Engine losing power after running for an hour

[Tony Brooks]

That is a PRM hydraulic gearbox and if it suffers low oil pressure/lack of oil it will slip, but if it does when underway the engine revs will go up, so I doubt it is a gearbox fault.

 

 

[alan_fincher]

3 minutes ago, moiuk said:

Gearbox oil now changed. Not sure if it's hydraulic.  Issue still occuring.

 

Fuel value opened now as well.

 

I have also reoiled the nipple for the prop bearing. (Photo attached)

 

 

IMO I don't think it is great to have a stern bearing that doesn't hav a remote greaser capable of holding a good supply of grease.  If you really do only have a nipple to use for putting grease in, I think that is really quite unusual.

[blackrose]

14 minutes ago, moiuk said:

 

 

What's all that fluid in the engine spill tray?

[magnetman]

I have the same gearboxes on the 2  engines on Dulcinea. PRM Delta (now called PRM 150). If the oil goes low the propulsion does become intermittent as the clutch packs don't work properly because they are actuated by a hydraulic circuit. 

 

The oil is not only lube oil it is also needed to actuate the clutches. 

 

 

 

[Tony Brooks]

44 minutes ago, alan_fincher said:

 

IMO I don't think it is great to have a stern bearing that doesn't hav a remote greaser capable of holding a good supply of grease.  If you really do only have a nipple to use for putting grease in, I think that is really quite unusual.

 

I don't see any such problem with a ball bearing as long as it gets regular squirts of grease. The bearing will not hold much grease. That is unlike the plain bearing and packing etc. of the stern gland.

[MtB]

4 hours ago, Tony Brooks said:

How long have you been boating, because that tends to a classic symptom of a fouled prop, especially with fallen leaves.

 

 

I think you would have been right on the money with this, had it not been the middle of August! 

 

 

[Tony Brooks]

Just now, MtB said:

 

I think you would have been right on the money with this, had it not been the middle of August! 

 

 

 

As I said earlier, it is the wrong time of year for leaves unless there is a local problem killing trees, but unlikely.

[moiuk]

14 hours ago, Alan de Enfield said:

 

Thr pop shaft should have grease applied (pumped in) NOT oil.

 

Have you used grease or oil ?

I used grease (pumped in through the nipple)

[Tracy D'arth]

PRM hydraulic box uses ATF not engine oil.

Its not the gearbox that is loosing you power.

Edited August 17, 2023 by Tracy D'arth

[moiuk]

14 hours ago, alan_fincher said:

 

IMO I don't think it is great to have a stern bearing that doesn't hav a remote greaser capable of holding a good supply of grease.  If you really do only have a nipple to use for putting grease in, I think that is really quite unusual.

The stern gland has a remote greaser, and the bearing which is seperate as a nipple for greasing.

 

14 hours ago, blackrose said:

 

What's all that fluid in the engine spill tray?

It's oil that I haven't cleaned out yet. Been there since I bought the boat, presumably from changing the oil filter. The engine does burn through a bit of oil but not enough for me to consider it leaking as well.

 

13 hours ago, magnetman said:

I have the same gearboxes on the 2  engines on Dulcinea. PRM Delta (now called PRM 150). If the oil goes low the propulsion does become intermittent as the clutch packs don't work properly because they are actuated by a hydraulic circuit. 

 

The oil is not only lube oil it is also needed to actuate the clutches. 

 

 

 

When the issue occurs it struggles to turn the shaft almost to the point of feeling like it's going to stall. And yet reverse can be working. Does this sound like what could happen with this gearbox?  Oil has been replaced and yet it's still happening.

5 minutes ago, Tracy D'arth said:

PRM hydraulic box uses ATF not engine oil.

Its not the gearbox that is loosing you power.

 

What's ATF ?

 

As I said it's just like there is something wrapped around the prop.. maybe loosing power is an unhelpful term, as it looses forward thrust.. in neutral there is plenty of revs, in forward gear it can feel like it's going to stall..  After an hour's rest, everything is back to normal.

[MtB]

15 minutes ago, moiuk said:

 

 

What's ATF ?

 

As I said it's just like there is something wrapped around the prop.. maybe loosing power is an unhelpful term, as it looses forward thrust.. in neutral there is plenty of revs, in forward gear it can feel like it's going to stall..  After an hour's rest, everything is back to normal.

 

ATF = automatic transmission fluid.

 

This sounds more and more like something IS clagging up the blade and overloading the engine. When you engage astern it throws it off, then forward power is restored.

[Chewbacka]

Just a thought.  You said “When the issue occurs it struggles to turn the shaft almost to the point of feeling like it's going to stall.”  This implies that the engine, even with plenty of throttle, is unable to properly turn the gear box, which says to me a lot of friction inside the gear box.  If all the engine power is being absorbed by the gear box I would have thought it would be extremely hot and probably very noisy.  Is it?

[alan_fincher]

19 minutes ago, Tracy D'arth said:

PRM hydraulic box uses ATF not engine oil.

Its not the gearbox that is loosing you power.

 

That's not right, surely?

The PRM hydraulic box uses engine oil.  Some time back PRM started specifying ATF in the manual box, but I'm not aware of them having made that change for the hydraulic one.

[moiuk]

1 minute ago, MtB said:

 

ATF = automatic transmission fluid.

 

This sounds more and more like something IS clagging up the blade and overloading the engine. When you engage astern it throws it off, then forward power is restored.

 

Should I have refilled this gearbox with ATF then? I was told by the previous owner to use the same engine oil (10/40 mineral).

 

I will check the blade again..  consistently happening after an hour or so travelling and then all is clear and working again after an hour or so rest (without me clearing the blade).

[MtB]

Or are you saying when the problem presents, the engine won't go fast in ahead, works fine when you try astern, and then, it still won't rev in ahead if you go back into ahead immediately after using astern? 

[moiuk]

Just now, Chewbacka said:

Just a thought.  You said “When the issue occurs it struggles to turn the shaft almost to the point of feeling like it's going to stall.”  This implies that the engine, even with plenty of throttle, is unable to properly turn the gear box, which says to me a lot of friction inside the gear box.  If all the engine power is being absorbed by the gear box I would have thought it would be extremely hot and probably very noisy.  Is it?

It's not any more noisy than normal. It's hot to the touch when I replaced the oil (after resting for an hour).

2 minutes ago, MtB said:

Or are you saying when the problem presents, the engine won't go fast in ahead, works fine when you try astern, and then, it still won't rev in ahead if you go back into ahead immediately after using astern? 

Correct. I get more thrust in reverse, but this action makes no difference to it struggling to go forward.

I'll try and grab a video of it later this evening which might make it easier to understand what I am saying.

 

One thing I have noticed about this engine/gearbox is that when I increase the throttle there is a delay as this is applied to the forward motion (in normal use). Maybe this is the hydraulic gearbox?? But it's like it builds up to my throttle request as it applies that to forward thrust. Difficult to describe..

[jonathanA]

11 minutes ago, moiuk said:

Should I have refilled this gearbox with ATF then? I was told by the previous owner to use the same engine oil (10/40 mineral).

no !  I think Tracy might have been having a senior moment there.  conventional practice is to use the same oil as the engine oil. 

 

X-posted with TB.

Edited August 17, 2023 by jonathanA
x post

[Tony Brooks]

3 minutes ago, moiuk said:

Should I have refilled this gearbox with ATF then? I was told by the previous owner to use the same engine oil (10/40 mineral).

 

No, you should not. I am not so sure about 10W40, but those boxes use engine oil and if that is what your engine uses it is correct. I would have expected 15W40, but I doubt it will make any difference.

 

It is the PRM mechanical boxes that us ATF.

 

Have you tried it with the fuel filler off?

 

Have you looked to see if the flame plug is flaming all the time the engine is running?

 

You won't get a valid diagnosis if you don't answer the diagnostic questions you are asked - even if you don't think they have any value.

 

have you felt the stern gland when it slows down to assess the heat?

Where is the gearbox oil cooler? I can't see it in the photo or how it is cooled. I understand some tank cooled Betas used the heat exchanger core in the exhaust manifold, and it caused problems for the gearbox because of over hot oil.

 

If your gearbox oil cooler is working properly, I would not expect the box to be more than rather warm to the touch. So, in theory, the extra heat could be caused by a slipping ahead clutch, but then the shaft and boat would slow down, but the engine should stay at more or less the same speed.

 

A delay in fully engaging ahead gear could indicate a slipping ahead clutch. I think that you need to watch the engine and shaft while this is going on so you can judge if the shaft speed and engine speed always stays proportional to each other as   they rev up and down.

 

 

[MtB]

19 minutes ago, moiuk said:

Correct. I get more thrust in reverse, but this action makes no difference to it struggling to go forward.

 

Ok thanks. So plenty of power in astern but hardly any in ahead no matter how many times you switch between the two, but wait an hour and it all fixes itself?

 

This won't be stuff on the blade I don't think. But in fact I can't think of anything capable of causing this behaviour. 

 

Yes a video would be good and might yield clues. And as Tony asks, please go through the thread and answer all the questions. Even if you've satisfied yourself they are not relevant, please tell the board what you found when you checked. 

 

 

 

 

 

[moiuk]

34 minutes ago, Tony Brooks said:

 

No, you should not. I am not so sure about 10W40, but those boxes use engine oil and if that is what your engine uses it is correct. I would have expected 15W40, but I doubt it will make any difference.

 

It is the PRM mechanical boxes that us ATF.

 

Have you tried it with the fuel filler off?

 

Have you looked to see if the flame plug is flaming all the time the engine is running?

 

You won't get a valid diagnosis if you don't answer the diagnostic questions you are asked - even if you don't think they have any value.

 

have you felt the stern gland when it slows down to assess the heat?

Where is the gearbox oil cooler? I can't see it in the photo or how it is cooled. I understand some tank cooled Betas used the heat exchanger core in the exhaust manifold, and it caused problems for the gearbox because of over hot oil.

 

If your gearbox oil cooler is working properly, I would not expect the box to be more than rather warm to the touch. So, in theory, the extra heat could be caused by a slipping ahead clutch, but then the shaft and boat would slow down, but the engine should stay at more or less the same speed.

 

A delay in fully engaging ahead gear could indicate a slipping ahead clutch. I think that you need to watch the engine and shaft while this is going on so you can judge if the shaft speed and engine speed always stays proportional to each other as   they rev up and down.

 

 

My mistake. Yes I used 15/40 mineral.

 

Yes have tried it with the fuel filler off (no difference)

 

Have not yet tried it with the air cleaner off to see how it looks. Can this be when I first start the engine, or when the problem shows itself?

 

Have not yet felt the stern gland when it happens, will do that tonight when I move.

 

I'm not sure what the gearbox oil cooler would look like. With Google it to see if I can figure that out. I will check how hot the gearbox is next time it happens as well 

The engine definitely has a slow down, so it's not just slipping.

 

The engine speed (revs and how it sounds) seems to match the shaft speed. The delay is between applying throttle and the engine speed responding. When in neutral it responds immediately. 

 

I think a video will work better than me using words. Will take a video tonight of it when I first get going and if I go far enough for the problem to occur what it is like when I loose thrust.

 

One other thing I remember is that as I am on the Thames there has been an hour of running it hard, and then the problem shows itself fully  when I stop for a lock. It does offer some slowdown before, but when I stop and then try and put it into forward gear again it struggles to even move forward in tick over. The issue is much worse.

Gearbox cooler.

 

Pipes from the gearbox are connected to the engine cooling pipes (attached to the skin tank).

[Tracy D'arth]

Sorry, brain fade.

[magnetman]

PRM Delta uses ordinary engine lube oil. 

 

It is the smaller mechanical type that use ATF. 

 

 

@moiuk if you stop the engine when this happens can you turn the shaft by hand? 

 

 

 

Of course if the shaft is very hot this might be a bad idea so check temperature. 

 

I wonder if there is an internal problem with the gearbox which can cause it to lock up in forward gear. 

 

A called to PRM NEWAGE might be worthwhile. 

 

Its a PRM Delta / PRM 150

 

 

 

 

 

 

 

[MtB]

1 hour ago, moiuk said:

but when I stop and then try and put it into forward gear again it struggles to even move forward in tick over. The issue is much worse.

 

That's interesting. Would you say the boat goes noticably slower at tickover when the problem is present, than it goes at tickover when it is not present? 

 

Also, I've not noticed if you've said whether the exhaust smokes badly when the problem is present and you put the speed control to MAX. Or if anyone even asked! 

 

And does the engine rev up ok when in neutral? 

 

 

[magnetman]

If the issue is 'much worse' when selecting forward gear it seems to be a gearbox problem or a badly fouled prop which has not been correctly checked.  

 

 

 

 

 

From this 2020 thread apparently the man to talk to at PRM NEWAGE is (was in 2020) a gentleman called Andy. Good name. 

 

Same gearbox in that thread. 

 

 

Some lovely photos of the innards in this thread 

 

 

This was an interesting picture from Richard  @RLWP Primrose engineering)

 

[img]http://www.primrose-engineering.co.uk/wp-content/uploads/balls.jpg[/img]

[BWM]

I suspect it is either the plumber block (bearing), or more likely, the packing or stern bearing - the latter, if worn can sometimes trap debris or stray bits of packing.