I was just coming to the end of my Triple SU conversion and all was going well. As the coolant was drained, I decided to go ahead and replace the distributor with a vacuum advance one and push on HT leads. While removing the old HT leads I loosed the head bolts to remove the HT lead sleeve bracket and found one loose, and it just spun. I pulled the bolt and it moved up a couple of inches so I believe I have a broken head stud. I managed to remove the head bolt by clamping the stud shaft with locking grips and ratcheting the bolt.
I am almost afraid to ask, but what is the way forward with this. Does the engine have to come out or is this something that can be worked on in place ?
The engine was running well before this with good compression so was not planning a rebuild. Any advice appreciated as I am a bit worried about this one.
I have a similar situation and will eventually have an head gasket leak. I don’t know how long that stud was gone already, could be years. From an accessibility point, engine out will be better as the stud needs to be removed from above and through the frost/welch plug.
The main problem on long stud engines is that the coolant will escape here or blow the stud out through the hood. Repairs are either by removing the stud, bodging it with a time-sert and a short stud, or re-machining larger threads and using a one-off head stud for that particular one. I try to keep driving until something gives and hope that I can then replace the whole engine.
The good news is that the stud was almost gone anyways. Either you source a new block or engine, or you remove the head and do an incomplete repair that nobody here will like. That, or engine out for a while.
Sorry.
David
Ps-from the first picture it might be possible that you removed the stud instead of the nut, but I doubt you hadn’t noticed that. It would pay off to get the SU’s out of the way and inspect the welch plugs, same as I will tomorrow.
It shows the cylinder head stud lengths and their location in three arrangements depending on engine # (your Series II is likely the long-stud engine). Check the stud length against the chart. Does it look like the bottom-end threads have sheared off? How about a pic?
On 40 degree type mornings I will get a little dribble of coolant down the side of the block just a little bit aft of the distributor. So far though it always stops once I get a little heat into the engine. When I first noticed this about 17 years ago I checked torque on all the head acorn nuts and they were good. I have not tempted fate and tried to remove any of them since. I keep a close eye on that spot (and the coolant level) and luckily so far it has never gotten worse so I too will keep driving it until something gives. I think it really runs good especially for a 51 year old engine.
So after a week of licking my wounds I will start looking at getting this issue resolved. I have come to terms that I will almost definitely need to pull the engine to get at the stud and sort it out, so just wanted to check what the process should be before I start dismantling anything:
Compression check and leak down test.
Remove the loose part of the broken stud and determine where it broke i.e. how much is missing.
Depending on (2) remove the adjacent frost/welch plug and see whats there
Pull the engine.
Please comment on the above sequence as I hope to make a start this weekend, if I can source an engine hoist.
Here is the most clever method of repairing this I have ever been involved with. It was invented by a DC Patent Attorney (and a very smart man!) who did not want to remove his engine of his S2 .
He started by finding buying an assortment of (hobbiy) brass tubes,. They are manufactured in sizes which telescope. The largest tube he bought would slide over his one broken stud. The several other tubes nested snugly inside of one another and rested on the end of the stud. Then he bought some gun drills (very long drill bits). He started with the smallest one (perhaps 1/8 inch dia.). He began by sliding the largest tube over the tiny piece of broken stud, then slid the ones he needed into the tube, Finally, he patiently and slowly began drilling into the broken off end of the stud in the block. The drill remained centered by the brass bushings. Once he had drilled a suitable distance, he stepped up to the next size drill bit, removed the necessary brass tubes. and then the next size drill bit. I think his last gun drill bit was the tap drill size for the tap size for the stud. I mailed him my T handled custom made tap which has travelled all over the US including Hawaii. I will gladly loan it to you. His job was successful and I do believe he posted the pictures and how to do it 5 or 10 years ago.
I wrote about my experience with the broken head stud years ago. I was able to remove while engine was in place. Had access through freeze plug, tried penetrant for days and heat, no luck. Had cut a slot with dremel tool on top of stud, no go. What the heck had nothing to lose so took a long drill bit and by eye and feel started to drill. Had made a small dent in top of stud and notice the slot on stud had moved. Stud came right out, a very lucky moment.
Glenn
Glenn, I have subsequently had an experience with a big block Mopar and a friend suggested I use a left-handed drill bit, Sure enough, the drill barely started when the broken bolt shank came out,
Mike
No I have not removed the broken part of the stud yet. I wanted to get feedback about how to progress before doing anything. I was thinking that if it ends up that I have to remove the engine to fix the issue, it might be a good idea to do a compression/leak down test first. But maybe that is not relevant if I end up opening the engine anyways.
I like the idea of the left hand drill bit, sounds reasonable that it could loosen it as you drill.
So I guess I should just go ahead and remove the broken part of the stud to get a better idea of where the stud broke and remove the Welch plug.
If you have access to the relevant welch plug, I would remove that
that may open up some options, including building the stub with mig, and/or weld a washer & nut on, the heat helps loosen them.
I have got a couple out by making a couple of long drills out of standard cobalt bits (drilled & welded into rods, head was off, engine out, stub was flush with block
its a nasty situation, but can be repaired with patience
In the case I mentioned, I don’t think he removed the plug. He worked from the top and was able to drill out the broken stud and clean up the hole with a tap and install a new stud. Mike
