Which bolts?

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modelman093
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Re: Which bolts?

Post #11 by modelman093 » Mon Dec 01, 2014 1:51 am

If you have access to the engine manufacturer's parts list, with a bit of luck it will say stud/ bolt followed by the size and thread so that will solve the issue of the correct size. Assuming of course that someone has not had the problem previously and gone up a size!
You say that the heads have snapped off so does that mean that you have the manifold or flange removed and the shanks of the bolts/studs are proud of the manifold? if so, slip a decent sized nut over them and weld the nut and shank together with enough amps to not only get a good weld but to warm the whole lot up.Let them cool and then try again to shift them. With a bit of luck the heating and cooling may have created a bit of "wiggle room" . If so give them a good squirt of Plus Gas or even diesel (not WD40 which is useless in this instant) and work them backwards and forwards - little at a time back and forth increasing the back bit all a time with plenty of your chosen lubricant* - softly softly catchee monkey!! * there is a school of thought that favours melting candle wax around the shank so that it works its way down the thread - but never tried it myself!
In my opinion, most times thread extractors, especially the tapered ones, are a waste of time and a snapped off extractor just compounds the problem.
If you are really up S***s Creek cart the head/manifold off to an engineering or tool making company that has spark erosion equipment and get them to erode the offending items and broken extractor out - or cut your losses and see if you can pick up a second hand manifold or flange.


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Mikerb
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Re: Which bolts?

Post #12 by Mikerb » Mon Dec 01, 2014 9:51 am

Thank you very much Fred.

Apparently they should have been studs and nuts, but someone has obviously messed around with it and replaced them with bolts instead. I just hope he's not used a different type and ruined the thread.

I've ordered a 7/16 tap, and have the helicoil set on standby. Fingers crossed.

Also thank you modelman093. I'm way past the welding nuts on and using extractors. they are now pretty much drilled out ready for a threading tap. But even drilled out I couldn't even punch the remaining thread out!! Bit of a nightmare.
I was however using WD40 so I'll remember that and use Diesel next time ;)

I did see a video where a guy was heating the manifold red hot and applying wax, but it was so hot the wax was combusting, I can't imagine this would be penetrating at all at those temperatures.

Mike


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