Overheating Problem No Solution found??

[Bogdan Crisan-Lupa]

Hi all,i am new on this site.
I have my z3 m44 1.9 143 hp.
One problem-
So,i checked everything,i changed the water pump brand new,thermostat,i checked if the radiator is blocked somehow it is not.
My engine overheats when i go on the motorway.It goes really fast to red,and when i switch on the heating in the car the needle goes down to the normal temperature.I have bled the cooling system,i have zero leaks,i checked my engine central gasket and it is absolutely fine.The car works as it should but i need to have the heating in the car switched on at all times. I have been to 3 workshops no one knows what the problem is.
As a sympton only half of the radiator heats.The down part to be exact,while the upper part is cold as ice. I checked the radiator for blockage and path is clear.
I have a viscous coupling,no electric fan no air conditioning.
Is as simple as it gets,yet i haven't fixed it.
So,Please i need some advice from someone who knows,or someone that had this problem before.

Thanks.

 

[t-tony]

Have you a) tried it with no thermostat fitted?
And b) Tested the thermostat in a kettle to ensure it is opening fully and at the correct temperature?

Tony.

 

[Antm72]

Sounds like the rad is blocked you may be getting flow but only through half the rad.
A rad hot at the bottom and cold at the top is air locked or blocked. It should uniformly heat in my view.

 

[t-tony]

Across the full width of the radiator. Hot at the top gradually cooling towards the bottom.

Tony.

 

[Sean d]

That sounds like trapped air at the top of the radiator

 

[5harp3y]

I'd be replacing the rad

 

[Bampz]

Hi, did you have the heater on the hot setting when bleeding the cooling system ? And some members have recommended raising the front of the car to help bled the air from the system

And welcome to the forum from Pembrokeshire

 

[Bogdan Crisan-Lupa]

Thanks all for replying and just to confirm i have been to 3 different mechanics.We tried everything,we tested everything. We even changed the water pump,thermostat and these 2 parts were in absolute working condition.
My car overheats on the motorway if the heat switch in the car is turned off and if its on the temperature is normal until i go above 160 km/h.
After that i can't do amything about it i need to slow down and turn the heat on the 4th position. Its horrible in the summer even with the top down.
My guess is that the water heater valve has a problem. I ordered a new one and if it doesen't work i'll buy a new radiator as well.
If you have different opinions let me know. I need outside the box thoughts.
Thanks again

 

[t-tony]

Thanks all for replying and just to confirm i have been to 3 different mechanics.We tried everything,we tested everything. We even changed the water pump,thermostat and these 2 parts were in absolute working condition.
My car overheats on the motorway if the heat switch in the car is turned off and if its on the temperature is normal until i go above 160 km/h.
After that i can't do amything about it i need to slow down and turn the heat on the 4th position. Its horrible in the summer even with the top down.
My guess is that the water heater valve has a problem. I ordered a new one and if it doesen't work i'll buy a new radiator as well.
If you have different opinions let me know. I need outside the box thoughts.
Thanks again

Good luck Bogdan, I hope you can get the car working OK. Merry Christmas.

Tony.

 

[Bogdan Crisan-Lupa]

Good luck Bogdan, I hope you can get the car working OK. Merry Christmas.

Tony.

Thank you tony
Merry Christmas

 

[Pingu]

You say that you bled the system.

Did you follow the correct procedure?

https://www.newtis.info/tisv2/a/en/...anuals/17-cooling/17-00-cooling-check/2T8RcXP

especially the part about turning the heater to MAX, and selecting fan position 1. You need the ignition ON.

Bleed it like that to start with, then run the engine as described.

 

[handsomejackuk]

never had to raise the front of mine to get it bled just followed the instructions with the heater fan switch on number 1. bit of a squeeze on the rubber hoses usually is enough to get the air out... check and recheck a few times the coolant tank level when cool and mine has been all good.. i only changed out the thermostat have had the water pump off and ideally should have changed it, also did get the radiator off and back flushed the radiator both ways to make sure its nice and clean...

best of luck with it....

 

[FRANKIE]

Hi all,i am new on this site.
I have my z3 m44 1.9 143 hp.
One problem-
So,i checked everything,i changed the water pump brand new,thermostat,i checked if the radiator is blocked somehow it is not.
My engine overheats when i go on the motorway.It goes really fast to red,and when i switch on the heating in the car the needle goes down to the normal temperature.I have bled the cooling system,i have zero leaks,i checked my engine central gasket and it is absolutely fine.The car works as it should but i need to have the heating in the car switched on at all times. I have been to 3 workshops no one knows what the problem is.
As a sympton only half of the radiator heats.The down part to be exact,while the upper part is cold as ice. I checked the radiator for blockage and path is clear.
I have a viscous coupling,no electric fan no air conditioning.
Is as simple as it gets,yet i haven't fixed it.
So,Please i need some advice from someone who knows,or someone that had this problem before.

Thanks.

Welcome to the forum from Egg Harbor Township, New Jersey. I'm trying to think of what the problem is given all the information you have provided. I was once fooled by a faulty thermostat into believing that my car was actually overheating. I'm assuming that you know for a fact that the car is overheating and it's not just a false reading. A loose drive belt or faulty tensioner for that belt could cause the water pump to work improperly. If those components are operating correctly, then I have to look at the facts. It would seem that normal operation is enough to overheat the car. Adding the extra cooling capacity of the heater core gives enough of a cooling capacity to bring the operating temperature back to normal. Running the car at higher speeds and thereby increasing the cooling needs of the engine at the higher rpms proves to be demanding too much of whatever cooling capaacity your radiator and your heater core can provide and the car once again starts to overheat.
I believe that is why the other forum members as well as myself, believe that there is a blockage, either air or another obstruction in the radiator. Again, this is assuming that all the other components are operating correctly. I could be wrong. I once saw where an old rubber water hose would collapse at times and interfere with the flow of coolent. Please keep us informed on your progress in solving this problem.............Frankie

 

[raymond]

I would try a kenlow fan to cut in a little earlier and perhaps "waterless" coolant https://www.evanscoolant.com/ My neighbour uses it in his Caterham and speaks highly of it. In the eighties I had a droopsnoot Firenza. After an engine rebuild it melted plug leads and over heated like crazy. Turned out to be the timing was a few degrees out. Could your car have a similar problem ie cams not set up correctly ?

 

[handsomejackuk]

you can monitor actual engine temperature with an obd reader and the torque app i use it a lot its good to view other engine statistics too... mine will also verbally inform me when engine temperature has been reached... it would be good for you... my engine temp reaches about 97 degrees withing 3 miles of driving usually quicker if i am under load travelling uphill.. it will also drop by about 3 degrees when i turn on the cabin heaters...

21200872_353840258385727_7698799074940566206_o by handsomejackuk, on Flickr

21558953_358177424618677_6608485237815440445_n by handsomejackuk, on Flickr