HELP Spark Plug #5 is stuck
Thread Starter
Senior Member
Joined: Nov 2004
Posts: 409
Likes: 8
From: Bowie MD
2017 GLE350 4MATIC, 2009 ML350 4matic, 2005 4maticWAGON (sold), A Pre-facelift W210(sold)
HELP Spark Plug #5 is stuck
I have a 09 ML 350 wiith 270k miles.
I need help removing plug #5, the car is not shaking vigorously ( back fire)
Any suggestions would be appreciated. I don't want to force it and brake the plugs.
I need help removing plug #5, the car is not shaking vigorously ( back fire)
Any suggestions would be appreciated. I don't want to force it and brake the plugs.
MBWorld Fanatic!
Joined: Oct 2019
Posts: 5,237
Likes: 1,802
From: Colorado
G550
You're saying that you've removed the boot and the spark plug is seized? You might try running the engine for a couple minutes to see if warming the block helps. A bit of penetrating oil at the plug base might help (wick up any excess with a paper shop towel before pulling the plug out).
Thread Starter
Senior Member
Joined: Nov 2004
Posts: 409
Likes: 8
From: Bowie MD
2017 GLE350 4MATIC, 2009 ML350 4matic, 2005 4maticWAGON (sold), A Pre-facelift W210(sold)
You're saying that you've removed the boot and the spark plug is seized? You might try running the engine for a couple minutes to see if warming the block helps. A bit of penetrating oil at the plug base might help (wick up any excess with a paper shop towel before pulling the plug out).
**Update... a little online research said DON'T use WD-40... They suggested KROIL.
I'll gt order one now.
thanks
Super Member
Joined: Jul 2016
Posts: 714
Likes: 133
From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
Kroil
Definitely use Kroil and soak the area. Slowly start out then back in … back and forth applying more Kroil it will get in the threads and work. Hopefully the plugs have been changed in the past.
MBWorld Fanatic!
Joined: Jun 2002
Posts: 7,276
Likes: 172
From: So. Oregon Coast
C230 Sport Coup + 2006 W164 ML350 + 99 Ford Escort RIP
Try a heat gun to heat the plug.
Do not remove plugs from an aluminum head on a hot engine, EVER!
Aluminum heads you gotta go slow. After soaking for a few days with the
Kroil, move the wrench back and forth to try to work the penetrating oil into the
threads, start small tiny movements. Too much, and you'll take the thread with the plug.
Gradually work the plug out, and with every counterclockwise turn, turn it back
again partially, working the penetrating oil into the plugs.
I actually had to do this recently on my wifes 06 ML350. I didn't use Kroil and
I only waited a day. I found out about Kroil in the W211 diesel threads.
They have an issue they call the black death where the injectors get baked in with oil
that turns to asphalt more or less. And Kroil is apparently the penetrating oil of choice.
I bought some (expensive and not available locally) but so far have not used it.
Eventually you'll get it out. I also said a prayer while doing it.
I had a plug work itself loose once and fly (kabonk off the inside of the hood)
out at 55mph in a 70's Toyota PU. Searching in the dark on a rural road, I got so lucky.
Plug was resting comfortably on a bumper bracket. Threads were f'd. I forced it back in,
drove home, and later added a helicoil. Only problem when I went to change the plugs next time,
the helicoil stuck to the plug. So I bought another one.
Do not remove plugs from an aluminum head on a hot engine, EVER!
Aluminum heads you gotta go slow. After soaking for a few days with the
Kroil, move the wrench back and forth to try to work the penetrating oil into the
threads, start small tiny movements. Too much, and you'll take the thread with the plug.
Gradually work the plug out, and with every counterclockwise turn, turn it back
again partially, working the penetrating oil into the plugs.
I actually had to do this recently on my wifes 06 ML350. I didn't use Kroil and
I only waited a day. I found out about Kroil in the W211 diesel threads.
They have an issue they call the black death where the injectors get baked in with oil
that turns to asphalt more or less. And Kroil is apparently the penetrating oil of choice.
I bought some (expensive and not available locally) but so far have not used it.
Eventually you'll get it out. I also said a prayer while doing it.
I had a plug work itself loose once and fly (kabonk off the inside of the hood)
out at 55mph in a 70's Toyota PU. Searching in the dark on a rural road, I got so lucky.
Plug was resting comfortably on a bumper bracket. Threads were f'd. I forced it back in,
drove home, and later added a helicoil. Only problem when I went to change the plugs next time,
the helicoil stuck to the plug. So I bought another one.
