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head bolt/stud leaking

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wheelie View Drop Down
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    Posted: 22 Nov. 2022 at 7:24pm
  I know this has been gone over several times at least. I've read several posts in a search and just want to clarify a bit. Soooooo..........

  A friend of mine called me and said that one of the head bolts on his 3A is seeping antifreeze. One just behind the thermostat housing. He says he can turn the nut by hand, on the stud, when the engine is cool but after driving it and getting engine warm, it is tight enough that he can no longer turn it. Makes sense. 

I asked him to confirm that just the nut is turning and not the stud itself. Waiting to hear back.

So, if it's just the nut, I will re-torque the head bolts in sequence, starting at a low torque value and working up to spec on a cold engine. 

However, if the whole stud is turning, I'll spin it all the way out, after draining down the coolant, and try to clean the stud and reseal the bottom threads (into the block) with #2 Black Permatex. 

My question is: Do you just turn the stud in by hand until it's tight or what??? Is the stud to be torqued to a certain value and if so, how to do you torque something that threads into a through hole? Or is it not a through hole? I assume that if coolant can pass by the threads of the stud, it must be a through hole. Maybe I'm misunderstanding. 

If none of this works, I guess the head will come off. Or maybe he'll just throw some stop leak in it at that point, as mentioned in past threads, though it will go against my advice and better judgement.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Oldpappy Quote  Post ReplyReply Direct Link To This Post Posted: 22 Nov. 2022 at 10:02pm
I have never replaced a stud with the head on, but AFAIK there is no torque value on just installing the stud, but I am not sure how you are going to turn it to get it snugged into the block. May be able to jam two nuts onto it and use that, but to get it all the way in the top nut won't have full thread. You could use a bolt in that position instead of a stud and nut.

It is troubling that he can turn the nut by hand. It is was ever properly torqued in the first place this should not be possible. I am wondering if the threads are stripped out in the block.


Edited by Oldpappy - 22 Nov. 2022 at 10:03pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote drm101 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov. 2022 at 8:35am
I would pull the head and replace the head gasket, as well as inspect all the studs and the threads in the block, and shave the head flat. It's easy and inexpensive. If you need a bolt, they have them at Tractor Supply for a reasonable price. I just did this in summer and Fel Pro makes a gasket for the L134.
The studs do go into the coolant passages. I have heli-coiled several of the head bolt threads in our block. It seems like every time I pull the head, which thankfully isn't often, I have to heli-coil a hole or two. 



Edited by drm101 - 23 Nov. 2022 at 8:44am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CJ2A60 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov. 2022 at 12:46pm
I wouldn't try to seal those holes with permatex. A heli-coil, as drm101 points out, is the correct solution if the threads are messed up.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Bruce W Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov. 2022 at 1:45pm
  If the threads are NOT messed up, they still need to be sealed, and Permatex #2 has worked well for many years. Im not saying that it’s the only thing that will work, but it’s what I use. 
  I would not pull the head until it became evident that it was actually needed. I would R&R that stud and clean and seal the threads as you suggested. I would attempt to tighten the nut to spec first, to determine whether the threads are still viable. If it won’t tighten, well then, you know what comes next. 
  The stud holes are through, into the water jacket, hence the need to seal them. They have a bit of a shoulder at the end of the threads that butts against the block, but they shouldn’t be tightened against the block any more than hand tight. I suspect that the act of torquing the nuts also tightens the studs in the block a bit more. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote CMCSSeabee Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov. 2022 at 5:50pm
That is exactly what I would do, in that exact order. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote cpt logger Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov. 2022 at 6:31pm
X3 on what Bruce W said.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Oldpappy Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov. 2022 at 6:50pm
The engine I was working on today had been leaking around several of the studs as testified to by the rust that had accumulated around them. I had the head off anyway, so I pulled and replaced all of the studs with new ones. None of those I pulled appeared to have been sealed.

I too like Permatex #2 for this.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote wheelie Quote  Post ReplyReply Direct Link To This Post Posted: 23 Nov. 2022 at 8:07pm
  Thank you gentlemen. My friend is out of town for Thanksgiving so, I will start on this next week maybe. 

Very nice clarification on my questions Bruce. Thank you. 
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