J D 8 Posted July 1, 2019 Share Posted July 1, 2019 The exhaust on my Enya 90 came loose in flight. Result now is the thread in the head is damaged. Can a helicoil or similar be fitted to sort the problem or any other method ? Thanks John. Quote Link to comment Share on other sites More sharing options...
kevin b Posted July 1, 2019 Share Posted July 1, 2019 It certainly can, but rather than try the job yourself, speak with Just Engines, or Jon at Laser Engines, for advice. Quote Link to comment Share on other sites More sharing options...
Jon H Posted July 1, 2019 Share Posted July 1, 2019 depending on the damage you might be able to tap it and go again. I think they are 11x.75 threads in there. If its totally stripped out then a helicoil might be the only option. Not something i can help with im afraid Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 1, 2019 Share Posted July 1, 2019 There is a post on here, that I cannot find ! ! ! From a guy who puts in new inserts John However, do try Just engines Personally, I would tap out to an oversize selecting a bolt size that can be drilled out and adapted as an header Quote Link to comment Share on other sites More sharing options...
Bruce Collinson Posted July 1, 2019 Share Posted July 1, 2019 The guy who helicoils plug threads is on BMFA Classifieds. BTC Quote Link to comment Share on other sites More sharing options...
Peter Miller Posted July 1, 2019 Share Posted July 1, 2019 The is (or was a chap) who can do it, he advertsied on the BMFA classifieds. Very reasonable price and super fast service, He can strip, clean and reassemble the engine and test run it too. Yes, he is still there, it is in Services. Mainly glowplug threads but maybe others too. Edited By Peter Miller on 01/07/2019 14:09:46 Edited By Peter Miller on 01/07/2019 14:13:27 Quote Link to comment Share on other sites More sharing options...
J D 8 Posted July 1, 2019 Author Share Posted July 1, 2019 Thanks to all for the info. I would be happy to do the fix myself if I can get the right size helicoil [ to far gone for a rethread ] Will give the chap on BMFA site a go. Cheers John. Quote Link to comment Share on other sites More sharing options...
Don Fry Posted July 1, 2019 Share Posted July 1, 2019 Wise move JD8. That's not an easy fix. Even when you have the right bit to go in, you have to have to clamp the motor at the right angle while you cut the thread, off a drill press, or lathe. By hand, on a guess, is fraught. Accepted, if messed up, the cost is the same, a new head, but, plus time, plus the helicoil. Quote Link to comment Share on other sites More sharing options...
kc Posted July 2, 2019 Share Posted July 2, 2019 Didn't Brian Winch - Wizard of Oz- do an RCME article on this in recent years? Probably gave the thread size there. Quote Link to comment Share on other sites More sharing options...
onetenor Posted July 2, 2019 Share Posted July 2, 2019 From the OP's original post it seems that the thread is damaged but no bolt to remove. If so this IS a simple repair. An in your hand job. If experienced a vise job if not. Depending on how much damage there is it may be possible to tap directly with No1 tap then 2 and finishing taps in their turn. If not drill out using the correct drill then the taps as before. Turn taps 1/2 turn forwards and 1/4 back. This avoids the tap bunching and jamming and as is easily done with these small sizes snapping in the hole.Advice as using oil in alloy thread cutting varies but I always use a drop of light oil run down each flute on each tap. NOT MUCH.In fact Paraffin/Kerosene would do the job. Btw giving cutting tools of all types a kero and toothbrush bath cleans off old oil etc and keeps them sharper longer. This also applies to nuts bolts screws etc before re-assembly .Less chance of dirty threads jamming and binding causing stripped or breakage of threads . Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 2, 2019 Share Posted July 2, 2019 Posted by J D 8 on 01/07/2019 19:01:42: Thanks to all for the info. I would be happy to do the fix myself if I can get the right size helicoil [ to far gone for a rethread ] Will give the chap on BMFA site a go. Cheers John. The Enya 90 Exhaust thread size is M11 x .75mm Note Point 75mm Quote Link to comment Share on other sites More sharing options...
J D 8 Posted July 2, 2019 Author Share Posted July 2, 2019 It is the exhaust outlet in the head that is damaged, the exhaust came loose in flight and wobbled about enough in a few minuets to wear the outlet oval so a rethread will not do. I have plenty of experience with engineering jobs [ just overhauled the fuel injection pump on my tractor ] Finding the right helicoil is the problem. Been busy and have not yet tried to find the chap on the BMFA site. Quote Link to comment Share on other sites More sharing options...
onetenor Posted July 3, 2019 Share Posted July 3, 2019 There is lodsa stuff about thread cutting on the like of engineering forums (FORAE) etc and that prog I can't recall that shows lots of new stuff via the net. Quote Link to comment Share on other sites More sharing options...
Denis Watkins Posted July 3, 2019 Share Posted July 3, 2019 Posted by J D 8 on 02/07/2019 23:04:24: It is the exhaust outlet in the head that is damaged, the exhaust came loose in flight and wobbled about enough in a few minuets to wear the outlet oval so a rethread will not do. I have plenty of experience with engineering jobs [ just overhauled the fuel injection pump on my tractor ] Finding the right helicoil is the problem. Been busy and have not yet tried to find the chap on the BMFA site. Yes JD The destroyed thread in the cylinder head was, until destruction M11 x .75mm thread The idea being, to move on from here knowing you started at M11 Find or make an M13 x 1mm insert, and tap the inner to M11 for the existing silencer Tap the head M13 x 1 Edited By Denis Watkins on 03/07/2019 07:09:00 Quote Link to comment Share on other sites More sharing options...
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