Is there any "trick" you know of to loosen a spark plug that won't move?
Posted by SomeDudeFromBerlin@reddit | askcarguys | View on Reddit | 13 comments
While did some other repair on my car as a ~~quick and easy~~ potentially expensive and annoying maintenance item I wanted to change my neglected spark plugs. Most of them went fine, but one got harder to turn and is now not turning in any direction (with the force I am willing to put on there to not rip it off). I am 100% shure I did not turn it in the wrong direction.
I already soaked it in penetrating oil for a few days - nothing.
I have a Smart City Coupé so the engine bay is very tight and I can't see if the Spark plug came out partially or is still fully "threaded in" at the bottom and just chewed up the thread because the spark plug is kind of burried at the bottom of a deep hole.
The only solution I can think of is to run the engine to heat the block. But because I don't know if I partially loosend the spark plug I also don't know if or what damage I could do. Is this my only option? What damage could I do?
KilroyKSmith@reddit
Your best bet at this point is a mechanic. Tell them exactly what you've done. They will probably not take responsibility for breaking the plug, but they have the tools and experience to ease it out it it's possible.
The fact that it turned a bit and then seized is concerning. A seized plug can be nearly impossible to remove without very advanced equipment (like an EDM machine...).
SomeDudeFromBerlin@reddit (OP)
I fear that any operation that requires the engine being disassembled or removed from the car by a mechanic is not financially viable, regarding the value of the car (wich is sad because really like that little thing). In any case if an EDM machine is involved.
In that case my best bet would probably be to just run the engine with the compromised plug and enjoy it as long as it lasts.
I still have hope for the penetrating oil. I remember that at my antenna it needed 2 weeks of repeated application to break it loose.
I was really hoping for some trick mechanics use to solve that kind of problem.
KilroyKSmith@reddit
Mechanics are fond of:
Penetrating oil
Heat
Impact wrenches
You've already done #1, #2 might be difficult because you'd have to heat up the head and not the spark plug, but #3 might be a good choice. The repeated pounding from an impact gun might be useful compared with the constant force of a ratchet handle.
Hmm, perhaps you could go about #2 with a slightly different approach - freeze the plug (making it smaller) rather than heating the head. Get something cold (dry ice (don't touch it!), electronic component freeze spray, liquid nitrogen), and place it/drip it on the plug - you want to cool the plug down, and not the engine. When you think it's cold enough, go ahead and try to remove the plug.
SomeDudeFromBerlin@reddit (OP)
That's a good idea. Freeze Spray on the Plug and a hair dryer on the Head (I wouldn't want to point a heat gun at all that plastic intake). I didn't know of that product. Thanks, now I have new hope.
Slipknot31286sic6@reddit
Always start your engine and warm it up for a few minutes before touching spark plugs or coil packs. If not gonna be a bia to remove.
SomeDudeFromBerlin@reddit (OP)
But inserting new plugs in a hot engine is not advisable. So you always take them out, wait until cool and then insert?
PckMan@reddit
Is it an old plug not coming out or the new plug getting stuck and not turning? Either way there's a chance this is caused by the plug being cross threaded which is no bueno for you. Other reasons could be gunk in the spark plug well getting between the threads of the sparkplug and engine head or corrosion.
In any case your best bet is penetrating oil, working it left and right, and patience. Panicking or going full gorilla is not the move. You need to keep soaking in penetrating oil and working it left and right with the socket with the hope that you can induce some movement in either direction and the oil will get in between the threads.
SomeDudeFromBerlin@reddit (OP)
It is the old plug not coming out. There is a puddle of penetrating oil sitting above the Plug since saturday and I can induce absolutely no movement at all.
I could at the beginning but then It siezed up.
PckMan@reddit
You can run the engine. Steel and aluminum have different thermal expansion rates. Just make sure not to burn yourself when you try again. If it started coming off it sounds like your best bet is to try to thread it back in a bit again. It helps to use a torque wrench in such cases. They have long handles but also you can set the wrench to tick if you're getting into dangerous levels of force so that you know to stop.
Other than that, all you can do is keep spraying, trying it a bit, and then repeating that until it gets out. A lot of the time even if it doesn't seem like anything is happening, the penetrating oil does eventually get in after days of spraying and trying it. Patience is key here. It might seem like nothing's happening but it's better compared to snapping it off and having to deal with that.
SomeDudeFromBerlin@reddit (OP)
Then maybe I will show some patience before running it. It's submerged in oil since Saturday.
The problem is it is completely seized up and I can't thread it back in before running it.
I always torque the spark plugs down to 20nm (with a torque wrench). But my normal big ratchet is definitely big enough to snap a spark plug.
PckMan@reddit
You could try an impact gun on it. If you can fit one there that is and with great care not to snap it but it is the only other option. If you just give a few short bursts it should be fine. Don't push it if it doesn't seem like it's moving.
Dry-Discipline-2525@reddit
I would run the engine to warm it. Listen carefully and if it make an awful sound or smell shut it off but it should be fine
SomeDudeFromBerlin@reddit (OP)
I really hoped there was an aditional magic trick.
I will be verry worried while doing that.