Headgasket failure

[Rik]

So the last few years we've had a multitude of coolant leaks: Waterpump, multiple hoses, cracked header tank etc. Also had to top up the level in the header tank many times, while the overflow tank stays at a steady level.

The new header tank we put in is now completely spherical after the system has been overpressurised. We also see bubbling in the header tank when the cap is removed. Conclusion: blown headgasket.

This overpressurisation is likely the cause of all our earlier failures too. My first question: Is there any other possible cause, besides the headgasket?

Second question: how can overpressurisation happen? Isn't the dalek cap supposed to keep the system at about 1 bar?

Thanks!

[mioba]

If its a JX. The heads cracks between the valves leading to what you describe. Gets worse when hot as the heat expands the cracks.

How old is the head.

Either way you need to remove the head to determine. JX heads can(not) be skimmed. Tolerances are so low if too much metal (over 80 thou) is taken off the valves will kiss the pistons.

[mioba]

As a side. Your blue cap sounds like it failed if a JX. It vents to the tank behind the licence plate and sucks back in.

The main tank should not pressurise to the extend to describe.

Again assuming a JX

[Rik]

Thanks. It's a CS, i figure the same applies then.

It was a new cap, but i've heard before they're often a bit "pooh" quality

[mioba]

Same applied with a CS.

Are you handy to DIY and have Bently.
These engines are damn eaay to work on if you can the above.

[Rik]

Relatively handy but no experience with the insides of engines.

I do have the Bentley as PDF somewhere, I'll check tomorrow. I feel I can probably do most of the stuff but I am a bit scared of everything to do with the injection pump.

[mioba]

Its. all in Bentley.

You can get all the tools cheap
enough online (injnction pump kit inclides cylinder locking tools)

You will need to do the timing belt and tensioner. Its all easy if you can follow instructions

[Rik]

Thanks. None of the vw-specialists in the Netherlands can do it in time so I might actually want to do it myself.

I did check the Bentley and most seems quite straightforward. Next to a new cambelt and pulley, anything specific I should know?

And what specialty tools do I need? The pulley tensioning spanner, pump locking pin and cam locking thingey i know, but i also saw something in the Bentley about a specialty tool set to align the gasket itself?

[mioba]

There are a couple of studs to align the gasket.
They will be in the block so no issue.

Make sure you have good quality (12 point i think) for the head bolts They are v tight for that first 1/2 turn and a breaker bar.

wobble bar extensions for the manifold nuts/bolts.

Be ready to buy a new head.

Seriously. Just follow Bentley and take your time.


measure piston protrusion to determine notches on HG.

Elring do all gaskets kits you need.

Final tools. BW order page at the ready.
Swear box.

[Rik]

Thanks Mioba! I've decided i'm going to try it, will be ordering the parts in the coming days. Really hope the head is fine...

Unfortunately no BW for me as I live abroad.

More questions might be coming after I've started

[clift_d]

The service info for the CS is in the same service guides as the JX, which I think contain a bit more info than Bentley - I've sent you a link to download them.