Hi,

I have a Sierra Cosworth 4x4 and the header tank is swelling and header tank cap is venting off once car has reached normal operating temperature.

I have checked the compression and all cylinders are 150psi +/- 5psi. Bubbles can be seen however coming from the turbo coolant return pipe to the header tank. Exhaust is not smokey.

How does the water flow through the turbo? Could the exhaust gases be leaking in here somehow?

At my wits end. Please help!



Cheers,
Pete.

 

Unfortunately, compression tests don't tell you everything.

I had exactly the same compression readings (150) on my engine, which overheated when used hard (with more restrained driving, temp was normal), and air bubbles to the header tank from the turbo return.

Head gasket - say no more.

 

Thanks very much. It's good to get advice

 

if you want to prove it 100% connect the turbo return straight to the water pump outlet then the air cannot come from the turbo.

 

sorry to say, but it could also be a cracked block. would open up more as it gets hotter. i had that fault. but you could be lucky and it could just be HG