Stuck spark plug won't turn (s70 1998, aluminum block)

louty · Post by **louty** » 16 Oct 2012, 15:29

sons car, first time we eknow of of plugs coming out,
so have a super stuck spark plug. all rest came out right. none had any signs of antisize or anything on them
one will not budge. wont go int the tighten direction or loosen direction
other plugs were very well worn so this one does need to go.
went on line and typed in stuck spark plug in aluminum cylinders some answers dont seem to fly
1) air gun....first I dont have one at this house, second seems like that would strip things
2) soak the hole with pb blaster, well if the sealing washer is doing its job, how would pb blaster eek by it and not compression when running?
3) pull head and take to a machine shop...ahhhh, dont really want to try that
4) do wiht engine hot.....well right now engine is cold....wouldnt a hot engine expand and make things tighter ?

my impact scredriver thing, the kind you hit wiht a hammer, will accept a extension, that I could then put the spark plug wrench on and smack it, but really am afraid fo stripping things or, breaking a plug down in the hole

so there must be on eof those good old trick out there, any one got a good idea ?

byeboy · Post by **byeboy** » 16 Oct 2012, 15:56

My personal suggestion, and I'm no expert:

Liberally (regardless of your political leanings...

) spray the PB Blaster down to the plug base (using the little plastic tube)...allow to soak down at least overnight . Check next day with strong flashlight to see if it has seeped down into the threads...if it has, re-apply and wait another 1/2 day. Drive to a shop to have them hit that one with Impact Wrench...it may do it, or it may strip the threads. If the threads do strip SOMETIMES they can be repaired with a Helicoil..if not, the head has to be removed and sent to the Machine Shop (the shop is the easy part, removing it is a PITA, and will require a new gasket set, and might as well do the valves, timing belt, tensioner, and water pump while in there..($$$$)

A four foot pipe on your 1/2" drive breaker bar will get it out, but I personally feel that has a stronger chance of bringing the galled threads along with the plug, ruining the threads in the hole. If you have an independent shop you use for other things, you should just ask them how they deal with stuck plugs in aluminum heads...they encounter that all the time, and should be pretty expert.

volvobaggen · Post by **volvobaggen** » 16 Oct 2012, 15:59

I would put some oil down the hole, and leave it there for a few days. Last time i changed plugs after buying my car, some of the plug holes had oil in the from some clumsy person who refilled it before me. The plug holes I had oil in them were the easiest to get the plugs out from.

Be careful and gentle, after the oil works its magic, screw in very small increments at the time, soak with more thin oil if needed.

I have also heard that you should wait for cold engine before changing plugs, don´t ask me why, but maybe the plugs are hotter and retains more heat the sorrounding aluminium and therefore expands more and get stuck?

What brand were the plugs? I have always been sceptical to this trivalent coating(chrome) that is supposed to prevent galvanic correosion.

Good luck!

Post by **rspi** » 16 Oct 2012, 16:30

PB Blaster. I don't know how that stuff gets by but it does. I would spray that down the hole and let it sit over night.

Then I would install the other new plugs, start and drive the car for 5 minutes to get the head hot, then pull the plug. Heat gets bolts and stuff off so I don't know why it wouldn't help here. It will likely be so easy you'll shake your head.

Post by **jblackburn** » 16 Oct 2012, 16:33

Oil (or PB Blaster) will make its way down to the threads even with plugs tightly in there.

Post by **rmmagow** » 16 Oct 2012, 19:40

50% Acetone, 50% ATF. dump in the plug hole. This worked for me in a similar situation, I let it sit overnight. Careful, pretty flamable I would think.

Post by **rmmagow** » 17 Oct 2012, 06:52

I wanted to add. If all of this doesn't work, rather than trying a giant, powerful air tool you might want to look at Harbor Freight's battery powered impact wrench for around 60 or so bucks. This tool is powerful enough to remove lug nuts all day. I would get an extension and the right size impact socket. Place it over the stuck plug, do a quick hit in the tighten direction, immediately followed by a quick (3 seconds or so) in the loosen direction all this time leaving the PB or whatever in the hole. I'd try some increasingly longer runs in the loosen direction. The battery powered impact wrenches are pretty powerful but nowhere near as powerful as an air device. This might work for this situation.

Post by **cn90** » 17 Oct 2012, 09:36

1+ on PB Blaster, it is basically thin lubricant with ability to penetrate the spark plug's threads.

You need to read this from BMW forum:
http://forums.bimmerforums.com/forum/sh ... p=23839077

Also read the post by "adev":
http://forums.bimmerforums.com/forum/sh ... ?t=1516692

louty · Post by **louty** » 17 Oct 2012, 11:29

done
soaked over night with the 50/50 mix. and it popped loose with less torque than I was throwing at it last night.

worked it out slowly
half turn out, half turn in
one turn out, half turn in
two turns out, one in
then all the way out.

I had not been feeling any resistance, but just thought Id take it easy

then new plug, antisieze on, worked in slowly, did not tighten
pulled out, cleaned off, new antisize, install for good

Post by **jblackburn** » 17 Oct 2012, 12:05

Woot! Patience and not brute-forcing things usually pays off.

Unfortunately, the nuts at mechanics don't understand that. I've had them strip an oil pan plug, a valve cover bolt, and broken a lug nut they tightened with a flipping air wrench.