#2 plug coming loose

[adamm]

Anybody have any ideas? This has happened a couple of times now.

A visual inspection of the plug shows it to be clean, with clean threads, no damage etc. Thought perhaps I hadn't done it tight enough to begin with. But approx. 1000 miles later and it had come loose again.

Has anybody experienced this before or have any suggestions?

Cheers!

[Scott Sislane]

Sounds like your threads may be suspect. Maybe you need to re-thread it and install a helicoil.

[ray_]

Hmm. But before helicoil you might try a new plug fist. Or switch one from another cylinder and see which backs out then.

There's a torque spec too, right?

What plugs ya running?

GL,

Ray

[adamm]

They're the Bosch Super 4s. I've done a lot of miles with this particular set without any problems before which is what I find peculiar - the thread wouldn't just 'give up' would it??

Switching a couple round sounds a very sensible thing to do.

I think there is a torque spec but I only have the BMW plug tool that you just stick a bar through to tighten.

[Napes]

Although you imply you don't have a torque wrench, here is the correct torque for the plugs to give you an idea: 18-22 lbs/ft.

Bob Napier

[adamm]

Thanks Bob, I'll have to see if I can acquire a plug socket from somewhere so I can use my torque wrench.

[Scott Sislane]

sorry, I assumed you would have tried a diff plug in that hole already. torque spec? I don't think that comes into play here, but I'm not a mechanic.

[adamm]

Nah, the first time it happened I'd assumed it was just a one-off, I was on the road so just tightened it up (exhaust manifolds are bloody hot!!) and thought nothing more of it. This time it's happened I was pulling into my car park at work and heard the distinctive noise like a blowing exhaust so again, didn't have another plug with me or time to 'play'.

I'll grab 5 minutes this weekend and see what I come up with. Thanks chaps

[jrhone]

yep happened on my first 2002....MANY years ago...the threads are stripped....it will happen faster and faster until it wont stay....

[Jbird]

+3 on the heli coil. I inherited a motor from a friend that would spit #4 plug out every 1000 miles or so. heli coil strightened it right up.

[adamm]

yep happened on my first 2002....MANY years ago...the threads are stripped....it will happen faster and faster until it wont stay....

Oh happy Friday! Bugger it!

Thanks for the input everybody. Let's hope it stays put for at least a little longer...

[Mike87]

If new plugs are not torqued correctly (to spec) the crush washer will not deform and the heat cycles will loosen the plugs.

Find a socket and use the torque wrench.

If the threads pull or you cannot get to torque, do the helicoil repair.

[Mike Self]

way into its threaded hole. It's just possible that carbon has coated the innermost threads to the point that you think the plug is seated, but it isn't. Then it will work loose. I think it has to turn nine revolutions before it seats, but that's from (possibly faulty) memory. Try one of the good plugs to confirm.

Use a properly sized and length spark plug thread chaser down the hole, then try the plug again and see what happens. If that didn't help, then it's helicoil time.

cheers

mike

[TobyB]

If it's coming loose but is successfully retightening, the threads are OK.

For now.

Mike S is on the right track- take the plug out and look at the crush washer

at the base. If it's completely flat, the plug can work its way out, as the differential

expansion between the steel and aluminum can loosen it.

If it's completely uncompressed, the same thing can happen.

Buy new NGK plugs (BP6es, stock # 7333) and try again.

They're so much cheaper and easier than having to fix it if

the hole strips. And new Bosch have becone a horror story...

When you tighten them (13/16 spark plug socket and a bar won't set you

back more than 20 quid, and you don't need the world's best quality for this)

you'll feel the washer hit the bottom of the hole, then you'll start to feel the

washer crush. It's a skoogy feeling, but pretty distinct.

Give it maybe an eighth of a turn after you feel the washer,

and it'll be as good as it can be.

hth

t

[jgerock]

+ 2 on checking for crud in the plug hole. Also make sure a 2nd washer isn't stuck to the head.

If you do install a helicoil insert, make sure to follow the directions. In my first VW, someone had installed a helicoil and it always came out with the plug. PITA.