m20 running hot and cold...

[drools]

My (e30) m20 has been acting wierd lately...In traffic & extended idle, it starts to overheat (eventually approaching 3/4 mark). Scary stuff when waiting for a green light...But once I get going, it quickly swings to the cold side. Even 40-50km/h will drive the temperature gauge almost down to 1/4 mark. On highway ~140km/h, it's UNDER 1/4 warmSo I have 2 theories:1. The thermostat is stuck half-openMeaning not enough flow to radiator @ idle, hence over heat. And too much flow to radiator during driving, hence "overcooling"2. The temperature gauge is broken (not likely)Now, 2 questions:1. What's wrong with my car?! #1 or #2 or something else...2. How to check whether a thermostat is working properly?

 

[dvng]

could be fan clutch, radiator leak (hence losing pressure therefore cooling is not efficient), check coolant hoses, check expansion tank cap, check electric fan for a/c (see whether it is kicking in during operation of a/c) all these could contribute to overheating...

 

[bmwky]

most likely your fan clutch shot oledi.

 

[moots]

i'll bet someone else's balls it's the fan clutch.....

 

[E34EuroTouring]

1) Fan Clutch.
2) Water pump. Is that functioning properly. Easy to determine.
3) termostat: either stuck half closed. replace that if , it has been years since you last change it.
4) Flush coolant. Put 50% distilled water and 50% BMW green coolant. I find about 4 litres coolant to 6 litres of distilled water is sufficient.

You might want to check if your Aux fan is working when the A/C is on. A non-functioning Aux fan will cause overheating at the stoplight/idling when A/C is on.

 

[tyke]

either fanclutch,thermostat.
get it checked at ur mech dude.
btw,how u been?havent heard from u in a bit!
congrats on ur wedding againg bro.
rgds,
-brad-

 

[Zoggee]

Originally posted by E34EuroTouring@Aug 5 2005, 03:52 PM
1) Fan Clutch.
2) Water pump. Is that functioning properly. Easy to determine.
3) termostat: either stuck half closed. replace that if , it has been years since you last change it.
4) Flush coolant. Put 50% distilled water and 50% BMW green coolant. I find about 4 litres coolant to 6 litres of distilled water is sufficient.

You might want to check if your Aux fan is working when the A/C is on. A non-functioning Aux fan will cause overheating at the stoplight/idling when A/C is on.

as i say before...you shud be the guy la.. to get the IAD award for technical contribution.

happens to me .....too..!! :beaten:
I was advise to do all that you posted. but the radiator flush/service thing is good.

 

[2cents]

Originally posted by Zoggee+Aug 5 2005, 11:48 PM-->QUOTE (Zoggee @ Aug 5 2005, 11:48 PM)

 

[SimpleSoul]

I ve got the same prob. overheats while stationary with Ac on without Ac its fine on idle... If its running, it will go back to normal.
So far I ve change the fan clutch, electric fan, thermostat and flushed the radiator twice.
What else is there to be done?