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BMC 1.8 and gearbox oil, prop not engaging properly


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I've just left a boat yard with a new (second hand) narrowboat that I bought. Before pickip I had them put in a new/reconditioned BMC 1.8 and gearbox. First time I tried to leave the prop wasn't engaging properly, upon checking the gearbox was had no oil. The engineer claims he had put oil in, and taken the boat for a spin, but that as it took time for the oil to distribute around the system, it had gotten low. Topped up the oil and all was well...

 

Until two days later. About a day's cruise away and the prop was acting funny again, though not quite as bad as before. Had a look and saw a few drops of water coming in everytime prop tried to engage. Realised I hadn't turned the stern gland after cruising. Did that, and tried to check the oil in the gear box. Problem is, the oil is clear and those dipsticks are near impossible to read. Looks like might be some oil underneath the gearbox, though could also be mostly water. Put in a little bit more oil, hardly any really, and all seems fine again.

 

Could not turing the stern gland greaser have made it harder for the prop to engage? Or does it seem my new gearbox has a leak?

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Can you please tell us exactly what gearbox you have (manufacturer and type).  People will be able to advise far better given that information.

Who supplied the "new/reconditioned" engine and gearbox, (it can't be both, of course!).  If you don't want to name names, can you please say if it was at least from someone specialising in engines for canal boat use.

The bit about getting "low because it takes time for oil to be distributed" sounds like bo**ocks, and would make me concerned.  It is possible your gearbox has an oil cooler, and you do need to recheck levels after running the engine, as they can drop somewhat after the oil cooler gets filled, but for that to occur only takes seconds.  No self respecting engineer should have given the boat back to you without checking the oil level with everything full.

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2 minutes ago, alan_fincher said:

The bit about getting "low because it takes time for oil to be distributed" sounds like bo**ocks

 

Well, If you fill a PRM gearbox to the mark when the cooler and pipes are empty, then run the engine, you'll find the level has dropped quite a bit because it has been distributed around the system

 

So, not quite bollocks

 

Richard

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1 minute ago, RLWP said:

 

Well, If you fill a PRM gearbox to the mark when the cooler and pipes are empty, then run the engine, you'll find the level has dropped quite a bit because it has been distributed around the system

 

So, not quite bollocks

 

Richard

Which is what my post says. (Well I didn't mention the pipes, but you can't have an oil cooler without the pipes).

EDIT:

And more to the point I was challenging " took time for the oil to distribute around the system" - it will happen within seconds, so no excuse for not immediately checking, and topping up again if necessary.

Edited by alan_fincher
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2 hours ago, Poppin said:

I've just left a boat yard with a new (second hand) narrowboat that I bought. Before pickip I had them put in a new/reconditioned BMC 1.8 and gearbox. First time I tried to leave the prop wasn't engaging properly, upon checking the gearbox was had no oil. The engineer claims he had put oil in, and taken the boat for a spin, but that as it took time for the oil to distribute around the system, it had gotten low. Topped up the oil and all was well...

 

Until two days later. About a day's cruise away and the prop was acting funny again, though not quite as bad as before. Had a look and saw a few drops of water coming in everytime prop tried to engage. Realised I hadn't turned the stern gland after cruising. Did that, and tried to check the oil in the gear box. Problem is, the oil is clear and those dipsticks are near impossible to read. Looks like might be some oil underneath the gearbox, though could also be mostly water. Put in a little bit more oil, hardly any really, and all seems fine again.

 

Could not turing the stern gland greaser have made it harder for the prop to engage? Or does it seem my new gearbox has a leak?

On many gearboxes the distance between max and min is about the length of the screw in thread of the nut that holds the dipstick so:

 

Remove and wipe oil off

 

Drop back in but do not screw in.

 

Lift out, turn on its side and either:

 

1. lay bottom of dipstick along the back of your hand

2. Lay the bottom of the dipstick on a piece of tissue

 

Both will allow you to see how far up the dipstick the oil is.

 

As you did not screw the dipstick back in the minimum mark is now taken as maximum and usually the bottom of the dipstick roughly equates to  minimum.

 

Note - no gearbox identity so may not be correct re levels.

 

 

Edited by Tony Brooks
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Hello all,

 

Thanks for your replies so far. im going to get the unit information when I get a sec but for now here's an update:

 

Made it through crick tunnel without issues thankfully. Immediately after however same issues hit us. Prop stopped turning properly, sputtering and struggling. Made it to a shallow bank and had a look. Added a little more oil, worked again so managed to make it to a better mooring 5 mins further. 

 

Would almost certainly be a leak wouldn't it? The engineer who fitted it is apparantly coming in the morning. Wouldn't a reconditioned gearbox be tested for leaks? What is the procedure for finding and fixing them? I'm really hoping we won't have to wait for a whole new gearbox to be installed. 

 

Bit of a s**t start to our journey, especially since I really emphasised my concerns before leaving and got his assurances all was ok

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4 minutes ago, Poppin said:

Hello all,

 

Thanks for your replies so far. im going to get the unit information when I get a sec but for now here's an update:

 

Made it through crick tunnel without issues thankfully. Immediately after however same issues hit us. Prop stopped turning properly, sputtering and struggling. Made it to a shallow bank and had a look. Added a little more oil, worked again so managed to make it to a better mooring 5 mins further. 

 

Would almost certainly be a leak wouldn't it? The engineer who fitted it is apparantly coming in the morning. Wouldn't a reconditioned gearbox be tested for leaks? What is the procedure for finding and fixing them? I'm really hoping we won't have to wait for a whole new gearbox to be installed. 

 

Bit of a s**t start to our journey, especially since I really emphasised my concerns before leaving and got his assurances all was ok

Check that the propshaft turns easily by hand when in neutral. If too stiff the box might be overheating.  A friend of mine burnt out a PRM150 because of this. He'd forced oversized packing into the stern gland. I had to renew the box and had great trouble freeing the propshaft. RLWP ended up with the old box.

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It certainly sounds as if the gearbox is losing oil. It must be going somewhere, though, so it might be worth checking if the fluid underneath is water or oil.

The boat we used to have a share in went through a period of the gearbox losing oil. In our case, it was coming from the gear change shaft. There is an "O" ring in there, which holds back the pressurised oil. One tip is to touch the underside of the gear selection assembly with a finger. If you get oil on your finger, the "O" ring is leaking.

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There's three possibilities (assuming the drain plug is done up) for oil leaks on a PRM150 - input shaft seal, output shaft seal and selector shaft seal. The last of those is a relatively quick job (15 minutes if the access is good) which can be done in situ, the other two require the gearbox to be removed and if it's the output shaft seal, dismantled.

 

With the engine stopped, cooled down etc, follow the control cable to the selector lever on the back of the gearbox, and run your finger round under/behind the lever - if it's dry, the it's not that one.

 

Repeat under the output flange where the box joins the shaft coupling. You can'ts get the the front one as it's in the bell-housing.

 

The other possibility is a leaky oil cooler - but that normally fills the box with water which promplty turns into "mayonnaise".

 

 

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It is a hydraulic PRM box but I'm unsure which one., 150 I think. I've found that the oil pump bolts can leak oil, they have wee copper washers under the heads. The oil pump housing is the round thing next to the propshaft coupling.

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Unless I'm misreading what I'm seeing, this picture to me appears to show a brass plug on the side where the flats have been all but rounded off.

Not what I would expect on a reconditioned gearbox.

IMG_20180523_185725239.jpg.ef6626f09a981

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1 hour ago, alan_fincher said:

Unless I'm misreading what I'm seeing, this picture to me appears to show a brass plug on the side where the flats have been all but rounded off.

Not what I would expect on a reconditioned gearbox.

IMG_20180523_185725239.jpg.ef6626f09a981

That's the dipstick filler plug. The picture is on its side.

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12 minutes ago, alan_fincher said:

Of course it is.

 

Surely it's still horribly mangled though, by the look of it?

I agree it certainly looks well mangled. Not what I would expect on a reconditioned gearbox. Maybe it got like this after the recondition.

Edited by Flyboy
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If the heat exchanger has an internal leak, the gearbox oil will pass into the cooling water. If the engine is keel or side tank cooled, it will be in the engine cooling water.

If the heat exchanger is cooled by canal water drawn in and discharged overboard, the oil will be in the canal!

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17 minutes ago, Boater Sam said:

If the heat exchanger has an internal leak, the gearbox oil will pass into the cooling water. If the engine is keel or side tank cooled, it will be in the engine cooling water.

If the heat exchanger is cooled by canal water drawn in and discharged overboard, the oil will be in the canal!

Looks like the end of the skin tank in the photo

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Update: 

 

We were expecting the engineer from the wharf this morning. Instead a less experienced kid turned up, a trainee I think, saying the guy was waiting in the car apparantly too sick to come to the boat... Well, young guy does "basic checks" and tightens a few things. Basically tells us nothing new and that if the problem continues will have to go all he way back and have the engine out. 

 

We don't trust these guys anymore and need a second opinion. There is a marina a little further along who have the facilities to lift out so may have to stop there. 

 

Odd thing is this: I can see dripping under the engine itself. It is oil and it is frequent, every 6 seconds or so. But the engine oil dipstick has remained normal through all of this, it's only he gearbox getting drained. 

 

 

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7 minutes ago, Poppin said:

Odd thing is this: I can see dripping under the engine itself. It is oil and it is frequent, every 6 seconds or so. But the engine oil dipstick has remained normal through all of this, it's only he gearbox getting drained. 

 

Are you sure it's not coming from the oil cooler or the hoses / hose connections on it (more likely)? It will be on the port side of the engine, follow the hoses back from the gearbox. There's not a lot of difference between max and min in the PRM boxes, although ours seemed to run OK with a very low level when we had a leak from the selector shaft.

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13 minutes ago, Poppin said:

Odd thing is this: I can see dripping under the engine itself. It is oil and it is frequent, every 6 seconds or so. But the engine oil dipstick has remained normal through all of this, it's only he gearbox getting drained. 

 

Sounds like it could be the gearbox input shaft seal is leaking into the bellhousing, which presumably has a drain at the lowest point, and it is either dripping from there or running along the underside of the engine and dripping from the sump.

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1 hour ago, David Mack said:

 

Sounds like it could be the gearbox input shaft seal is leaking into the bellhousing, which presumably has a drain at the lowest point, and it is either dripping from there or running along the underside of the engine and dripping from the sump.

If it's the seal leaking into the housing, presumably it won't need craining out to fix?

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2 minutes ago, Poppin said:

If it's the seal leaking into the housing, presumably it won't need craining out to fix?

as long as your engineer knows that the engine and gearbox are separate parts there shouldn't be any need (assuming you mean craning out the engine)

 

usual method would be...
1. undo propshaft from gearbox
2. slide prop & propshaft backwards to give some clearance
3. remove gearshift cable
4. either remove gearbox oil cooler from engine or gearbox (depends which is simpler)
4. remove gearbox from engine

 

 

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