Thread: Coolant tank pressurising

You can do a gas test on the coolant, also check for bubbles in tbe expansion tank and a new rad cap is cheap, just in case that isn't releasing at its designed pressure before you condemn the head gasket.
BTW, do you know what type of gasket was used ?
Composite or MLS ?

Thanks Rick

I'll try a cap first...

Not sure what was put in to be honest - it was done by a reputable Canberra Landy mechanic. Didn't know much about them at the time so didn't think to ask.

Ive read/heard good things about MLS - so if the cap doesnt fix it up...

Originally Posted by KevG

Thanks Rick

I'll try a cap first...

Not sure what was put in to be honest - it was done by a reputable Canberra Landy mechanic. Didn't know much about them at the time so didn't think to ask.

Ive read/heard good things about MLS - so if the cap doesnt fix it up...

My first head gasket (LR original composite) blew at over 400,000klms (odometer stopped working at 387K), IMO the head gasket blows because the head warps between 2 and 3 cylinders and the gasket blows.
Was the case with mine and many others I have read of on this Forum, even after machining the head the new composite H/G blew shortly after. Replaced with good quality composite H/G but didn't remachine head, gasket blew again, so replaced composite gasket with steel shim gasket and still unmachined head and have had no problem since. IMO the warping of the head causes the composite gasket to blow, even after machining the head the gasket blew again in the same spot and the depression in the head was back. I believe the composite gasket cannot handle the warped head, whereas, in my case at least the steel shim gasket is standing up well after nearly 2 years of use (Knock on wood), Regards Frank.

Basic checks before head gasket are:
-check for leaks (even if everything is relatively new)
-new cap as Rick suggested
-check for bubbles in expansion tank

However I still think head gasket is most likely.

If the head gasket has started to leak, but not completely blown, it will not appear to overheat (especially with factory temp gauge), but will still use coolant and increase the cooling system pressure. Unfortunately it still points to head gasket going VERY soon. Catching it at this point is actually great, because you can avoid the overheat and any further damage. Continuing to drive it without a more accurate temp gauge than the factory one is risking engine damage.

Thanks gents

I have also had an hour or so Sunday tightening up all of the clamps on the hoses - a couple were a little loose. Took off the thermostat fill point and topped the coolant up - seemed to take a fair bit - maybe I just had an air lock. With everything topped up started the truck, warmed it up with the cap off - a bit of surging but no bubbling of concern. There were little bubbles that looked to be from the surge. Hand over the tank opening I couldn't feel a pressure build up. Heater was running nice and toasty in the car.

I'm wondering if I have had a bit of an airlock as the result of a loose clamp...

I've ordered a new cap so I'll drop that on when it arrives and see how it goes.

KevG

Keep the old cap as a spare for emergencies, Regards Frank.

All a bit weird - got rid of the airlock, popped the new cap on and the coolant level has sat at the top of the level indicator post for the past couple of weeks.

My best guess is that betweena faulty cap and a couple of loose clamps were at fault, glad i didn't go down the path of the head gasket.

Thanks for the tips all

KevG

That's a great result.