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10-13-2010, 06:55 PM #1
OT: dry ice to remove spark plug in Al head
A bit off topic. My wife's Ford escape has had the original plugs in the Aluminum head for 100,000 miles. I have heard there is a chance they will have siezed and will strip the head when I remove them. I suppose I can squirt penetrating oil on them and let sit a day. I was wondering if packing dry ice around the plug would help. pack them down then wrench off while cold. With a AL head and Al block I doubt I could really cool them much anyway.
I think I will wait until Winter. My Plan is to use normal torque and see which ones will come out then decide if I really need to replace them all.
10-13-2010, 07:31 PM #2
Aluminum has a larger thermal expansion coefficient than the steel plug body. Cooling
it will make the plug tighter I think.
10-13-2010, 07:45 PM #3
Cool it when the engine is about 140 deg F. Its not about how cold you can get it, but the temp difference. Let it sit for awhile after you cooled it, and then try. Disclaimer: I've never tried it, that's just my instinct talking... The more you can move the metal before you put a wrench on it, the better the process will go.
10-13-2010, 08:04 PM #4
Your already worried about having a plug strip? Just replace them and use anti seize on the new ones.
If your really worried, mark the plugs and let the dealer replace them. Then check to make sure they did.
10-13-2010, 08:12 PM #5
Other way around. Sounds nuts, but heat the plug with a torch and then cool the head with ice or dry ice. The steel plug will expand, but the aluminum will dissipate it so fast that the steel will still expand faster than the aluminum. The effect is that the plug presses the female threads outward and loosens up. Packing the aluminum in a cooling medium while the plug is hot will enhance the effect. This is how I remove seized drain plugs from badly corroded pump housings, heat them until they glow, pack the housing in ice and hit it with a rattle wrench. Works about 85% of the time.
Main thing is to let the aluminum cool before trying to back out the plug. Aluminum is hot short, so heating it to expand, or trying to remove a hot plug will usually strip the threads out.
Try them first and see how they act. If they come out fairly easily, don't bother with heating or cooling, just take them out. If they do strip anyway, you can get them helicoiled, so it's not a total panic situation.
Totally agree on the anti-seize.
10-13-2010, 08:16 PM #6
I don't have a ton of experience with aluminum heads, so this is somewhat limited.
When the plug is tight in the head, the gasket that is around the plug seat, or the seal made by the tapered seat, will be sealed enough that penetrating oil will never make it to the threads.
Like Jim points out, the head will expand and contract more than the plug. A propane torch applied to the head near the plug threads when everything is cold may expand the head enough to help release the threads. If they break loose and turn a little, stop and let everything cool down before trying to take them all the way out.
It seems like a lot of times the plug will start to turn out, maybe a half a turn or so, then get tight again. This could be from the carbon on the end of the plug starting to pull into the head, or the very end of the plug that is exposed to the combustion heat is swelled or scaled.
If the plugs do start to turn out some, that is the best time to use penetrating oil. I think you have a much better chance of actually getting oil on the threads. If they break loose, put penetrating oil on them before trying to back them all the way out.
Another thing that works very well on stuck stuff is getting everything fairly hot and melting wax or a crayon into the area of the threads. If you can get the wax to run down into the threads it works great as a lubricant and you can apply it when things are hot enough that penetrating oil will just burn off. Of course, this would also have the best chance of working if the plug backs out enough to get the seat sealing area or gasket loose enough to let the wax run in.
10-13-2010, 08:20 PM #7
Different application, but...
I have had great luck removing rusty, seized brake bleeder screws from iron calipers by heating the bleeder screw until it's red hot, then quenching it quickly with ice. I have no idea if this would work well on a steel/aluminum interface, though, so factor that into your thinking.
My view is, if you are that concerned about the possibility of stripping, do what 67 Cuda suggests and take it to the dealer. Replacing a set of plugs can't be all that expensive.
10-13-2010, 08:50 PM #8
No don't take it to dealer, They will let some kid work on it and break the plugs off in the head. Then they will want to install a new head and charge you for it. After all you can't drive it home with busted sparkplugs.
10-13-2010, 09:16 PM #9
This is a v6 enginer running sidewise. cost is about $200 to have dealer replace the plugs. They are not open on weekends. You have to remove the intake manifold to get to the rear plugs.
10-13-2010, 09:45 PM #10
Just try to take them out, I have had more trouble with plugs that have been iron heads for 100,000+ miles. Just be reasonable, no 2' breaker bars. use never seize on the new plugs.
10-14-2010, 03:51 AM #11
I had a plug stick in my wifes car a while back, I sprayed the plug very good with Kroil penetrating oil,, then let the car idle for about 15 minutes to get it good and warm with the oil around it. The following day after the engine was cooled back down the plug came out pretty easy. Anti seize the new ones for sure as you put them back in.
10-14-2010, 05:46 AM #12
Friend of mine fought the plug battle for days on a combine engine trying most of the above methods.What finally worked was a Proprietary spray(don't remember the name) which cooled the plug and this worked- somewhat like the dry ice I would think.
10-14-2010, 08:06 AM #13
I once took the plugs out of Mazda truck, they had been left in there for a long time. The problem was the band of carbon that had built up on the very end thread of the plug, this damaged the threads in the alloy head on the way out. I got away with it, and used never-seize on the replacements. It reminded me to not leave the plugs in for too long.
10-14-2010, 08:33 AM #14
10-14-2010, 03:28 PM #15
10-14-2010, 04:16 PM #16
Sometimes if you crack/snap a fastener tight first it will break the bond. Do that to brass fittings, hydraulic, & pipe threads.
10-14-2010, 04:41 PM #17
A standard in my shop was "Never" remove plugs from a Hot engine. The plugs are almost all longer than the diameter, so the head expands longer in lenght than diameter.
If they break loose and lock, now spray a penetrant at the plug, then screw in, then out, do that a few times and they should come out. You can also run the engine with the plug broke loose, for a while, then try again.
10-14-2010, 04:47 PM #18
Just begin by removing the plugs normally. If one feels like it's beginning to seize, squirt some oil so it drips down the threads, then work the plug in and out a little at a time till it's all the way out. you just down want to keep picking up more and more aluminum on the way out. The in and out motion keeps redistributing the lube.
10-14-2010, 06:53 PM #19
Lycoming, who has been making aluminum heads for around 80 years, says to remove a stuck spark plug:
1) Warm engine.
2) Use an inverted funnel - small side around the spark plug - aim a co2 fire extinguisher at the plug. The inverted funnel keeps the co2 off the head itself.
3) Let fly the co2!
4) Unscrew plug.
Since I always used the Champion graphite based spark plug never seize I didn't have to try this .
10-15-2010, 09:23 AM #20
Ditto on Kroil. Stuff is beyond amazing, but I strongly recommend the overnight approach. It goes where no other penetrants go, but it takes time.