Mangled spark plug electrode in 292 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Canada20 · 08-28-2003, 01:43 PM

Hey all. Has anyone encountered a mangled electrode in their engine before?

It's a rebuilt-to-stock '69 292 I-6 so I don't think there should be any trouble from the pistons. When I got the truck a couple of years ago, it was blowing steam out the tailpipe like crazy and when I had a chance to remove the plugs and have a look, plug 6 was bent. I remember reading somewhere that it's possible for valve guides to wear badly enough to allow enough movement for a valve to connect with a sparkplug and that may explain the steam. I kinda doubt the head was ever converted for use with unleaded gas......

Just trying to get a handle on what to expect.

Thanks

Greg

stelth2002 · 08-28-2003, 03:47 PM

Umm, it has to be something like that. I just pulled mine to put oil in the holes and they all looked good. Is there something that coule have got in the intake and possibly fell into the combustion chamber? Other than that it has to be piston hitting it or a valve.

Class of 69 · 08-28-2003, 09:58 PM

Steam is from boiling water, which indicates the presence of coolant in the combustion chamber. I agree that something may have gone down the carb, but either way, I would suspect a cracked head, from the foreign object as the cause of the coolant leak. A common cause is a blown head gasket, but I've never seen a head gasket bend the electrode. Do you remember if the steam smelled sweet?

Canada20 · 08-29-2003, 08:03 PM

well.....it definitely WASN'T a valve colliding with the electrode. I gotta figure out how to post pics but let it be said that it was definitely a foreign object (a screw that should've been holding a flange for the air cleaner housing bolt worked it's way free and went on a holiday).

The #6 piston is at the top of it'sstroke so I can't tell if the cylinder walls are OK but I'm betting not. I think I might need an engine swap....

Greg

08-28-2003, 01:43 PM	#1
Canada20 Registered User Join Date: Jun 2001 Location: Calgary, Alberta, Canada Posts: 802	Mangled spark plug electrode in 292 Hey all. Has anyone encountered a mangled electrode in their engine before? It's a rebuilt-to-stock '69 292 I-6 so I don't think there should be any trouble from the pistons. When I got the truck a couple of years ago, it was blowing steam out the tailpipe like crazy and when I had a chance to remove the plugs and have a look, plug 6 was bent. I remember reading somewhere that it's possible for valve guides to wear badly enough to allow enough movement for a valve to connect with a sparkplug and that may explain the steam. I kinda doubt the head was ever converted for use with unleaded gas...... Just trying to get a handle on what to expect. Thanks Greg __________________ No such thing as a stupid question, right?

08-28-2003, 03:47 PM	#2
stelth2002 Young Gun wth Fast Inline Join Date: Jan 2002 Location: Idaho Posts: 1,475	Umm, it has to be something like that. I just pulled mine to put oil in the holes and they all looked good. Is there something that coule have got in the intake and possibly fell into the combustion chamber? Other than that it has to be piston hitting it or a valve. __________________ 1967 Chevrolet LWB with built 292! 415 ft. lbs of torque, 4 speed :O with 27% overdrive too, 3.73 Posi. Frame and body done... getting painted!!!

08-28-2003, 09:58 PM	#3
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	Steam is from boiling water, which indicates the presence of coolant in the combustion chamber. I agree that something may have gone down the carb, but either way, I would suspect a cracked head, from the foreign object as the cause of the coolant leak. A common cause is a blown head gasket, but I've never seen a head gasket bend the electrode. Do you remember if the steam smelled sweet? __________________ 69 GMC K10 ..some restoration required....still..

08-29-2003, 08:03 PM	#4
Canada20 Registered User Join Date: Jun 2001 Location: Calgary, Alberta, Canada Posts: 802	well.....it definitely WASN'T a valve colliding with the electrode. I gotta figure out how to post pics but let it be said that it was definitely a foreign object (a screw that should've been holding a flange for the air cleaner housing bolt worked it's way free and went on a holiday). The #6 piston is at the top of it'sstroke so I can't tell if the cylinder walls are OK but I'm betting not. I think I might need an engine swap.... Greg __________________ No such thing as a stupid question, right?



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