What causes this??

[shimp]

Picked up a MK IV 1990 peanut head motor from demonmaestro for pretty cheap $$$, was said to be running motor when it was pulled by original owners, but you know how that goes, not usual for someone to pull a motor for no reason.  I didn't care as along as the bottom end didn't have stacked bearings and it didn't so I picked it up despite the fact that it wouldn't turn over all the way, will be using it for my Suburban as a temp motor while the original motor gets rebuilt nicely, this one will be a slap together deal.

Anyway, got it home took the heads off, first thing that was obvious when I pulled the heads is all kinds of black flakey stuff came out of every cylinder, and some were oily'er than the others, the valve stem seals were shot to hell so it had to be burning lots of oil. 

See attached pic, wondering if the black buildup in the cylinder would cause that piston damage.  Note that it' only at the top of the combustion chamber where it's really small and flat.  Someone said it could have been running VERY rich (bad O2 sensor?????) for a long time with total disregard to fixing it, just kept driving it, and this happened.

 

[ChryslerJet]

That Looks like something was hitting it to me.

 

[shimp]

That Looks like something was hitting it to me.

Yep, but head itself showed no signs of anything hitting or marring it up like that, just a large clump of build up black junk on the small flat part of the head right above where the piston is messed up.  Pretty sure nothing was hitting it, other than the buildup, at least there was nothing in there, though could have been at some point.  Maybe there was at one point and because the piston was jacked up and it was detonating, the black junk was worse in that cylinder than the others.  I know there are some half decent mechanics here so I figured I'd post it up and we can play guess what did it game.

See next pic:

 

[shimp]

Note the small hole suspiciously shaped like the majority of the damage in the top left corner of the piston....  I wonder if I will find something in there once I pop that piston out of the block....????  Maybe the tip off a spark plug?

 

[slowboat13]

Carbon buildup can be some pretty solid stuff.  Is that a hole in that piston?

 

[slowboat13]

I was thinking the exact same thing...mabe the previous owners were not high on maintenance and a tip burnt off of a plug???

 

[ChryslerJet]

Aluminum is a lot softer than steel something that could damage the piston could not leave a mark on the head.  I think I see some damage on the bottom left corner of the cylinder.

I would like to see what that cylinder looks like with the piston down in or out of the hole.

 

[HellinnFrnt]

At least it's not a Ford.....  whatever.gif

 

[shimp]

Aluminum is a lot softer than steel something that could damage the piston could not leave a mark on the head.  I think I see some damage on the bottom left corner of the cylinder.

I would like to see what that cylinder looks like with the piston down in or out of the hole.

Your wish is my command.

No damage to ANY of the cylinder walls in the whole motor, other than some surface and recent fingerprint rust, the cylinders are very nice.  Hard to get a good pic with it down but here you go.

 

[shimp]

BTW: ignore what looks like damage down by the piston at the bottom of the cylinder, simply reflection of top of piston from Camera Flash.  It is nice, smooth, shiny all the way down in every hole.

 

[shimp]

Carbon buildup can be some pretty solid stuff.  Is that a hole in that piston?

Yes there IS a hole in the piston on the very edge top left corner.

So what causes all that build up? 

What could prevent it and/or remove it without taking motor apart?  Fuel system cleaner?  Seafoam?  Run a little diesel in the gas once in a while?  Some obscure Gumout product of some kind?  Just wondering.  Never seen it that bad in ANY engine.

 

[slowboat13]

My guess would be alot of city driving, lowest grade of gasoline, little or no maintenance...Personally I stretch my gasoline engines out every once in a while to blow as much of the crap as I can out.

 

[shimp]

Well then the 4.8 in my 2004 Chevy shouldn't have ANY buildup LOL, It sees 6,000 and WOT daily.  I was suprised not more responses, probably just not much interest since it's not 12:1 with dual 4's or a Dominator LOL.  Was really wondering what anyone thought about running a little diesel in the gas every now and then.  Especially if it has no Cats or O2's, or planned on replacing the cats/O2's anyway.  Like say you got an older model car/truck with some pretty high miles and wanted to get the "soot" out of the motor so it don't look like this one in the end what would work good?

 

[shimp]

I read up on putting a little diesel in with gas, like just a LITTLE diesel, not a large amount, and it's a mixed opinion deal.

Some say it will make things WORSE, some swear it makes it better, but have no real proof other than the fact that they didn't have any failures.

So I don't know.  We used to keep the old Red Farm Use diesel fuel here, about 300-400 gallons in a big tank out back for the tractors and trucks, but then they started cracking down on using the red diesel in non-farm trucks and the price went through the roof and now we just buy that blue diesel, put it in 5 gallons cans and dump it in the tractor.  The Red diesel had a lot of sulfur in it, which should clean and lube things like valves, even in a gas engine. Don't know about that blue diesel.  Maybe that's why the difference of opinion is so great, people who had bad experiences used the blue diesel... it's dry, no sulfur as compared to the Red diesel right?

I know it's just as easy to add some fuel system treatment/cleaner to your gas tank when you fill up, as it would be to put a little diesel in, but the problem is, which of those products really works?  If you buy diesel to mix in, you know what you are getting, it's diesel.  If you buy those cleaner/treatment products you may just be getting some garbage that doesn't do anything.  Which one works?

 

[KONA77]

the only product I've found to work for cleaning the fuel system was Lucas,  i had trouble with me cougar,  spent $100s of dollars on that techron concentrate bullshit,  filling up at the chevron station, nothing for a long time I finally put 12oz of Lucas in and in 40 miles the is was gone,  and the Lucas is supposed to good to burn the carbon out of the cylinders,  never pulled an engine apart that had Lucas ran through it so don't know...  there's my .01  :smile17:

 

[Becket]

Chris, Something was in there with that Piston, Maybe the Piece that is Missing from the Piston, Maybe something else, Is it Possible that the Head was replaced and the damaged Piston left to Rot?

But there is the Possibility that the Head was not damaged by whatever tore up the Piston.

 

[KONA77]

Chris, Something was in there with that Piston, Maybe the Piece that is Missing from the Piston, Maybe something else, Is it Possible that the Head was replaced and the damaged Piston left to Rot?

But there is the Possibility that the Head was not damaged by whatever tore up the Piston.

judging by the pic,  I have to agree with Gas-hole

 

[KONA77]

and it may have bad oil rings,  and that's why there was a build up,  just a thought

 

[Patchman]

With all that carbon in it, carbon will glow when heated from combustion. Therefore it leads to detonation. Detonation will destroy pistons if allowed to continue! So the cause was probably detonation due to cheap gas and running it hard. That would be my guess! I have seen too many 1 ton Chevys with broke pistons due to detonation and abuse! :smile30: The diesel in the gas will really only serve as a upper end lubricant! It's not gonna hurt anything. My old machinist use to recommend us running a little in the fuel in our performance motors. I started using Marvels or Atf for the same reason. :smile16:

 

[Crusader]

A buddy of mine used to put a little bit of diesel in his oil about 100 miles before he was going to change his oil. He swore that it cleaned the inside of his motor so it would last a lot longer. Well...about a year later he ended up swapping out his engine because it took a crap on him...lol. Who knows....

I've used the Chevron with Techron that Roger mentions above.....but haven't noticed any improvements. I think I will get the Lucas cleaner now that he recommends it.