Head gasket, valve and piston question

mkmskm

mkmskm

Senior Member
My car suddenly started to overheat shortly after I had to loosen the ignition stud to replace the cable. Suspecting the head gasket I pulled the head today, but what do I look for? The valves at the front of the block looked almost a little surface rusty, the two rear exhaust valves kind of whitish. There is some carbon on the pistons as well - how should I clean everything up before putting on a new gasket?
 
Pistons, I scrape wire brush, steel wool the tops. the block Scrape all of the old gasket make sure you get around the studs good,use a shop vac to clean as you remove material, the head I wire brush on a drill to clean and check for flatness install with a copper gasket and copper spray.
 
On both my A,s I dont use the cable clamp.I carry a spare dist,already pre-timed to the engine that has a short armored cable with a plug in connector on the end that joins the wire between the wiring tunnel & the junction box.I can change the dist in about 2 minutes flat & be on my way. Maybe mkmskm, when you loosened the cable clamp it removed the torque at that stud & allowed water to seep into cyl & enough coolant was lost to make it overheat.It may only have needed to be torqued down again & topped up again to be OK.
 
I agree with columbiA and would have tried the car after filling the coolant and retorquing the head.
If the distributor cable clamp is to be off for more than a few minutes I'd reinstall the nut. A member in our club lost his new babbit job after the nut was off overnight and he didn't realize antifreeze had seeped into the cylinder and past the rings. It wiped out his new babbit job.
 
I always drain down the cooling system before messing with any head nuts. Been screwed to many times by water getting into the cylinders and crankcase.
 
the whitish valves are signs of running hot or running lean. If water were seeping in, the carbon would be gone from the area where it seeped. The steam cleans the area. Some combustion gases could have been seeping into the water jacket and caused the over heating, but now that the head is off, its moot what you should have done.

Clean the block thoroughly by scraping off as much of the gasket and sealer as you can. I like to use Rolok discs for the final clean up as they get all the old sealer, carbon, mineral deposit, etc. If the studs are in, be certain to clean well around them. Using a vacuum to suck up the debris as you work is a good idea. Before you button it up, draw down the pistons and clean any debris that got down between them and the cylinder wall. A final wipe down of the deck with a brake cleaner soaked rag will get it squeaky clean. Now would be a good time to have a machine shop check the head for true flatness and surface it if necessary.
 
I had retorqued the bolt and although it looked good from the outside it still got hot. When I pulled the head all of the pistons had light uniform carbon except #3 which had only some in the middle, the rest of the piston was shiny. This is the one I suspected was affected by bolt #7. The old head gasket was copper and didn't have much in the way of sealant as it came off clean. I scraped it clean and then wiped it with brake fluid. I ran a magnet tipped pointer and pulled a bunch of rust from the back of the water jacket. All but two of the head studs came out with the nut and the other two came out pretty easily but they all looked ugly so new ones have been installed. I painted the head and will put it back on tomorrow with a new modern style gasket. The funny thing is I pulled what looks like a barn nail out of the water jacket.
 
I've also pulled a few wires from blocks. Those wires are used in the casting molds, and a few often get left behind.
 
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