Author Topic: Gasoline on spark plug  (Read 4419 times)

KSalzer

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Gasoline on spark plug
« on: February 29, 2008, 01:26:34 »
I have a '65 230SL that I had out the other day in our gorgeous 70+ degree summer weather here in Southern California (sorry East Coasters!).

First off I should say that I'm mechanically minded, but certainly no mechanic. The following story is stretching my diagnose/repair abilities to the limit, so I'd very much appreciate some input on this from Those Who Know.

The car decided to take this particular day to start running on five instead of six cylinders, so I examined the spark plugs first. When taking the spark plug wire off of #6, it pulled the metal core of the spark plug right out. Aha, I thought, I've found the problem.

After replacing that plug I got to #3. It was clearly fouled, black (not white at the spark like the other plugs) and covered in gasoline, as if it had been dipped in it. I should add that only the interior, metal part of the plug had gas on it, not the ceramic, outer part. I've since replaced all six plugs.

My question is this: was the gas coating plug #3 a cause or symptom?

In other words, was the gasoline on the plug due to the plug's failing and not firing, therefore not burning the gas away during combustion? Or was the gasoline coating likely due to some other bigger factor, in essence "drowning" the plug, thus causing it to fail? What could cause this?

Many thanks in advance for your thoughts.

Kris Salzer



merrill

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Re: Gasoline on spark plug
« Reply #1 on: February 29, 2008, 12:17:35 »
could be that the cold start selenoid on your intake manifold is leaking or not shutting off.



Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230
Matt
Austin Tx
66 230 sl - "white"
78 300 D - Blue
98 C230

mrfatboy

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Re: Gasoline on spark plug
« Reply #2 on: February 29, 2008, 12:31:29 »
After you drove it with the new plugs what do they look like now?

1969 280sl
Signal Red
1969 280sl (Aug 1968 build)
Signal Red
4 Speed

KSalzer

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Re: Gasoline on spark plug
« Reply #3 on: March 07, 2008, 18:16:25 »
Thanks for all your suggestions; I'll be taking another look at it this weekend and will report back anything unusual.

Kris

Benz Dr.

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Re: Gasoline on spark plug
« Reply #4 on: March 10, 2008, 10:09:48 »
One wet plug indicates an ignition problem. Try a new plug first and then check your wires. If none of this helps try switching injectors. If the problem moves to the next cylinder it's a bad injector. Injectors don't fail that often and I think you will find it's just a bad spark plug.
If it was a leaking CSV almost all of the plugs would be dark but not usually wet.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
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1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC