Volvo MD11c

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Swanrad2

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The old engine is running sweet as a nut.
We couldn't get water through it until we figured the water gallery in the gear box (through which the raw water passes before it enters the pump and then the block) is blocked - some oil in the pump. I want to go sailing so there seems to be three choices which each appear to have their supporters:
1. By pass the gear box cooling and put water directly into the pump/block (suggested by some Volvo fans as the college being surplus to strict requirements in UK waters)
2. Get a compressor and try to force air through the cooling gallery in the gear box then try cooling again (damage?)
3. Option 1 but with SME form of temperature alarm (suggestions?)

Option 4 is to try and relocate a lost (and very kind offer) of a gearbox and replace the existing one - I'd rather do that next season as it might scupper any chance of sailing this year.

Thanks
 
My inclination would be to fix it but then we've got a motor boat and I wouldn't like to run the gearbox for long without cooling . How difficult is it to remove the water pipes close to the box? I've never had to try on ours. You could check the pipes and get a probe into the gallery. Perhaps you've done that already. If that doesn't produce a result I'd try the compressor. What damage do you imagine you'd do? The box is robust and I don't image the blockage is that substantial. It may be a crazy thought but could you put an air connection to the drain plug so that you are blowing the obstruction outwards instead of through the gallery?
What concerns me is your statement of 'oil in the pump' If there's oil in the water pump I'd have thought there's a break somewhere. Have you checked the gearbox oil to see there's no water there?
Good luck.
 
Vonasi said:
Sounds like you have the same gearbox as we have on our MD17C. Think it is called the MSB gearbox?

I had a problem with the gallery around the outside of mine a few years ago as it obviously corroded through or cracked allowing salt water to mix with gearbox oil. As a temporary get me home bodge I bypassed the gallery by wrapping a coil of copper pipe around the housing and then wedged aluminium blocks between it and the gearbox casing where ever it didn't touch. I'm in the Med though so I figured gearbox cooling was more important and I was half way up the Aegean and home at that time was down in Crete! we only put about four hours on the engine but it appeared to keep it cool enough. I later replaced the gearbox with a used one.

If you have oil in the pump it could be coming from the impeller pump shaft seal? I suggest you check the gearbox oil to see if it is emulsified and if not then I would try flushing the gearbox channel with dilute hydrochloric acid to remove the blockage and then flush it with plenty of fresh water.

Oh and another bit of advise - never accidentally put synthetic oil in the gearbox - it'll last about 25 hours before you lose gear selection and need a rebuild!
Click to expand...

Cheers, the water outlet from the gear box is full of black oily stuff so I think the oil is seaping into the water cooling channel and being pumped up into the impeller housing. The oil isn't emulsified so I think it probably happened over winter (poor winterisation maybe). Looks like the only way to figure out if it will,work or not is to run it in gear for an hour and monitor the temperature of the casing. Anyone have any idea what the safe operating temperature of a gear box casing might be?
 
Vonasi said:
It seems strange that when my casing failed it drew salt water in whereas yours is sucking oil out?
Click to expand...

The boat is out of the water so we haven't run the gear box under load yet. It is just pumping water at the moment in neutral. I think we will drain fp down and refill the gear box on the assumption that it has pushed sea water into the oil and sucked oil/sea water into the impeller housing but in very low volumes, insufficient to make it to the exhaust outlet.
 
Is that terminal, doesn't sound good?

scottie said:
Burnt cone linings
The female cones in some of theses boxes had a "ferodo" insert
Click to expand...

Is there any downside to judiciously blowing it through with a compressor to see if there is just a blockage that needs sorting?
The oil in the box itself is fairly clean by the way.
 
Swanrad2 said:
Is there any downside to judiciously blowing it through with a compressor to see if there is just a blockage that needs sorting?
Click to expand...
I'd certainly try it on ours. I don't see what harm you can do to the jacket as long as you do it 'judiciously' as you say. I'd have thought the obstruction might be at an elbow where the hoses join the jacket if your set up is like ours. Have you taken the hoses off and probed gently with a flexible wire. I'd also try probing gently from the drain hole.

The clean oil is good news.
 
How does the oil get from the impeller pump to the gearbox? Surely it's a one-way system.

Does the gear box get hot enough to cause salt deposits? some patio cleaners contain hydrochloric acid but not all. Google helps. You can buy the acid (36%) on ebay for about £12 including postage

Incidentally I change the gearbox oil every 100 hrs or the end of the season which ever comes sooner.
 
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Swanrad2 said:
That seemed logical!
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Please tolerate me on this because I'd like to know in case I get the same problem.
1 Where's the logic in saying the oil is coming from the gearbox if the oil in the gearbox is clean and the oil in the water is black? What have I missed?
2 If the oil is coming from the gearbox is that a problem that needs fixing?
I can see that the replacement gearbox should solve all these problems.
 
albineer said:
Please tolerate me on this because I'd like to know in case I get the same problem.
1 Where's the logic in saying the oil is coming from the gearbox if the oil in the gearbox is clean and the oil in the water is black? What have I missed?
2 If the oil is coming from the gearbox is that a problem that needs fixing?
I can see that the replacement gearbox should solve all these problems.
Click to expand...

Tolerated!
If I take it from the start of the engine firing up again. No water makes it through the gearbox (the oil here was low and I have topped it up). When I circumvent the gearbox - cooling water by the bucket. There is a problem with the gearbox (I forgot that I had topped the oil up and not run the engine in gear so it will be clean. I have swapped the water pump (seals and all). Maybe logic was stretching my diagnosis a bit far - but if I have swapped one of the bits tha might be leaking and I still have a fault with the remaining one, chances are it is that which is causing the main problem.

There is so little water making it through to the cooling system (none to the exhaust) through the gearbox that there is some kind of issue. I am going to do the following immediately.

1. Attempt to flush the gear box with a little pressure/prodding
2. If this cant be done I am going to circumspect the gearbox cooling (most farm machinery cools the gearbox at ambient temperature). I may install a fan that runs when the engine runs if anyone think this might make any difference at all.
3. When I get my hands on it I will swap out the gearbox and have a good poke around at it on the bench.

As I said, maybe logic was stretching it a bit - more swapping bits until the problem stops!
 
There is a thread on the WOA forum about MD11C cooling, a few posts by me as I have tried stuff.

You may get away with bypassing the gearbox if the engine is cooled properly, my problem was that bypassing the gearbox didn't improve engine cooling. If the engine is cool it may not overheat the gearbox.

The cooling flow through my engine went from about a litre a minute when it was overheating to the current 3l a minute when I can motor at 2000 rpm for as long as I can stand the noise.

Water flow measured by catching the exhaust in a bucket for a minute.

I take it you have a good flow if you open the sea cock with the strainer out, I hadn't but I have been chasing blockages in the engine cooling galleries too.

Not had a problem with the gearbox yet, fingers crossed.
 
aquaplane said:
There is a thread on the WOA forum about MD11C cooling, a few posts by me as I have tried stuff.

You may get away with bypassing the gearbox if the engine is cooled properly, my problem was that bypassing the gearbox didn't improve engine cooling. If the engine is cool it may not overheat the gearbox.

The cooling flow through my engine went from about a litre a minute when it was overheating to the current 3l a minute when I can motor at 2000 rpm for as long as I can stand the noise.

Water flow measured by catching the exhaust in a bucket for a minute.

I take it you have a good flow if you open the sea cock with the strainer out, I hadn't but I have been chasing blockages in the engine cooling galleries too.

Not had a problem with the gearbox yet, fingers crossed.
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Great cooling.
New head gasket, new thermostat, new exhaust manifold cleaned channels wherever they are found and the engine is squirting like a race horse! The temperature sender's not working now though, but the engine is lovely and cool so there should be very little transfer of heat from engine to gearbox when in neutral. We wait to see what happens under load!
Fingers crossed - I've waited a very long time for some good luck.....
 
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