Engine Block Thread Repair ???

[55 Fargo]

Hi all, did not intend to bring this problem to yet another thread but here goes.

I have drilled out my seized and broken off manifold bolt, but the problem is I drilled off center, my hole is now out of round, 1/3 of the threads are gone, and the bolt does not seal the hole, it will leak coolant as it is now.

I want to repair this, but how?

I have heard of filling the bolt hole with JB Weld then inserting the bolt abck into the hole, which squeezes the excesss JB weld out, and hopefully fills in the void in the bolt hole. You need to allow the JB Weld to set, and then it would be sealed all around, would this work?

Man I always get my self to some fine messes................Thanx Fred

[oldmopar]

You can get a larger stud and tap the hole to match the size of the new stud

Ed

[JIPJOBXX]

How much tread do you have left? I would say that if you have less that 1/2 I would go with a helicoil set up. Easy to do with the proper kit. I stated in another part of your continuing story of a boy and his dog or should I say a man and his machine? That a helicoil set up is easy to do if you follow the instruction and even a cave man could do it.

So here is the set up on Parts America and it will include everything you will need to renew your old stud:

www.partsamerica.com/ProductList.aspx?CategoryCode=3482&SearchFor=Thread+Repair+Kits

[JIPJOBXX]

One other way you could do it would be to use a step down stud! This is a stud that is one size bigger than you have now. One end is threaded to match a bigger hole and the other end is the same size as you have bogger up! But that would require you to drill out your present hole to the next size and get a stud to fit that hole and have a machiniest tread one end to 3/8" threads. This is not a big operation and would probably cost the same as if you put a helicoil set up in place. Jon

[55 Fargo]

Here is a pic of the out of round hole, and one with the bolt screwed into it, there is a gap on the bottom left side.

[p10plymouth]

Another suggestion is tap it till you get a really good thread then drill your manifold out so that you can ether have a stud or bolt, we've done that many times good luck.

[55 Fargo]

Hi, do you mean tap to oversize, such as to 7/16 or 1/2 inch or ??.

This could be done, as this hole requires a bolt, and the manifold can be drilled to a larger size.

Let me know if I am thinking as you are........Fred

[kencombs]

It is going to be difficult to get any new hole properly aligned with the manifold hole. The drill will follow the offcenter pilot hole you already have.

I would suggest installing the manifold, then use its' bolt hole as a guide to drill the hole to the next oversize or to the proper size to tap for a helicoil. The helicoil, or some other brand of thread repair insert, is the best solution in my opinion.

If the manifold hole winds up oversized a little, it won't be a problem, just use a washer or two under the bolt head.

[p10plymouth]

Hi, do you mean tap to oversize, such as to 7/16 or 1/2 inch or ??.

This could be done, as this hole requires a bolt, and the manifold can be drilled to a larger size.

Let me know if I am thinking as you are........Fred

Hi Fred thats what we would do and have done .... Just so we understand the hole that you made has to be somewhat centered when you oversize the hole it will make a new center then tap.... then drill the manifold little larger if the hole is off.. good luck

[JIPJOBXX]

By the looks of that hole you might get away with using some BJ Weld. Is there any thread at the bottom of the hole? I mean past the old stud material? As a rule of thumb for strength in holding a bolt or stud in place all it hast to have is the tread inside the hole be as deep as the tread you have on your stud. By that I mean if you have 3/8" tread left on the bottom of the hole and the stud is 3/8 wide than your never going to get more holding power than that anyway.

Back to using BJ Weld sence it of the opinion of a few people here to use the manifold as a guide than why not just try to use the BJ Weld first and let it set up and see if it will hold the stud in place when you tighten down a nut on the bad threaded stud? If the stud backs out than you can just go to plan B and use the manifold as a guide and drill and tap a hole to the next size.

[Plymouthy Adams]

Fred (rockwood) based on the fact that you have drilled off center and the fact that you could easily repeat this mistake if you attempt the repair process warrents that you SHOULD take it to a machine shop for repairs. They have the correct tools, fixutures and procedures down to an art. The next mistake could very well cost you an engine block..weigh the risks verse the cost...

Sometimes it is hard to follow advice..but on this one, I see it your best option.

[JIPJOBXX]

Tim is probably write if you don't feel confortable with what you are doing. I would try that idea with the BJ weld first and see if it will work that way. It will only cost you a few dollars and if it doesn't than maybe go to a shop that can drill and tap that hole correctly. Jon

[JIPJOBXX]

Keep us in touch with what your doing and remember its only a piece of iron and it can be fixed. Now oft to the parade and I hope my car does not fail me. Jon:cool:

[p10plymouth]

Hi Fred one last thing sometimes we do not drill we just use a over size tap we use snap on never had a problem just use grease (coat it ) and go slow in then pull out clean repeat... good luck from the looks of yours I think you should be able to just tap it...

[55 Fargo]

Hi all, not that I am willing to do this as a repair, I tested the following.

I mixed a batch of JB WEld, filled and old lug nut with it, placed the lug nut on a 1 inch by 1 inch peice of tin, then soaped up a 1/4 inch bolt with sunlight soap, inserted it into the center of the lug nut with the JB in it. I let this sit for 6 hours, unscrewed the 1/4 inch bolt, it left nice threads inside of the JB, it still has to fully harden and cure, will screw the bolt back in tomorrow for a final test.

Okay I can try this method, using the jb and a long 3/8 stud, if it sets up and seals great, I am back in business.

Or I can tap out this hole with a 7/16 tap, then use a 7/16 bolt, I will need to drill out the manifold hole a bit. Or I can use a stud with 7/16 course on one end, and 3/8 fine on the other end, then file or dremel out the manifold hole a bit to compensate for the slight misalignmant.

Do any of these solutions seem okay, as I don't think I can hire anyone to fix this, nobody want to anyway................Fred

[Norm's Coupe]

Fred,

I don't know how well the JB Weld would hold up in that application. (Not saying it won't, just that I don't know). That said, if you are going to try it, you can also spray the bolt with silicone spray, then put the JB Weld around it. The bolt will come out just as easy, or easier than with the soap and water. Also, if you have any threads at all left in the hole, I would chase them before making the repair.

Guess what you are doing is worth a try. If it doesn't work, you can always drill it out a little larger and use a larger bolt, the helicoil.

That said, I won't do any drilling in my block like that. I would have done what Tim Adams said and take it and have it done by a professional. Thats probably the best advise.

[grey beard]

Fred,

Can you install the manifold and still get to thiis hole with your drill and tap? If so, I suggest you do as several on this thread have already suggested, and use the manifold as a jig to do the drilling. Use your 7/16-inch drill, and worki slowly as possible. Keep the bit wet with oil or WD40, and every few minutes, stop and blow out the hole and surrounding area with shop air, if you have it. (Cover the carburetor theoat firsrt.)

Once you have the new hole finished, tap it carefully. I like to turn one full turn, then remove the tap and blow out the chips, then repeat this until you are into the hole completely.

If the hole is into the water jaciet - and I'm almost sure it is - use some good grade of thread sealer and install a new grade 8 bolt and two flat washers. Then torque it just like the rest of the manifold bolts.

I had one stud fail on my own manifold when I assembled the engine - second from the front, in fact. Did this same fix with the manifold on, and it is working perfectly. A bolt will hold things just as nicely as the original stud ever did, in my considered opinion.

Let us know how it goes for you.

[billwillard]

If you use a 7/16" drill bit what size bolt will you use?

[55 Fargo]

Hi all, okay nothing has been done yet, I have done some investigation work, my JB Weld test with a soaped up bolt inserted into the JB went very well. The bolt unscrewed after the JB cured hard as a rock.

I also have estimated my outer clearance aorund the bolt, when it is in the out of round hole to be less than a 1/32 of an inch, more like the thickness of a paper clip, the outer edge is the worse, it isn't quite as bad down in the hole.

I am contemplating a couple of fixes, one would be to use a manifold stud, long engough for the purpose, I would fill the hole with some JB Weld screw in the stud, and let cure, and hope for the best. Even the way it is now I can srew in the bolt, and it does not move aorund or back and forth, so with the remaining threads and the JB Weld it should form a tight bond inside and seal up the gap as well, this is theory right now.

Or I can tap the current hole to 7/16, drill the manifold to accomodate, I may need to make the hole in the manifold a little oblong for the fit being off a bit, not sure yet though.

So that is where I am at right now, am I crazy or what, I am broke, so I need to possibly go shade tree.

The JB Weld is amazingly tough nad hardens very nicely, different than fibreglass or bondo, its good to 500 degrees f, hope that should be adequate in a bolt hole on the bolc, the water jacket is behind, don't think this area would be over 500 f................Fred

[Norm's Coupe]

Fred,

If the bolt is tight, I'd go with the easy way first. I'd just put some sealer on the bolt or stud and cross my fingers and toes for it to seal up. If not, the worst that can happen is you have to remove the stuff again and try something else. Won't hurt anything, just takes time to do it.

[55 Fargo]

Hi Norm, I may have a diesal mechanic, a brother of friend come and give it a shot, but as you say time is what it will only cost, I know it will work at first,, it may be a problem down the road, but on the immediate it would seal up just fine.

Time is becoming a premium these days, I am hearing it from the Wife too, after this job is curred, I am taking a break for at least a month and doing work on the house and yard, which has been a long time coming, plus my folks aren't getting any younger, want to hang with them a bit, while there still healthy...........Fred

[48mirage]

Here is an alternative to the helicoil that even has GM on their side. A little more work but a solid connection.

http://www.timesert.com/

[Plymouthy Adams]

look on the page..the Triton Ford is very bad for spark plug holes blowing out..have seen a few of these and I avoid Ford as much as I do GM...but..still think the head must be removed to use...

[Normspeed]

I'd try the JB, but make sure the bonding area of metal in the block is squeaky clean first. Just use enough to fill the off center area of the hole and do the soap or silicone thing with the bolt. JB hardens overnight but it really needs a long cure to fully toughen up.

The intake and exhaust bolts or studs aren't really meant to be torqued down real heavily, The original threads and JB filler should work. Use some sealer when you put er together.

[Norm's Coupe]

I'd try the JB, but make sure the bonding area of metal in the block is squeaky clean first. Just use enough to fill the off center area of the hole and do the soap or silicone thing with the bolt. JB hardens overnight but it really needs a long cure to fully toughen up.

The intake and exhaust bolts or studs aren't really meant to be torqued down real heavily, The original threads and JB filler should work. Use some sealer when you put er together.

Norm,

The silicone should go on the bolt, not inside the hole. The purpose of the silicone on the bolt or stud is so the JB Weld won't stick to it. If you get the JB Weld on the bolt when filling the hole without the silicone on it, the bolt won't come out because the JB Weld glued it in as it cured. By having the silicone on the bolt you will be able to unscrew it when the JB Weld cures, without damaging the JB Weld repair.

Using a small amount of soapy water (on the bolt only) will have the same effect as the silicone. However, by using soapy water it could cause small air pockets in the epoxy as it cures, then you don't have an even surface to get a good seal around the threads of the bolt.