Coolant issues again

[Matt-B]

Ok let me start by saying i have an m50 NV in a 318is

-M42 rad
-m20 82 C thermostat (replaced this a few days to see if it was the issue)

I had my heater core hoses mixed up, but now there on again in the right spots...


my problem: Lower radiator hose is cold, upper is warm/hot

and my temp sender ( later m20, single brown prong) is not registering on cluster, basically it never "warms up"
still blow cool from heater vents with heat on


thoughts??

thanks guys

[Jand3rson]

Tested your thermostat?

[Matt-B]

I can test the 1 i replaced when dinner is over i suppose :(

will they all open in boiling water?

[Van Westervelt]

Always had one of these in the kitchen growing up, and they work perfect to test thermostats.

[BlapBlap]

Im having the exact same problem. And still havent figured out the issue...

[Boosted E30]

Water pump?
Maybe a kink in one of the coolant hose's going to the heater core or somthing like that.

Otherwise having the upper hose warm/hot and lower one cold usually the cause is a air bubble, if your T-stat is working properly.

[samiam3356]

Jack the front of the car up a bit. While the car is warming up squeeze the upper hose when it starts to warm up. It will take a while to get the bottom hose warm. Blower on the car set to high and on full heat. Shouldn't take more than 20 minutes.

BTW is your valve for the Heater core on the top or bottom?

[Matt-B]

its on top

[CorvallisBMW]

Sounds like t-stat is not opening properly. Test it, and bleed with the front end jacked up.

[Matt-B]

I did that and bleed it at wishno's house...i guess Ill re do it...


I really want to make the picnic

[LJ851]

Sounds like a stuck thermostat OR a big air bubble somewhere .

[Matt-B]

I will re-bleed today and check thermostat for it to work in boiling water, now that hoses are fixed at heater core

[Matt-B]

And another question, is the radiator cap suppose to draw in air from outside? mine seems to seal the system 100% and when i crack it, i hear air going in

[CorvallisBMW]

No, the system is under pressure not vacuum. Yes it is supposed to seal 100% to maintain pressure, when you crack it you are hearing pressure escape. When the engine is hot, crack your bleed screw. You'll see steam escaping, not being sucked in.

[LJ851]

And another question, is the radiator cap suppose to draw in air from outside? mine seems to seal the system 100% and when i crack it, i hear air going in

On an expansion tank style system like bmw uses the cap is for sealing and pressure relief when necessary. It is not at all uncommon for a little pressure to escape during engine operation , particularly if higher temperatures are achieved. When the system cools it will most certainly create a vacuum which would be obvious when you open the cap . My bone stock M20 does this all the time. This is not your problem, tho...