed is that the temp gauge is not working, second is that heater is blowing cold air, and third is that I cannot tell for sure if the tstat is opening.

Now I have searched and just want to confirm with the M5x/S5x veterans on what I need to fix this. Here is what I have gathered, if you can please confirm.

1. Swap E30 coolant temp sensor into the M50? (Which one blue or brown?)
2. The spider hose should be connected to the upper heater core hose and the hose coming from the cylinder head should be connected to the bottom heater core hose for the heat to work?
3. The incorrectly installed spider hose might explain why there is an air bubble in the head no allowing the tstat to open correctly?

I believe I used the brown one from my old m42. Can't remember for sure though, but almost positive.
Spider hose should be on the bottom one. Realoem has a diagram of the system on there, and they even have it labelled which is the in and which is the out flowing in the system. That definitely helped me for reference on the cooling system.

[RobertK]

I believe I used the brown one from my old m42. Can't remember for sure though, but almost positive.
Spider hose should be on the bottom one. Realoem has a diagram of the system on there, and they even have it labelled which is the in and which is the out flowing in the system. That definitely helped me for reference on the cooling system.

When I did some searching I found one reference that said that spider hose connects to the top heater core hose.

Post #2

http://www.r3vlimited.com/board/showthread.php?t=94514&highlight=coolant+open&page=2

Which one is it?

Also, I need to purchase a M42 coolant temp sender to replace the M50 sender?

[mongule]

If your wondering if your T-stat is opening, just put your hand on the rad, it should feel warmer to the touch, and also the top hose should be warm.

Make sure you bled it well, as I had a t-stat not opening due to an air bubble after I was sure it was bled. Jack up the front of the car, it helps alot.

Use the brown temp sensor from the e30.

If all your getting is cold air the hoses are crossed.

[mongule]

double post.

[RobertK]

Ok, the top hose is warm, and radiator gets hot BUT I swapped in my E30 temp sender and my coolant gauge is still not working. The temp gauge worked just fine before the swap and I'm 100% sure the connection on my cluster is good.

Do I need a different temp sender? The one I'm using now is from an early model M20 - with 1 prong. I noticed the M50 harness has 2.

[mongule]

Yep my temp sender also has 1 pin and works fine. I'm leaning towards a wiring issue here.


Your thermostat is opening.

[RobertK]

NM... Is working now, bad connection.

Radiator bleed was sucessful and heat is working great now.

[mongule]

Allright man good show.

[318isbmw]

NM... Is working now, bad connection.

Radiator bleed was sucessful and heat is working great now.

Sorry bout that, was going off of memory. Glad its workin out now.