E36 Cooling System Help Needed

[Teezy_F30]

Olaz Fanatics .. so been helping my cuz work on her car .. its a 1996 E36 318i Motorsport 1..

her radiator needed a change for a while now, so she eventually got one from Silverton Radiators .. changed the Radiator .. filled her up with coolant/water mix as directed .. started car up .. ran fine .. but ... heres where problem 1 comes in ...
RHS hose gets moer hot .. LHS hose is ice cold .. therefore no water was flowing through .. we let the car cool down, stripped out the thermostat .. tested it in boiling water .. and well the 18yr old original part was expected, not working ..

since we were changing thermostat, i suggested to her we do the water pump aswell .. so i sourced a Bher Thermostat and Hepu Water pump with metal propeller ..

Saturday we got to changing the parts .. thank God we decided to change the water pump .. there was not much of the plastic propellers left on the original pump .. So all good and installed .. cleaned the engine up a bit .. filled up new coolant/water mix .. bled the system for air .. started car up ..... and exactly the same as last time .. RHS pipe gets very hot .. LHS hose is ice cold .. ( this is determined from standing infront of the bonnet looking at the engine .. ) so its the drivers side that remains cold ....

no we dono wtf is going on .. but noticed that the radiator fan starts spinning as soon as the engine starts .... is this normal?? ..... this is problem 2..
we unplugged the fan from the switch on the side of the radiator .. after about 5 mins, the hose on that side starts warming up, so this would mean that water is now flowing through .. plug switch back in .. 5 mins, that pipe is ice cold again ...
is it possible that the switch is faulty? thats the reason the fan is continously running?

any help and advice would be much appreciated .. :thumbs:

 

[Matty27]

I had a mate of mine with the same problem on his e46 compact, and for him it was the same faulty fan switch the bottom LHS hose also stayed cold. As with cars it could be many things, but I would start there. Hope you get it sorted, I know with the e46 you have to replace the whole unit, but that is just my 2 cents.

 

[Major]

Sounds to me like your system still needs bleeding. Did you fit the thermostat correctly with the arrow/hole pointing to 12 o'clock? Remove the radiator cap and loosen the bleed screw, run the system until it's warm, put the heater on full blast, squeeze the upper hose, etc, and see if you're still getting bubbles. If that works and you do get air out the system, let the car cool down completely overnight and make sure you fill it up again in the morning as levels will drop when cold.

As for the fan, I'm assuming we're talking about the electrical fan, does it start spinning as soon as the engine starts first thing in the morning? If yes, temp sensor is faulty, but it doesn't solve your problem here. Otherwise it's doing it's job, and that's why when it's on the hose goes cold and when it's not working the hose warms up becase, well, you've turned off the fan that's meant to help cool it down. I don't think you're getting proper coolant flow in the first place, and the temp sensor could well be picking up hot vapour and not hot coolant.

 

[Zound]

What you are experiencing is normal in my opinion but I'm not sure if you have bled the system properly, very important!

What's happening is that your temperature sensor on your cold (left) hose has not reached the threshold temperature to allow flow through that pipe. I believe it needs to reach about 91 Celsius before it starts to allow the coolant to flow and cycle through the engine block. The engine is first allowed to get to operating temperature before the cooling system starts managing the temperature. You can monitor and see this happening live time if you have telemetry from an OBD2 type tool.