JB Weld Repair
 

Well after months of searching we were able to get our hands on a rather clean, low-mileage, 5.9 engine (Insides are VERY clean, outside needed refinishing and painting as it was from a rather wet/salty area and there was some rust buildup but nothing overly major for a 16+year old motor). When taking it apart to do cleaning, gasket replacement, and some part swaps, one of the exhaust manifold studs got stuck in the block, snapped off flush with the head. Of course we first went to an EZ-Out as the solution, and that was working decently.. right up until the point where the EZ out actually snapped off flush with the head as well... SO after ALOT of work it finally was drilled out fully (leaving a larger hole than the stud on the right side with only the left side retaining its threading). So the solution has been to place in a new bolt using the remaining threads, and assuring its properly aligned with the manifold holes, and then fill in the missing area with JB Weld (NOT HIGH HEAT!) Its been in for a few hours and the bolt is firmly in place and screws well thus far BUT im very concerned about the long term effectiveness of this repair, ESPECIALLY the heat it may or may not be exposed to.

Ive included some photos for reference, obviously the excess would be ground down and smoothed for a flush surface.

Will the regular JB-Weld work fine for this fix, and hold up over time? Should I be worried?! Is MAJOR engine malfunction a risk due to this?

EDIT: I wanted to clarify the decision to use or not use high heat wasn't made by me :P

Did you ever hear of a helicoil? There are other names/brands but all do the same thing. I don't think jb weld will hold up with that amount of heat.

I am curious why you are even putting that amount of effort into those heads. If you have them off already, just replace them. Odds are VERY good that you have cracks around the valve seats in any event...... There are much better alternatives available...... (provided its within budget.....)

What makes you think the heads are cracked? And no, the heads aren't off as gaskets aren't cheap for them. Engine is in very good condition, certainly better than anything at a junkyard within 300 miles, and budget is a big issue yes. I don't think a helicoil would work given the size and shape of the hole drilled out.

Mainly because it is a VERY common problem on these engines. If the engine has greater than 80K miles on it, then chances are EXTREMELY good that you have some cracks.

That said, since you do not have the heads off, and budget is a concern.... Run 'em, and see what happens. You are going to want to grind that repair is smooth as you possibly can, in order for the exhaust to seal properly...... and I wouldn't put a lot of torque on that bolt either. (tighten it last......)

Given all of your concerns, but figuring that it won't hold, I would try to clean out the hole and tack a stud in there (then grind down the high spots around the stud).

could you drill that back out and use a thread insert?

I would think, that with some heat and force, that thing will pop right out.

are you talking about the insert coming out?


also, I don't see where they make those things very long....might be an issue with enough threads to grab good unless you could somehow rig two of them in the new hole.

No, the JB weld "repair."