Oil leak

[Terrierious]

Hi all,

 

We have always (since purchasing 2years ago) had an oil leak from the vent type fitting on the right hand side of the picture on top of the gearbox. It does not leak a huge amount but we would like to rectify - does anyone know what this part is and why it might leak? We have checked the oil level which is ok and have tightened the fitting but have had no joy. Engine is an Isuzu. We have also had it looked at by 2 engineers but neither could give an explanation.. Any ideas appreciated..

 

Thanks

 

 

 

 

 

 

Edited January 6, 2013 by Nb Trikeri

[Tony Brooks]

Hi all,

 

We have always (since purchasing 2years ago) had an oil leak from the vent type fitting on the right hand side of the picture on top of the gearbox. It does not leak a huge amount but we would like to rectify - does anyone know what this part is and why it might leak? We have checked the oil level which is ok and have tightened the fitting but have had no joy. Engine is an Isuzu. We have also had it looked at by 2 engineers but neither could give an explanation.. Any ideas appreciated..

 

Thanks

 

 

 

That is the gearbox breather and the most obvious reason it is leaking is because the box is overfilled. Dipstick under the large brass hexagon filler bottom left of the box. This is a PRM mechanical box, possibly a 120, and they used to say fill with engine oil. I think they changed that to Automatic transmission fluid last year so check direct with PRM unless another member confirms this (I have a Spanish built ZF box on mine so not much first hand experience).

 

 

Edited to add:

 

I do not know if this box should have a baffle below the breather. If it should and has fallen off or was never fitted that might explain it. Maybe Richard knows. Some have a spring and ball under the small domes cover. If this PRM is like that and it is missing it could also explain it.

Edited January 6, 2013 by Tony Brooks

[MtB]

I'd be more concerned about the lack of a flexible coupling on that prop shaft, assuming the Isuzu is on flexible mounts.

 

No problem if its bolted down rigid though, but that is unusual with a modern engine.

 

MtB

[churchward]

I'd be more concerned about the lack of a flexible coupling on that prop shaft, assuming the Isuzu is on flexible mounts.

 

No problem if its bolted down rigid though, but that is unusual with a modern engine.

 

MtB

Also looking at the photo one of the bolts attaching the coupling to the gearbox looks to be broken the remains and the nut looks to be in the oil tray under the engines. it is at the bottom left corner of the gearbox

[n.b.Goldie]

Also looking at the photo one of the bolts attaching the coupling to the gearbox looks to be broken the remains and the nut looks to be in the oil tray under the engines. it is at the bottom left corner of the gearbox

 

Misaligned motor?

 

Regards

Ditchdabbler

[Tony Brooks]

Misaligned motor?

 

Regards

Ditchdabbler

 

 

That would do it of its jumping about, but the OP does not seem to mention excessive vibration.

[Terrierious]

Thanks for the responses so far, I do not know a huge amount about engines but learning fast! The gearbox has been filled with engine oil as advised by a service engineer, has not been overfilled though. It is possible that parts are missing from the vent, where can I just buy a new one? I have tightened the gear box sump to ensure that is not leaking.

 

Regarding the engine, it is mounted on flexible mounts, recently one bolt snapped off on the prop shaft, yesterday another has sheared off but maybe because one had already gone? Looking to replace all the bolts once I have worked out how to fit them in! The engine does vibrate a bit, and has recently developed a seeking noise which is not a fan belt. Looking for a good mechanic in the Iver area soon.....

[boots]

I was in touch with PRM last year after our 120 developed problems, and yes they do state ATF and not engine oil for the 120.

[RobinJ]

That is the gearbox breather and the most obvious reason it is leaking is because the box is overfilled.

Think more likely its getting hots and is leaking due to expansion, of course over-filling won't help.

OP doesn't say how far they are going or how often it leaks?

[Tony Brooks]

Thanks for the responses so far, I do not know a huge amount about engines but learning fast! The gearbox has been filled with engine oil as advised by a service engineer, has not been overfilled though. It is possible that parts are missing from the vent, where can I just buy a new one? I have tightened the gear box sump to ensure that is not leaking.

 

Regarding the engine, it is mounted on flexible mounts, recently one bolt snapped off on the prop shaft, yesterday another has sheared off but maybe because one had already gone? Looking to replace all the bolts once I have worked out how to fit them in! The engine does vibrate a bit, and has recently developed a seeking noise which is not a fan belt. Looking for a good mechanic in the Iver area soon.....

 

 

That sound horribly like a badly aligned engine. If it is on flexible mounts it really should have some form of flexible coupling. It looks as if you have space for an Aquadrive or Pythondrive that remove all the alignment problems and reduces the stress on the engine mounts. If cost is a factor I would suggest you look at a Centaflex coupling. Definitely get the alignment checked.

 

Er - what "sump", do you mean sump plug? If so have you made sure the soft washer on it is present and still soft enough to seal?

[bizzard]

Installations like that are typical of inland waterways so called marine engineering of recent years.

The quickest and cheapest way of dealing with that is to chuck the rubber engine mounts and mount it solid and properly aligned, the little extra transmitted noise would be worth it.

I'm not a fan of any single type of flexible coupling Centaflex, R&D or otherwise used with rubber engine mounts,''stern tube bearing wreckers'', better than nothing though I suppose like the OP's installation, although not so bad with the slightly more flexible water lubed rubber Cutless stern unit, although the stress on the sterntube can still be horrible. Ideally as Tony Brooks says, an Aquadrive or Python drive or even an adapted vehicle propshaft or go solid.

I'm not sure if there are that many marine engineers left on the inland waterways anymore that actually understand boat propshaft installations and alignment.

[Tony Brooks]

Installations like that are typical of inland waterways so called marine engineering of recent years.

The quickest and cheapest way of dealing with that is to chuck the rubber engine mounts and mount it solid and properly aligned, the little extra transmitted noise would be worth it.

I'm not a fan of any single type of flexible coupling Centaflex, R&D or otherwise used with rubber engine mounts,''stern tube bearing wreckers'', better than nothing though I suppose like the OP's installation, although not so bad with the slightly more flexible water lubed rubber Cutless stern unit, although the stress on the sterntube can still be horrible. Ideally as Tony Brooks says, an Aquadrive or Python drive or even an adapted vehicle propshaft or go solid.

I'm not sure if there are that many marine engineers left on the inland waterways anymore that actually understand boat propshaft installations and alignment.

 

 

I am not convinced that going solid mounted would produce more noise - especially as the shaft may well be way out of line. At the moment the shaft is being banged about in the bearings and that produces noise and vibrations. I now suspect that the engine is being jumped about by the shaft so the mounts may be "bottoming out" and producing noise/vibrations.

 

I too have grave reservations about modern practise. How many new installations are supplied with a dummy flexible coupling so they can be accurately aligned?

[Terrierious]

Thanks for the responses, it all sounds really bad?!?!

 

I have very little mechanical expertise, is installing a flexible coupling straight forward? This seems like the easiest option, engine re-alignment sounds time consuming and terribly expensive?

 

Regarding the gearbox, I am going to get a new oil drain seal and also a new breather, drain and fill with ATF, hopefully this might solve this! The engine is not used huge amounts maybe 20 hours every month or so, never had any issues with it so far. The vibration is minimal however when you look at the engine in gear is is moving around a bit! I will have to look around for some one mechanically minded to maybe have a look over the engine to find the best solution :-(

[bizzard]

I am not convinced that going solid mounted would produce more noise - especially as the shaft may well be way out of line. At the moment the shaft is being banged about in the bearings and that produces noise and vibrations. I now suspect that the engine is being jumped about by the shaft so the mounts may be "bottoming out" and producing noise/vibrations.

 

I too have grave reservations about modern practise. How many new installations are supplied with a dummy flexible coupling so they can be accurately aligned?

Quite, it would probably be much quieter than the OP's present arrangement. Even if they are accurately aligned with the dummy or otherwise, they won't remain accurate for long, rubber mounts slowly sink and deteriorate from the word go especially if they get oily which is often the case. Most stress is applied to the stern bearing when the boats idling along in gear when the engines more likely to be trying to range about.

And of course the builders sacrifice a proper reliable driveline setup for a few inches of extra accomodation space by stuffing it all right up the stern as possible. And of course much cheaper to do than a proper marine installation, but of course most of their punters wouldn't understand or be interested in this anyway and will be only interested and impressed by the accomodation size.

Edited January 7, 2013 by bizzard

[alan_fincher]

Also looking at the photo one of the bolts attaching the coupling to the gearbox looks to be broken the remains and the nut looks to be in the oil tray under the engines. it is at the bottom left corner of the gearbox

Well spotted.

 

 

Presumably the two uninsulated ends of the wires hanging down towards the sump under the prop-shaft relate to a bilge pump currently missing?

 

Hopefully they are at least fused, in case anybody turns the switch on, and the live end contacts the hull!

 

I'm guessing from the look of it this may be a Liverpool Boats boat? That arrangement of a flexibly mounted engine with absolutely nothing flexible in the drive train seems to not be unusual. Plus that lowered sump for the pump looks "Liverpoolish".

 

IIRC forum member Stuart had big problems with such an arrangement on an LB boat. I think it may even have caused engine and gearbox to part company, although I maybe remembering the wrong event......

[bizzard]

Thanks for the responses, it all sounds really bad?!?!

 

I have very little mechanical expertise, is installing a flexible coupling straight forward? This seems like the easiest option, engine re-alignment sounds time consuming and terribly expensive?

 

Regarding the gearbox, I am going to get a new oil drain seal and also a new breather, drain and fill with ATF, hopefully this might solve this! The engine is not used huge amounts maybe 20 hours every month or so, never had any issues with it so far. The vibration is minimal however when you look at the engine in gear is is moving around a bit! I will have to look around for some one mechanically minded to maybe have a look over the engine to find the best solution :-(

Its simple to just remove the remaining prop shaft nuts and bolts, push the shaft back and inch or so and then bring forward again and you will probably see quite plainly ''misalignment'' as the two half couplings come together, the gearboxes one will probably be too low because of engine mount sinkage for a start.

[Terrierious]

The wires are not live, I need to install a new bilge pump and floating switch. This is also something I need a mechanic to do, as I am unsure of the wiring arrangement!

 

If anyone knows of a good mechanic in the Iver/Uxbridge area please do let me know. Hopefully I can get this sorted as I plan to do a lot of cruising this year....

[lexicon]

Peter Wakeham at denham could be worth a call.