Diesel disaster - help!

[roberth]

Tootled down to the boat on Saturday with the intention of going to Boulogne.

Went to start engine - Yanmar 2GM20 - nothing but a click and dimming of lights. Plenty of power in batteries. Try to swing engine over by hand to see if some electrical problem - can't move it.

Call guy in who keeps lots of engines going in the area. He loosens starter motor in case dogs not disengaging - still tight. Suspects head gasket - he's away or a week, then intends to take head off to see what he can find.

His theory being that raw-water cooled engine gives no warning of head gasket failure - gradual seepage, don't notice for a while. But likely to have got worse recently, then engine not turned over in past month, means corrosion and jammed pistons.

Certainly seems plausible - this engine seems to be seized solid, yet when last used was running as sweet as a nut, and no unusual sounds or indications anything was wrong.

My main gripe is that the engine is only three years old, and has approx 250 hours on the clock.

Has anyone else heard of an engine failing so soon? Any possible reasons why? I shall also be quizzing Yanmar when I know more.

Thanks in advance for any light you can throw on this.

 

[Malish]

Might be siphoning

Do you close the raw water inlet seacock on leaving the boat?
Do you have an anti siphon valve fitted?
What is the route of the exhaust pipe?

 

[fireball]

When was the last time you used it?

 

[Pye_End]

I agree - water up the back more likely.

How does the sump oil look?

 

[spannerman]

Yanmars give very little trouble, we have 20 yr old 1 and 2 cylinder thumpers still going on their original head gasket, suspect as others have said the trouble lies elsewhere in the installation.

 

[cindersailor]

If there are decompressors try turning over with them activated. If it is locked up due to water in the cylinder(s) this will allow it to turn over. If still locked solid the pistons are presumably stuck in the bores.

 

[TheBoatman]

If you feel able enough, I would loosen both injectors and then with the throttle shut try and crank the engine - if there is any water in the bores it will "blow by".

WHEN LOOSENING THE INJECTORS DON'T REMOVE THE CLAMP PLATE OR NUTS COMPLETELY THE INJECTOR NEEDS TO "POP" UP BUT NOT OUT.

If the engine turns over then after say 10 secs - re-tighten the injectors and give her ago.

BUT - you will still have to find out why water got into the bores in the first place.

Peter.

 

[kandoma]

propeller running free ?.... a blocked propeller will block the gearbox and the blocked gearbox will block the engine from turning over.

Myself, I would not allow anyone to open up my engine without positiv proof that the interior is rusted. I would remove first the exhaust collector and the valve cover (this is nondestructive) and try to find some traces of saltwater damage.

If I would have positiv proof, that the engine is frozen solid, I would remove the engine and give it to a professional shop for rebuilding.

Its very easy to remove the head, just a couple of nuts and off you go. Putting the thing back again is the expensive part.....

Peter

 

[Anonymous]

Listen to kandoma. I was about to write what he has already written. If the head needs to come off then get it done by a workshop you trust off the boat and since it is now out of season, get a couple of prices. Good luck.

 

[andy_wilson]

In agreement with some of the others, properly installed and serviced you should have no problems for 20 years or 5,000 hours. I would always advise least invasive investigation first.

Try to turn on starter or by hand (spanner on crank pulley) with decompressors on. If that works whip the injectors out, inspect the combustion space with a torch for signs of corrosion, give a goodly dose of oil into the piston top and continue to turn with de-compressor lifted.

Check the sump oil and if no sign of emusification or floating water, try and start her.

 

[roberth]

Thanks to all so far.

Anti syphons fitted, seacock always closed when left.
Tried turning over decompressed.
Prop free - checked this - shaft turns freely.
Engine last fired up a month ago.

Guess I could try the injector idea to see if there is water in the bores, and investigate further.

I would also expect engine to run trouble-free for thousands of hours - much more investigaton needed before invasive surgery, it seems.

I'll keep you posted as the the eventual outcome.

 

[Skyva_2]

This would not explain the seized engine, but our new Yanmar 4JH has a start relay which failed within a year. A quite obscure problem, it was the third engineer who recognised it.

 

[Anonymous]

Check that your water pump isn't seized. Slacken alternator belt and check that the alternator (you haven't got a fresh water pump?) is not seized.

 

[kieronriley]

siezed gear box it happened to me took the engine apart and after rebuild found problem b//t//d

 

[supermalc]

These raw water cooled engines, the same as the older YSE?B?M should have the exhaust elbow changed after 2 years. When this fails it allows water to enter the engine and so become water locked. Bent con-rods are usually the result.

 

[Anonymous]

Methinks that the key factor in this diagnosis is that the engine was running sweetly when last used, then seized when tried a while later. Sounds like a corrosive build-up rather than internal structural damage.

Could be corroded cylinders, of course, but we have no evidence of that yet. There are other things to check first.

 

[euroe]

Sorry to read of your trouble. You asked if anyone had heard of similar problems with a comparatively lightly used engine. Unfortunately, diesels need hard work and often. Unlike petrol engines, they will develope all kinds of ailments if left inactive for prolonged periods. Just like us!

 

[Anonymous]

This is often said and not quite true, I suspect. True, diesels left idling for long periods tend to get glazed cylinders suffer carbon build up on the head and valves if the head temperature is too low - but we are talking about very low power levels - tickover and thereabouts. Have a look at the curves published by an engine manufacturer and you'll see that they engine is fully spec'd and rated down to at least 10% of its max power.

Like anything else mechanical, diesel engines wear due to friction and components can ultimately fail due to prolonged stress. You don't get friction and stress when the engine is off - though you do get corrosion, which is a different issue and requires clean oil. If you usually run your diesel at a high power level then the frictional wear will be higher than at lower power levels. This is a fact. If you run your engine at a high power level the stresses are greater than at lower power levels. This is a fact. The facts tell us that your diesel engine will last longer if you don't make it work too hard. These are facts.

No doubt there will be some who will disagree with me and try to argue against the facts - I expect this because the old wives' tale about needing to run a diesel hard is so ingrained in our culture it will linger for as long as diesels are made. To those of you with an open mind on the subject, please do your own research before coming to your conclusion; look at the engine curves supplied with the full workshop manuals and pause, and ponder. Read the workshop manual and the engine manufacturer's operators' manual (not necessarily your boat manufacturer's manual) as there might be special instructions for your engine type -no doubt some have special instructions. But be very critical of the old chestnut that diesels necessarily need to be driven hard. They don't. If you do, they will not last as long and they will burn vastly greater diesel.

 

[Ships_Cat]

I largely go along with what you say Lemain (a worry perhaps /forums/images/graemlins/smile.gif) and an example of the falsity of claiming that diesels need to be run hard lies in comparing commercial and pleasure ratings of engines and then that with what fleet operators run them at (they are usually very sensitive to both engine reliability and life).

For the same basic engine which may go into commercial or pleasure service the manufacturer will likely rate it differently for commercial service (as a MCR - maximum continuous rating) than for pleasure service - it will be rated at a significantly lower power output for commercial use than pleasure. Also a pleasure engine may have further limits put on it such as operation at full power for 2 hours in 24 or some such. All that because pleasure engines are run infrequently so can get a long life in years even when rated in a manner that gives them a short life in hours (when compared to the same commercially rated engine).

Then when a commercial boat is designed the operator will usually (well the knowledgeable ones do) specify what percentage of MCR he wishes to operate at and the required boat speed at that - often that operation is 85% MCR, so he will come up with, say, 35 knots at 85% MCR, at a specified loading condition of the vessel.

So we have the situation where a commercial engine will be rated lower than the same engine is in pleasure service plus the commercial operator then usually operates it much lower than that rating again - the purpose of the manufacturer's downrating of the engine and the operator not wishing to work it hard is entirely for reasons of extended life and reliability.

Therefore diesel engines do not like to be worked hard and another marina myth bites the dust.

John

 

[Anonymous]

[ QUOTE ]
I largely go along with what you say Lemain (a worry perhaps /forums/images/graemlins/smile.gif)

[/ QUOTE ] Your therapist will be very pleased with your progress /forums/images/graemlins/smile.gif