It started out innocently enough...Doesn't it always? When I took the car off the road in November 2006 the cylinder head had developed a slow weep between cylinders 2 and 3, just above the engine block number plate. In this picture you can see the greenish coolant where the head meets the block. Trust me, its there - just above the engine number plate, below spark plug number 2. You see it. I know you do.
No problem - whip off the head, change the gasket and we're good to go, right? Not so fast. Late model heads are prone to cracking in this region. Max Fulton at Flying Circus English Cars also told me that late model blocks can sag in this area, or the block can pull up around the studs. So what could it be? Its an old British car - how could it be anything but a simple gasket failure?
I drained the cooling system, unhooked the hoses and took off the valve cover and rockers. Here we are after backing off the head nuts in a spiral pattern as described in the shop manual. Check out the stud with the nut still on. It unscrewed easily directly from the block. Interesting....
When pulling the pushrods angle them to the side so the tappets will stay aligned. Its important to remember the order so I pushed them through a box and labeled each. Wow - look at how professional I am.
With the pushrods out I unhooked the manifold and pulled it back away from the head.
At this point you can lift the head away from the block. That is what the manual says. Reality was more complicated. The head was stuck to the block at the stud indicated by the green arrow. I could rock it up and down on each end but it is stuck in the middle! Blue arrow shows the location of the weepage and red arrow the stud the screwed easily out of the block.
I repeated applications of my new favourite penetrating oil (hmm, that sounds dirty) Kroil www.kanolabs.com over a period of a few days to the top of the stud and where the head meets the block. I also applied some light heat from a propane torch and some gentle tapping with a hammer on the top of the stud. After a few days it came loose! What suprises will be found underneath?
Cylinders 2,3 are similar to 4.
And now for something rather different! Cylinder 1 has carbon but has a light grey appearance. This may indicate a gasket failure resutling in coolant "steam cleaning" the top of the piston.
The location indicated by the green arrow was full of "grit" that reminded me of a hard water scale or buildup. More evidence of a failed gasket.
Here are the valves. These look okay but only a pressure test will tell definitively.
Now its off to the machine shop for pressure testing, magnafluxing and a valve job, assuming all goes well and no cracks are found in the head. Could it be that easy?
