Cleaning Pistons?

[Trevor]

I've removed the pistons from my truck and replaced the conrods, before I put new rings on what is the best method to clean the carbon deposits from the pistons themselves?

 

[clivehorridge]

I would use a wire brush, manual and/or angle grinder attachment brush, unless you get better and more technical advice. Just take care not to gouge into the aluminium.

You can chemically dissolve it, but I can't advise what with.

 

[ModelMakerMan]

Scotch pad or scotch wheel in a drill would be less abusive than a wire brush.

 

[clivehorridge]

Scotch pad or scotch wheel in a drill would be less abusive than a wire brush.

Always a matter of judgement on the degree of build up of the carbon. Some can be light and removed easily with a scotch wheel, others, in my experience, need a sharp chisel or blade because even an aggressive wire brush hasn't effectively made any impact on the hardened carbon scale that sometimes accumulates.

Do you have any photos of the offending carbon?

 

[mrdelmonti]

A couple of the offending pistons, looks to be baked on quite hard.

Posted of Trevor's behalf.

 

[ModelMakerMan]

Id try the scotch wheel first then move onto something a little more aggressive if it doesnt budge.

 

[Bat21]

Make sure you clean the piston ring grooves too.

The best way to do this is to snap one of the old piston rings and use it as a scraper to get the carbon out of the grooves

 

[clivehorridge]

I go with both of the above, it's important that the rings are free to find their own centre in the bore and that they're not stuck to the piston profile.

 

[AndycruiserguyLomas]

If you wanted to go the whole nine yards with them you could remove them from the rods, take off the rings and have them bead or vapour blasted. It will remove all traces of carbon and the pistons will be ready for ring installation. Usually motorcycle shops offer this service.

Andy

 

[Trevor]

I've been using Scotchpad and 1500 wet/dry with WD40 which seems to be making things smooth and bringing the colour to a sort of gunmetal grey. Not sure if they'll get shiny but do they need to?

 

[clivehorridge]

IMO no.

They will soon gather carbon again once the engine is fired up, but having cleaned them, this will stop that build up from accumulating into something detrimental to performance.

I would say that cleaning the ring channels is the most important aspect, if the rings stick in the piston, they become ineffective and of course by allowing compression to pass into the crank case, this leads to excessive emissions from the breather, a smelly engine, poor performance, oil consumption and everything nasty that lesser vehicles (mentioning no names of course) suffer from!

 

[Beau]

I recently cleaned the Intake manifold removing heaps of carbon build up, of course though it wouldn't have been as tough as those.

Anyway I used a very very strong carbon remover which is mainly used to degrease burnt on carbon from cookers. I soaked it in this for couple days and found that I could then easily scrape the carbon away showing me the metal.

 

[Mark N]

bead blaster (note BEAD not sand!) and to get in the ring grooves (if the blasting media doesn't get it all) take a section of an old ring (2-3in's) and make a little scraper tool by gluing it into a handle from a hand size piece of wood. Dull the cut off edge slightly so it doesn't dig into the aluminium of the piston groove and you have yourself a perfectly sized scraper.

If it works on aircraft engines - should be fine on cars right?

Cheers
Mark

 

[DVSLUX]

The ideal way to do it is dip them into an acid bath, then use a broken ring to make sure the ring gaps are completely clean

 

[nivapilot]

Soak'em in EGR cleaner, them lightly scrape