Possible gearbox trouble - oh woe

[Tranona]

Blocked exhaust run is unusual but not impossible, so first thing is to remove the exhaust elbow attached to the engine. It is the crook shaped bit that connects to the exhaust piping. It will not be easy to remove as it has been on there for years. However it is this bit that gets blocked and even a small hole in the middle will allow the engine to rev to maximum in neutral because it is not producing any power like that. once you have the exhaust hose off you may be able to get a finger (with a glove on -oooer!) up the pipe to asses how coked up it is. Regrettably there is no alternative to removing and cleaning, but hopefully it will not be so bad as to fall apart as you poke the muck out.

Not all as bad as it sounds compared with other things you have done on your boat.

 

[anoccasionalyachtsman]

Is it possible that you moved/dislodged/bent something when you were doing your skeg repair?

 

[Robert Wilson]

Is it possible that you moved/dislodged/bent something when you were doing your skeg repair?

I would say impossible as the skeg damage was nowhere near the propeller shaft.
Unless fillings or debris wafted up into the exhaust through-hull. Again unlikely.

All work was done externally.
Thanks, though

 

[Robert Wilson]

Blocked exhaust run is unusual but not impossible, so first thing is to remove the exhaust elbow attached to the engine. It is the crook shaped bit that connects to the exhaust piping. It will not be easy to remove as it has been on there for years. However it is this bit that gets blocked and even a small hole in the middle will allow the engine to rev to maximum in neutral because it is not producing any power like that. once you have the exhaust hose off you may be able to get a finger (with a glove on -oooer!) up the pipe to asses how coked up it is. Regrettably there is no alternative to removing and cleaning, but hopefully it will not be so bad as to fall apart as you poke the muck out.

Not all as bad as it sounds compared with other things you have done on your boat.

I'll think about this, thank you.
You're saying I have to unbolt the exhaust manifold from the block?

It sounds like a real bitch of a job.​

Nightmares tonight, methinks.

 

[Tranona]

No, just the elbow which is attached to the heat exchanger/exhaust manifold. Look at a photo of the engine to get an idea of the layout before you delve in.

You have exhausted - excuse the pun - all the possibilities to do with the transmission so the problem lies with the engine either not getting enough fuel to produce the power under load or the exhaust restriction limiting the power.

 

[Robert Wilson]

OK.
O'll sleep on it and have a good snopp around before I attack with the ratchet wrench.
Mucho skinned knuckles ahead.............

G'night.

 

[Norman_E]

Is it possible that the morse control is moving the fuelling lever of the injector pump far enough to give the engine full revs in neutral, but is not in fact moving it all the way? I don't know the exact set up of the Kubota engine but all engines will rev harder in neutral on a given amount of fuel than they will under load.

 

[Robert Wilson]

That's what I'm going to check tomorrow. I thought I had established that before launching, but I need to be 100% sure - before I start removing exhaust pipes and fittings.
I suppose there is a small chance that I missed the final few millimetres of travel. This might have been caused by a tad too much force when the cable had dried out over two years ashore.

A simple, but not cheap, problem to remedy.

 

[anoccasionalyachtsman]

All work was done externally.
Thanks, though

Ah - I had visions of you upside down in a tiny space getting to the top of reinforcing rods and where lying on something important is both painful and inevitable.

 

[Robert Wilson]

Not that time, it was only the bottom of the skeg which I "modified".....
However, the next stage of "propulsion problem tracing" will most definitely be as you feared

There times when I am glad I was a diminutive hooker and not one of the other seven in the pack!

 

[LittleSister]

Is it possible that the morse control is moving the fuelling lever of the injector pump far enough to give the engine full revs in neutral, but is not in fact moving it all the way? I don't know the exact set up of the Kubota engine but all engines will rev harder in neutral on a given amount of fuel than they will under load.

The Morse/Teleflex and engine control doesn't control the amount of fuel, it is not a throttle. It sets the engine speed, and then a governor supplies enough fuel for it to reach that speed. As the engine can reach full revs in neutral, it's not the engine/Teleflex control that's the problem - it is already moving far enough to reach that speed, and Robert has said he's checked and it reaches the stop.

One possibility (as several people have suggested) is that it's not getting enough fuel to reach the 'called for' speed, but that would be the result of some restriction in the fuel supply, and nothing to do with the Teleflex or engine control lever..

 

[Robert Wilson]

The Morse/Teleflex and engine control doesn't control the amount of fuel, it is not a throttle. It sets the engine speed, and then a governor supplies enough fuel for it to reach that speed. As the engine can reach full revs in neutral, it's not the engine/Teleflex control that's the problem - it is already moving far enough to reach that speed, and Robert has said he's checked and it reaches the stop.


One possibility (as several people have suggested) is that it's not getting enough fuel to reach the 'called for' speed, but that would be the result of some restriction in the fuel supply, and nothing to do with the Teleflex or engine control lever..

And late last night I found photos on my laptop to prove that full movement is available.​

What might cause such a restriction to the fuel supply, other than dirty/blocked filters?

Clogged injectors?
A duff lift pump?:nightmare:
A duff injector pump?:hororr:

 

[Forty_Two]

Could there be a blockage in the tank outlet pipe, maybe a screen filter or such inside the tank? Worth checking.

Seen a few posts over the years with semi blocked fuel pipes causing power loss.

Good luck..

 

[Robert Wilson]

Thanks for your good wishes. Fuel could be a problem I suppose, although when changing the filters before re-launch diesel flowed freely enough.
A bit too freely , unfortunately!
I'll check fuel flow again tomorrow before I set to with the socket set on the exhaust system

What baffles me most is that everything was working fine before the boat was brought ashore in September 2015. I can't see that anything has deteriorated so drastically while ashore.

Perhaps the kind wise ones following this thread may care to comment on that?

 

[Robert Wilson]

Update:-
Yesterday I checked the fuel delivery system and all was ok, from tank to injector pump.

I managed to clean the gearbox ID plate
NEWAGE 1206226 00611 33D2 MADE IN ENGLAND
The 88D2 may be 83D2

As to the checking of exhaust pipe blockage it was a "fail".
The manifold* is impossible for me to remove as two of the four small nuts are inaccessible.
The rubber hose has welded itself to the s/s "down-pipe". So I'll need to cut it off, but only when a replacement arrives from Force4.
Guess who forgot to measure the I/D size? Doh!
Another trip across the Loch just to measure it...…….

* The manifold and downpipe arrangements are roughly as follows.
Two cylinder ports enter a cylindrical chamber (approx. 50mm o/d by 150 long) which proceeds into a pipe of approx. 50mm diameter. This curves up to where the anti-syphon loop joins then drops to where the rubber hose connects.
At some point the water cooling pipe joins the system (can't remember if it's before or after the anti-syphon - and didn't take a photo. Another Doh!)
The length of the s/s pipe from chamber to hose is approximately 500mm.

So there is no way I can inspect the exhaust by removing the manifold, without specialist tools. It looks like cutting-off the rubber hose and inspecting "up" with an endoscope.
I still don't know what I would be looking for - soot, gunge, collapse?

Any thoughts on the above and how to proceed would be very much appreciated, as always.

 

[Tranona]

What you should be finding is a clear hole the same diameter diameter as the pipe. What you will find at least is a bit of carbon which is not a problem. What you don't want to find (or feel) is a small diameter holes in a solidified mess of carbon and crud from salt water deposits.

Expect the original diameter is in the range 40-50mm but the engine caan still run even if this is down to 10mm - until you put load on it and back pressure restrict the engine's ability to rev - just what you are experiencing, hence the advice to check.

 

[Robert Wilson]

I have just spoken with Newage PRM and Lansing Marine who manufactured and supplied the gearbox in April 2005 (respectively).
The thoughts are that there is nothing wrong with the gearbox and probably/possibly not the exhaust, rather it could well be the injector pump.

I am trying to contact a qualified Marine Engineer who should be able to investigate the pump - but he's on holiday!

I don't want to start dismantling the pump etc with my limited knowledge of what goes where and what does what!

Watch this space.

And as usual, thanks for all the comments and thoughts.
:encouragement:

 

[Robert Wilson]

Update:
I thought I had checked the air filter, but no.
Oil in the housing and filter full of black oil.
Auto garage mechanic suggests this may be from worn piston tings allowing oil back into the filter intake, via the crank-case breather hose.
This would account for loss of power, but why so sudden a drop off in power? Two years ashore with no use perhaps causing rusty/cracked rings?

I took the boat for a spin (on engine) without the filter in and she went much faster, albeit still only 1600rpm. Achieved 5kts into a noticeable breeze.

Fingers crossed this may be the cause - and I can wait a while to attend to the rings. It'll still mean the engine out to get at the crank, big ends etc.
Hey ho!

I'm still investigating the "soot in the exhaust" just to be sure.

Any comments on the air filter/piston rings idea?
No noticeable black smoke from the exhaust

 

[Tranona]

Could be stuck rings from the long period not being run, but normally one would expect poor starting as well because of the drop in compression.

 

[capnsensible]

Dont want to raise false hope but I got a little bell going tingaling from a while ago. I think I had similar symptoms on a Yanmar and it was the fuel lift pump knackered. OK til on load then revs fell off and eventually the engine stalled.

Thoughts anyone? Mebbe tree, wrong, barking up?