JP3M Starting Handle Clutch , How Does It Work? Any Photos of One in Bits?

[PrimusStove]

Hi ,

 

I’m trying to understand exactly how the starting‑handle clutch system works on a Lister JP3M. Mine is currently not working and wont engage, before I start stripping anything down I’d really appreciate a clearer idea of what’s inside and how the mechanism actually engages/disengages.

Does anyone have:

• A description of how the clutch is supposed to operate?

• Photos of the assembly in pieces?

• Any tips on common failure points or things to watch out for when dismantling it?

I’ve searched around but can’t find a good breakdown of the mechanism itself. Any guidance or pictures would be hugely appreciated.

Thanks in advance

Edited March 18 by PrimusStove
spelling

[Tonka]

42 minutes ago, PrimusStove said:

Hi ,

 

I’m trying to understand exactly how the starting‑handle clutch system works on a Lister JP3M. Mine is currently not working and wont engage, before I start stripping anything down I’d really appreciate a clearer idea of what’s inside and how the mechanism actually engages/disengages.

Does anyone have:

• A description of how the clutch is supposed to operate?

• Photos of the assembly in pieces?

• Any tips on common failure points or things to watch out for when dismantling it?

I’ve searched around but can’t find a good breakdown of the mechanism itself. Any guidance or pictures would be hugely appreciated.

Thanks in advance

Is this the rachet affair that connects the chain to the crankshaft. If so I would have thought it would be similar to any handstart engine so you may have more chance of finding a drawing

[PrimusStove]

Hi Tonka , it is that bit , the trouble is as with any boat its really difficult to access and from what I can see , its looks to be tucked up behind the fly wheel and the only way to remove the fly wheel would be to remove the engine , which would  be a major problem, I'm kind of hoping that a good soak with WD would free it up but as far as I can tell the hand start has never worked since the engine was put in the boat in the 80's, as you say I will have a look around for images from other engines. Cheers 

[David Mack]

From memory, there are pawls fitted to the back face of the flywheel, with springs to hold them against a rachet wheel attached to the sprocket which is chain driven from the overhead starting handle shaft. So when you turn the starting handle the pawls are engaged and rotate the crankshaft.

When the engine is running, centrifugal force throws the pawls out of engagement with the rachet wheel (but as the engine slows to a stop, the springs overcome the centrifugal force, which is why you sometimes hear them clicking as a hand start engine comes to a stop).

Most likely reasons it is not working (assuming the mechanismi is complete) are either that the springs are broken, or that the pawls no longer rotate freely on their shafts. WD40 might address the latter problem.

 

[Tonka]

20 minutes ago, PrimusStove said:

Hi Tonka , it is that bit , the trouble is as with any boat its really difficult to access and from what I can see , its looks to be tucked up behind the fly wheel and the only way to remove the fly wheel would be to remove the engine , which would  be a major problem, I'm kind of hoping that a good soak with WD would free it up but as far as I can tell the hand start has never worked since the engine was put in the boat in the 80's, as you say I will have a look around for images from other engines. Cheers 

On a Beta BD3 there are grease nipples which would then make sure grease gets into the inner workings. It's on the opposite end of the engine so not behind the fly wheel

[David Mack]

Thought I might have something on the laptop! Here are two pages from the JP2/3M manual showing the hand start arrangement.

[PrimusStove]

than you David , that's brilliant.

[PrimusStove]

Just a quick update....My brother gave the mechanism a good soaking of WD and swears he heard a click when turning the engine over via the fly wheel... further soakings of WD to follow with fingers crossed, but seen as we are currently changing out the liners at present we have removed the starting handle shaft and wont know if the WD has really done the trick.

[Tony Brooks]

5 minutes ago, PrimusStove said:

Just a quick update....My brother gave the mechanism a good soaking of WD and swears he heard a click when turning the engine over via the fly wheel... further soakings of WD to follow with fingers crossed, but seen as we are currently changing out the liners at present we have removed the starting handle shaft and wont know if the WD has really done the trick.

 

WD40 is not a penetrating oil. It is a water disperser. Try Plusgas or another proper penetrating oil.

[PrimusStove]

Just now, Tony Brooks said:

 

WD40 is not a penetrating oil. It is a water disperser. Try Plusgas or another proper penetrating oil.

I will give Plusgas a go Tony , Thanks