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Water in the gearbox.


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Two days ago the stern gland started leaking badly at the same tie the bilge pump packed in, consequently I had quite a bit f water in the engine hole. Today, when going to repack the gland I saw emulsified oil in the drip pan. On checing the gearbx oil it was full of emulsified oil.

 

I have not yet looked to see where the ingress / egress occurred but once found and rectified any advice on how to clean out the gearbox? It's a PRM 150

Edited by Dr Bradley
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DON'T run it!

Drain the box from the plug, not by sucking it out, Remove the hoses and oil cooler and drain and leave all  to drain overnight. Get ALL the oil out.

Fill with fresh oil, should be perfectly fine but check it again next week and if still white change it again. The clutch linings are cardboard, long immersion in water wrecks them, short term they survive.

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8 minutes ago, Boater Sam said:

The clutch linings are cardboard, long immersion in water wrecks them, short term they survive.

Unlikely on a 150, I've only ever found the sintered ones in them and the Deltas that came before

 

Richard

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29 minutes ago, Dr Bradley said:

Two days ago the stern gland started leaking badly at the same tie the bilge pump packed in, consequently I had quite a bit f water in the engine hole. Today, when going to repack the gland I saw emulsified oil in the drip pan. On checing the gearbx oil it was full of emulsified oil.

 

I have not yet looked to see where the ingress / egress occurred but once found and rectified any advice on how to clean out the gearbox? It's a PRM 150

 

Did the bilge get so full that water might have entered the gearbox through a breather on the top? If not then that is unlikely to be the source of the water in the oil. 

 

Usually this happens when there is a leak in the oil cooler. So check that hasn't pinholed before refilling with oil.

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I was sure that 150 was similar cone linings to 160 which are card. If not, that's good, the gears will stand water providing it is not left too long.

 

The oil cooler is under more oil pressure than coolant pressure so coolant cannot enter the oil that way even if the cooler is holed, and that is pretty unusual too. I am assuming of course that this is a skin tank cooled engine.

When you say emulsified oil, what colour is it and how do you know? have you drained any off? Or is it just on the dip stick? Can you suck a sample up with a thin tube? Don't drink it!

 

The remedy is still the same but it would be vital to establish how the water got in there in the first place.

 

If you remove the hoses from the oil cooler and fit one across both the unions on the gearbox to keep the oil in, you can run the engine off load for a good while to charge batteries and if there is a coolant leak into the oil gallery you will soon know! Don't run the boat very far if you bypass the heat exchanger in this way, the gearbox will overheat.

Whilst you have the bypass fitted you could change the oil for peace of mind. That will ensure that any pool of water in the bottom of the box will be drained off, the water will settle out slowly as long as the engine is not run to stir it all up again.

Get back to us and tell us what you find.

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Alan, I don't know how the water got in but oil also got out hence the emulsified oil in the drip tray. Sam, the above cleats your questions think. Thanks for the bypass idea to obtain electric I first have to find the leak which must exist.  Solve that then how do I clean the gearbox. 

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Sorry you missed the point.

If the cooler is holed there will be masses of oil in the coolant water and little in the box.

It is impossible to pressurise the cooling system without running the engine unless you have another heat source to heat the engine.

I am reasonably sure that a PRM box pressurise the hoses and the cooler whenever it is turning, else how would it engage a gear without oil pressure? And the oil needs cooling when in neutral too, as when charging batteries.

 

If I am wrong, then so be it, but logic dictates I am correct.

Edited by Boater Sam
smellings
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Thought it was worth mentioning; It says on my 150 instructions to use mineral oil only and not semi or synthetic oil.

I have read in the past that 150's can leak around the gear selector shaft (o ring?)  If this has failed could it allow high bilge water to enter the box and subsequent leaking out of the box?
Just trying to think out of the box ;)

Edited by Guest
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43 minutes ago, Boater Sam said:

Sorry you missed the point.

If the cooler is holed there will be masses of oil in the coolant water and little in the box.

It is impossible to pressurise the cooling system without running the engine unless you have another heat source to heat the engine.

I am reasonably sure that a PRM box pressurise the hoses and the cooler whenever it is turning, else how would it engage a gear without oil pressure? And the oil needs cooling when in neutral too, as when charging batteries.

 

If I am wrong, then so be it, but logic dictates I am correct.

The spool valve dumps the oil from the pump straight back into the box body when set to neutral. When a gear is selected the oil is directed to the clutch piston that in effect has "no way out" so it s pressurised. In neutral there will be flow but the only pressure in the system will be caused by friction or restrictions in the pipes and circuit.

 

So there will be far less pressure in the hydraulic system when in neutral than when a gear is selected. This is standard hydraulic spool valve practice. However on a Lister LH150 things are different because oil pressure is used to get neutral and astern so the spool valve dumps the oil when in ahead.

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Point taken Tony. Its correct practice with a spool valve control. How then does the oil cooler function when the box is in neutral for hours charging batteries?

Does the dump from the spool valve block in reality dump through the cooler? The oil pump runs continuously whether in or out of gear.

I've never been brave or foolish enough to undo a hose with the engine running!

 

The smallest of internal leaks in the cooler heat exchanger will result in oil in the coolant no matter what.

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2 hours ago, catweasel said:

Thought it was worth mentioning; It says on my 150 instructions to use mineral oil only and not semi or synthetic oil.

I have read in the past that 150's can leak around the gear selector shaft (o ring?)  If this has failed could it allow high bilge water to enter the box and subsequent leaking out of the box?
Just trying to think out of the box ;)

Well that differs from my PRM 150 instructions that says "engine oil"  which covers all types of oil IMO.

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3 hours ago, Boater Sam said:

Point taken Tony. Its correct practice with a spool valve control. How then does the oil cooler function when the box is in neutral for hours charging batteries?

Does the dump from the spool valve block in reality dump through the cooler? The oil pump runs continuously whether in or out of gear.

I've never been brave or foolish enough to undo a hose with the engine running!

 

The smallest of internal leaks in the cooler heat exchanger will result in oil in the coolant no matter what.

I agree about the oil in coolant.

 

I can see no reason why the spool valve would not be on the pump side of the oil cooler so it cooled the oil whatever "gear" the box was in but even if not the heat generated in the oil is when the oil is being pressurised, that is when its in gear. This is why the LH 150 does not need an oil cooler. The only time oil is pressurised is in astern or neutral. I know this does not answer the question about running in neutral for battery charging on a LH 150 but it does on any other common hydraulic gearbox.

2 hours ago, Flyboy said:

Well that differs from my PRM 150 instructions that says "engine oil"  which covers all types of oil IMO.

Answering you and Flyboy

 

But I am sure PRM assume that the owner will stick with the type of oil recommended by the engine mariniser and that is mineral oil. Anyway I can't see that synthetic oil can do any damage to the gearbox internals.

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5 hours ago, Flyboy said:

Well that differs from my PRM 150 instructions that says "engine oil"  which covers all types of oil IMO.

That is interesting. Our box is 18 months old and clearly states this. If I can find the manual easily i will photocopy and post.

The answer is here: http://www.prm-newage.com/help-centre-marine

Edited by Guest
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2 hours ago, Tony Brooks said:

I agree about the oil in coolant.

 

I can see no reason why the spool valve would not be on the pump side of the oil cooler so it cooled the oil whatever "gear" the box was in but even if not the heat generated in the oil is when the oil is being pressurised, that is when its in gear. This is why the LH 150 does not need an oil cooler. The only time oil is pressurised is in astern or neutral. I know this does not answer the question about running in neutral for battery charging on a LH 150 but it does on any other common hydraulic gearbox.

Answering you and Flyboy

 

But I am sure PRM assume that the owner will stick with the type of oil recommended by the engine mariniser and that is mineral oil. Anyway I can't see that synthetic oil can do any damage to the gearbox internals.

I did wonder why synth or semi would do any harm, but am not qualified to make that judgement.

I do know I was told for years that synth was "not suitable for canal engines," but people seem to be using it now. I have stuck with mineral in our Vetus for 15 years and not likely to change now! (Vetus say synth is fine in the engine, as did Thornycroft in their version of the same donkey.)

Edited by Guest
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I.ve flushed through with fresh oil several times until there is no sign of emulsifying. I.ve then run the engine for a shprt time with n adverse effects. I;m now running a bit lionger with regular checks. so far nothing going wrong so a complete mystery as to how water got in and emulsified oil got out.

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1 hour ago, Dr Bradley said:

I.ve flushed through with fresh oil several times until there is no sign of emulsifying. I.ve then run the engine for a shprt time with n adverse effects. I;m now running a bit lionger with regular checks. so far nothing going wrong so a complete mystery as to how water got in and emulsified oil got out.

Seems odd. I was in our engine hole before and looking at the PRM it is hard to imagine how water could have got in/oil got out. Small weep on drain plug or output shaft came to mind. (this assumes heat exchanger is OK.)

Edited by Guest
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