Plonkers

[iamamanc]

Hi
I was talking to an old diesel guy today about nailing (pinking)
He said there is another thing to consider and that is the "plonkers." On some engines there is a pyramid type thing on the top of the piston on to which the injector sprays the fuel thus spreading the fuel evenly onto the top of the piston before ignition.
As I understood it my engine OM606 may not have these conical, pyramid things on the pistons. There could be a bar that sits directly under the injector nozzle onto which the diesel is sprayed thus dispersing the fuel evenly on the piston. Anyway he told me that in time these can burn or melt if things are not set up right and this can cause nailing. My question is does the OM606 have the pyramid things on the pistons or does it have “plonkers”
Cheers
Adrian

 

[Ian B Walker]

It has, in your words, Plonkers.

 

[GrahamC230K]

Who's winding who up?

 

[Ian B Walker]

No wind up, read his post properly.

 

[GrahamC230K]

No wind up, read his post properly.

I have thanks.

 

[iamamanc]

Hi
What's the real name for these things. I am in Yorkshire don't forget, here names for things can be a bit odd but straightforward, - the diesel plonks on those metal bits - kind of thing, hence plonkers

Anyway do you concur that if these things are burnt they can cause nailing. Or could it be that by having my injectors refurbed and the pressures set a little above spec (so the springs can bed in) this is causing the nailing

Believe me the first thing I said when he told me it could be my plonkers was rubbish.

Anyway cheers
Adrian

 

[DieselE]

The diesel does not spray onto the piston unless there is something wrong with the injectors. The shape on the piston induces swirl in the air inducted into the cylinder and the atomised fuel is sprayed into the swirling air. The aim is to get even combustion.

 

[Dieselman]

Thje OM 606 has a seperate pre combustion chamber with a spray bar so the fuel can't be sprayed straight into the main cylinder. The pistons are flat topped as the pre combustion chamber design doesn't require high swirl pistons.

I really doubt there is anything wrong with the pre combustion chambers. You could have them withdrawn and checked but I don't think you will find anything.

For info only direct injection engines require high swirl pistons as the air fuel mixing takes place in the main cylinder, not a pre chamber. The fuel should never touch anything metal, either piston or cylinder wall, otherwise the heat of it combusting will melt through that part. A good reason to run injector cleaner..a squiffey injector can cause serious damage to a direct injection engine.