1.25 Zetec Blown Valve

Hi,

Just looking for some general advice here. I help someone look after their 2000 Fiesta 1.25 Zetec which has been run on a very tight budget - so a serious lack of servicing over the last three years has seen it up to 122,000 miles. It has been drinking oil for some time now and smoking on startup and we suspected worn valve seats. Last Sunday it lost power with a severe misfire. It was towed to a garage and diagnosed with cylinder number 3 having zero compression. No further investigation's been done but the general consensus is that no.3 has blown a valve. They don't think it's the head gasket but the head has not been removed.

Given that the owner has very little funds to repair the car and the rust bug is starting to bite, it's not economical to pay the hundreds of pounds for a garage to repair it.

I have some limited mechanical knowledge and thought I would ask if anyone could tell me how costly and involved it would be to do one of the following myself:

1) Replace the damaged valve(s) and have the head skimmed before refitting the cylinder head

2) Get a used cylinder head from a scrappy, have that skimmed and fit it

Re. 2, can I use a Mk4 1.25 cylinder head? I am aware there are slight differences between the Mk4 & Mk5 1.25 engines but don't know if that extends to the head.

Any advice or suggestions much appreciated! If it doesn't seem viable it'll get scrapped but would be good to give it a reprieve, cheaper than a replacement car.

Thanks,

Phil