To skim or not to skim?

the jester · Post by **the jester** » 25 Apr 2011, 10:27

I'm going to replace the cylinder head gasket on my engine,
I'm under the impression the head will near skimmed as a matter of course...

That's an assumption of mine based on ignorance,

Is this the case ?
Or is the head warping not the usual?

How will I know if it needs skimmed or not?

Thanks again

spider · Post by **spider** » 25 Apr 2011, 10:52

I would say have it checked to see if its flat (with a straight edge) or you can take it to wherever you were going to get it skimmed and they will check.

Might be worth having it crack tested too.

When I did mine, I took it and left it with them for a crack test and a skim, cost was around £60 (about eight years ago) although not sure if that was a good price or not. I'd taken the cam / buckets + shims out but left the injectors in (just covered the inlets with rubber glove tips and cable ties)

Post by **Peter.N.** » 25 Apr 2011, 15:01

There is a lot of work in changing a head gasket, I think it would be false economy not to have it skimmed or at least checked. I would replace the gasket with a steel laminate one if you can get one, they seem much tougher.

Peter

the jester · Post by **the jester** » 27 Apr 2011, 00:12

thanks guys
Im going to pull the head off and see whats in there...

there is an excellent machine shop in town, Im in Rallyville so the machine shop has a good reputation

dieselnutjob · Post by **dieselnutjob** » 27 Apr 2011, 23:16

it only needs skimming if it isn't flat
get it checked and act accordingly
last time I did a head gasket was maybe 15 years ago on my sisters car.
I polished the head with wire wool and it was so smooth you could see your face in it
It did create quite a bit of dust that needed cleaning up though
it did seal down fine
the car was a 309 1.9 diesel

citronut · Post by **citronut** » 28 Apr 2011, 07:51

only have as little as possible skimmed, as the more you have removed you will need to have the valves sunck into the seats,

because there is a minimum depth they can be or they will contact the pistons,

also i belive it is as important to slacken/undo the head bolts in the correct order, as it is torquing them down or re/fitting,

just crack each one off in the reverse order for torqueing them down,

so ever decreaseing circle startting at one end,

regards malcolm