How to clean coated pistons without damaging the coating?

[skpyle]

Hello Gentlemen,

I am going through the L94 6.2L engine in my 2013 Escalade ESV.
SUV and engine have 175,*** miles on them.

I am having the cylinders lightly honed and installing new rings.

All 8 piston crowns are reasonably clean. Most of the carbon wiped off with a brake cleaner soaked rag. I have removed #3 piston/rod assembly. The ring lands are reasonably clean, with some carbon. The oil control rings are not gunked up. The underside of the piston has some varnish, but not awful.
The coating on the skirts is lightly worn at the center, but not bad. The rest of the coating is intact.

The coating is what is giving me pause. I have been a gearhead for a few decades. Cars, trucks, bikes, small engines. This is the first set of coated pistons I have dealt with.

Normally, if I am to clean a piston, here is the process:
-soak in my enameled pot of ancient carburetor dip
-rinse/scrub in my parts washer with nylon brushes. Solvent is PSC 1000 solvent.
-thoroughly rinse with brake cleaner

This works quite well.
However, I am concerned the above methods will remove the skirt coating.


Soooooo...what kind of advice can you give me on how to clean my pistons without hurting the coating?
I have googled various searches to no effect.


Thanks for your time!


Photos are still on my digital camera. I will download them and get them posted.

 

[skpyle]

Moderators, please help me with the title, as I am illiterate...

Please insert the word 'to' between the words 'How' and 'clean' in the title.

Thanks!

 

[homesick]

Moderators, please help me with the title, as I am illiterate...

Pleas insert the word 'to' between the words 'How' and 'clean' in the title.

Thanks!

This could be interesting. I get the idea that we're supposed to modify our own titles, but I don't know how, either.

joe

 

[skpyle]

Aha...not only am I illiterate, but I am stupid, too.

I edited my original post, and was able to fix the title. It never occurred to me that I could edit the title that way. I wasted more time trying to find listed moderators to ask than actually trying to fix the title.

Thanks for the help, joe!

 

[skpyle]

Moderators, please help me with the title, as I am illiterate...

Please insert the word 'to' between the words 'How' and 'clean' in the title.

Thanks!

Nevermind, joe helped me figure it out.

 

[skpyle]

Here are photos of #3 piston:

Piston crown after wiping off with a brake cleaner soaked rag.

Piston crown, removed from cylinder.

Underside of piston. Varnish I want to get rid of.

Sides of piston. There is some carbon build up above the first compression ring, and between the first and second compression rings. Oil rings are not gunked up. Varnish on the sides I want to clean off.

 

[skpyle]

Piston skirts definitely show wear from 175,*** miles, but do not look awful. Coating is reasonably intact. I don't want to damage it.




I have not yet removed the remaining 7 pistons. I do not have any reason to think they will look any different than #3.
Will know soon enough.

 

[donjetman]

Put it back together as is and start using mild cleaning oil Valvoline Restore & Protect.
or
For a much more aggressive cleaning oil use Valvoline Premium Blue Restore.

 

[homesick]

Nevermind, joe helped me figure it out.

Wow, I've never been a legend in anyone ELSE's mind before.

joe

 

[SpareParts]

Personally with the coating worn like that i would replace the pistons.

Benefits of piston skirt coating:

• Frees up horse power normally lost to friction.
• Provides back-up lubrication if the primary lubrication has gone
• Reduces wear which increases engine life
• Meet the demands of high revving, short piston skirt and long rod motors
• Reduces heat that can cause galling and seizing
• Produces tighter piston-to-wall clearance

 

[roc1967]

Personally with the coating worn like that i would replace the pistons.

Benefits of piston skirt coating:

• Frees up horse power normally lost to friction.
• Provides back-up lubrication if the primary lubrication has gone
• Reduces wear which increases engine life
• Meet the demands of high revving, short piston skirt and long rod motors
• Reduces heat that can cause galling and seizing
• Produces tighter piston-to-wall clearance

I didn't see any meaningful damage on the pistons, I'd re-use them, as I've done many times. This is not a F1 engine.

As for the coating benefits listed, they are mostly Marketing, not real life.

 

[skpyle]

Put it back together as is and start using mild cleaning oil Valvoline Restore & Protect.
or
For a much more aggressive cleaning oil use Valvoline Premium Blue Restore.
View attachment 470574

Tempting, but my OCD will never let me put something back together without cleaning it.


Thanks!

Wow, I've never been a legend in anyone ELSE's mind before.

joe

First time for everything. Welcome to my world.

Personally with the coating worn like that i would replace the pistons.

Benefits of piston skirt coating:

• Frees up horse power normally lost to friction.
• Provides back-up lubrication if the primary lubrication has gone
• Reduces wear which increases engine life
• Meet the demands of high revving, short piston skirt and long rod motors
• Reduces heat that can cause galling and seizing
• Produces tighter piston-to-wall clearance

Understood. Not quite ready to bite the $850 Mahle bullet yet...
Thanks!

I didn't see any meaningful damage on the pistons, I'd re-use them, as I've done many times. This is not a F1 engine.

As for the coating benefits listed, they are mostly Marketing, not real life.

This is my goal, I just have to get a warm fuzzy that I am making the correct choice.

Thanks!