1608 cylinder head issues

[18Fiatsandcounting]

OK, my turn to ask a question now. I pulled the cylinder head off of my '71 spider this morning, as I need to fix a spark plug hole that was pretty stripped. And of course, I found 2 other issues:

1) the middle head bolt on the intake side was extremely hard to remove, but I finally got it out. The problem wasn't the threads into the block, but rather the sides of the bolt were totally gunked up with dark grey crud that had almost welded the bolt to the smooth inside bolt bore of the cylinder head. Anyone ever seen that before? Indication of a problem?

2) Part of the inner "ledge" is corroded away on the opening in the cylinder head for the thermostat housing, the ledge that the thermostat would lay on if this engine had a thermostat in this location (I have the external thermostat). The top surface of the cylinder head (where the 4 housing bolts screw into) is fine, but it's that inner round ledge that's corroded. Any solutions? The cylinder head has never leaked coolant in this location. Can this area be welded up and a new ledge machined? Heavy dose of Permatex of one flavor or another (not my 1st choice, of course)?

The car has always run fine, and of course I went to change the spark plugs, found a stripped hole, and now here we are. Sigh...

-Bryan

[RRoller123]

Probably "galling", regarding the gunk.

https://www.youtube.com/watch?v=RCq-THCJhqQ

[18Fiatsandcounting]

Probably "galling", regarding the gunk.

https://www.youtube.com/watch?v=RCq-THCJhqQ

Thanks, and this might be part of the issue. I looked at things more closely, and here's what I found. The head bolt threads, and the threads in the block, were fine. However, the "channel" through the head, where the head bolt passes through, was filled with this charcoal grey gunk and causing the bolt removal problem. To be honest, it looks exactly like the soot buildup that you see in the combustion chamber or in the exhaust manifold, and so my conclusion is that there has been a very slight exhaust leak (perhaps over decades) into this head bolt area. Soot and oil and heat and years of time is likely a good recipe for some tenacious gunk. Maybe even gumpcukrus.

The good news is that I cleaned up the bolt with a wire brush and ran a drill bit through all 10 bolt holes in the head, and all is well again. To my knowledge, this engine has never been disassembled, and I have no idea how many miles the engine has on it since the speedometer is not original.

Anyway, today I'll clean up the head and drop it off at the machine shop tomorrow to address the spark plug threads and thermostat housing issues.

-Bryan

[RRoller123]

Classic gumpcukrus.

[18Fiatsandcounting]

Update: I got the gumpcukrus cleaned out of the 10 cylinder head bores for the head bolts, and all is well. The cylinder head is now at the shop to fix the spark plug hole stripping issue. Should be no problem. As for the corrosion on the thermostat housing opening in the cylinder head? My machine shop guy said to clean it up with a wire brush, and build up that "ledge" with JB Weld, and shape it using a razor blade, before the epoxy fully cures. He said this usually works just fine.

So, I should have the head back later this week. Meanwhile, valves look good, all studs and threads are good, and yes, I owe Dinghyguy some clocks. Different thread.

-Bryan

[dinghyguy]

Bryan
Got enough shims?
Cleaned your crankcase breather?
Cleaned your starter wiring connections?
Just trying to find things for you to do while waiting
Cheeers
Dinghyguy

[18Fiatsandcounting]

Yep, Dinghy, I have a whole shim set (5 each of all the shim sizes). Cleaned the breather, and I did the starter motor last year. So, to keep me busy in the interim, I'm rebuilding my bicycles. Finished one, now starting to work on #2. Hey, when my Fiat doesn't start, my options are: 1) try the Jag (almost as reliable as my Fiat), 2) ride my bike (usually works), or 3) ask my wife for a ride (embarrassing for me), or 4) walk.

-Bryan