Heating issue

M

Mrmct

Member
Hi all.

Bit of advice if anyone can help!

Z4 e85 3.0. Heating blowing cold on passengers side vent. Warm on the middle vent and hot on the drivers vent. Any ideas? Local garage has had a look and wants to take the dash out to work on the problem. Thinks there may be a blockage. There are two very small coolant leaks at the thermostat and bottom of the rad. I had to top up the expansion tank. Garage advises they bled the system too.

Don't really want to accept a massive bill if this is some known issue on these cars and I can try to resolve myself.

Thx
 
Get the leaks sorted, change the coolant and bleed the system.

If you have leaks, you’ll have air in the system.

:thumbsup:
 
1000rr said:
If you have leaks, you’ll have air in the system.
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This. The air will be drawn in and cause problems like the ones you describe. Fix the leaks, fill and bleed and you’ll more than likely be warm once more :)
 
Thanks both. I've heard these are a nightmare to bleed.

Would the leaks really cause the variation in temperature dependant on vent? Thought an airlock would give heat or no heat?

Is there any info on the best way to do it right?
 
I replaced my thermostat and waterpump earlier this week and bled it afterwards whilst the front was still up on ramps. I've bled the system once before after fitting a new expansion tank. It's certainly not a nightmare. I found it very straight forward on both occassions.
I would suggest you replace your thermostat and radiator, refill with fresh coolant and bleed it correctly. Fairly certain this will cure your heater problem. :thumbsup:
 
Not sure there’s any need to replace the radiator, but an airlock sounds the most likely.
 
I think the garage has the right idea. There is probably a sticking vent flap in the air handling system. This has been observed on other forums but the first I have seen on the Z4. You might free it up by switching from defrost to heat a few times. The foam they use to seal the flaps can become sticky.
 
The flaps are servo driven so have quite a bit of torque. I doubt they are likely to stick as such but maybe some kind of spindle failure or perhaps electrical / connection problem on the servo.
 
Mrmct said:
Just to add closure on this. New thermostat and full coolant flush/renew and we are all good again :D
Click to expand...

Just for info was it blowing cold from the passenger dashboard face vent or the passenger footwell vent ?
 
Mrmct said:
From either. Middle vent was luke warm, drivers slightly warmer again. But not hot.
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Different to mine then. Mine is hot on all dash vents and the drivers footwell burns your feet. the passenger footwell is blowing air but very cool.
Had the vents reset by DLV but it’s made no difference.
I’ve read some have restricted the flow into the driver footwell and that has improved the passenger side. It’s the only thing that doesn’t work on the car and on the rare occasion we use it in the cold we use the face vents and heated seats.
 
Have you tried taking the glove box out and manually making sure the valves are moving? This was my next thing to try before dash removal.
 
Mrmct said:
Have you tried taking the glove box out and manually making sure the valves are moving? This was my next thing to try before dash removal.
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I'll give that a go next spring when it comes out of hibernation :thumbsup: :D
 
Mrmct said:
Just to add closure on this. New thermostat and full coolant flush/renew and we are all good again :D
Click to expand...
Can I ask, was it the thermostat you replaced or the radiator temperature outlet sensor?
I have the same issue with cool air coming out of the left hand side, luke warm mid and slightly warm on the driver's side, have tried vacuum bleeding and still no joy.
I don't think there's an issue with the engine thermostat myself, but the rad sensor could well be duff, or more likely I damaged it during the first flush which is when the problems started :oops:
Cheers
 
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