M20 cylinder head service limits?

[mitchc]

SO I've identified a oil leak from the head above #3 exhaust port, due to overheating. I am going to pull the head soon, but am wondering just how much it can be serviced before it has to be scrapped. Do I need to start shopping for a new casting somewhere or is there much that can be machined on these things? I don't know if anything has been done to it before I bought the car, when it had just over 100K mi. (it now has 160K)
Any experieces appreciated.

Mitch

[E34-520iSE]

Firstly, get it checked for cracks. If it's crack free then you can rebuild it. Then have new valve guides pressed in (if necessary), skimmed etc, no problem. Here in the UK I had my M20 head skimmed for £15, the rest of the re-assembly was done by me. It took a few days but the car runs lovely now without having sooty piston-tops or a smoky exhaust.

HTH,

Shaun M

[mitchc]

Shaun, Do you know how much can be machined safely from the head to bring it back to the necessary flat surface?

Mitch

[E34-520iSE]

I certainly do - according to the Bentley manual the MINIMUM head height (top to face) after skimming is 124.7mm, so as long as your head's not warped, you could get three skims out of it (well over a million miles if looked after!). If I remember correctly there is a marked area in the combustion chambers, I'll have a look at my spare head for you tomorrow to double check.

HTH,

Shaun M