[Vwdiesel] Decoking pistons

[Roger Brown]

mark shepherd wrote:
> Greetings,
> Hopefully someone will be up on the other side of the world.
> 
> Just taken my pistons out for a rering, I was having a 'little difficulty starting. Fuel economy averaging about 45 to 48 UK mpg. 3 pistons have single stuck rings,top or middle some of the gaps could be as big as 1/16th- 1/8th of an inch!!
> Bores good, and hastings rings fit to middle of VAG gap spec.  Pistons are great and so are all bearings. It loks like my nocking for the last 20 to 30 ooo miles was exhaust valve clash. I always set belt accurately, but I overskimmed the head, and so this mayexplain that.
> 
> However my question is this.
> Should I remove the thin layer of carbon deposit between top ring and piston face? 
> 
> Regards
> Mark

I stumbled across a rather effective way to de-carbon pistons. When I was rebuilding the 
engine in my Toyota, I had the head off fora few weeks. To prevent rust, I had sprayed 
down the top of the block and pistons w/ WD40. In itself it did nothing to the carbon, but 
after one somewhat foggy night, popped the hood to find the carbon had all bubbled up like 
it had been hit with paint stripper. It came off easily with a wooden scraper. So I think 
it was the combination of the WD40 and the moisture in the air that did it.

This is what it looked like afterward:
	http://www.4crawler.com/4x4/CheapTricks/EngineMods/Engine01.jpg


-- 

   Roger