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Rusted spark plugs

5K views 21 replies 16 participants last post by  terracefarmer 
#1 ·
Wanting to change plugs in 6 cyl JD 55 combine.They are quite rusted,broke one,got it out and replaced.What can I do to make the other 5 easier?The engine runs,should I run it up quite warm and try again?
 
#3 ·
If it was me I'd soak them down with my favorite weasel piss, run the engine to warm everything up, soak them down again and let everything cool down before tackling them. The warm/cool cycle(s) will help the penetrant to get down the threads. At least you don't have to worry about aluminum heads - they may fight like hell but they're not likely to destroy the head on the way out.
 
#6 ·
I have soaked them a few times with weasel piss and ran the engine to warm up a few times,will keep doing this a few more times and try them again.Should I spray a little ATF in intake when running to try and lube up threads from the inside?
 
#12 ·
Our FD restored a 1927 fire truck in my shop. To remove the plugs this is the order of events that need done:

1. Soak the crap out of them with penetrating fluid.

2. Drink mass quantities of beer afterward.

3. When all beer is gone and everyone is lit soak again. Take extra care to not involve any tools at this point.

4. Remove after hang over subsides.

Your results may vary.
 
#20 ·
I like your suggestion but would an EP oil like CIH Hytran be an advantage for dry rusty threads to not seize while trying to turn out? For years I have kept a jug of clean used Hytran and added a generous amount of Powerup when refilling my squirt cans which I use for everything. Adding some acetone to make a penetrating oil seems like a good idea.

Also when removing tight rusted threads I think it is worth mentioning that if it is moving to be patient and work it out. Stop. Work it back in. Stop and add more penetrating lube. Work it out. Repeat often and watch to see if you are gaining. If you are trying to get the nut off of badly rusted exposed threads on a u bolt, zip cut the excess threads off. They didn’t need to be that long in the first place and if you can get the old nut off and replace with a new one, you might be able to reuse the u bolt. I recently did that on a big 1” special u bolt on the camel back suspension on my 1974 Mack crane truck. The bolt broke at a sharp corner where it went around the saddle. We cut off excess thread, heated the nut red hot with acetylene torch, worked it off, welded the broken bolt, cleaned up the fine threads with a thread file and after working some moly grease into the nut and threads, put it all back together and went to work. A couple hours of downtime and almost zero cost. I know you are not supposed to be welding on things like that but could you even get a new one and when?
 
#21 ·
Heat and impact wrench..
Fwd and rev with the impact.
Heat and I've found that melting a candle on it after heated up really good works... the paraffin melts down quite thin and doesn't seem to burn off as easy.
If you can heat the plugs with a torch to hey them red hot the expansion and contraction will help break the threads loose... try hot, then try to let it cool and shrink
If nothing works I'd try breaking the porcelain out and welding the center... use a mig... I've never had luck doing this with a stick welder.
Take your time
Good luck.
 
#22 ·
How did it go to get the plugs out? Or did you have to take the head off and have a machine shop get them out for you? Anvil had the best suggestion, candle wax, especially if you can the plugs to move even the slightest bit, we then add candle wax and it usually saves the threads inside the head and makes getting the plugs out so much easier.
 
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