E34 535i underheating

[Ricky318i]

As opposed to the other thread in this subforum, my car seems to constantly under heating.
My temperature takes long (+/-30mins of driving) to get to half temperature and then cools to about 1/4 when cruising, coming to half again when stuck in traffic.

like seen here in this pic:

I notice my car runs much better and is lighter on fuel when warm, but runs rich when trying to get to half temperature (as is it probably should do).

Could this be an indication of a thermostat stuck open?

 

[Nikhil]

yep thermostat is acting up.

 

[Fordkoppie]

Good time for a coolant flush while you do the thermostat as well.

Those auxiliary heater solenoids on the e34 don't take kindly to old/dirty/wrong mixture of coolant.

BTW - this is also where you bleed the system

 

[Ricky318i]

Good time for a coolant flush while you do the thermostat as well.

Those auxiliary heater solenoids on the e34 don't take kindly to old/dirty/wrong mixture of coolant.

BTW - this is also where you bleed the system

Hi, I've done the coolant flush recently and replaced the dirty water with a 60/40 mix. I am planning a thermostat replacement and might even just replace the water pump while we're at it.

 

[thisISmyothercar]

Good time for a coolant flush while you do the thermostat as well.

Those auxiliary heater solenoids on the e34 don't take kindly to old/dirty/wrong mixture of coolant.

BTW - this is also where you bleed the system

Hi, I've done the coolant flush recently and replaced the dirty water with a 60/40 mix. I am planning a thermostat replacement and might even just replace the water pump while we're at it.

Good idea, I'd recommend doing both water pump and thermostat as both are fairly inexpensive and prone to failure.

We're no mechanics but my father and I managed to replace the radiator, water pump and thermostat on his e34 520i in one go on a Saturday morning many years ago. It was also running cold but behaved perfectly after we replaced everything. Just be careful not to break any plastic clips

 

[Zound]

yep thermostat is acting up.

+1

 

[Luis Malhou]

also look at checking if the viscous fan is operating correctly. If the viscous is stuck it will keep turning at high velocity all the time.

 

[Ricky318i]

This turned out to be the thermostat that was missing. :hammerhead:

Installed a thermostat and working fine for more than a year now.

 

[bmw69]

This turned out to be the thermostat that was missing. :hammerhead:

Installed a thermostat and working fine for more than a year now.

Mine was missing the thermostat as well and behaved the same.
I assume because the viscus wasn't working and that's how they "fixed it".

 

[Ricky318i]

My viscous fan is working fine. So I have no idea why they did it. I've driven in traffic in 32deg heat outside with no problems.

Just wished my aircon worked through

Sent from my E6653 using Tapatalk

 

[bmw69]

Just wished my aircon worked through

Sent from my E6653 using Tapatalk

My aircon also didn't work at first.
Found that there was no gas in it so the switch prevents the aircon from turning on.
Filled it and found a massive leak at the condenser.
Replaced that and its working.
Now the compressor just makes a noise at idle but otherwise works.
Hopefully yours just needs a re-gas.

 

[Ricky318i]

Could you tell me where you had it re-gassed and if they filled it with old R12 or the newer R134a?

Sent from my E6653 using Tapatalk

 

[bmw69]

Could you tell me where you had it re-gassed and if they filled it with old R12 or the newer R134a?

Sent from my E6653 using Tapatalk

I had it done at loud and clear in Table View.
Couldn't tell if it was the old or new, thinking its the new one.
Can give them a call and ask what they have, 021 557 4155/6.
Mark is the owner.
Its not cheap though, about R550 for a complete refill with die to find any leaks.
Not sure if there is any other way to find leaks for an aircon without actually re-gasing it with die, don't know much about them other than the fittings are different between the Old R12 and the new one.