Z3 1.9 overheating problem

[Traindriver69]

hi all
Brought a 02 1.9 Z3 roadster a couple of weeks ago for my other half as it was her dream car well it's turned into a nightmare for me.
A couple of days after buying it the temperature gauge started rising luckily we were not far from home on lifting the bonnet I saw the fan was not running so started a bit of googling and looked at the fan switch.
I removed the plug and shorted it across and fan started running so thought it was that but after replacing it still the same also checking what coolant was in it there was just water properly been overheating for a while so I also replaced the water pump brand new coolant and tried bleeding it a number of times but it's still the same.
I have noticed that when the gauge starts to rise And I pull over to have a look parts of the radiator and lower hose are stone cold so the fan switch is cold and won't work.
My question is do people think it could be an air lock or could it be the thermostat the only way to lower the temperature while driving is to turn the heater on full any help would be very welcome.
Many thanks in advance.

 

[Sean d]

hi all
Brought a 02 1.9 Z3 roadster a couple of weeks ago for my other half as it was her dream car well it's turned into a nightmare for me.
A couple of days after buying it the temperature gauge started rising luckily we were not far from home on lifting the bonnet I saw the fan was not running so started a bit of googling and looked at the fan switch.
I removed the plug and shorted it across and fan started running so thought it was that but after replacing it still the same also checking what coolant was in it there was just water properly been overheating for a while so I also replaced the water pump brand new coolant and tried bleeding it a number of times but it's still the same.
I have noticed that when the gauge starts to rise And I pull over to have a look parts of the radiator and lower hose are stone cold so the fan switch is cold and won't work.
My question is do people think it could be an air lock or could it be the thermostat the only way to lower the temperature while driving is to turn the heater on full any help would be very welcome.
Many thanks in advance.

Sounds like its the thermostat to me @t-tony in fact I'd bet my Z on it, did you raise the front of the car when bleeding

 

[t-tony]

If you haven't replaced the thermostat yet that would be my next port of call. These cars can be very difficult to bleed. Drain out and catch the new coolant and then flush the system through with a garden hose, Disconnect the heater hoses and flush that out too.
Rebuild with a new 'stat and try again.

Tony.

 

[Bampz]

Hi and welcome from me in Pembrokeshire
I would try as Sean and Tony advice and when bleeding the system raise the front of the car and make sure heater control is set to hot as you fill system
Good luck

 

[Traindriver69]

The first time I didn't and the heater would not work when reving the engine so I raised the car and bled it again and the heater was working again but still overheating.

 

[Sean d]

The first time I didn't and the heater would not work when reving the engine so I raised the car and bled it again and the heater was working again but still overheating.

Just because the heater is working doesn't necessarily mean that all the air is out of the system, do as Tony says and when bleeding raise the front on a jack, I did my 2.8 recently and could not get the heater blowing hot, so raised the front and it erupted with trapped air,
Fill the system and replace cap, put heater on hot, fan low, open bleed

 

[Mazza]

The method as per Tony and Sean Is the way to go.

My 1.9 had the opposite problem as in running cold. I changed the thermostat, jacked up the front of the car, put the heater to full and filled the system really slowly ( after flushing with a hose) and bled the air out. After a couple of weeks found that there was a slight rad leak, so ended up puttting a new radiator in, and after refilling the system with the same method, it has been running ok ever since. I did find over the next couple of weeks the level was dropping in the expansion tank by a couple of mm as air was being push round the system.

Book version

 

[Traindriver69]

Hi all
Ordered a new thermostat off eBay which came today took the old housing off to find no thermostat in it why was I not surprised anyway put the new one on started up the Z3 and after a while coolant started pouring out from where the radiator hose connects to the thermostat.
Got my calipers out and discovered that the new housing where the hose connects was smaller than the old one so was not sealing so I got anotherone from eurocarparts and this one sealed fine bled the system and touch wood all fine.out of interested what is the wire for that plugs into the thermostat.
Many thanks