Yanmar shuddering when put in gear

Sea Change

Sea Change

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I've got a 4JH5E, shaft drive, fixed prop, with about 1200 hours on it.
It generally behaves impeccably but there is one problem that I'd like to get to the bottom of. When I put it in gear, I need to wait a few seconds before I put any revs on, otherwise I get an awful shuddering, banging, with the engine jumping around on its mounts.
When it first happened I was pretty alarmed and assumed that we had a bad engine mount, however testing it with revs on but not in great shows no problem. And if I wait a few seconds in idle after engaging gear, I can then up the revs without any trouble.

Any suggestions?
 
This is one area that I accept that hand must dip into pocket ... I get the yard engine guy to check it out ...

If its something not quite aligned properly - that initial in gear then pulls it into alignment - that will only get worse ... IMHO.
 
noelex said:
If the engine mounts are fine a defective damper plate is one possibility.
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This does seem to fit the bill.
With the engine not in great, I can change throttle as much as I like without replicating the problem, so I don't think it's the mounts.
 
Sea Change said:
This does seem to fit the bill.
With the engine not in great, I can change throttle as much as I like without replicating the problem, so I don't think it's the mounts.
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mmmmm my 4-99 Perkins had one of its mounts fail ... I could start engine and rev it fine ... nothing appeared wrong ... put it into gear and all hell was banging away down there.

Until real torque is put onto the setup ......

Just saying.
 
Refueler said:
mmmmm my 4-99 Perkins had one of its mounts fail ... I could start engine and rev it fine ... nothing appeared wrong ... put it into gear and all hell was banging away down there.

Until real torque is put onto the setup ......

Just saying.
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Interesting. I have had a cursory look at the mounts and couldn't see anything wrong, but it's not really that easy to tell and the access could be better.
 
Sea Change said:
Interesting. I have had a cursory look at the mounts and couldn't see anything wrong, but it's not really that easy to tell and the access could be better.
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OK .. I know ...

The original installer used Petter mounts for the 4-99 - totally inadequate ... but anyway - the mounts looked fine visually - it was when Alan (Diesel yard guy) put a bar under the engine and lifted - the centre bolt was broken out of the mount body.

Its why I suggest that maybe better to just get the engineer in and sort ?
 
Refueler said:
OK .. I know ...

The original installer used Petter mounts for the 4-99 - totally inadequate ... but anyway - the mounts looked fine visually - it was when Alan (Diesel yard guy) put a bar under the engine and lifted - the centre bolt was broken out of the mount body.

Its why I suggest that maybe better to just get the engineer in and sort ?
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The boat is in the USA where semi skilled yard labour starts at $100/hr... calling somebody in will be something of a last resort!
 
Lets be honest .. it could be something simple or it could be something a lot more.

Passing Folly Inn one time with that boat - I picked up a bit of net ... it was if the whole transom was breaking up .. the juddering and noise was something else. Alongside at Newport - tide out - there it was ... a quick flick with boat hook and it fell off .. but no amount of reverse / fwd engine removed it.
 
First mate has just reminded me that there seems to be a bit of a temperature effect here- if the engine has had time to warm up it behaves a bit better. And when the ambient temperature is higher, it seems happier too. Which intuitively makes me think it might be inside the gearbox, and related to oil temperature.

I've split a box from an engine before, to replace an oil seal, so I'm not too daunted by the thought of replacing the drive plate.
 
Neeves said:
Something attached to the prop, poly bags, bit of rope - but I'd assume you have already had a look.

Jonathan
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Or a damaged prop

You don't say that you have had a look (at the prop). Your description is identical to a common problem in HK, rubbish caught on the prop. When racing the youngest adult crew member was given the task of checking the prop prior to a race start, was it clean, was if folded properly (I know your prop is fixed).
 
Refueler said:
Lets be honest .. it could be something simple or it could be something a lot more.

Passing Folly Inn one time with that boat - I picked up a bit of net ... it was if the whole transom was breaking up .. the juddering and noise was something else. Alongside at Newport - tide out - there it was ... a quick flick with boat hook and it fell off .. but no amount of reverse / fwd engine removed it.
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I can categorically rule this out. It's been behaving like this ever since we launched, and I've dived under the boat almost daily in clear water since then. I'd have noticed if there was something in the prop!
 
Sea Change said:
I can categorically rule this out. It's been behaving like this ever since we launched, and I've dived under the boat almost daily in clear water since then. I'd have noticed if there was something in the prop!
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It was more a comment genmerally - not directed to you.

I have a 'Fishing camera' and also various such as GoPro I can submerge to look under the boat ...
 
Ah, been here, done that. I had exactly those symptoms. I have a 4JH. You can be pretty confident that it is the cone clutches failing. Sorry, it’s not good news. I replaced the gearbox with a new one because it wasn’t much more expensive than the rebuild cost and much quicker. I was fortunate to find a new old stock gearbox on the shelf which I bought for about £1,500, that was very lucky.

I am fortunate to have an excellent engineer on site, he diagnosed it in a flash after I’d spent months trying to understand what was going on. It is caused, commonly, by poorly adjusted gearbox control linkage which causes the cone clutches to be held very slightly open at all times. Failure is only a matter of time.
 
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