theis has always happened to my car e30 m40-m42,even when i changed engine, everytime i turn on the air cond,temp rises,maybe its the dodgy little electric fan for the aircond,its got white blades,are the other m40 fans white?

My small electric fan is black. Most likely some other part of your cooling system is not working properly or has a leak/etc.

no leaks,fan clutch ok,newskool blades(not them noisy ones)only problem is when i turn on the aircond,but then its a good way to get my temp up,otherwise takes ages to warm up...

How old's the radiator?
What kinda coolant mixture are you using?
Thermostat is the correct temperature spec?

radiator is as old as the car..1991,bme coolant,thermostat??duno,even with the old engine with a new thermo didn't help...

Well just some ideas:
- Radiator is old, maybe the fins are clogged or certain flowpaths are broken (by stones etc) so the efficiency is not as good already.
- Thermostat might be the wrong spec, i.e. the temperature at which it opens and lets coolant flow through, if it's too high, then it opens too late and the engine can't cool down enough. But I doubt this tho since M40 already uses one of the higher temp ones - 88C

same thing with my old daihatsu rocky,aircond on= temp up!thnx for the ideas!!

for a age of the radiator of 91, it should have been made into a front end of the new 5... re-cycled...hehehe

it's the radiator... borrow a good used one and try it for a few days.. see what's wrong...by the way, is the radiator the overflow tank together or the M20, pre-Ljet or the motronic type ?

yep together,will try to source another radiator...thnx!

okay dunno might help or not

your aircond on baru temp naik, logically speaking if u using electric fan, when aircond on, the electric fan running at the same speed, whereas it should runs quicker, the engine idling oso faster since the ecu detects tension driven by compressor belt therefore engine temp naik but cool air by fan is lower.

Kalau air radiator cepat habis, radiator is working kalau tak bocor, if not it got to do with waterpump or thermostat and maybe your electric fan switch.

Ntah betul tak pun tak tahu, try luck lah nih

Nak tanya satu soalan sebab aku x brp paham sgt sistem BMW ni mcm mna.

E30 aku bila start je enjin fan trus jalan. Is it normal or the fan is wired direct?