Stuck spark plugs

Dieseltech

Well-known Member
Location
Akron, Indiana
Neighbor brought over his M670 LP, wants a tune up as its missing at times. Tractor has never been inside, none of the spark plugs will move. I've had it warmed up by running, not sure if penetrating oil would help if the plug gaskets are doing their job. Would appreciate any ideas to get them out without breaking them. Thanks in advance!
 
You may have to try both heat and penetrating oil. 18mm thread plugs in that one, right?

I sure hope the threads on the plugs don't go all the way through the head into the combustion chamber.

I can recall one U engine I had to weld a 1/2" bar in what was left of the plug to get them out. Turned it with a pipe wrench. But they did come out.
 
Use an impact. You will be much less likely to break them. Maybe try it with engine hot, theh cold. The expansion and contraction along with the impact vibration may do the trick. Drilling them out is no fun.
 
My 2 cents. Never had one break off cold. Have had one break off hot. I vote for cold. I'd start with a 1/4 drive impact (I really like my 18V cordless Milwaukee). Use repeated short bursts. If you're unsuccessful, step up to the big guys ( I really like my Snap-On 1/2" drive cordless impact). Again short bursts and hold your breath. If that doesn't do it, you're likely doomed to breaking them off.

That's the trouble with the LPs. They don't foul plugs so it can be years before one has any cause or inclination to remove them.
 
Every once in a while new craps Makes life easier on the older stuff. A ford triton 5.4 has caused great leaps in the subject of spark plus removals. If you can get the extractor kit for one and the impact didn't work ( try that first ) you'll spin it right out. If its not feasible to buy the extractor knock the protruding porcelain off with a hammer and screw a drywall screw or similar into the electrode of the plug and use that to pull the porcelain out of the steel nut. The nut will then unscrew easily. This is a last ditch resort obviously but beats pulling the heads and the ford garage does it every day.
 
In addition to what Curt says LP burns dry and clean so there is no residue to coat the area around the threads. When installing new plugs ALWAYS put a generous amount of Anti-seize on the threads.
MMDEL
 

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