Got my Z back from having a new radiator, water pump, cam belts, iridium plugs, accessory belts and it overheated again. The radiator bottom connector had cracked off and so the water was gushing out. I assumed this was why it was overheating - the water drained out after 30 mins of driving and began to boil.

I drove 2 hours back from Wigan to Leeds with no probs but as I stopped at home the needle went into the red. Hiteq tested the head gasket and compression and said it was OK. They did 50 miles in it with no probs.

No water missing this time just hot.

Fans are all working correctly.

Before the radiator burst the car overheated three times for no apparent reason with about 4 months between each incident.

Could this be the thermostat and how much are they? What's involved in changing it?

 

Oh dear, sounds like you're having the same problem as I have been having ever since I got the Zed back in June.

 

Got told the head gasket was gone, not so.

 

Got told the radiator needed recoring, did that and still overheated.

 

New thermostat, rad cap etc., still overheated.

 

My suggestion is you take it one bit at a time to eliminate different causes. You've already changed the radiator, so that should be okay. Next change the thermosat. I know you've had it done before but it is possible that the new one was not working propperly or was even for a different type of car (happened to me - Nissan put in the wrong thermostat - twice!). Next I'd advice you to change the radiator cap. The bleed valve could be stuck and cause it to overheat when stationary (when in motion the cool air rushing over the engine might just be enough to keep it from overheating.)

 

All this may not help you but it is a start. Let me know how you get on because I'm still struggling with the same issue.

 

Oh yes, before I forget - fill up your expansion tank with about 600ml of coolant. When the engine gets very hot it will need extra coolant. If the tank is empty the engine will overheat.

 

Cheers mate!

 

Danny

Thanks for that.

I spoke to Hiteq again and he said it sounds like a circulation problem. Could be a blockage somewhere which needs pressure flushing out or possibly just a bad airlock.

He recommended filling the system up through the rad bleed screw hole instead of the rad cap as normal. Said it will take a few goes to do and let the bubbles settle out but it gives better results on these cars apparently...

Worth a go anyway until I get the 'stat replaced.