Head Gasket

[agilchrist]

Will a bad head gasket be apparent by looking at it?
I had white smoke from the exhaust, and the radiator would pressurize as soon as the engine started.
I pulled the head, and the head gasket doesn't have any obvious tears. The head and block appear flat using a straight edge. Should I put it all back together w/ new gaskets? Or do I need to pull the block and have it and the head magnafluxed?

Early 85 NA 944

[KEV951]

cant mag an aluminum head, there is a different process. look for darker spots or areas on the gasket,

[John_AZ]

I had the same issue. White smoke just after start up.

Get the head to a shop and have them do a 3 angle grind on the valves and a couple thousands off the bottom. Your straight edge is not accurate.

The shop will check to see if the valve guides are worn.

Here is a link on how good shops check for cracks:
Bennington Motorsports

Get new head nuts.
There are a few other things you should do with the head off.

GL
John

[agilchrist]

??? My Haynes manual says to check flatness w/ a straight edge and feeler gauge. If that's not accurate, should I rig up something with a dial gauge?
The valves were replaced & ground and new seals installed ~10k miles ago. I'm hoping they're still good. The engine overheated, that's why I suspect the head gasket. Would that damage the valve guides?

[John_AZ]

Depends on how high the temp was and how long the engine overheated. Your first post only mentioned "white smoke".

You could take the head to the shop you had the machine work done and have them check.

The valve guides should be OK with just 10K on the head.

GL
John