andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,218
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Nov 14, 2013 14:42:23 GMT
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Got a damaged thread on an exhaust manifold stud, will have to take the engine out to replace it!
I'm going to try and re-cut the thread with the engine in place using a thread cutting nut.
The stud is a M10 (17mm spanner size). Would it be better to use a smaller imperial thread and re-cut the stud entirely?
Is there a slightly smaller imperial thread for a 10mm stud, or are the nearest imperial threads too large or too small?
Does this make sense?, I'll try the M10 thread cutting nut first, but it's good to have a back up plan!
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,218
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Nov 14, 2013 14:52:23 GMT
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Or perhaps try 10mm coarse, rather than 10mm fine?
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Nov 14, 2013 15:25:16 GMT
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Hi, 3/8" is within a few thou of 10mm so not any use, The next size down is 8mm / 5/16". Asking a proper die to rethread 10mm down to 8mm / 5/16" without removing some of the thickness is asking a lot. A die nut is for cleaning up damaged threads not cutting new. Changing from fine to coarse removes some of the thread completely so not ideal. I take it clearance for a drill is the hurdle?
Colin
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Nov 14, 2013 16:04:32 GMT
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My approach would be;
Stick a nut on the stud, weld it on with a mig, wind it out and replace
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andyborris
Posted a lot
Freedom is just another word for nothing left to lose.
Posts: 2,218
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Nov 14, 2013 16:39:43 GMT
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Unfortunately, it's not that kind of stud. It's a press fit in the down-pipe of the manifold and made from what looks like very hard stainless and un-gettable out without removing engine and probably the manifold too.
The guy who removed the engine use a grinder to cut off this one nut, then the guy who made the exhaust cross-threaded the nut onto this stud!
However, there is a bit of the stud still proud of the flange, so I'll get a nut die, try to put a bit of a chamfer on the studs end and try re-threading it.
What can I lose? Doesn't work,I'm going to have to remove the engine!
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Nov 14, 2013 17:14:37 GMT
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Seeing stud will need replacing some time anyway what about jamming any nut on and then tacking / welding it to the stud ?
Paul H
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MrSpeedy
East Midlands
www.vintagediesels.co.uk
Posts: 4,789 
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Nov 14, 2013 20:55:00 GMT
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Why not just clean up the original thread with an M10 dienut?
You'll be surprised how effective they can be.
Then fit either a stainless or brass nut. An extra couple of quid spent now will really pay dividends later on.
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