rev 1 turbo problems with cooling system

[mr2mk2]

Hi all,

I have a track day booked for Tuesday but unfortunately I am having problems with the cooling system. We have tried bleeding it quite a few time over the past month or so because I can hear air in the heater core. Also, I keep having to top up the coolant even though there are no obvious signs of leaks. The hfh were replaced recently to cure a leak from them. It will drive a hundred miles or more with no problems but then could take it out and within a few miles the temp will rise towards the red. Let it cool down, top up and bleed and then everything OK again for a while. The radiator doesn't have the little pipe at the side of the bleed screw to attach the bleed pipe so I'm not 100% sure all the air is being bled out. I am now thinking that the cooling system is pressurising due to a leak in the head gasket as coolant is filling the overflow to the top and sending it out of the overflow pipe. Rad cap has been changed for a known good one. Does anybody have any ideas?

[bobhatton]

Hi all,

I have a track day booked for Tuesday but unfortunately I am having problems with the cooling system. We have tried bleeding it quite a few time over the past month or so because I can hear air in the heater core. Also, I keep having to top up the coolant even though there are no obvious signs of leaks. The hfh were replaced recently to cure a leak from them. It will drive a hundred miles or more with no problems but then could take it out and within a few miles the temp will rise towards the red. Let it cool down, top up and bleed and then everything OK again for a while. The radiator doesn't have the little pipe at the side of the bleed screw to attach the bleed pipe so I'm not 100% sure all the air is being bled out. I am now thinking that the cooling system is pressurising due to a leak in the head gasket as coolant is filling the overflow to the top and sending it out of the overflow pipe. Rad cap has been changed for a known good one. Does anybody have any ideas?

Sounds just like a head gasket problem

[mr2mk2]

Thanks Bob,
Track day is off then. Had similar problems on the track last year and then the HFH started leaking so thought this was the problem. Could the leak from the head gasket cause this to fail?

[3sgte]

Check the coolant pipes that go to the heater . They run above the fuel tank .

Not immediately obvious unless you remove the under trays and see if there is evidence of leaking either in the form of rust marks on the fuel tank or wet on the upsides of the under trays .

You can also loosen the heat shield on the bulkhead in front of the engine and peel it back to check the pipes that way .

Definitely worth checking before you start pulling your head off

[mr2mk2]

Thanks, will do. There are no under trays on the car so will be easy to check.

[MartinF]

Make sure you check the radiator cap, if it's old and not sealing properly you could be losing coolant.

[mr2mk2]

Yes thanks, I've checked this, I put a new one on it not so long ago and have checked it today with a known good one that had no problems on a n/a. Both 0.9 bar.

[mr2mk2]

No signs of leaks from heater pipes that run above fuel tank.
I guess a compression test will show a pressure loss if the combustion gases are leaking into the cooling system. Is this correct and what should be the pressure for the cylinders?