Changing Spark Pugs

[baileysd46]

Hi Everyone,

I was changing my spark plugs in my 1971 280sl today and one of the plugs was almost impossible to get out. Well, I finally got it our and I guest I may have not put in right the last time  and I saw what looks like some aluminum in the treads of the removed spark plug. What should I do?

Thanking you in advance for your help!

Scott

[Richard Madison]

Two suggestions:

Put the plug top into a length of rubber tubing. Hold the plug over the hole, then twist it in the first few threads by turning the rubber tubing. The tubing will not let the plug screw in unless the plug is properly seated in the hole...this helps prevent cross threading.

Also, to help the plugs easier to remove, put a small amount of anti-seize compound (the stuff that prevents thread lock) on the plug threads...various brands are around.

Richard M, NYC

[Cees Klumper]

And in terms of your one possibly damaged spark plug hole I would suggest trying to see how the new spark plug goes in using Richard's method. If it does not feel right, probaly you need to look into the helicoil solution (plenty of ino on this site if you do a search). Good luck!

[baileysd46]

Hello,
Does anyone know where I can get information about using the Richard’s method with regard to changing a spark pug.
Thanks,
Scott

[Naj ✝︎]

Hi, Scott,

If the threads are not too badly damaged, you can use one of these tools to clean/repair the threads:

http://www.pvrdirect.co.uk/productinfo.aspx?catref=VS625

And how it works:

http://www.youtube.com/watch?v=-sL9jQcRZek&feature=related

Naj

[Naj ✝︎]

Hi, Scott,

Richard replied your other post:

Put the plug top into a length of rubber tubing. Hold the plug over the hole, then twist it in the first few threads by turning the rubber tubing. The tubing will not let the plug screw in unless the plug is properly seated in the hole...this helps prevent cross threading.

Also, to help the plugs easier to remove, put a small amount of the stuff that prevents thread lock on the plug threads...various brands are around.

Richard M, NYC

[badali]

Do they sell the tool in the US or should I just order it directly from them in the UK?  I have one that was cross threaded in my 4.5 V8 many years ago.

[dirtrack49]

Scott,

I just went through some problems with my plugs not coming out of my 66 230SL recently.

On number 4 and 6 I had to use a thread chaser to clean up the threads in order to install the new plugs.

You can buy a 14mm spark plug thread chaser at just about any auto parts store. I got mine at the local Autozone.

Depending on how much damage there is to the threads, you might be able to clean them up and avoid the neccesity of buying the expensive specialty tool or needing a helicoil.

One thing I found helpful was to guide the thread chaser in carefully using a long socket extension and doing it by hand. I would go a couple of threads or so, and back the thread chaser out a couple. Back and forth until it would go in with little to no resistance.

After you get your threads cleaned up, make sure you use a little anti-seize compound on the new plugs. Also like everyone else has mentioned, it is better to start your plugs back in by using a piece of rubber hose to hold onto the plug while you start them into the plug holes.

Hope that helps and good luck.

[Theo]

I too am changing my sparkplugs: Can anyone suggest a brand and/or type of the anti-seize compound to apply to the sparkplug threads. I have heard that copper-based is good (?).
Also what about just using WD40? --i.e. it helps loosen hard-to-get-off items.

Last question: for the piece of rubber hose, what is the preferred length, is it the shorter the better to have a more direct feel as the the threads are rotated, also the interior/exterior diameter of the hose (I have some hose handy but its too big, won't hold the plug)

Theo
1966 230SL Euro

[thelews]

No, WD-40 is not an anti-seize lubricant of lasting value.

You want a molybdenum disulfide.  Paste lubricant, can/tub with a brush on the cap.  Pretty much available in any auto parts store, the picture below, from Amazon.com.

And, by the way, it sticks to everything and makes a mess, so use sparingly and carefully.

[J. Huber]

If you don't think you'll use a whole container of the Moly paste for anything, NAPA and others usually have a small packet (like Ketchup) at the front check-out counter. Same brand as John's I think... One packet is more than enough...