Running dry for hours. .. what damage could have been done?

[Rachinwokingham]

This is a strange tale of a boat that apparently started itself. Repeatedly.

We recently bought a 20 year old Oyster 55 in Corfu and found a marine engineer with a good reputation to service our M90 Perkins engine and generator. We left him the keys and returned to the UK for a week only to get an alert from the marina three days later. 'Your boat is running and smoke is coming out of the back but no water is running from the boat exhaust'. WTF? We called the engineer who swore it was impossible. He had been working on the boat the day before but swears he had left everything switched off (including the seawater inlet stop cock).
He quickly came on board to find the engine running, the starter motor repeatedly firing, the starter motor wiring and plastic casing above it a smoking melted mess and the boat full of black smoke. We were very lucky that the boat hadn't caught fire. According to our neighbours the engine had been running for at least five hours and the winch above the engine was hot.
We are insured but our problem is this. Apart from finding out what on earth went on, the engineers who swear it is an electrical problem are telling us they are '99.9% sure' the engine is OK. They did a compression test which was 'fine' and they say the coolant never boiled over, proof that the engine didn't overheat. We will be covered by insurance for the rebuild of the starter motor, rewiring work and new starter motor batteries. But what damage might have been done internally to our engine that might not show up on a compression test and cannot be seen by a visual inspection?

Thanks for any suggestions!

[SailingFan]

Well, that is something you don't see every day...

OK, I am relatively new to these compared to most of the seasoned salts here, but these are the things that come immediately to mind. Remember that they are not all the potential issues, but that I am offering them as food for thought for both you and for the other members here to consider and rule in or out as experience and wisdom with this powerplant dictates for those who consider this thread. I am also including a few other boaty things that you should consider before signing off on the claim check as well...

Check the piston rings. Pull the head and check, don't just rely on "ok" compression, look for shavings in the oil and on top of the pistons, as well as wear and scoring on the sleeves. These issues may not be there, but it would suck if they were and you did not know for a month or two... Hopefully you will catch it before you cannot prove it was recent damage! Make sure they replace the head gaskets after this if such is normal custom for that engine (no need making more issues).

Check the injectors for damage, though I am not sure that would be likely if the engine kept starting. I am wondering how it stopped to restart though (or did it just keep reengaging the starter on a running engine?). That in itself is of interest to me. Could the fuel pump have been forcing diesel into an "off" engine to the point of causing it to run without ignition being enabled? That sounds awfully like what this is, but I was unaware it was possible. Checking the volume of oil in the block may tell you if this happened because I had a gas engine with a damaged fuel pressure regulator that flooded cylinders AND the block when it washed past the rings. The engine locked up, and when I pulled the plug the "oil" shot past me like it was Kerosene (and I suppose it sortof was)... Engine acted like it was locked up, but gas does not fire on compression, DIESEL DOES. Again, don't know if that is possible here, but others will know more than I - just a thought.

There are multiple other things, to include the wiring in the engine bay, that you will want to check too because the adjuster may not want to even consider all this, and it can cost more than tearing the engine apart if additional damage is considered in the claim. This includes the wiring near the exhaust, the starter, the block, and any metal brackets attached to the above (aka, almost any loose wires and probably bundled ones too may show issues later if they were against a non-cooled engine, especially if the heat on that external winch is what you noted).

I would consider that the exhaust elbow/s may have damage (depending on construction) or form weak places later (if it is plastic or some form of weaker alloy, but it is not as severe if steel) because water is supposed to go through with the exhaust, cooling it. The same with the remainder of the exhaust system, hoses, muffler, the works need checked. The muffler is supposed to have water running through, it may have issues (maybe cracking or melted thin spots that crack through prematurely) later.

There may be some smoke damage in the boat interior that will keep coming back (will smell great in the summers). That alone will do wonders for resale value.

The starter is of course likely a goner or at least used best as an emergency unit after a total rebuild, but you need a new starter mounted. They may not want the old one, so a rebuild could give you a good emergency unit if you are out away from civilization much, and you already paid for it once. But you need to know the starter is at least as good as it was. Was the original of clean appearance? If so, you need a new one. If it looked very used, then a quality and warranted rebuild could be ok (depends on your taste, I would ask for the best case and get what I could).

You may want to check all the hoses, because it is possible that the inlet hose collapsed with the kingston valve closed, and it could potentially cause wall weakness, depending upon the state of hose when all this started. You will need to examine the water pump for sure. It likely has a damaged impeller, something you won't see without pulling the thing off the engine and taking it apart. Check the seals for the water pump shaft as well.

Starter switch may have an issue so needs checking, as well as all the starter wiring, and did the mechanic install the starter or any electrical equipment immediately before this happened (maybe should have used a shim or two on the starter and did not?)? I can't think of how it would have kept engaging if not misaligned (assuming it did not start the engine to begin with), but someone else may have seen such a thing on this engine.

I would sure love to know what is decided as the cause for the spontaneous ignition without the key being in the switch though. I will be watching this thread to be sure!

[Kenomac]

Oysters are routinely outfitted with water separators in the exhaust system, so you shouldn't see water and exhaust spitting from above the waterline. Only exhaust fumes from above and the exhaust cooling water comes out below the waterline.

Very alarming to most who're unfamiliar with this feature. Relax, your engine is fine. You just need a new starter motor, then buy a spare to include in your spares inventory. The black smoke inside your boat was from the burnt plasic on the starter motor.

Check with Oyster after sales department to verify your boat was equipped with separators for the engine and generator if unable to check yourself. If it was... maybe it's time to find a new mechanic.

[SailingFan]

Originally Posted by Kenomac

Oysters are routinely outfitted with water separators in the exhaust system, so you shouldn't see water and exhaust spitting from above the waterline. Only exhaust fumes from above and the exhaust cooling water comes out below the waterline.

Very alarming to most who're unfamiliar with this feature. Relax, your engine is fine. You just need a new starter motor, then buy a spare to include in your spares inventory. The black smoke inside your boat was from the burnt plasic on the starter motor.

Check with Oyster after sales department to verify your boat was equipped with separators for the engine and generator if unable to check yourself. If it was... maybe it's time to find a new mechanic.

That is great news!

[SailingFan]

So how did the motor start itself?

[Kenomac]

Originally Posted by SailingFan

So how did the motor start itself?

Oysters don't require a "key" to start, instead, there's a run/start switch at the helm station. So if the engine breaker switch was turned on and somehow there was a short circuit in the starter motor/ and/or the mechanic left the "run" switch in the "on" position... the engine can start itself. Normally, there's an alarm to indicate the "run" switch is in the "on" position, but this can be broken.

[SailingFan]

Hmm.. Thanks. Seems that there is a flaw in the design that could cause all manner of mischief if someone were to want to take a joy ride in the vessel when the owner is away. Heck, it could be an errant seagull, even if everything is working correctly!

[dwedeking2]

If you're away the breaker should be off

[transmitterdan]

All diesel engines on sail boats should be fitted with a battery disconnect switch. When leaving the boat for an extended period the switch should be opened so the engine cannot start. Failure of start switches (key or button type) is common enough to warrant the switch.

If the fresh coolant water did not boil over then your engine should be no worse than it was. Investigate why there was smoke as that problem may have existed before this incident. And change the raw water impeller.

[DumnMad]

Originally Posted by transmitterdan

All diesel engines on sail boats should be fitted with a battery disconnect switch. When leaving the boat for an extended period the switch should be opened so the engine cannot start. Failure of start switches (key or button type) is common enough to warrant the switch.

Yep, same thing happened on a dredge I was associated with. Key solenoid I think. The engineer should have turned off the battery disconnect and shut off the fuel supply.

[Kenomac]

Originally Posted by SailingFan

Hmm.. Thanks. Seems that there is a flaw in the design that could cause all manner of mischief if someone were to want to take a joy ride in the vessel when the owner is away. Heck, it could be an errant seagull, even if everything is working correctly!

No flaw, you're supposed to turn off the engine battery connect switch when away.

[sailorboy1]

Originally Posted by Rachinwokingham

But what damage might have been done internally to our engine that might not show up on a compression test and cannot be seen by a visual inspection?

Thanks for any suggestions!

I would get a qualified engine mechanic to check out the engine, not take the thoughts of the electrical guy.

[belizesailor]

Ive experienced the same auto-crank issue w Volvo engines. In that case it was a short exacerbated by a design flaw (a lead in the relay box which was not fused, but should have been...it is now).

As suggested, turn off the start battery switch when away...just in case.

[DeepFrz]

There are several threads on CF that document the problem of self starting. Google custom search under the search button should bring them out.

Here is a link to one of them.
http://www.cruisersforum.com/forums/.../t-138625.html

Here is another one:
http://www.cruisersforum.com/forums/...-a-128209.html

[danielamartindm]

This makes the head hurt. Others far more knowledgeable than I have given sage mechanical advice. My advice is this: Have a good diesel mechanic go over your boat with a fine-toothed comb. You have a window of insurance coverage for this "incident." If there is occult damage not apparent right now, it will become "normal wear and tear" in the future if not included in your insurance claim. Be CERTAIN you have a comprehensive list of the damages, or you may find yourself eating them at some future date. Insurers' primary fiduciary responsibility is to generate a profit, not to indemnify us.