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Hi all, a while back I cleaned up some 80 euro S pistons using Berryman Chem-Dip. This was the first time I used this stuff. I was amazed at how well it cleaned with minimal effort. No scotchbrite, so heavy scrubbing. Thought I would share my experience with you on youtube.
FWIW when cleaning Porsche 928 pistons dont use anything tougher than a toothbrush.
If that Berrymans is not damaging the iron coating then it looks like it is a safe thing to use.
Otherwise I have had good luck with soaking the pistons in full strength simple green
I took a set of 85 928 pistons to the machine shop and they put them in the cleaning tank,
when they were done the iron coating was eaten away,
thus the pistons were not good .
FWIW using a wire brush or wheel or a scotchbrite pad will also damage the iron coating
The old full-strength Berrymans Chem dip caused some corrosion on aluminum if left in there for more than a minimum time. Parts left overnight would come out very dark grey and pitted, less than the ideal 'solution' for dirty pistons.
In the wayback daze, I put tape on the OD of the piston from just above the top ring down, so there's no chance of damage to the critical ring lands and skirts. Then it gets some mechanical cleaning with a brass wire brush on the grinder/polisher shaft, but not to the point where you are changing the metal at all. Just get the carbon chunks off. Then some spray gasket remover for whatever's left, and for the ring lands. Hand brass brush for the tops, nothing more than a stiff-bristle parts cleaning brush for everything else. All done in a plastic or rag-lined metal cleaning tray so no chance of damaging anything.
Thanks. Yeah, they must have diluted the formula quite a bit. The new stuff seemed to work well. I also hosed some aluminum Ford heads overnight and did not see any damage. My original thoughts were to soda blast the pistons, but I understand that will damage them. I used to try and get the carbon off with carb cleaner and a brass brush. So much work. Guess I am getting old and lazy.
FWIW when cleaning Porsche 928 pistons dont use anything tougher than a toothbrush.
If that Berrymans is not damaging the iron coating then it looks like it is a safe thing to use.
Otherwise I have had good luck with soaking the pistons in full strength simple green
I took a set of 85 928 pistons to the machine shop and they put them in the cleaning tank,
when they were done the iron coating was eaten away,
thus the pistons were not good .
FWIW using a wire brush or wheel or a scotchbrite pad will also damage the iron coating
If the iron coating is gone, why not just recoat them with ceramic skirt coating like they do on modern performance pistons. It may work even better than the original iron coating.
If the iron coating is gone, why not just recoat them with ceramic skirt coating like they do on modern performance pistons. It may work even better than the original iron coating.
It doesn't.
Even the Porsche 997.2 "Locasil" won't stay on. (There's people getting rich fixing this fiasco.)
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
If the iron coating is gone, why not just recoat them with ceramic skirt coating like they do on modern performance pistons. It may work even better than the original iron coating.
Many have tried various coatings. AFAIK none have succeeded with an otherwise untouched cylinder block. Alusil is a strange material it seems.
Many have tried various coatings. AFAIK none have succeeded with an otherwise untouched cylinder block. Alusil is a strange material it seems.
so why don’t they re coat the pistons with the original “iron” ..ferrous coating.
This is something I have never understood. The technology is there to put all sorts of coatings on all sorts of thing’s. Why do people try an reinvent the wheel with various coatings on the pistons used in our blocks. Only one works right?...use it.
so why don’t they re coat the pistons with the original “iron” ..ferrous coating.
"They" do. The problem is: it comes off fast.
This is something I have never understood. The technology is there to put all sorts of coatings on all sorts of thing’s. Why do people try an reinvent the wheel with various coatings on the pistons used in our blocks. Only one works right?...use it.
What I know about this subject will fit in a Dixie Cup. 50% of it I've learned from Greg Brown and my head guy. The other 50% from interwebbing.
With respect to coating the pistons, apparently, only Mahle Gmbh (Germany) can coat the pistons without the coating coming off. If you order Mahle Motorsport (the US subsidiary IIRC) pistons, whatever technology they use to coat pistons results in about 1 in 4 shedding the coating in the first 10s of hours with the expected results. As far as what technologies are used, I have only hearsay.
As far as the cylinder walls are concerned, our 928 blocks cast from Alusil are a thing of the past. The Lokasil process, invented by Kolbenschmidt , that Greg referred to above is what Porsche uses now (and since the 997-era engines) which allows the cylinder block to be cast from 'cheap' aluminum. It entails 'impregnating' the cylinder walls with silicon during the casting process. (It's a bizarre thing they do too.)
I have no idea what Porsche uses now for piston coatings. I would suspect that it's a ferrous coating since the Lokasil process is supposed to result in cylinder walls that are Alusil.
05-21-2017, 08:16 PM
How to clean 928 Porsche pistons
