Do cast iron engines need to be machined during a head gasket replacement ?


Torque Junkie
Ford Focus mk2
I have a 2006 mk2 Ford Focus Sport 1.8 TDCI

Several months ago a hose came off and the car overheated for about 10 - 15 minutes.
After replacing the hose all was well for about 3 months, but then I notice it is loosing about 1 cup full of water per week but there are no other symptoms of head gasket failure , no oil/water mix, no obvious power loss, no smoke .e.t.c.

A chemical test revealed bad head gasket but am just wondering if that was from old contaminants from when the head gasket went last time.

So I'm planning on having the head gasket replaced, I was told by a mechanic friend that

A. - Because my car engine is cast iron the only machine work it will need is a head skim

B - He said if the block was cracked e.t.c. then my car would be overheating now, which it's not doing.

however, a different mechanic friend told me it would need the whole block pressure tested as well ?

which is true ?

Get the head and block examined before doing anything else.

I'll certainly be getting the head skimmed , can the block be examined by my friend who will be doing the work or does it need to be examined at the engineering shop ?
Do a compression test before the engine it's dismantled. Blocks rarely distort. It didn't sound like the grassy job had been done right. Hairline cracks inside an engine are notoriously hard to spot.
If you do need to change the head gasket then IMO the head should be checked for warping and if it was my car I would clean out all the carbon in the ports and at least have the valves reseated.

I would also clean up the inlet manifold runners if you want to do the job properly.

Similar threads

Please watch this on my YouTube channel & Subscribe.