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#1 Allopy Sump plug thread
Posted: Mon Jan 20, 2014 2:55 pm
by andrewh
Just looking at my 3.8 Alloy sump and notice that some Herbert has part stripped the thread in the past. Damn, anyone carried out a similar repair on this? Of course I could look at a Helicoil, just wondered whether there was a specific kit out there for just this problem, which cannot be unique?
#2
Posted: Mon Jan 20, 2014 3:42 pm
by 38E
Andrew,
My sump was cracked along underneath the plug thread and had always leaked slightly.
When I did some work on my engine a while ago, a friend who has a machine shop welded up the crack, then he made a stainless insert which was permanently threaded into the sump and then he finished it off with a new plug with a O-ring seal.
Probably not a cheap fix if you had to pay for it but it worked perfectly. There is a pic of it here amongst my engine photos on J-L:-
http://www.jag-lovers.org/snaps/snap_vi ... 1196733326

#3
Posted: Mon Jan 20, 2014 4:19 pm
by andrewh
thanks for the information. that is a very nice fix and I guess gets around the problem once and for all. As you say not a quick fix and will require me finding someone to turn me up a stainless fitting. I will give this one some thought , if anyone else has something a little easier please let me know. Are these taper plugs? I suppose I should have looked at the plug itself, I assume it must me as its not got a washer on it?
#4
Posted: Mon Jan 20, 2014 7:48 pm
by christopher storey
There should be a copper washer on it, which I think is C2296/1 . I think the plug is a straight rather than taper fitting but I can't remember the size. I don't really see the point of a stainless insert - they are really quite hard to machine and only achieve the same as a helicoil
#5
Posted: Mon Jan 20, 2014 8:15 pm
by PeterCrespin
christopher storey wrote: I don't really see the point of a stainless insert - they are really quite hard to machine and only achieve the same as a helicoil
Have you no soul Christopher? When the last E-type turns to dust on our lifeless post-apocalyptic planet, and the final radioactive cockroach turns belly-up amid the flakes of iron oxide blowing in the merciless hot wind, an Alien bestriding the desolate scene like a colossuss will stub his toe on a crumbling chunk of powder-white aluminium, to reveal a shiny sump plug insert.
Immortality Chris, immortality! :-)
(It's too cold for the garage, hence this tosh...)
#6
Posted: Mon Jan 20, 2014 8:28 pm
by andrewh
Helicoil seems favourite. Think the thread is 5/8 18. Unf cheapest kit ?55. Bit dear for one use though!
#7
Posted: Mon Jan 20, 2014 10:35 pm
by abowie
#8
Posted: Tue Jan 21, 2014 3:40 am
by 38E
[quote="christopher storey"... I don't really see the point of a stainless insert - they are really quite hard to machine and only achieve the same as a helicoil[/quote]
Well, this permanent stainless steel repair was made for me by a friend who has a machine shop. I think he knocked up a bunch of them at the time. (He also produces a line of spin-on oil filter adapters for vintage Jaguars and other cars on his CNC machines.)
There are quite a few advantages of a properly installed steel insert over a helicoil type repair.
-The plug seats down solidly against the flange when tightened with full torque without the tendency to wind the repair thread deeper into the sump.
-An O-ring is a much better sealing arrangement than a copper washer.
-The insert thread will never weep oil as a helicoil might.
And also, a helicoil type repair needs to be carried out by a competent person, unlike the spark plug repair a supposed "expert" did to a friend's airplane recently. The whole thing came loose during a flight and the spark plug popped out. I don't need to tell you the rest of the story...

#9
Posted: Tue Jan 21, 2014 8:13 am
by andrewh
Thanks guys. The plug at coolcats is a strong possibility although I reckon is perhaps a fix if you dont want to remove the sump. As mine is off now off the time to carry out a more thorough job. I though the Helicoil will lock itself into the new thread perhaps with the help of some loctite?
Only problem I can see is centralising the drill at that size in a large existing hole. Ummh