Piston Kleen, Removing carbon from pistons Options

[dknechtly]

I have my engine pulled apart for a rebuild. As expected the pistons were carboned up and I dreaded the chore of cleaning. I found this stuff called "Piston Kleen" and let them soak a couple of days. It took the carbon all off! Outside, underside, ring grooves. Some places I just wiped off a little bit. It did a great job. Saved a lot of work and potential piston damage. I just wanted to pass along the good info.
I couldn't find it retail anywhere. Just ordered from the web site. Free and fast shipping.

http://www.orisonmarketing.com/pistonkleen.html

Edited: I have plain old 1.7 original pistons. When I was researching this, I did see some of the cleaners harmed aluminum. This does not. Just gives you nice, clean, unscratched or scraped pistons.

[Matt Romanowski]

I believe it was an early form of alusil, like in many Porsche engines. These still use a aluminium piston but it has iron impregnated into the surface.

The bore is what is impregnated with silicon, the pistons are bare. You can moly coat or DLC the pistons, but that is not what Porsche has done. They do nikasil on the bores.

[Mark Henry]

I believe it was an early form of alusil, like in many Porsche engines. These still use a aluminium piston but it has iron impregnated into the surface.

The bore is what is impregnated with silicon, the pistons are bare. You can moly coat or DLC the pistons, but that is not what Porsche has done. They do nikasil on the bores.

No.... (IMG:style_emoticons/default/rolleyes.gif)

Nikasil pistons are bare, alusil pistons have a coating, "iron coating" is probably a bad technical term, but is one a layman would understand.

Pistons, Rings and Coatings
Years ago, GM used a hypereutectic alloy in their Vega four cylinder engine. That engine had its own problems but rebuilders were left in the dark as to how rebuilding should take place. Given the relatively high tech nature of materials and machining vital to restoring wear surfaces in these cylinders, rebuilders experienced failures when employing tried and true methods used for cast iron blocks. Even when correct surface generation processes were employed, failures continued. The fix then was to sleeve with cast iron liners and install standard aluminum pistons and garden variety cast rings.
So what was missing in this exercise? What eventually became clear was that piston skirts had to be coated and ring faces should be barrel shaped if Alusil cylinder bores are to be retained as a wear surface. When this news finally hit the rebuilding industry, rebuilders already had a workable fix by sleeving with cast iron liners. But that fix is not always possible with modern engines using Alusil as a sliding seal or wear surface.
Early in the process, piston coating for use in aluminum cylinder bores became know as “tining”. As it turns out, “tining” piston skirts was indeed a thin layer of plated tin used as a wear or scuff barrier between aluminum pistons and aluminum cylinders. “Tining” then became a euphemism for several piston coatings that acted as wear barriers. Some manufacturers used a variety of coatings that included nickel–tungsten (Ni–W) plating, electroless Ni plating, Ni–P coatings with ceramic particles such as boron nitride (BN), SiC, or Si3N4, as well as titanium nitride physical vapor deposition (PVD) coating, diamond-like carbon (DLC) coating, spray cast iron and hard anodizing. Not all of these coatings proved reliable against scuffing Alusil cylinder bores and were eventually replaced by more robust piston coatings we see in use today.1
Due to the abrasive nature of Alusil and the affinity aluminum has to itself; this coated barrier greatly reduces seizure of component parts. A stock aluminum piston would simply not survive even in a well prepared Alusil cylinder bore. Further, barrel shaped ring faces were used to glide across correctly honed and etched silicon particles without dislodging them. Beveled ring faces utilize a scraping action which may be detrimental to an Alusil wear surface. Exercise caution when selecting a suitable ring pack for use in Alusil bores.
Further, many different ring materials are used for Nikasil® and Alusil but some of the better ones are Gas Nitrided, Ion Nitrided or titanium coated tool steel. There appears to be some consensus that using a barrel shaped ring for either Nikasil® or Alusil cylinder bores works best. However, always go with the coating or cylinder alloy manufacturer’s recommendation for a suitable ring pack.