First Problem with the Z4!!

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Evans_Dale

Member
 Birmingham
Wondered if anybody could help or shed some light on an issue with my Z4 3.0 2004 SMG

Started to notice that it was taking longer than usual for the hot air to come through the Air Vents about 30min or so, when it finally does come through hot its only for a minute or so and then it goes back to being barely warm. while this is happening the car temperature seems to rise past half way and then all of a sudden go back to being central and stay there. i am assuming this is linked but no idea where to start or what to change first.

Any Help is Appreciated
 
It's very hard to tell what's wrong without tearing the car apart to be honest

Just a few possibles:
- Any of the mix 'doors' aren't opening and closing properly inside the HVAC unit itself
- The air isn't being heated by the engine before entering the HVAC unit
- The ducts from the HVAC to the cabin are leaking / dislodged

Hope that helps :)
Probably doesn't.. :evil: :oops:
 
Are you getting hot air from any of the other vents ie windscreen. Check oil and anti freeze levels before you look at anything else
 
Without chance to test, my first suspicion would be the thermostat. But as raymond.harper quite rightly said above, check antifreeze levels first.

Andy.
 
is the engine temp needle taking long to get to 12 oclock position? if so it will be a faulty thermostat their cheap £35

what id do first though is bleed the system propelly. take cap off coolant start engine fill up expansion tank untill needle is popping out, put cap on let the car idle untill warm. Put heaters on full temp/speed. Then release the bleed nipple on the expansion tank very slowly untill you see coolant coming out. Then the system will be free of any air and fully bled. Check the heaters are now hot again if not open bleed nipple and bleed again untill heat is working inside car. If its still not working the other possible after would be your final stage resistor for the heater £40 or the actual heater matrix which is a lot. hopefully its just needs a bleed to get any trapped air out and that will work.

so could be

air lock (bleed system)
thermostat
final stage resistor
heater matrix
 
goldbcfc said:
is the engine temp needle taking long to get to 12 oclock position? if so it will be a faulty thermostat their cheap £35

what id do first though is bleed the system propelly. take cap off coolant start engine fill up expansion tank untill needle is popping out, put cap on let the car idle untill warm. Put heaters on full temp/speed. Then release the bleed nipple on the expansion tank very slowly untill you see coolant coming out. Then the system will be free of any air and fully bled. Check the heaters are now hot again if not open bleed nipple and bleed again untill heat is working inside car. If its still not working the other possible after would be your final stage resistor for the heater £40 or the actual heater matrix which is a lot. hopefully its just needs a bleed to get any trapped air out and that will work.

so could be

air lock (bleed system)
thermostat
final stage resistor
heater matrix
Click to expand...

Thanks for the Advice i will have a look at bleeding it over the weekend and see if that helps and get a thermostat as they are not that expensive and work up to the most expensive part.
 
yeah bleed system then if its taking long to get to the 12 oclock position on gauge the thermostat is most likley very common on a lot of bmw's. If the speed is irratic or blowing funny thats the final stage resistor sometimes known as the hedghog sensor fits under your stering whee. The heater matrix is last resortl
 
goldbcfc said:
yeah bleed system then if its taking long to get to the 12 oclock position on gauge the thermostat is most likley very common on a lot of bmw's. If the speed is irratic or blowing funny thats the final stage resistor sometimes known as the hedghog sensor fits under your stering whee. The heater matrix is last resortl
Click to expand...

Managed to get the car in the Garage yesterday and Bleed the system it took a while and several attempts but its fixed the problem and all is working well again although i did notice the smallest of leaks from the expansion tank so I've ordered on of those. thanks again for the help. :thumbsup:
 
Check the quality of the anti-freeze, previous owner may have used only water
 
yeah the expansion tanks are crap on the earlier bmw's one day it will just split and leave you with no coolant so its good you spotted it early.
 
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