E85 Z4 Suspected Head Gasket

[Ddoooooon]

Hi Everyone

Wonder if someone might be able to assist with some expert advise . I suspect I have a head gasket issue , wont know until I strip next week with my mechanic . Only issue I had with my Z4 was the water pump ( we all know the coolant systems are complete shite )

Anyway replaced that last year & also the bleeder nipple on the coolant pipe .

All was well , the problem I now have is that the motor is very thirsty for water. There are no water leaks , but the water is boiling after driving and also having to top up water at least every 2 days . The temp gauge goes past the half way mark like its going to overheat then re-sets itself perfect in the middle where it should be.

Can anyone advise if they have had this problem what was the cause & how you went about sorting it out ?

From what Im seeing I suspect its the head gasket , could be the seals but not sure .

Appreciate your help.

Many Thanks

(Based in Cape Town)

 

[Solo Man]

Had a problem with my son's 1999 E46 328i which blew the expansion tank. Upon replacing the tank and bleeding it started overheating after a short drive. Eventually replaced both the waterpump and thermostat (i thought that the waterpump impeller might have come loose but it was fine and no leaks from there) and after bleeding had my obd reader on the car and went for a drive whilst monitoring the exact temp of the engine/water. It would go up to max of 96 degrees and then come down to about 92 hovering around there depending on the gradient of the road whilst travelling. Been checking it against my own 3l Z4 roadster and found the temp to be much the same when travelling. My conclusion is that the thermostat got stuck in the closed position which caused the overheating and hence the burst expansion tank. That car uses the electrical thermostat as on the later 3l i think. I suggest you replace the thermostat and see if the problem is solved. Must just add that there was no milky stuff in the oil, no air bubbles in the expansion tank upon starting the car and no water leaks. If you want to make sure about the head gasket being blown or a crack in the head, take it to silverton radiators where they can do a gas leak test on the radiator which should tell you if you have exhaust gas in the water which normally points to a blown gasket or cracked head. We did not test the 328i for that as we took a chance upon it being the pump or thermostat. They charge R150 for the rad test, btw.

 

[Ddoooooon]

Thanks Solo Man , I appreciate your response . I was thinking it could have been the thermostat as that was the only part I did not replace when changing the water pump and the way the needle was moving and re-setting led me to think it could be the Thermo. Will do the radiator test and see what it comes back with.

Can I ask where did you get the replacement Thermostat? I know BMW will have , but are there any other stockist ?

Many Thanks

 

[Solo Man]

Sorry for the late reply, only saw your reply now. My son bought the thermo from Goldwagen i think. The agents are about double the price. Fitted perfectly. Febi i think it was.

 

[Ddoooooon]

Sorry for the late reply, only saw your reply now. My son bought the thermo from Goldwagen i think. The agents are about double the price. Fitted perfectly. Febi i think it was.

Appreciate it , im off Thursday so going to get started on it and see what needs to be done .