md2b rebuild question

[hamishnf]

Hi all,
On a volvo penta md2b the combustion bowls in the pistons are not central, they are slightly offset. Should the pistons be installed with the bowls closer to the air intake/handstart device side, or closer to the exhaust manifold side of the engine? Any help would be much appreciated.

 

[VicS]

Hi all,
On a volvo penta md2b the combustion bowls in the pistons are not central, they are slightly offset. Should the pistons be installed with the bowls closer to the air intake/handstart device side, or closer to the exhaust manifold side of the engine? Any help would be much appreciated.

There is a workshop manual at http://www.bluemoment.com/downloads.html

Hopefully that will show or state how the pistons should installed.

It says directly under the injector

 

[hamishnf]

Hi VicS,

Thanks for the quick reply, I have read the manual, it states that the bowls should be "directly under" the injectors, which implies they should be on the exhaust manifold side, but it isnt completely clear as the injectors are angled in the head and the tips actually point to the air inlet side. The engine I am currently 'rebuilding' has the bowls on the inlet side (pistons installed by previous owner) and I suspect he put them on the wrong way round. If any md2b owners are out there please let me know!

 

[VicS]

The diagram in the parts list

http://www.marinepartseurope.com/PentaPictures500/5564.jpg shows them on the inlet side. Maybe thats what is confusing the issue

They are the same as the MD11C but i dont remember us having any doubts about which way they went when we rebuilt that !

 

[VicS]

Its perhaps made clearer in the MD11C manual which states:
"NOTE! The recess in the top of the piston
must come immediately under the nozzle."

The key words i think are immedeiately under the nozzle

 

[hamishnf]

Hi all,
Just found a big photo of an MD17C with the head off in Calders "marine diesel engines". The recess is on the manifold side/starboard side, I phoned motortech in portsmouth and they seem to agree.

 

[VicS]

Hi all,
Just found a big photo of an MD17C with the head off in Calders "marine diesel engines". The recess is on the manifold side/starboard side, I phoned motortech in portsmouth and they seem to agree.

In other words immediately under the injector nozzle like the workshop manuals say.

There's a good photo in the MD11/MD17 workshop manual too.