Should I leave the piston as it is or should I clean the carbon deposit? I put some engine oil in the surface and wipe it dry while the heads are in the machine shop. It seems like some carbon deposit got in between the piston and the cylinder wall. Would that be a problem?

Also how much do I need to clean the surface of the block? There are some marks from the old gaskets. Do I need to clean them off too?

2000 DII, 110K

 

That looks like alot of carbon build up, you dont use premium do you?

The mating surfaces should be clean, so all of that left over gasket must come off.
Use a razor blade and scrap it all off.

I do know know what would be the best way to remove the carbon from the pistons.
You dont want it getting in between the piston and the cylinder walls.

 

Not that bad, if you want you can use Chem-Dip and clean it all off. It doesn't look like valve guides or anything serious.

 

Rotate each piston to TDC so you limit the debris falling in the cylinder. Borrow your wifes bottle of nail polish remover and brass pot scrubber pad from the kitchen. Plug in your shop vac and proceed to clean the top of each piston one by one, rotating to TDC for each piston. Scrub 30 secs, then suction. Repeat until you have a smooth surface.

 

If the carbon deposit is not because of the fuel that I used, does that indicate some other problems?

I only used Chevron Supreme with Techron (Octane rating 92) or Supreme Plus with Techron (Octane 94) since I brought the truck 2 years, 20,000 miles ago. I am using Napa Gold oil filter and Rotella T 15W40, and I change my oil every 3,000 miles.

 

OK, good that you are using good gas.
This must be old deposits then, meaning from the previous owner. If they used the wrong gas this is what can happen.
Personally I wouldnt worry about it, it wont hurt anything.
Break off any loose stuff and then let sleeping dogs lye.

 

That carbon is bad, especially if you are using Chevron, I mean there is no excuse for it.
I would try to clean it up some before putting it back together, if not and you deal with it with additives while the engine is running, you are going to be throw some big chunks of carbon and getting some nasty knocks once in awhile.

 

It's just modern day fuel, it sucks. I pulled apart a Tahoe for head gaskets yesterday with less miles that looked worse. You can't run crabs anymore without three fuel filters. Just a sign of the times.

 

Get the heads glass beaded and machined that way your surface is perfect. I bet they will be a bit warped anyways. Also that is not normal deposits IMO, my truck ran rich
(bad O2 sensor) for a while before I did my head gaskets and it did not look that bad, mine were very clean. I bet you are burning oil you may want to look at your valves. Clean them up with some solvent cleaner and be sure to use Techron concentrate every 3000 miles and do a Seafoam induction cleaning every year.

Also a very good idea would be to use a top end lubricant like marvel mystery oil, TCW3 (marine 2 stroke oil), Lucas UCL etc at a rate of 1 ounce per 5 gallons of gas especially during the winter.

 

I cant remember where I read it but this is 100% true.
Gas today is is of a lesser quailty than even 10yrs ago.
Fuel injectors are not as picky as carburetors and therefore they dont need to make it as deposit free.
If you tried to run todays gas in a carb after 50k you would need a complete rebuild because it would be clogged.
Not to mention that the harder it is to get the crude oil out of the ground the more expensive it is so to keep the price of the end product lower they lower the quality.
So they put additives in the gas at the pump to make up for it, additives are cheaper than refining it better.

Anybody who uses cheap gas will pay for it in the long run.