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914World.com _ 914World Garage _ combustion chamber anomaly...crusty lava rocks

Posted by: sean_v8_914 Feb 6 2007, 12:28 PM

2.0 D-jet with 5000 miles

notice how it is in teh upper third by the plug. nothing near the OD

it is crusty. looks like lava rocks in the middle

the head did not leak, pic is deceiving

Attached thumbnail(s)

Posted by: sean_v8_914 Feb 6 2007, 12:29 PM

the back of the piston has brown varnish stain

Attached thumbnail(s)

Posted by: SLITS Feb 6 2007, 12:30 PM

Mainly deposits from shitty gas additives & some burnt oil. Not a problem ... clean it and reassemble.

Ok, so you posted a second image ..... I might take exception about the head leaking, but the photos are Ahandiesque that it is hard to tell.

Posted by: sean_v8_914 Feb 6 2007, 12:30 PM

that light spot is where I picked off a chunk

Attached thumbnail(s)

Posted by: Lawrence Feb 6 2007, 12:31 PM

Carbon build-up.

Running rich, probably. Burning oil, maybe?

Looks like you might have had an oil leak there... cylinders not well sealed to the case.

Good thing you caught it.

Posted by: sean_v8_914 Feb 6 2007, 12:33 PM

I think it was an event rather than an ongoing accumulation

any complaints about ARCO gas? I have been running 91. it pings a bit on 87

Posted by: sean_v8_914 Feb 6 2007, 12:34 PM

the oily drool marks are from washing the outside prior to disassembly

Posted by: sean_v8_914 Feb 6 2007, 12:35 PM

teh oil filler neck was leaking and caused a mess

PS. the motor always runs great(not right now while in pcs)

Posted by: sean_v8_914 Feb 6 2007, 12:39 PM

the plugs have always read lean...coffee cream brown with slight ashy white-ness

Posted by: sean_v8_914 Feb 6 2007, 12:41 PM

the photos were taken by a German (H.M.)

Posted by: SLITS Feb 6 2007, 12:41 PM

Back in the days Shell was the worst for similiar deposits .... the deposits would be white / grey if it were additives alone called ash deposits. Remember, you live in a state where to produce clean air out of vehicles and especially during the winter enough additives are added to fuel to choke any engine. It doesn't make the gas better, it just pleases the tree huggers, legislators and oil companies.

The brown on the back of the piston is normal with overheated oil.

Posted by: Dr. Roger Feb 6 2007, 12:43 PM

second vote for crappy gas.

I used to work for a test fuel additive lab and that looks like it.

I'd run that tank empty, put some techron high grade in with an injector additive, then run 76 high grade daily IMHO.

Unless you have some unocal blue gas in your state. that shtuff was a top performer back when we were rating different fuels.

Posted by: SGB Feb 6 2007, 01:02 PM

Roger-
what type of gas do you use?
There really is a difference?

Hey, I have those aftermarket compression raising devices, too! I have been having 'em incrementally installed (apparently, b/c I buy CSOB gas).

Posted by: Dr. Roger Feb 6 2007, 04:29 PM

I use chevron or an additive for cleanup. techron is sold to other oil companies and sold under other names. its about the best stuff on the market. I like to run something with methanol for daily driving (76 gas).