I have about 81K on the shortblock and I justpulled my trick flow heads to find the 4 and 6 pistons ar elike falling apart, I can rub my hand across the top and it feels granular and sandy and even comes off on my hand. Any suggs? Coolant leak? detonation?

 

that is a good question....good luck man!

 

Probably detonation.

 

I took a better look after i calmed down. I can scratch the whitre stuff off with my fingernail. The piston is nice and smooth under there. once i start to scratch is off it turned brown and sandy. cylender 1, 2, 3, 4, 1/2 of 5 and 6 are kinda gritty 7 and 8 are fine. the bores have no crakcs and I can still see the cross hatch marks. If everything is ok is it possible to rerun them or can i just get new pistons?

 

Running any additives? Possibly an octain higher then you need?
When pistons go they chunk, I havent seen any start to deterorate. Is possible to get a picture uploaded?

 

My girlfriend is coming over tomrorow with a camara. i will take a pic. on the head side. the exhaust valves are redish and the intakes are like a dirty carbon buildup. Looks normal though I will shoot pics of those. It looks like literally crusty white stuff (that doesnt sound good lol) anyway whats detonation look like? PLugs are all beautiful. ONly additive I used was ocante booster like 10,000 miles ago and i just put a bottle of stabil i nteh gas and drove it 8 miles back home for the winter. thats all

 

i'm thinkin carbon deposits on the pistons. i know i had that too except my you could peel off.

 

my guess is dirt or build up on the pistons, post a pic and you'll get a better informed reply

 

you guys will have pics of each piston tongiht after I get home from school.

 

Theory. Last year my car burned oil like a ****. 1/2 quart every 150 miles. plugs look black and I could even see the blue smoke. I replace intake gaskets and find out that the oil was going down the screw in stud holes into the intake passage. I teflon tape it and all is well. burns 0 oil and plugs look great. I'm thinking this is major buildup from las tyear and since its layed the top layer got hot and burned. I took a can of carb cleaner and towels and went after a top of a pison and it cleaned up nice. There are no nicks or scratches on the top. Nice and smooth. What do you guys think? doesnt detonation make nicks on the piston tops? I never hear any detonation.

 

Yeah I thought you meant the metal was rough.....its probably just carbon buildup then...nothing to be worried about. Take some pictures and we'll tell you for sure.

 

Mkos,

You're making this WAY too easy, man. If you post those pictures here, you'll probably get probation or banishment. I'd still like to see them.

If you have a die grinder, get a wire cup brush and clean each piston at TDC. Once you're down to clean metal, you can see what's happening. My guess is that the piston domes are just fine. Are these plain cast aluminum? Cast hypereutectic alloy? Forged?

 

In the future, before you pull a head, it's a good idea to pour in about a quart to a half gallon of water into the carb while it's running. Trickle it in slowly while working the throttle to keep it from stalling. This usually cleans out any carbon on the pistons and combustion chambers. Makes for a cleaner inspection.

 

ive heard of misting or adding water slowly to "clean" out the carbon but a half gallon... isn't that a little too much?

 

Yea Its a bit much. I'm personally not in favor of adding any water to an engine unless were talking coolant. A better idea would be run down to the parts store and buy a berrymen upper engine cleaning kit $25. It comes with a can of cleaner that hooks directly to intake vacuum and suck it up while the engine idles. I guess you could save the can and use water but wouldent be my choice.

 

A quart for maintanance once a year and yeah.... a half gallon prior to tear down, especially a rebuild along with Berryman in the crankcase. It sure makes tear down and inspection a breeze. For maintanance, I will just change the oil afterwards. It's also a great way to find an exhaust leak. Water will spray out of the tiniest holes making the leak more detectable.

If your going the wire cup brush at TDC route, use a shop vacuum with the crevace tool to suck the carbon that made it's way around the piston crown. Some of that stuff is pretty gritty and could scour your bore.

 

This topic has been battered around quite a bit on this site. Here is the link to one skirmish.

https://www.thirdgen.org/techbb2/sho...er+in+the+Carb

It has worked fine for my carbed motor. TPI seems a bit more complicated.

 

i dunno lol stock 89 L98 shortblock

 

Are they actually peices of something, like chunks of valve or piston, or is it just... uhh... stuff?

 

Stock slugs should be plain cast silicon aluminum, and shouldn't exhibit the microscopic flaking of forged pistons under high heat/stress conditions. If you see real metal chunks on cast pistons, you have a serious problem. My guess is that unless you are running really lean for long periods or are "on the bottle", the substance is just a deposit, and not part of the piston.

As for cleaning with water, you can also scan these threads:

https://www.thirdgen.org/techbb2/sho...hreadid=174734

https://www.thirdgen.org/techbb2/sho...hreadid=102500

 

pics are uploading as we speak

 

Number 1

Driverhead

Passhead

#7 #5 #3

Like I said it all comes off with my fingernail.

 

looks like carbon deposits to me

 

matt:

i'm going to say that it's from your oil burning last year. that looks like a lot of carbon.

looking forward to seeing everything in person on sunday,

 

I've seen worse. Looks like carbon and stuff. You could try your best to clean it off before reinstalling the heads, or just not worry too much about it. If it were me, I would try to clean that crap off.

 

Oh, NO! I'd change the pistons. Not because of the deposits - that can be cleaned off. But the pistons are so, well, dished...

 

LOL

 

Hey Vader, I just noticed you have an "ICON" thingy in your sig.....do you have a member page or something? J/w.

 

Guess you didn't notice the ICON Motorsports thingy was a clickable link.

 

Uh, yeah, but I didn't find a Vader page.

 

Man, why bother even cleaning those things?? They're just gonna get dirty again anyway!!

 

Vader's still just a newbie in ICON, he's not even off probation yet But some one of these days, maybe hopefully some one of us might get motivated and update the member pages; it's been about 2 years since anybody got a wild hair and did that. And if he behaves himself, maybe we'll issue him a page too.

Seriously, the piston damage looks like what happens when the carbon deposits from long street use suddenly get ignited from unaccustomed blasts of high oxidant and fuel content, making the carbon ignite and glow, and corroding the metal.

Those pistons have no business in a nitrous motor anyway; or rather, nitrous has no business on a motor with those pistons in it. Consider yourself lucky they lasted however long they did, consider this a sign that they need an upgrade, and just put the right thing in there.

 

I never used nitrous.

 

Doh.... Sorry!!! I thought you were for some reason.

In any case, that's what it looks like; carbon that accumulated over time, and thenm got lit off by subsequent usage. The heads look fine though, no sign of running particularly rich or lean, or oil burning, or any of that, so it's probably a result of something in the past.