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Fixing pitted bore with JB-Weld or other epoxyQ:hello all,,,have just begun work on a 6 hp IH M, and found the cylinder to be pitted in a number of places,,, i;ve heard several times about using a filler such as JB weld to fill the pits, but have never tried it,,,,,,, any comments about how reliable this repair would be, the proper way to apply it, and tips on honing it after it cures would be appreciated,,,,, bill boyce bboyce@swat.coop lost prairie, arkansas A:About 15 years ago my brother and I repaired four deep grooves in the cylinder of a Fairbanks Morse 3 hp. Z caused by an errant wrist pin with J-B Weld. We pulled the piston a few months ago just to check and the repair has held up extremely well. If you just feel and don't look you can't even tell it had been damaged. The engine has run several hundred hours (some of them under heavy load) since the repair.Be sure to grind the pits out to get to clean metal before filling with the epoxy. We have found that the spray cans of "Brake Clean" to be an excellent solvent for the final cleaning so there is no oily residue in the area. After putting the J-B Weld in the grooves we covered it with wax paper and used a large diameter wooden dowel to press it into the grooves and form it to the shape of the cylinder to minimize excess. After it set up we did some careful hand sanding to get the high spots and then honed the cylinder with the type of hone that locks the stones in position rather than the spring loaded type. This way we avoided getting high spots in the area of the epoxy. I think that if I were to do it again I would try using an oiled piston ring pushed through the cylinder to act as a squeegee to remove the excess and properly shape it to minimize the amount of honing needed. It would probably be best to wait for the J-B Weld to just start to set up so there wouldn't be any sagging or running. Our Ruston & Hornsby SPB also had some bad pits in the cylinder wall that we successfully filled with J-B Weld. Regards, Larry Evans Arcadia, Southern California, USA mailto:lfevans@pacbell.net http://www.oldengine.org/members/levans/ A:I know a lot of people who have done it with success. In fact, I've neverheard of it not working, although I'm sure there are some failures out there that people don't want to talk about. After cleaning the cylinder thoroughly and applying the JB-Weld, some people smooth it out with a piston or piston ring. Of course, it will need to be honed smooth Orrin oiseming@moscow.com A:Two things here. One, it MUST be clean. A light bead or sand blast on thearea to be repaired is the best. Two, the filler is just that! it stops the blowby. the rest of the cylinder metal actually takes the load of the rings and piston. as the temp never gets up high, it does its job well. I have an engine with lots of rust pits in the bore that got filled with Auto acryllic paint when it was painted. 10 years later, its still in the pits, it doesnt blowby and I cant see this ever changing while it ticks over all day at a show. Reg & Marg Ingold. Newcastle, NSW, Australia. randmingold@hotkey.net.au http://www.oldengine.org/members/randmingold A:I've been told by a Belzona rep friend (in the same class as Devcon and JB Weld) that the best results with any epoxy will be had if the area is -totally- clean...............then, he added another "must" for the best adhesion. Right before applying the epoxy, take a torch (can be propane) and play it on the area to get it just hot enough to drive out any moisture. Let it cool a bit then apply the epoxy.Take care - Elden DuRand Kentucky, US of A! edurand@bellsouth.net <mailto:edurand@bellsouth.net> A:Good point. Two notes on this. Some of the epoxy mixes, such as JB, will set MUCH faster if any heat is present. It doesn't take much. Probably a 50 to 75 degree increase will shorten the set time by half or more. I have never used any of the epoxies on an internal portion of an engine (such as a scored or pitted cyl. wall) and leave that to a cyl. bore or sleeve. But, I have used a considerable amount on exterior cyl. cracks. What I have done in the past is sandblast the area of the crack (maybe 1/2 inch each side) then "V" with a 4 1/2" grinder. Then heat lightly (just to the point that you wouldn't want to leave your fingers on it for more than a second or so) then apply a small amount of the epoxy at the center of the V. The epoxy, when heat is present, becomes much more fluid and will run into any open crack. This will allow the epoxy to actually enter the crack rather than just be a surface repair. I've never had trouble with one I have done this way and some of them have been done for 15 to 20 years. I had one engine that had a crack in the cyl and it was a nice original. I didn't sandblast but did V it. Then I took some of the epoxy and mixed some fine iron powder with it. I then heated the V and applied the epoxy. After I had it layer up to the level of the cyl, I lightly filed it down smooth, even with the sides of the cyl. I then took a muratic acid solution and applied it to the epoxy. The iron powder caused it to get a "light" rust and presto, the repair almost disappeared.Tommy Turner lcjudge@scrtc.com Magnolia, KY A:Indeed, I was a bit terse in my reply and did not go into detail aboutsurface preparation. At the hydro plant where I worked before retirement, we used Belzona to repair turbine blade and throat surfaces damaged by cavitation. It produced a longer lasting surface than the conventional repair: air-arc gouging, welding, and grinding smooth. In order to keep the Belzona from flaking off in big sheets, it was absolutely vital to abrasive blast down to a clean surface, then apply heat from huge electrical resistance heaters, overnight, before applying the Belzona. As a matter of interest, the workers obtained a beautiful, blemish-free surface by waiting until the Belzona was partially cured, wetting it and their hands with water, then smoothing it out with their hands. BTW, folks have commented about the cost of Belzona, but they were let off cheap. The product we used cost $1,500.00 US per quart! That was 10-15 years ago. I have no idea what it costs, now. Orrin oiseming@moscow.com ... This article is part of the Stationary Internal Combustion Engine Frequently Asked Questions (FAQ). This series is a combination of my views and knowledge and the views and knowledge of other people - most of them members of the Stationary Engine Mailing List (More info on ATIS). Those articles which were written by others are © Copyright to the author. Those articles written by myself are © Copyright to Paul Pavlinovich.
Got comments?If you would like to comment on any part of the FAQ please do so by using theDisclaimer:It should be noted that the information given in this document is considered to be good advice by the people who give it, however any legal liability lies strictly with the reader. The contributors are hobbiests not professionals. |
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