8N plug problem

I recently split my 8N (front mtg distributor) and replaced the clutch and transmission oil seal. Put it back together and all is good. I had removed the hood/gas tank to make hoisting front end easier so I decided to change spark plugs. Number 2 was rusted and being in a hurry (that always seems to bring tiding of bad news) I broke it. I tried an EZ out to no avail (square fluted one). I even heated it (I only have MAPP gas) to no avail. So as a last resort I drilled it out with a drill bit that was close to the major diameter of the plug hole. I was doing this without removing the head so I used a hand held drill. I re-tapped it and somehow I managed to ruin several threads. The result is the plug is loose for the first few threads and finally locks in on the last 1 or 2 threads. I had to not use the spark plug metal gasket to accomplish this. I ran the tractor for about 10 minutes and the plug did not blow out. What should I do now? Leave it alone? Use Locktite on this plug ( I hate this)? Go the helicoil route? Any suggestions would be appreciated. By the way I did clean out the cavity using a small magnet prior to running.
 
Since you had full access to the plug, I am unclear as to why you did not use a 6 point socket with a long wrench handle and some "Kroil Oil" or similar penetrating fluid. The only things available you now is to hope that 2 threads will hold it in place, questionable, as it may not seal well(or blow out under the power stroke) with 120 psi, a "helicoil" or a new replacement head(best solution). When I do this kind of work I always use "never seize" on the plugs and threads in the block.
 
Wanna try something I did to a restaurant meet slicer?

Clean out the bore totally with laquer thinner. On only the outer most (in this case) bore do a smooth surround with LocWELD (not Loctite but same company). Let it set up a little . . . put a thin film of grease on the plug and thread it in but not to maximum tightness. Leave it over night and you'll probably find you get the plug nice and snug. The LocWeld forms new threads.

I said only the outermost threads to ensure that you don't push any locWeld into the cylinder. They say JB is as good, but I'm not so sure. JB probably stole the formula from Loctite. :shock:

anyway it worked like a charm on the meat slicer and the restaurant owner was suitably impressed. :D

But of course Helicoil is the tried and true.
I'd be inclined to try this though. Because you grease the plug it will of course be removable and the LocWeld will stay behind.

Even with sockets and ratchets, you still have to be careful that your force is tangential to the lay of the plug by using applied countering force with your free hand on the ratchet head.
 
I agree with Grapeview.
Helicoil it.
You can get the kit with proper size drill bit, tap and coil.
Probably any Napa, Oreilly's, etc will have it.
Pretty easy fix.
 
simple one like this, I'd fix it right as the other posters said.
But.......if you go the jury-rig way,
(Which I do understand, ya do what you have to sometimes.)
If I had to 'rig' it, I would use a anti-fouling adapter, and rig that in, then the plug can still be changed easily with 2 wrenches,
without disturbing the head threads.
 

The inserts I get from NAPA that are called "Sav-A-Thread" made by Helicoil are just like a Timesert... I think KD is the supplier.... I don't have a NAPA repair kit are # for a 18MM so make sure what ever you get is made for a cast iron head. Timeserts are the Cadillac repair :wink:
 
I wouldn't trust any epoxy type bonding agents in something that has such great temperature and pressure cycles, and I wouldn't want to depend on a thread or two to prevent a white hot plug from launching itself into your gas tank...; imagine the ramifications of that. The time to do a timesert ought to be worth it. You obviously have the talent, I hope you take the time.
 
next time you get a stuck one.. use an impact set on low and blip it out.

As to your current dilema.

you can get a new head

you can go the insert route

you could braze in a anti fouler adapter

braze up the hole and retap oe threads

you can drill and tap a couple sizes large, install a plug, grind it flat, then drill and tap for oem sized plug
 
Thanks for the replies. Based on cost and my ability (no welder) I decided to go with the helicoil. I ordered the Helicoil brand Save-A-Thread. I'll use some high temp Loctite to help lock in the insert. It should be here in about 3 days so I'll post a followup on the progress. I've had this tractor about 30 years so I would like to keep it going. I don't really have a good place to work on it (shed with dirt floor) so some jobs are challenging. I grew up on a farm and we used a Farmall Super A and a mule. I never learned to plow with the mule (Dad let me ride while he plowed) but I spent a lot of time on the little Super A. We row cropped about 100 acres with the tractor and mule. I don't have to have a tractor - I just enjoy working with it and there is no pressure to "fix it now". Time with my tractor is probably like some folks time playing golf - fun and frustrating.
 

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