Search This Blog

Tuesday, January 31, 2012

Head Gasket Replacement

A low top speed in 4th gear suggested that something was wrong. Adjusting the timing didn't help. A drop in compression in cylinders 2 and 3, and no indication of problems in the oil or coolant, suggested a blown head gasket. Taking the cylinder head off showed that was in fact the case, and so the gasket is in the process of being replaced.

It's turned out slightly longer to do than normal, first due to a slight bit of damage to the fibre covering the metal core of the replacement gasket the first time around, which allowed the coolant to leak out. The fibre covering is quite delicate and comes away from the metal core easily.

Head off again, a replacement gasket was installed, and all seemed well, but then when starting the engine, there was a fairly loud ticking noise which suggested that something metal was hitting something metal in the head or rocker cover.

An initial investigation seemed to indicate a pushrod wasn't seating correctly in the tappet cup, but when the head was off again a detailed look at the tappets, rollers, pushrods, rockers and camshaft surfaces indicated that everything looked in great shape. I may have just maladjusted the tappet clearances, in spite of it being relatively easy to do, but to be safe I've asked that Steve come over and have a look at things, to be sure.

Other than that, taking the head off is not a difficult operation, but having done it three times in one week, I've found ways to make it more efficient each time! It's also been a great excuse to clean everything up.

Below, cylinder head removed, and engine block covered while waiting for Steve's next visit. Cylinder head is suspended from engine hoist.

Rocker assembly prior to removal. Tie wraps prevent the springs from pushing the assembly apart when lifted.

A handy way to make sure all bolts and pushrods are reinstalled in the same order they came out. The rocker assembly was later taken apart, cleaned and inspected. The springs don't exert much force, so disassembly and re-assembly was pretty easy.

Rocker assembly removed, and head disconnected from everything.

The old copper head gasket. Can you see where it's burned through? : )

Carbon on the pistons:

In case you missed the burn-through: : )

After the initial cleanup. Tappets and rollers have been taken out, cleaned and inspected, and the camshaft surfaces inspected, as well.

3 comments:

  1. I have never considered pulling the head with the manifolds attached! I think I am going to do that very thing now. I have a lot of water in the oil and I am hoping it's only a blown head gasket. I had some minor head work done quite a few years ago, but relatively few miles since. It was actually just idling when it let go and starting eating coolant....

    ReplyDelete
    Replies
    1. This comment has been removed by the author.

      Delete
    2. I think that as I learned more, the final gasket replacement only took 25 minutes. Leaving the manifold on certainly helped. :)

      Delete