Combustion cylinder Before and after pics

Post by **darrylrobert** » 15 Feb 2021, 01:54

Had a very good conversation with a new indie volvo shop as my usual shop seems to have closed down. Anyway we discussed my knock sensor problem and he said it could be the timing (it is adjustable on both inlet and outlet cams) or try cleaning the MAF sensor (ihave done this recently, but i might try my spare), unfortunately they dont do any type of chamber cleaning like nut blasting when i asked about carbon build up, so i will try some things myself.

Here is a before cleaning pic, i really want to poke a screwdriver in there and see how deep it is but i think thats bad?..what about when i soak it with seafoam can i use a brush or something, as long as it doesnt scratch right? I intend leaving the seafoam soak for two or three days...good or bad idea?

: chamber carbon build up; inside 5 cyl.jpg (305.75 KiB) Viewed 1354 times

Post by **darrylrobert** » 15 Feb 2021, 02:03

So for those that dont know as i didnt, the carbon build up has a tendency to get hot and ignite the fuel mix before the spark plug causing a engine shockwave or pinging. I cant hear anything like that but read it could be happening..it also reduces the size of the chamber.

Post by **abscate** » 15 Feb 2021, 02:21

That looks a lot like mine. It won’t be too deep but keep your screwdriver away from those soft piston alloys

I had the head off so cleaning was easier

Post by **kallekula** » 15 Feb 2021, 04:44

I've been using this in the past for cleaning various things. VERY potent. Rubber gloves, mask etc feels needed. Ruined the plastic sink in the garage

: b101_2.png (328.23 KiB) Viewed 1336 times

Post by **RickHaleParker** » 15 Feb 2021, 07:10

If you can get your hands on it, Atco International's Buckaroo Engineers Solvent does a real good job of cleaning parts.

Post by **oragex** » 15 Feb 2021, 08:11

With the head off, I would try to toss the pistons to the sides, see if the compression rings move freely and are not stuck. Like pushing them them to all radial directions against the wall (small movement).

Post by **Blacklab467** » 15 Feb 2021, 18:02

My concern about removing that carbon buildup in situ would be that all that gunk runs down between the piston and cylinder. Some of it will invariably wind up in the ring lands, jamming up the rings from properly operating. Some of that burnt carbon is extremely hard and may become problematic.
I would lean towards leaving it alone and resisting the urge to clean it up unless the engine is out and the pistons are on a bench. Some may disagree with me on this one.

Post by **BlackBart** » 15 Feb 2021, 19:51

I asked the same thing last week. If your ring gap is right, where does the gunk drain to as you rinse it down?

Post by **jonesg** » 15 Feb 2021, 20:20

Blast it out the tailpipe.

Post by **BlackBart** » 15 Feb 2021, 20:26

It’ll scratch up the walls.