Help! Engine mystery, potentially dangerous

[NormanS]

The only time that I ever had a problem with the engine dying when slowed, it was a dirty fuel filter.

 

[essexboy]

If you cant find a French Beta dealer, paint it blue and tell them its a Nanni !

 

[cryan]

Some bigger engines have a mechanism where the governor is effectively engaged by lub oil pressure. The theory being that if there is a sudden drop in pressure the engine stops. I have no idea if Kubota have a similar system, as I said I have only encountered it on bigger engines. However the symptoms you speak of are identical to what happened on those engines if they had been worked hard and suddenly slowed down. The oil was hot and so thinner, you slow the oil pump down, the pressure drops and the governor cuts the fuel. The solution on those engines was to clean the coolers, both oil and jacket water.
Perhaps you should check if the engine is running hot? You might need a cooler clean to reduce the engine temps?

As I said though, I have no experience of Kubota governor. A read of the service manual should reveal if its a possible cause.

 

[Birdseye]

As always with a problem, start at the simple and basic end rather than go for the difficult and expensive faults like governors. First of all, check the drag on the shaft - is it so difficult to rotate that its stalling the engine? Then check the fuel supply - have you got filters full of diesel bug? Have you got air leaks? Check the air filter / air intake. Is it part blocked? Any problems with the alternator / drive belt that is increasing load and stalling the engine? Is the idle speed correct ? Check oil and water levels and exhaust water not because these alone could cause a problem but because they might indicate a fault that could do so.

After all this then you are into the more difficult bits. Your engine will have a governor and this governor is there to ensure a minimum idle speed amongst other things. If this governor isnt functioning correctly / sticking, it could let your engine speed drop away to nothing. Assuming that everything else looks OK and the engine runs well under load, I would suspect the governor.

 

[mtb]

I have a 3 cylinder beta 20, about 15 years old

After it has been running continuously at medium to high revs for about 48 hours it cuts out when the revs are dropped to approach a berth. It has done this twice after long windless Biscay crossings. It has also done this after a 6 or 8 hour passage

Coming into a harbour is not when you want your engine to cut out

The filters are clean, the tank is clean, the idling speed has been adjusted to run smoothly. The engine runs perfectly at high speed then it just dies as you slow down

I thought I had cracked it today by slowing very gradually but it still died

All advice very welcome. We still have another 700 mms to get home

You could stop outside harbour and allow the engine to cool a bit before going in

My thinking is if its to hot, the cooling system isn't up to the job re a blockage or worn pump perhaps you can check or maybe wait until your home

 

[Lakesailor]

Mention of valve clearances early in the thread baffled me. Yes, it is reported that incorrect valve clearances can cause eratic idle. But I have run and worked on many, many engines over the years and never come across one which had a running problem resolved by adjusting tappets.
Big clearances can cause poor performance and starting. Tight clearances can cause burning of valves, but the symptoms only appear once the damage has been done. In either case either the rattling or the banging and popping would alert you.
I'd definitely suspect a fuel supply problem. Probably the injector pump/govenor rather than the fuel line.

 

[haydude]

¿

I used to have a similar problem. I found the tick over speed was a bit low. I adjusted upwards a little and I no longer have the engine cutting out going from highish throttle to neutral.

It may be a combination of low idle with lower compression when hot. Perhaps time to check compression and change the piston rings.
Any abnormal oil consumption?

Also if you never checked valve clearance in 15 years... It should be done periodically.

 

[lw395]

Mention of valve clearances early in the thread baffled me. Yes, it is reported that incorrect valve clearances can cause eratic idle. But I have run and worked on many, many engines over the years and never come across one which had a running problem resolved by adjusting tappets.
Big clearances can cause poor performance and starting. Tight clearances can cause burning of valves, but the symptoms only appear once the damage has been done. In either case either the rattling or the banging and popping would alert you.
I'd definitely suspect a fuel supply problem. Probably the injector pump/govenor rather than the fuel line.

Fair comment (as ever), but tappet clearances are easily checked.
And an absolute thing, not related to other settings, just temperature.
Recently had an engine where they'd been badly miss-set, absolutely no point fiddling with anything with idle speed or govenor if they are significantly wrong.

 

[Fascadale]

Thanks once more for the thoughtful and considered replies

The engine barely uses any oil, and the exhaust is always clean. I took the air filter out last year and am yet to replace it.

The weather forecast is looking good for the channel so I think we will leave Camaret today and try for a Ramsgate: should be able to sail most of the way. The weather then looks bad for the North Sea which will force a three day maintenance stop. First under the microscope will be the fuel system then the tappets. I suspect that the govenor may be a bit too complicated.

If we are motoring towards a harbour I plan to stop the motor for a while before we get there.

Why is life never simple?

 

[ghostlymoron]

We had a similar problem last year on the river rhone. The engine would run fine at 1500rpm but would often cut out when we slowed to idling when passing through a lock. It turned out to air leaking in at the CAV filter which was cured by tightening it up more. (there was a long thread on here last year)
Also after 15yrs, it would be wise to check your tappets.

 

[mtb]

We had a similar problem last year on the river rhone. The engine would run fine at 1500rpm but would often cut out when we slowed to idling when passing through a lock. It turned out to air leaking in at the CAV filter which was cured by tightening it up more. (there was a long thread on here last year)
Also after 15yrs, it would be wise to check your tappets.

WHY
if there isn't a problem don't fix it
He stated no oil being burned no noisy tappets
these old diesel engines are basic things not high performance racing, change the oil regular grease any thing that needs it but leave well alone
it could be as simple as poor quality fuel or an air leak due to high temp causing things to move no way is it tappets or low compression

 

[Lakesailor]

First under the microscope will be the fuel system then the tappets. I suspect that the govenor may be a bit too complicated.

Don't discount it because it's difficult. References to air leaks are surely limited to the ingress of air into the fuel line. Air for combustion just falls (is sucked) into the cylinders and unlike a petrol engine inlet air leaks don't effect the fuel/air ratio.

If you are having a stop-over why not get a diesel mechanic to have a look?

 

[lw395]

Air leaking into fuel system is a possibility, but why does it not cause misfires when running at higher revs?
The lift pump is then flowing more fuel, sucking harder, should be drawing in more air?
I might suspect the lift pump.

 

[Fascadale]

Just spoken to the very helpful John at Beta

He has suggested that air is being sucked back into the return rail from the fuel return pipe. At his suggestion we are now fitting a longer pipe into the system to create a "pigstail" or loop in the system which should prevent the return of air, similar I suppose to a U bend in a water system

Interestingly when we did start looking at the return system we did find a couple of fairly loose bull dog clips and a connection that could be twisted by finger, but no sign of any fuel leaks

We have managed to get some more pipe so will put in the pigstail and see if that's the answer. Losing half a gale here in Camaret, cloudy, not great so would not be going anywhere anyway

We live in hope

 

[Lakesailor]

There's your answer then. No wonder it's not sealing

See if you can get proper fuel hose clips like this.

The whole circumference reduces as you tighten it. Jubillee (worm drive) clips have a fixed radius sector where the screw is and don't nip down evenly

It may work. An easy thing to try out. Can you duplicate the symptom without a passage under motor?

 

[Noahsdad]

If your in Cameret I used an engineer there for an engine problem 4 or 5 years ago.
If your in the marina you've probably seen his workshop.
Just dug out his card.
"Mecamar"
Philippe Rossigneux
Tel 02 98 27 95 29
Mob 06 80 87 18 87
As I said it was a few years ago though last year I was there and saw the workshop still there.
His English is also much better than my French!
Fair Winds!

 

[ghostlymoron]

I'm not suggesting tappets are the cause of the current problem but 15yrs is a long time without adjusting them. Refer to your manual. I used to adjust tappets on my morris minor every 3 months and that wasn't a racing car either.

WHY
if there isn't a problem don't fix it
He stated no oil being burned no noisy tappets
these old diesel engines are basic things not high performance racing, change the oil regular grease any thing that needs it but leave well alone
it could be as simple as poor quality fuel or an air leak due to high temp causing things to move no way is it tappets or low compression

 

[savageseadog]

Check if there's any debris in the fuel tank. What can happen is the engine will run normally for long periods until the debris moves and blocks the outlet, after that it will hesitate and possibly stop only to restart without difficulty after an interval, and then block again as the flow starts. The debris can be lumps of diesel bug, rust flakes or swarf.

 

[mtb]

I'm not suggesting tappets are the cause of the current problem but 15yrs is a long time without adjusting them. Refer to your manual. I used to adjust tappets on my morris minor every 3 months and that wasn't a racing car either.

read it in a book did you

 

[ghostlymoron]

read it in a book did you

What does that mean? The Morris Minor handbook did recommend checking the tappets at every service and they had often changed since the previous one.