Spark Plug # 1 Wet & Sooty?!?

JMA-RUF · 03:36 AM

I was changing my plugs today and found that my # 1 plug was wetter than the rest of them

Is this a bad sign of warn/broken piston rings in that cylinder?

The others looked dry with thick soot, but #1 was a noticably wetter.

If a compression test reveals unusually low readings in that cylinder, am I up for big $$$$ to replace that one P&C?

Engine was rebuilt about 2-3 years ago though

Advice please?

ben parrish · 01-22-2007, 04:15 AM

Not a good sign. Before you totally freak, change the plug to a new one as well as the wire. Ensure that the plug is firing.
If this is not the cause, then it is either rings or a stuck valve. The motor will have to come out.

Hope it is the wire and plug.

Good luck,
Ben

JMA-RUF · 12:09 PM

Could it be a leaky injector, causing it to be wet? I can't really tell if it's wet from oil or fuel. I guess if it were fuel, it'd be smooth but this definitely has deposits on it. Most spark plug reading web sites show that it's oil fouling

I guess I need to get a leakdown done on it asap

Also, I looked at the ignition rotor and cap and they were extremely worn out, so I've replaced them too.

I might drive it around for a week and see if the same plug fouls with oil again

stlrj · 01-22-2007, 02:24 PM

It could be a bad ignition wire to #1 too which also happens to be a far more common occurrence than you might think.

Cheers,

Joe

JMA-RUF · 01-22-2007, 02:56 PM

Hi Joe. I have the red Magnecor KV85's on the motor... they've been on there for a few years now, but I'll check it out anyway. Thanks.

I haven't noticed any smoking at idle, cruise or WOT. Nor have I seen any smoke on decel, so I'd assume that's one of the symptoms of worn rings or valve guides?!?

javadog · 01-22-2007, 03:04 PM

You might also want to correct the cause of the "thick soot" on the other plugs, while you're at it. Plugs shouldn't burn this color if the mixture is correct.

JR

JMA-RUF · 01-22-2007, 03:31 PM

JR, I run very cold plugs, which are too cold for street. That, I believe, is the reason why it's fouling so badly. I'm going to a slightly hotter plug and will see how it goes.

roadhog · 01-22-2007, 04:17 PM

James
I would go with the plug recommended for regular use for a while.Also checking the air-filter and those sorts of things.I bet your engine is OK.If you have a bad ring you would see smoke,high oil consumption,and lower fuel economy.

Carbon buildup on plugs shorts the arc path to ground as carbon is an electrical conductor.
Good luck!

JMA-RUF · 01-22-2007, 05:26 PM

Thanks... will report back in a week or so on my findings.

OH, I don't have a leakage tester, only a compression tester. What's the process for testing compression reliably?

I know it must NOT be done on a cold motor. Do I just let the engine idle for ~5 minutes before pulling all the plugs and testing compression in each?

William930t · 01-23-2007, 02:51 PM

A compression test is a valuable diagnostic tool, but to be valid observe the following: valve clearance set properly, warm (engine), good battery & starter, throttle is wide open, all spark plugs removed and cranking during test is held to ten revolutions.

If you do the compression test yourself:

loosen plugs slightly
go out and drive car to operating temperature
bring back and shut off
pull fuel pump fuse
wait 10-15 minutes before completely removing plugs
do the test (dry)
try a second test with a squirt of oil in the cylinders (wet)

post your results on this forum, we like these type of numbers!

madmmac · madmmac's Garage

New plugs, cap and rotor. Drive it for a couple of weeks and pull the plugs again and have a looksee.

JMA-RUF · 01-23-2007, 03:21 PM

Quote:

Originally posted by madmmac
New plugs, cap and rotor. Drive it for a couple of weeks and pull the plugs again and have a looksee.

Yeh, before I go through the trouble of doing a lengthly compression test, I want to make 100% sure Cyl # 1 is behaving strangely. I'll drive it around for a couple weeks with new cap/rotor/plugs and see how it goes

Could just be that plug was overly fouled and was failing to ignite the fuel properly, resulting in that wet look

Fingers crossed!

WydRyd · 01-23-2007, 04:33 PM

If your engine isn't smoking at all, then that's a good sign! Agree, run it for a little while on the new ignition components and see if the same plug re-fouls. Could just be fuel wetting the carbon build up, making it look oily. It mustn't have been firing too good if it's wet

Might even be a leaky injector in #1 ?!?