Baffled Volvo MD11C User

[MBH]

What have I done wrong? How have I turned a simple fuel feed problem into a total engine "lock up"?

Background. I knew I would not be able to use the boat much this season, so I added a few drops of diesel bug protector to my fuel tank, and promptly forgot about it. About 2 months later, I started the engine and let it run for 15 minutes, (as it had not been in regular use), before leaving my mooring. After a couple of hundred metres, the engine died, and we manage to temporarily moor up to a berthed fishing boat. We spent the next hour determining that the coarse filter was totally gunged up with a black substance, presumably dead fuel bug. Still got no fuel through, so decided I needed to fill up fuel tank to ensure sufficient head of fuel to allow gravity feed to coarse filter. In the process of trying to pump fuel through, we had turned the engine over many times, by handle and by starter motor, with the compression levers up. The point being that the engine turned easily as expected! We had also tried hand priming from the fuel pump.

On returning to the boat the next day, with enough diesel to fill the tank, found the fuel still did not reach the coarse filter, and quickly established that the fuel feed line from the tank to the coarse filter was copmpletely blocked with black gunge, which had to be cleared using first a wire, then cleaning with fresh fuel. It was then possible to bleed the system in the normal way, using the primer on the fuel pump. Only then did the problem that is so puzzling come to light. The engine was locked up completely solidly. It is as though the gearbox is jammed in forward and reverse at the same time. (The prop shaft can be turned by hand whether the gear lever is in gear or neutral).

My main problem is that I cannot really believe that a major gearbox problem has coincidentally occurred just as I was working on the fuel system. But neither can I see how I could have immobilised the engine by working on the fuel system.

I have removed the starter motor, the hand cranking shaft and gear, and the rocker box covers with decompression levers, just to eliminate them as possible causes. Although I can't see how it could be the culprit, I intend removing the fuel pump, just in case!

Have I missed something obvious (or obscure)? Any helpful hints? Helpppp!

Mike

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[Mirelle]

I agree; there is no possible way that the engine jamming up could be a fuel problem. My engine, an MD2, is a distant ancestor, but it has a different type of gearbox, so I cannot help much, but if it is not the starter motor bendix drive failing to house properly I am flummoxed.

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[Johnjo]

Is it possible that that you have filled the exhaust with cooling water what with all the turning over of the engine, and flooded the engine causing it to hydrolic.
I note you have removed the decompressers so you would be unable to relieve the pressure,
Only a thought, but just maybe !

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[LORDNELSON]

I agree with the two other posts. Suggest you (a) go to the nearest Volvo marine engine dealer and discuss with him (b) remove injector and see if you have water in the cylinder.

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[Birdseye]

in some installations it is possible to pump too much water into the engin by turning over the way you have done , and without the hot exhaust gases to blow it out of the stern. the result is water flowing back into the cylinders and locking thew engine.

remove the injector(s) and see if the engine now turns (with inlet sea cock shut and outlet cock open) . if it does, and if water comes out of the injector holes, then the above is the problem. do an oil and filter change. hopefully, you have not bent a conrod with trying to turn the engine over.

if this is not the problem - volvo engineer!

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[MBH]

Many thanks to Mirelle, Mike27, Lord Nelson and Birdseye.

The suggestion that I have inadvertently pumped cooling water into a cylinder seems to fit all the facts. We certainly cranked the engine enthusiastically, though perhaps misguidedly.

Funnily enough, a local very experienced seadog had suggested hydraulic lock as a possibility, but we were discussing it in the context of a possible cylinder head gasket leak, so we agreed it was unlikely. The fact that it could be self-inflicted by pumping too much cooling water didn't occur to me and now puts hydraulic lock at the top of the list of suspects.

As injectors are a grey area for me, and in view of the damage I may have already done, your comments re calling in a marine engineer seem highly sensible.

I have therefore arranged a visit during the week, and look forward to posting the results of his findings in a few days.

Once again, many thanks for your helpful advice and comments.

Mike



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[vyv_cox]

If you have filled your cylinder(s) with seawater, which I agree sounds likely, leaving it in there for a week will cause considerable damage. Even your proposed couple of days may be enough to allow the rings to rust to the bores and the bores, valves, etc. to be badly pitted. I should get down there sooner, rather than later.

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[MBH]

I'm actually checking the engine with the marine engineer tomorrow morning, being the earliest time he could attend. It's the report back to the very helpful contributors to my query that will take a few more days. But your point is taken, and if you are right, the damage has already been done, as it is now more than two weeks since the sorry saga began. Many thanks

Mike


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[howardclark]

If the worst does happen and there is significant damage I would think long & hard about replacing with a different engine. As an ex MD11C owner, who only used volvo oil, volvo spares and volvo engineers, after a couple of major repairs I ended up with an old, 'expensive parts' engine which, had I bitten the bullet at the start, could have been replaced by for a net saving.
After changing boats I can't believe the difference in costs - my spares are now a pittance. As a result my mission is to tell anyone who listens that Volvo are a rip-off. They get business by selling to boat manufacturers at knock down prices leaving us to pay the penalty in high costs for the next twenty years or so- if it's knackered then get rid of it and choose a different make!


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[clyst]

Mike I'v sent you a PM ------Just click on the flashing Flagy thingy next to "mian Index"

Regards

Terry

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[Aeolus_IV]

I'll second that. Had I known before what I know now I'd have saved myself £700 and not tried to revive an old engine I knew was on its last legs. A new engine (not reconditioned) sounds like a lot of pain, but once done the benefits far repay the effort.

Jeff.

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[howardclark]

Any news yet?

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[MBH]

Report back on engine damage found by engineer.

The hydraulic lock diagnosis turned out to be spot on, and (unfortunately) the suggestion that the water would already have damaged the engine was equally accurate.

The local engineer disappeared further and further into the engine and eventually emerged with a bent push rod and associated cam follower from cylinder 2 with the piston in cylinder 1 seized up completely. It looks as though it was cylinder 1 that suffered from water ingress and then seized, whilst cylinder 2 was still trying to follow it round. There was no water in the cylinder, so it must have leaked down through the rings after doing the damage. The top ring was gunged up and wouldn't move in its slot (if slot is the right word?), the other rings looked OK. The top of piston was also all gunged up and proved quite difficult to remove from the cylinder liner.

Volvo (bless them) are doing their level best to discourage enthusiastic amateurs like myself from attempting any corrective maintenance on their engines, by ensuring I won't forget my mistakes in this episode, if for no other reason than the price of parts. Piston, push rod, cam follower and gasket set cost over £400.00 (including VAT). On the positive side, they did produce the parts within 24 hours, despite the fact that the engine is at least 25 years old.

Many thanks to you all for your interest and helpful advise.

A no longer baffled, but somewhat chastened MD11c User

Cheers,

Mike




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