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View Full Version : M20 headgasket replacement : stupid questions !



Zeuk in Oz
01-10-2006, 01:39 AM
So far so good, sons 1 & 2 are actually working together (wonders will never cease) and we are just about to remove the head.

Following Bentley it would appear that to set the timing to TDC we must
remove the timing belt. Is this correct ? There is no other way ?

I also then presume that the timing belt must be replaced as it will be de-tensioned, even though it is only 3-4,000 km old ?

To take the head to be tested and / or reconditioned, should we remove the exhaust manifold or intake manifold or both ?

What is the best thing to clean the head and other parts with as they are coated in that chocolate like mixture of oil and water ?

Sorry to ask such stupid questions, but Bentley presumes some knowledge that morons like me don't have !

By the way, Jeff, I have searched for these answers but came up blank ! :p

Cheers,

Bo

mattyb
01-10-2006, 03:12 AM
hi zuek, i cant answer any of those questions but daveM was rebuilding his a few weeks ago ,with pics and all.

E34-520iSE
01-10-2006, 05:13 AM
Hi Bo, I've had my head off a couple of times so I think I can help!
TDC is marked on the front flywheel/pulley.
The exhaust manifold & intake manifold need to be unbolted from the head and tied to one side out of the way before removing the head.
Cut the cam belt off to save mucking about with the awkward bolt on the tensioner. Once the head is off the tensioner is easily removed.
Unbolt the head removing the bolts in the Bentley order.
To clean the head before inspection buy a tin of engine degreaser. The instructions are on the tin.
Have a local machine shop check the head for cracks, as they are common in overheating M20's. They may recommend skimming.
You MUST replace the cam belt and ideally the tensioner too.
The new belt can be (carefully) pulled through the small gap between the lower casing and the front pulley.
After re-assembly bleed the system thoroughly to prevent overheating problems.

Hope that helps!

Shaun

632 Regal
01-10-2006, 03:10 PM
rotate the engine until the timing mark is at TDC. remove the intake and exhaust on the car so you can pull the head, i dont know about the belt thing.

Zeuk in Oz
01-10-2006, 04:25 PM
Hi Bo, I've had my head off a couple of times so I think I can help!
TDC is marked on the front flywheel/pulley.
The exhaust manifold & intake manifold need to be unbolted from the head and tied to one side out of the way before removing the head.
Cut the cam belt off to save mucking about with the awkward bolt on the tensioner. Once the head is off the tensioner is easily removed.
Unbolt the head removing the bolts in the Bentley order.
To clean the head before inspection buy a tin of engine degreaser. The instructions are on the tin.
Have a local machine shop check the head for cracks, as they are common in overheating M20's. They may recommend skimming.
You MUST replace the cam belt and ideally the tensioner too.
The new belt can be (carefully) pulled through the small gap between the lower casing and the front pulley.
After re-assembly bleed the system thoroughly to prevent overheating problems.

Hope that helps!

Shaun

Thanks Shaun,

More or less what I thought.

Fortunately the engine has never overheated so I am hoping the head will be OK - we will have to wait & see.

Zeuk in Oz
01-10-2006, 04:27 PM
rotate the engine until the timing mark is at TDC. remove the intake and exhaust on the car so you can pull the head, i dont know about the belt thing.

Thanks Jeff,

Love the snowman ! :D

632 Regal
01-10-2006, 08:26 PM
HAHA he had a joint in his mouth but someone stole it
Thanks Jeff,

Love the snowman ! :D