I think it is great that he is trying to save you money. However, I
agree with Gamini that it will be a bad failure when it goes. head
gasket failure can mean having to mill the head back to flatness if it
gets too hot and warps. Diesel heads sometimes don't take too kindly to
this. I can't remember exctly why, but I think it has to do with how
close the coolant passages are to the bottom of the head. I would
really suggest having the head gasket done before it does you in first.
Just my two cents.