Spark plug damage identification

[armadillon]

Anyone know what can cuasr this buildup on a plug? All other plugs looked healthy.






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[rfl]

Fuel additives or oil deposits well past the life of the plug.

 

[RonD]

+1 ^^

Google: image spark plug condition ash deposit

 

[ab_slack]

Any chance the others were replaced except that one?

 

[armadillon]

Negative. 6 of 8 were fine. The last two on the passenger side of my 97 Chevy 5.7 were like this. One was dry the other completely covered in crap. Like this:

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[tmcalavy]

Anything's possible...last 69 F250 with V8 that I bought, restored and drove for awhile had seven regulation Autolites torqued properly and one up front on the driver's side of the 360 motor jammed in tight...I PB Blastered it for a couple of days. Just before I pulled the engine I had the hood off, so I made a T-handle on the end of an ancient spark plug wrench in my old man's toolbox, leaned on both ends and it broke loose...turned out to be some bastard Champion, longer than stock with the gap almost closed from piston slap...black as coal, too. After that the 360 ran much better, hitting on 8 instead of 7...too bad the rings were toast.

 

[rfl]

Correct me if I am wrong, but the second photo is NOT the same as the first. Is it the same plug from the same cylinder and if so, what changed between the photos? Or is the second photo other bad one of the 8?

 

[kimcrwbr1]

Evidently you replaced all the plugs correct. Put in a new PVC valve and then decarb it with seafoam. After the engine is up to temp with the power brake booster pull in half a can of seafoam at a high idle and then quickly shut it down. Wait 1/2 an hour and then start it and run it around 2500-3000 rpms until the smoke clears. Is there alot of milkshake on the dipstick and breather cap? Maybe clean the breather filter what engine are we looking at?

 

[tmcalavy]

Maybe clean the EGR valve, too. There used to be plans on line for a PCV catch jar that you could install to pipe the PCV valve to a bong-looking glass jar that caught all that vapor and let it condense into crappy-lookin black junk...then the vapor went back into the engine. Did that on my 90 F150 one weekend cause I was bored and had all the stuff lying around...coffee can, glass jar, small juice can, bb's, vacuum T connections and hose. I was amazed at the crap it caught...never seafoamed that Big 6 after that cause I figured it had to be a lot cleaner inside. The crap it collected looked like old skunky gas or diesel but without the varnish smell.

 

[armadillon]

Its 97 Chevy K1500 vortec 5.7. The two plugs are separate. The first pic came from cylinder 6 and the other 8. Both of those are passenger side closest to firewall. Both had the ash deposits but the one from cyl 8 was covered in black oily residue. My guess was leaky injectors but after pulling intake the spider MFI (replaced last year) was not leaking. Did the fuel leakdown test and wasn't seeing any problems.

I've been getting the p0300 (random misfire) code and also the code for catalyst inefficiency banks 1 and 2. If the cats are now bad it'll be a result of the poor running condition.

PCV was changed and EGR was cleabed and volt tested 4 months ago. EGR was diagnosed as working.

Bad MAF or bad valves?

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[armadillon]

PS also did a compression test yesterday on all cylinders. 175-185psi on all cylinders.

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[RonD]

With good numbers on leak down and compression test it would have to be bad intake valve guide seals leaking oil.

Simple test would be to disable spark, pull EEC relay or equivalent to stop fuel injectors, and crank engine over a few times, pull out spark plugs and have a look for oil on the tips.

You can change valve guide seals without pulling the heads.
Air pressure method or rope method.

Also make sure PCV Valve and Vent hose are clean and working, if pressure builds up inside the valve covers from blow-by then even more oil gets pushed past bad seals, but the vacuum in the intake is usually enough.

 

[armadillon]

Thanks Ron. I'll check it out and then give an update. Valves were my guess if I had to choose.

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