Should I clean the tops of the pistons while head is removed?

[DrNick]

Engine is a 2JZGE, I have removed the head for some upgrades. The car was running perfectly well before I pulled the head so there is no damage to rectify. However there is a lot of black carbon buildup (flakes of it in some places) on the tops of the pistons.

Now that I am almost ready to put my brand spanking new shiny head back on I am really hating the look of those dirty pistons.

These things are stopping me from cleaning them

1. I have kept the timing belt meshed with the timing pulley in its original position and dont really want to turn the engine over.

2. I am worried about dropping bits of carbon into rings and scoring the bore when I start it up


I have had mixed views on this from various people so I would welcome some more opinions on what you all generally do in this situation.

[Billzilla]

It won't hurt, but about ten seconds after you start it they'll be fuzzy again. Better to get the mixtures right to reduce the carbon build-up.

[beerhead]

Yeah I normally clean them up. Just make sure you tape up all the oil and water galleries. If you've got major build up it'll decompress your motor and loose power though

[progkamol]

I cleaned mine up before putting the head back in ...

[TERRA Operative]

Same here on my 4AGZE. Just tape stuff up like beerhead said.

[progkamol]

+1 yes ... make sure u close up those holes before you clean ...

[DrNick]

Thanks for the responses chaps. Any suggestions what is good to use for cleaning the muck off with minimum risk of scratching things in the general area?

[litldv8]

+ 1 for no but if you must some carby cleaner in a pressure pack
make sure you tape everything up
have seen them turn into oil burners very quickly.
you will definately loose a little compression.
adn will have carbon back on the pistons after you drive it anyway.
neil

[TERRA Operative]

I just went over the piston tops in the GZE with a brass wire brush in a battery drill. Just enough pressure to take the carbon off, and the ceramic coating was left nice and clean.

Car still runs fine now, on a regular diet of 10PSI too, so I'm not complaining.

[allencr]

2. I am worried about dropping bits of carbon into rings and scoring the bore when I start it up

It won't score the bore, but it does stop the ring from sealing against the land for a while, maybe a long while.
Everyone has the urge, but I can't think of anything that is less useful for your engine then cleaning piston tops

[progkamol]

I used 500 grid sand paper on air orbit sander ... cleans the carbon off well ... it was on my friend lancer running 4G93 ... the car running til now (been about 16 months since) ... I know it sounds wierd and comments gonna be made bout this method but hey, it works. Alternatively scourers by hand will do the job quite well too ... make sure you close those wholes 1st tho.

[Shifty]

always used to pour a little water down the carby to clean it out while the engine way running

but i guess that shows my age

you could maybe spray some water into the intake post afm if you wanted, but yeah i wouldn't fuck with it if it's currently good

[bmak]

When a motor is still together Ive done nothing more than covered holes and blown any loose bits off with compressed air.
Any more is probably a waste of time.

[CrUZida]

I was gonna suggest that an easy way is to let the manifold suck some coolant in while just above idle.

Does a somewhat similar job to water injector, and should leave everything squeaky clean (ever seen how clean a piston is on a BHG?)

[allencr]

I used 500 grid sand paper on air orbit sander ... cleans the carbon off well ...... the car running til now (been about 16 months since) ... I know it sounds wierd and comments gonna be made...

Real sand on real paper?
Use a lot of grease, use a worn disk that has had the easy shit knocked off of it cause it's little stray bits of sand & space age materials are way harder then the alum & cast iron & chrome & molywhatever. One cyl at a time and protect/cover the other cyls. & oil feed from any stray dust & bits.