I have two head bolt holes with stripped holes. I have never used helicoils but don't know of a better option at this point. Any suggestions? Also, if I go that route, most of those I see advertised are stainless. Could that pose a problem later on? Thanks for any input.
Thanks, Mark. That would be nice to have but a little pricey for me. Hoping for a less expensive solution.
You can bolt your head on using holes not striped for a guide for a drill that is the right size for helicoils and the same size as the head holes.
Remove the head----buy the kit from NAPA supplying some coils and the tap used to install them as I recall it was about 25.00.
On my personal engine I usually install all holes with coils because its usually the last one that strips so you buy another head gasket.
After installing my rebuilt engine i was sorry to find one of my ball cap threads striped.With no way to drill to go to a larger thread the local machine shop friend provided me with a slightly larger meteric tap.I had to go to a large industrial supply to get the bolt i needed but it worked very well! Whoever pulls the engine next i hope they get the right bolt in the right hole.
Paul, that is my plan at the moment. The kits come with stainless inserts. Will this be a problem?
Ken, I looked long and hard at my 12mm tap. If it weren't for the slight difference in the pitch I think it would work. I may try--nothing to lose really, will have to drill any way. Has any one tried this?
My coils have been installed over fifteen years past.
Hope you folks are keeping high and dry!
We dodged the worse effects. Folks in east Texas, not so much. Having flooded last year I know how difficult it will be for those folks--physically, financially and emotionally. Now we have Irma to worry about.
John, to answer your question, there is no problem in using stainless thread inserts.
John: Here how Steven's tool fixed them. If you are interested, PM me. Thanks, Dan
Heli-coils work well
Thanks to all. I bought helicoil coils from NAPA earlier today and will start this evening. Will report on the outcome. Thanks again.
Put coils in 3 more holes last night (two had been done previously) and all seems well. Ran it for a short while but not totally satisfied just yet. Will put it on the road Sat. Thanks for all the info and suggestions. Also, I think Paul is right. If the head comes off again, all the holes will be repaired.
Hardest part of using Heli coils is aligning the tap. Aligning the drill is not a problem since the bit just fits inside the bolt holes of the head so its just a matter of positioning the head over the hole to get a straight hole. The tap is another matter. Lacking the ingenious tooling that Dan sells, I placed my block on a mill table and used a drill chuck and tap extension to align the tap before cutting. I was doing a restoration so the block was out of the car.
The guy who worked on the engine before me had done a couple of Heli coil repairs and the threads in the block were crooked. On those holes I used solid thread inserts. After seeing those crooked holes, I understood the importance of aligning the tap.
Richard, I can certainly see the advantage of the setup you are talking about. Would loved to have had it, but I felt it was too much money for me. If I were rebuilding or working on engines for other people and being compensated for it--different story. I got lucky on these I suppose. The only stumbling block was on one hole I didn't tap as deeply as needed and had to back out an installed insert. All in all it went pretty well.
I would clean the holes right to the bottom using a bottoming tap and compressed air to make sure all the debris is out. I am sure the threads are not stripped right to the bottom. You might consider installing studs with epoxy. If there is any thread at all they will not pull out, just another option. I am not a proponent of Heli Coil accept for light duty, there is as many failures as successes with Heli Coil.
what would the failure rate be comparing heli-coils vs epoxying the studs?
My experience after 30+ years of putting people into space and launching objects to far reaches of the outer planets, I never saw a heli-coil fail. On the other hand, I've seen them fail in old VW engines long after they were installed by teenagers, working on a dirt floor...but even then it took several years to fail. And as I recall the aluminum case had disintegrated around them.
I would trust a properly installed heli-coil. Modern epoxy is wonderful thing...but not for this application.
David, did the bottoming tap/air thing before first attempt as a matter of routine. After stripping, tried 3 1/2" bolts--too long. Tried with washer under head--stripped. Went to heli-coils and seemed to work fine. Drove it about 15 miles this weekend and if I had put gas in the tank every thing would have been swell! Thanks for the suggestion though.
thanks for the report
glad you had success
Also in the day and they may still be available to day, they made tap sets 1/32" oversize for stripped castings, I have some. The sample I have here is 7/16 + 1/32 they were available in all sizes. Equally you had to get an oversize bolt to fit.