Overheating Z3 M44

[Paul Weller]

Hi All

I am getting overheating on my z3 and wondered if this is a known scenario;

Water level is stable and I believe I have successfully bled the system. Car drives normally and temperature comes up normally and settles at a normal temperature for a few miles, then starts rising up again.

I am able to stabilise the situation by putting the heater on full and speed 4 on the fan (not me as my temperature is rising fast!)

It all started when I overfilled the system and stupidly ran it for a few miles with a part undo filler cap to let a little water evaporate! It appeared to spit most of the contents out and took me ages to refill successfully without air.

Thought s are;

Pump must be pumping as putting the heater on it shows it is getting flow by the temperature coming off.

Assume it isn't the thermostatic fan as driving at a good speed on level ground it still overheats and the rad should be getting enough flow.

As I see the temperature stabilise for a little while I assume that shows the thermostat is working.

Could I have a radiator blockage reducing its efficiency? Or anything else?

Paul

 

[Slam]

It could still be air in the system, did you raise the front of the car whilst filling bleeding

 

[jonco]

It could still be air in the system, did you raise the front of the car whilst filling bleeding

Agree - also did you have the heater on as you filled the system? With the top off the expansion tank - give your rad hoses a squeeze which will help displace any remaining air.

 

[Sean d]

You may well have blown the head gasket when you ran it dry

 

[bessieblue]

Try draining the system down and refilling with front end raised

 

[Paul Weller]

Agree - also did you have the heater on as you filled the system? With the top off the expansion tank - give your rad hoses a squeeze which will help displace any remaining air.

Yes I filled the last time on a steep slope and squeezed both upper and lower hoses.

 

[Paul Weller]

You may well have blown the head gasket when you ran it dry

Oil is OK and I didn't let it get higher than just into the red. Performance is still good.

 

[Sean d]

Yes I filled the last time on a steep slope and squeezed both upper and lower hoses.

Its definitely worth raising the front, I did my 2.8 at the weekend and couldn't get the heater to blow hot, I jacked up the front and it was quite obvious when the air started to come out

 

[Paul Weller]

Its definitely worth raising the front, I did my 2.8 at the weekend and couldn't get the heater to blow hot, I jacked up the front and it was quite obvious when the air started to come out

Did the jack thing also and the the water level is stable. I might just drain the system empty and start again after running a rad flush product.

 

[Sean d]

Did the jack thing also and the the water level is stable. I might just drain the system empty and start again after running a rad flush product.

I've not run mine out yet so still might encounter problems, I did fit a new rad, water pump, stat and housing and belt tensioner pulley

 

[t-tony]

Is the radiator hot at top and bottom?

Tony.

 

[Paul Weller]

Is the radiator hot at top and bottom?

Tony.

top is yes. havent checked the bottom yet. will do though

 

[jonco]

...............I might just drain the system empty and start again .............

Might be the best thing. I made a mess of mine the first time I did it and had similar symptoms to yours. Even went as far as having a head leak test done.
Drained it and repeated fill but with front jacked up, heater on hot set and blower 2 and squeezed hoses. All then ok and has been on the further 3 occasions I have had to do a full/partial refill. Good Luck.

 

[Ianmc]

This is most common with the M44 (maybe others also). Almost certainly air in the system. Having replaced my rad (for other reason) was unable to get all the air out of the system by normal means. I ended up going for a decent drive with a bottle of antifreeze and a bottle of deionised water in the boot. When the temp went above normal I pulled over, let it cool a little, slowly removed the rad cap (with a big rag) and slowly topped up the level. Repeated this a few times and all was well.
Not a prescribed method and care needs to be taken, but it worked well for me. Have done 3/4K miles since and all is good.

 

[Mazza]

Hi Paul,
Sorry to hear that it’s still not running correctly.

I’m only just up the road in Bognor, so if you need a hand, PM me. ( can’t do this Friday, but ok any other time)

 

[Paul Weller]

Thanks for that, may contact you if one last go by me fails when I try Friday.

 

[Mazza]

Hi @Paul Weller

Has the overheating problem been resolved now???

 

[Paul Weller]

Hi Malc
No, should have got back to you but still in depression!

Saturday I drove up ports down hill and litrally beached the z3 up the grass bank in the car park at 45 degrees. Hadn't let any water getting there or got any more air out so I sm pretty sure now it's not air. I am getting more convinced I have blocked cores in the rad. So planning to get it out next weekend. Just before removing I sm going to run it with the top hose off to see if I hsve good flow from the pump,
Paul

 

[Mazza]

Hi Paul,

Sorry to hear that you haven’t got to the bottom of the problem yet.

If you need to get a rad, I bought my new one on line from a company in Swindon, but when the part arrived it came from NRF UK Ltd in the West Midlands. The item number was 53849 ( for my 1998 1.9lt 140hp M44 Roadster). Cost was £56.66 delivered.
Telephone number is 01327 300242

Had no trouble fitting it, and has been ok since installation about 3 months ago.

Regards
Malc

 

[Gremlin]

I had this problem just a few months ago I’d changed pump thermostat viscous fan and hub flushed system through and back flushed. I took radiator out flushed separate and back flushed. It would drive like you said then the temp suddenly climbed. It turned out to be a blocked radiator core. If you get a new rad go for the upgrade one from euro car parts the core has bigger tubes on than original one. It stopped my problem straight away but make sure you need is properly.