When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
The problem with the Keensert is a 1/4"-20 insert requires a 7/16"-14 tapped hole and the OP can no longer drill to obtain a larger hole than the one he has with over 90 degrees of the hole missing. Cast iron is very brittle and has little tensile strength. Trying to go to a larger hole would result in disaster in my opinion. Once a crack starts is cast iron, it may propagate when heat and cool cycling occurs. Hopefully the cracks where the missing pieces broke off do not extend further down into the head. A welder would normally PT the cracks and drill a hole at the end of each to prevent additional cracking (propagation) during the heating and welding process.
I would research the application of any (JB Weld or other) epoxy, as it may require multiple layers to build it up to a significant thickness. The photo shows the remaining material is about 210 degrees of solid cast iron around the original hole. That may be enough to hole the coiled insert if the OP has already tapped the hole for it. A dam such as a piece of plastic tubing or even tape of some type or modeling clay may help create a form to hold the epoxy in place until it sets. I wouldn't remove the form before the 24 hour cure time to prevent disturbing the epoxy bond.
If using a coiled wire insert, I personally would put a stud in the coil insert and then apply the epoxy as the installation of the bolt / stud after the epoxy dries may spread the coiled wire threads and dislodge the epoxy. Just a guess.
What ever you decide to do, I would recommend trial fit the valve cover and verify bolt alignment before applying the epoxy.
Sorry about the news on crack propagation, I don't think it will happen, just a thought as a result of years of ASME, B31.1, & D1.1 problems I had dealt with, yea did that too. Now I am overthinking???
Good Luck.
Ron
I hadn't heard of a Keensert, but I just checked them out. Great idea and would seem to be an improvement over the standard heli coil. But as Ron points out, I can't tap in any threads. The oversized bolt that I found in the hole had cracked the wall of the threads thus a tap won't work on the remaining 210 degrees of cast iron.
I agree with all those that say take it to a good machine shop. That would be the ultimate fix, but if I do that, I would want to have the whole engine torn down and rebuilt. It's anyone's guess as to the mileage on this block. Since I'm not quite ready for that step yet, I'll temporarily push a rebuild off. I'll pursue the in situ repair as best I can and see what happens. Not an ideal situation and I know I will be running at risk if I can get the JB weld to work.
Last night I built a little dam around the coil, filled it with metal "enriched" JB Weld, and I'll let it sit for a minimum of 24 hours. I may come back tonight and add a little more to bring the wall up and match the height of the existing head/gasket surface.
My confidence in the JB Weld adhering to the cast iron is pretty low. However, I'll give it a go. As others have pointed out, this bolt doesn't need a lot of tightening torque, so maybe.......
Ron: Thanks for the ideas on the bolt alignment before applying epoxy. Unfortunately, given the fit of the heli-coil in the hole, I could only eye-ball the alignment. I would have loved to put a valve cover on with a bolt in place. I'm hoping I get lucky and the bolt alignment is in the ball park.
More to follow tomorrow.
John
JB Weld around heli-coil. Tonight I will build up a little more epoxy around the top part of the heli-coil so the surface of the epoxy is even with the head/gasket surface.
I'm not a fan of the JB Weld in this situation. A piece breaks off and into the engine may be an issue. It's really not adding and strength IMO. I think I would have cleaned the area the best with brake cleaner and used Black RTV
I can’t tell a lot from the pics. It appears to already have a Heli Coil in place. Often times people do not tap deep enough and the Heli Coil tapers in at the bottom creating a very tight thread which will break a bolt easily. Then the bolt is wedged in as well as broken off. Unfortunately imho that JBweld is not going to last as long as it took to set up. It’s just not for an application like this. Even if it were strong enough the repeated heat cycles and oil saturation are going to cause it to separate. You best option without removing the head is drill the bolt out. I can’t tell if there is a broken Ez out in it or not. If it is it would be very shiny from drilling and it would immediately kill any type of drill bit. You can drill it with carbide but it’s extremely difficult to hand drill with carbide. After you get the drill started very much at all any movement of the drill sideways will instantly snap the drill off. If it has a broken ez out I would suggest getting a few 3/16 ball nose carbide end mills, solid carbide. The ball nose will keep you centered and will cut better without chipping. After you get the bolt out you’ll need to remove the Heli Coil and replace it but you need to tap it a little deeper so it doesn’t grip the bolt again. I would use the 3/16 ball nose guided by the Heli Coil and drill about 5/8” deep to try and get any new thread you can. Using a Keensert or Timesert is going to be almost impossible to do by hand,with half of the hole missing. So I would avoid that period. Another option would be after you get the Heli Coil removed drill to 5/8 deep and thread for a 5/16 18 stud. You’ve got your hands full at this point. Welding can lead to additional problems. Good luck
How about placing a 1/4” steel nut directly over the broken stud and weld the nut internally to the stud. Then just back put the nut and the stud should come along for-the ride. Any mig welder should suffice
If John (JWolf) has aluminum valve covers, the valve cover is cast for 1/4"-20 bolts and would have to be drilled out for anything larger. He already confirmed the broken bit or extractor and could not drill it out. The broken item is below the surface and he prefers not to weld nor remove the head at this time. I also have my doubts about the JB Weld, but he has about 210 degrees of the original hole with threads, so it may hold the new heli-coil as the tension is straight up and prevented from lateral movement by the valve cover.
We each have to decide our method of attach and enjoy the success or accept the defeat alone.
Jaguar: Ron is right, the broken drill bit (or extractor) is too deep in the hole to get a nut close enough to it to weld. I do have a welder, but my welding skills are very basic and I would not want to attempt it.
Robert: Yes, you do see a heli coil in place. Yesterday, when I tried to tap some new threads in the hole in order to install a heli coil, a portion of the hole wall broke out (the hole had been drilled out by a previous owner/tech). They forced a larger bolt in and cracked a portion of the side wall). Consequently, it was impossible for me to tap any new threads so I took a heli coil, placed it in the hole and epoxied JB Weld around it. My hope is that the epoxy will hold the heli coil in place. Yes, I know it's a pretty slim hope. If it doesn't work, so be it, I'll move on to the next option.
I am certain that it is an EZ out or a drill bit that's broken in the hole. There is a very shiny piece of metal in there and the drill bits I've used just bounce off of it. It is firmly lodged in. Your explanation of the ball nose carbide end mill is very helpful. I did a google search and I see what you mean about the ball nose. That would allow me to hand hold a drill and carefully grind out the object. Then I could continue with the rest of the procedure you outlined to get some threads in.
Saturday or Sunday I will try to put a bolt in and see if it holds. If it doesn't, which the odds are it won't, I will go for the ball nose carbide end mill option. I will be researching this option in the meantime. Your experience is priceless and I appreciate your comments.
To All: Sorry for dragging this out so much. I always try to use the least invasive option first and if it doesn't work, I go to the next level option. Your patience and sharing of info is greatly appreciated.
I will definitely provide an update later this weekend.
Thanks,
John
John, I think your patient, cautious approach in regard to this problem is well respected by all. You are adhering to the old medical guideline: "First do no harm".
If it doesn't hold I would suggest using small Dremel style grinding stones to grind the piece out of the hole. It'll take a bucketload of stones and a ton of patience but I've seen it done.
A friend of mine with an auto repair shop called and said he wanted me to fix a broken bolt in an aluminum head. I had been closed for several years at this point but he said I don’t have any other options. He said it started out as a broken exhaust bolt the mechanic tried drilling it out. He broke an ez out off in it. Then he tried drilling that. He went off to the side and through to water. But he’s not done yet he started drilling around it with small bits trying to remove it. I think there were 4 small bits broken of as well. Then they asked a guy to come weld it in the car which wasn’t possible one due to location and two due to all of the steel that was now imbedded in the aluminum. I told him I would fix it but they had to take it off. I machined all of the garbage out, welded up the hole, and re drilled and tapped it. When it was finished you couldn’t tell they had been there but boy did they throw everything at it.
Using a ball nose end mill works best for me removing ez outs. I’ve always joked they shouldn’t sell those to mechanics. But I broken more than my share of them too.
If it doesn't hold I would suggest using small Dremel style grinding stones to grind the piece out of the hole. It'll take a bucketload of stones and a ton of patience but I've seen it done.
I agree with the dremel tool or die grinder, but would also suggest using ball shaped carbide burrs instead of, or in addition to grinding stones. Also, I'm no expert, but no one has suggested brazing the broken off area to replace the missing cast iron and fill the hole. Maybe that could be done in place then tap the brass instead of epoxies.
Also, I'm no expert, but no one has suggested brazing the broken off area to replace the missing cast iron and fill the hole. Maybe that could be done in place then tap the brass instead of epoxies.
In many cases brazing is a good option for cast iron repair. I have done several and would certainly not try to do it in situ. It requires a lot of heat, especially when dealing with oil contaminated cast iron. Also, to do it properly the entire casting should be heated and then when the brazing is completd it should be wrapped in heat blankets and allowed to cool very slowly over a period of several hours.
Ted
I had to remove a stripped bolt from my son's KTM rotor. I drilled and tried an ez-out. Just spun and was useless. I looked over at my work bench and saw a small torx bit. I pounded it into the drilled hole. It gripped ten times better than any ez out that I have used. A T15- thru a T27 might work.
I have absolutely no welding or brazing experience so I am reticent to ask this, but have any of you tried Muggyweld products? The company is online only and its' owner may have an answer for this problem. Worth a shot, I'd say.
I'm going to hold off on any welding options for now. I'm going to see how (or if) the JB Weld holds up. If it's no good, I ordered several 3/16" Ball nose carbide end mills as Robert suggests. I will know more tomorrow night when I dress up the epoxy and then Sunday assuming I can do a start up. Fingers crossed.
Update:
I waited until this morning to sand down the epoxy in order to give it more time to setup. I made a jig out of wood and was able to put a piece of sandpaper on it and keep it flat to the surface of the head. I cleaned everything really really well and then went about installing a new gasket. Since the bolt hole on the valve cover had be a little hogged out by the PO, I went ahead and applied some gasket sealer - please no comments about using gasket sealers, there's quite a few posts already out there on pros and cons. It's done.
I'll let the gasket sealer setup overnight and tomorrow I'll fire it up and see how everything holds together.
I'm hoping it works, at least as a temporary fix.
John The epoxy is setup and holding in the heli-coil. If this doesn't work, I'll go back and drill a deeper hole to extract the broken drill bit. I sanded the epoxy flat to the surface of the head. I ran a bottoming plug into the heli-coil just to make sure there wasn't anything in the threads. A new bolt will go down 1/4" into the hole until it hits the bottom of the heli-coil. Not as much threads as I would like, but since it's only torqued to 3 ft-lbs (36 in-lbs), I think it's enough. I didn't have a Moroso valve cover wing fastener as Charlie M suggested, but I did find this retro fastener head in an old parts box. I screwed a stud in and tightened a nut down just enough. Side view of the stud, the nut, and the retro fastener head. Yes, I was just a little off in the angle of the heli-coil when I epoxied it in. This is only a proof of concept, if this works, I will go back and replace the stud/fastener with something more appropriate looking. I am NOT building a rat rod!
This sure looks like a fine thread Heli Coil. Is it the original or did you add this. How did you get a Heli Coil in it if there’s an ez out still in there?
10-20-2022, 09:26 AM
I don't think it will happen, just a thought as a result of years of ASME, B31.1, & D1.1 problems I had dealt with, yea did that too. Now I am overthinking??? 
