carbon deposits on piston heads

[kop10320178 0]

hi i have a rado vr6

the head currently is being reconditioned at a specialist, the car is at vw,

i noticed that there is lots of carbon on top of the piston heads,

i asked the dealer about it, they said the engine block is fine, they did not seem helpful.

anyone else found this on theirs?

will tha carbon affect the engine in anyway?

does this need to come off?

if so how does it come off?

thanx jay

[flusted 0]

carbon build up can cause pinking, some people ploish the piston tops to prevent build up

[TREVR6 0]

anyone else found this on theirs?

 

this happens on all cars.

 

does this need to come off?

if so how does it come off?

 

Unless you're taking the pistons out then I wouldn't start picking at it as you may start to loosen bits that may come off after the engine is back together. It will be very hard to get it all off with the pistons in place as it will probably need soaking in degreaser and then a good bit of elbow grease!

 

I would either leave it alone or take the pistons out clean them properly and replace them with new rings.

[kop10320178 0]

thanx

could i spray them with a decoke agent

or should i just leave it alone?

[TREVR6 0]

I'd be very nervous of debris getting down between piston and block. How bad are they? Any pics? Are they just a bit black or realy thick, with flakes of carbon sticking up?

[kop10320178 0]

to be honest theres black on some of them not all,

i`m going up tomorrow to have a proper look, 1 of them had fluid on it,

the bores look brand new.

[VRTrickster 0]

Does it look any worse than mine, as Im not touching mine before I put my rebuilt head back on?

[kop10320178 0]

piston crowns look cleaner, but the bores are no were near as clean

unless its the picture.

[Kevin Bacon 5]

That is the site you always see when taking the head off a VR, although that one is pretty OK. I bet the honing marks are still on the bores?

 

Leave the deposits, they're not doing any harm.

[dubburke 0]

I suppose you could always use a good fuel such as BP ultimate, etc, then the pistons will not foul up as quick

[Roger Blassberg 0]

The folklore was always to place an old piston ring onto the top of the piston and then only to scrape off the carbon from the piston crown inside the ring. The idea was that this prevented any disturbance of the sealing of the piston in the bore. I don't know how relevant this is to modern engines.

 

Best wishes

 

RB

[mgbv8mike 0]

I thought that urban myth had been long dispelled....the only reason for the piston ring trick was to prevent carbon bits slipping between the piston top and bore.

 

Leave 'em as they are...I'm rebuilding the top end of my Rover V8 engine at the moment, and those pistons are looking much muckier than the block pic above.