Aircooled VW South Africa

Hi guys,
Believe it or not, was busy tinkering with my type 4 sub here on my bedroom floor a few minutes ago.
I've noticed that the pistons have some heavy carbon build up on the top, what would be the best way to remove this? I've read somewhere that one could use a strong oven cleaner like Zeb, or similar. . .
Any thoughts on this?

Always used a medium steel wire brush on a drill.

I've heard about the zeb option. Works good in the engine bay and brake dust dept.also. But do it in a ventilated area. If its very thick yeah wire brush it lightly.

I always use a wire brush on a drill. Also take an old piston ring, break it in half and use it to clean out the ring grooves on the pistons.

Hubcap wrote:I always use a wire brush on a drill. Also take an old piston ring, break it in half and use it to clean out the ring grooves on the pistons.

Sorry dude that is the ABSOLUTE LAST thing you should do!!!

When you start scraping away at your ring groves you gonna damage the ring seats which will effect you compression and ring operation... If you groves are that gunked up just think what state your rings are in. I know you dont wanna hear this but it's time to replace pistons and rings.

There is an article in the Technical sections which handles the importance good piston ring operation.

http://www.aircooledvwsa.co.za/viewtopic.php?f=8&t=60

It's a good read.

Vader, I know what Hubcap means. It is all right to do it that way. Just dont go DIGGING in the grooves....

If you groves are that gunked up just think what state your rings are in

Not always the case! I am busy rebuilding a rebuilt T4 'combi' engine. NEW pistons and sleeves where put in. SC never drove. Engine didnt even have the chance to break-in. Kept on bending #3 Exhaust pushrod, so engine was pulled. Stripped it down to the bearings and rebuilding it. Thing is, the pistons already have carbon build-up Rings still brand new. I think I might just get away with it cleaning off the crud with thinners, if not, I will run a broken in half ring throug hthe grooves, just to break the surface of the crud and then 'wash' the rest off.....

So yes, it can be done with success, just dont go and DIG into the piston with the ring.......

Everything in moderation, always work carefully and don't use the ring like a hacksaw blade.!! And then of course you put in new rings after the clean up.
I am more used to cleaning up pistons on 2 stroke DKW engines where carbon is more of a problem than 4 strokes.

Fine... Cool.... Each to there own...... I still dont think its a good idea but hay....

There's something wrong with your link. Opens up a JPG

Think fo it like this, the rings very rarely touches the piston in the groove as they 'expand' to seal with the cylinder. So as long as you dont scratch the surface, you are ok.(ok given, I am not saying that the rings NEVER touches the groove 'base'). Point is, with patience and care, the grooves can be cleaned. And even, if you get new rings, but cant get the carbon out of the grooves, do you replace the pistons too Vader?