Helicoil Cylinder Head Bolt

[tartan18]

The cylinder head bolt nearest the firewall and on the exhaust side needs to have the treads renewed. I noticed coolant leaking and when I tried to tighten the bolt it stripped the threads. The bolt is 8mmX1.25X50. I have never done a helicoil repair so I could really use some expert help. I understand the basic steps -- get the proper kit, drill out the hole, tap new threads, insert the helicoil -- screw it down into the hole, and then break off the small "tang." I also know about putting grease on both the tap and drill bit to keep metal shavings to a minimum.

Questions -- I am guessing that this bolt does open to a coolant source. Is that right and if so should I use some sort of sealant (ie locktite)?

The bolt that I took out has the threads beginning about 25mm below the bolt head. Do I only thread the helicoil until it is just below the top of the hole as the instructional videos show or do I screw the coil further down into the newly threaded hole?

What else do I need to know to not mess this up?

Thanks for all your help.

[So Cal Mark]

if it's 8mm it's not the head bolt

[tartan18]

Here is the location of the bolt in question. It is located next to the firewall and just below where the distributor used to be located. I installed the Allison Electronic Distributerless Ignition system.



Now I understand that I have to take the cam housing off to get the helicoil installed. Thanks Mark.

[grittracing]

i dont know why you would have coolant coming from anything right there! If anything it would be oil. Look at your hoses closely make sure something isnt leaking there. If not you may have head gasket issue.

[tartan18]

Today I had time to take the cam housings off (both the exhaust and intake). On the exhaust side I discovered that four of the holes had already been helicoiled. I will helicoil the far left lower one which is the one that I knew was stripped and I might go ahead and helicoil the others just to insure that I won't have to come back in here again. On the exhaust side there were also several bolt holes that had been helicoiled -- and again I plan on doing a preemptive repair on at least one bolt hole that looks suspiciously weak.

I am worried about the coolant leak on the exhaust side. There wasn't any coolant in the oil so it has to be coming from right below the cam housing bolt. There wasn't any coolant leaking from the coolant hoses that are near by. I am suspecting that gritracing is correct in that it might be the head gasket. Darn






This work did give me a chance to take out my old Weber 32 ADFA carb as I will be getting a new EMPI 32/36 from Allison Automotive shortly.

[azygoustoyou]

Darn that Gritracing!
Good luck on your fix and keep us updated on it all works out.
Thanks for the pic's too.

[tartan18]

I went ahead and took off the head. Once the cyl head was off I can't see where the cyl head gasket was breached. Overly cautious on my part.

I took the cyl head assembly to a local machine shop this afternoon. Here are a few pictures of the bottom end of my motor. Should I go to the expense of having this bored and such? Who knows the condition of the rings and pistons ??? Should I just bite the bullet and get that done ???? Is it wise to let sleeping dogs (Fiat engines that ran well( lie) ??






What else should I do while the engine is so broken down ???? I am thinking of replacing the starter with the newer gear reduction type such as sold by Mark. Thoughts ?? I don't have unlimited funds so I need to prioritize. I am also a rank amateur and I'm feeling that I am way over my head.

Thanks guys and gals

[tartan18]

My car is a 1975 with a 132A1.040.5 engine (non California).