MaK 8M20 Valve rotators

[Jimmy92]

Just wondering if anyone is or has sailed with this engine?

On all the units the inlet valves are rotating and not the exhaust valves, I'm sure I have read somewhere that if you are running diesel (which we are) its only the inlet valves that have rotators and if its heavy its all 4 valves but the back to back crew seem to think all 4 should be and have previously been rotating and have put a defect claim in.

Can anyone shed any light on this ?

[Clanky]

I can't remember whether the exhaust valves don't rotate or whether they don't have mechanical rotators, but rely on wings (or whatever they are called) to make them turn, sorry can't help more. I take it that this is a new build if you are talking about defect claims? MaK will soon come back and let you know if that is the case.

MaK - macht alles kaput / montags arbeitet keine.

[Chiefy]

I assume we've read the manual? The rotor caps are fitted at the top on those engines (well they used to be) so have a look if there are caps then they should be rotating, if not then they aren't.

However I've never bothered about them rotating and checking them is a ball ache, the M20 isn't big enough to have vaned exhaust valves.

[Jimmy92]

Thanks for the replies guys.

Yeah the back to back crew have put a guarantee defect claim into the yard as she is a new build.

Yeah the manual doesn't say which valves should have rotators just explain how to watch them go round and round haha.

In the planned maintenance description it confirms only the 2 inlet turn when running diesel so I'll use that as evidence to get the defect claim cancelled

Thanks for the help

[Clanky]

I seem to remember the M20 exhaust valves having vanes?

In any case, I wouldn't worry about having the guarantee claim cancelled, MaK will soon do that for you.

[Chiefy]

Hmmmmmm can't real now, but could be the case....... Anyway as I ask my engineers when they get the job in planned maintenance..... What you going to do if they aren't rotating?

As for the claim... Yeah MaK will bin that off themselves if they feel you are talking cobblers

[GuinnessMan]

Anyway as I ask my engineers when they get the job in planned maintenance..... What you going to do if they aren't rotating?

Look at it with a curious expression whilst scratching one's noggin?

[alistairuk]

Look at it with a curious expression whilst scratching one's noggin?

Hit it repeatedly with a hammer or other equally heavy object tends to be the engineering solution to most things

[Jimmy92]

What would be the best action for the rotators not rotating ?

Apply a small mixture of diesel+oil to the rotator and valve stem to try free them up ?

[Clanky]

On something like an M20, I would just change the head.

It is possible to change a valve rotator with the valve in place, but you need to be REALLY sure that the piston is on TDC.

[Clanky]

On something like an M20, I would just change the head.

It is possible to change a valve rotator with the valve in place, but you need to be REALLY sure that the piston is on TDC.

[swishwellingtons]

I had this same query on a previous vessel: back-to-back had logged that exhaust valves rotated as well as inlets. Found that a drawing showed only the inlets should rotate.

[Roscoe1983]

Heys guys Ive sailed with this engine on two different ships and its only the inlet valves that should be rotating.