stevebubs
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| posted on 24/7/14 at 09:11 PM |
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Spark Plug - Thread Repairs
Had a spark plug pop out on me in the tiptop tonight.
Typically - nowhere near home and in a suit; had to call the RAC man.
Wasn't watching too closely, but apparently he couldn't get a new plug to "grip" the threads so had to put the old plug in and
advised I would need a helicoil...
Q1: If the old "knackered" plug gripped, why wouldn't the new one? As it's gripped and firmly in place, I'm
semi-doubting the need to helicoil...
Q2: It's a durance v6 and an easily accessible plug hole on the front bank. Can the helicoil be fitted without dismantling the head?
Q3: (related to Q2) - anyone idea of approximate costs to get the helicoil fitted?
Cheers
Stephen
[Edited on 24/7/14 by stevebubs]
[Edited on 24/7/14 by stevebubs]
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Slimy38
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| posted on 24/7/14 at 09:37 PM |
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Only thing I can think of is if the old plug had cross threaded, and the threads had been damaged in such a way that only the old plug would screw
into place. It's a pretty weak thought though. Either way, I suspect it's only a matter of time before it pops out again.
I didn't think you could safely get rid of the swarf from the thread cut without removing the head? If you can remove the head yourself, getting
the helicoil won't be very much. Giving a garage the whole car and having them do everything will be more.
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stevebubs
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| posted on 24/7/14 at 09:44 PM |
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quote:
Originally posted by Slimy38
I suspect it's only a matter of time before it pops out again.
My suspicions, also - hence the questions...
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madteg
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| posted on 24/7/14 at 10:50 PM |
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Fit a helicoil and problem solved
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cliftyhanger
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| posted on 24/7/14 at 10:50 PM |
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Common practice to helicoil in situ. I recently borrowed a kit to do one on the mx5. That had a clever taper so no need to drill or anything. I sucked
the swarkf out using a shultz gun, but turning the engine over with the plug out would probably be OK (or there may be a "proper" method)
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DW100
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| posted on 25/7/14 at 06:01 AM |
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You get a special kit to helicoil in place. Dipping the tap in grease helps trap the swarf on the tap, take the tap out often and clean it. Same with
sump plug threads.
There is an element of risk with it, but if it all goes wrong you'll get a piece of swarf stuck on a valve seat end up with a misfire and have
to take the head off.
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Mr Whippy
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| posted on 25/7/14 at 11:46 AM |
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or swarf gets jammed between the piston and the bore giving you a nice scratch
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stevebubs
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| posted on 28/7/14 at 10:05 PM |
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Ok. Whipped the offending plug out today and put a new plug in....no idea what the hell the RAC man was trying to do, but the new plug went straight
in....suspect he had the wrong plug .... helicoil hopefully avoided...phew...
but now I have a droning noise from the front end....this car doesn't like me this month!!!
http://www.locostbuilders.co.uk/forum/52/viewthread.php?tid=192898
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coyoteboy
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| posted on 31/7/14 at 01:12 PM |
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I'm afraid I have little trust in AA/RAC folk (though I know a very good one) - my default position is trust no-one and figure it out yourself.
That way you learn, save cash and generally don't have to deal with other people. Also, carry basic toolkit in boot... 
I remember going on holiday each year as a kid with a classic rangerover, a full toolkit inc 1/2 torque wrench, spare rocker bolts and a helicoil kit
[Edited on 31/7/14 by coyoteboy]
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