Mysterious noise from my JP - any ideas?

[starman]

About three months ago my JP3M suddenly started making a heart stopping clattering noise while running quite hard. The sort of noise that makes you think something 'orrible has happened. But there were no other symptoms; no oil pressure or temperature issues, no rod hanging out of block, no clouds of smoke or steam and, once I cautiously tried the engine again it ran perfectly.

And has continued to do so until a couple of days ago when exactly the same thing happened. Again, I couldn't see anything amiss, the engine continued to run fine (and still does), nothing seemed to be loose or broken.

 

It's an odd noise too: more a metallic clattering that sounds like something has come adrift and is rattling about outside the engine rather than a deep internal sound.

 

The only other clue is that Starwoman thinks she saw smoke either coming from or near the intake 'silencer' as they call it in the Lister book. She can't be sure as she was at the other end of the boat when the noise started.

 

It's a real mystery - anyone got any thoughts?

[RLWP]

Time to do the listening stick trick to see if you can isolate whereabouts and which cylinder this noise is coming from

 

Richard

[Bobbybass]

Yup..

 

A bit of old pipe or similar...carefully held (out of way of moving parts)...so you can listen to different areas..

[RLWP]

I prefer a solid stick - bit of dowel or a screwdriver. Put the end onto the bit you want to hear and the other against your head somewhere near your ear

 

Richard

[bigste]

Drive plate?

[RLWP]

Drive plate?

 

You fancy speculating? How about piston rings, valve spring, loose valve seat, loose piston crown....

 

Best to do the listening and find out first

 

Richard

 

If his JP3M has a Blackstone box, it won't have a driveplate

[Timleech]

If there was any loss of power, and the clattering was in sync with the engine speed, I'd suspect a sticking valve.

 

Otherwise, definitely spend time trying to identify the general area on the engine.

 

Tim

[by'eck]

Had an unusual sound from my JP2M the other day which has since disappeared.

 

A few seconds after starting (only from cold) I heard a light but very noticeable metallic sound as though something was flailing loose in crankcase and hitting the inside. Frequency was seemingly half crankshaft speed and it disappeared within 10 seconds. Oil pressure was rising as normal. It did this three mornings in a row then stopped and hasn't done it since despite several cold starts.

 

I guess a stuck valve may have been the cause and would explain the frequency. COV valves had been used recently since doing river work, so maybe dislodged carbon?

[mattlad]

If there was any loss of power, and the clattering was in sync with the engine speed, I'd suspect a sticking valve.

 

 

Tim

That's my suspicion too. We had the same thing happen on the RN many years ago.

[starman]

 

You fancy speculating? How about piston rings, valve spring, loose valve seat, loose piston crown....

 

Best to do the listening and find out first

 

Richard

 

If his JP3M has a Blackstone box, it won't have a driveplate

I will keep a listening stick handy but as I said the bizarre thing is the noise sounds very loud but has only happened twice in three months, the engine ran fine even when noisy, the noise stopped after a while and the engine continues to be fine now. Some major mechanical event would surely show ongoing symptoms. Or would it?

[RLWP]

It isn't some other bonkers thing, like a pair of mooring hooks hanging up in the engine room banging together?

 

Richard

[starman]

It isn't some other bonkers thing, like a pair of mooring hooks hanging up in the engine room banging together?

Richard

I keep thinking it must be something like that or something clattering around between flywheel and guard but damned if I can find it. Maybe it will just have to be put down as 'one of those things' until....

[bizzard]

Perhaps starter motor loose or its pinion worn or loose and is pinging on the ring gear as the engine runs, (not let go properly after starting). If ring gear is shrunk on it may have shifted. Have had these things happen on a few vehicles over the years.

[martyn 1]

Very much a case of speculation without a closer inspection to narrow down where the noise in coming from but as Tim has mentioned before a good possibility would be a sticking valve (may only be momentary due to some dislodged carbon). Sounds like this may be likely if the smoke coming from the intake observation is accurate. You will need to narrow down where it is coming from a bit more for the folks here to help in more detail.

 

One other but possibly unlikely thing is a loose flywheel. I had one a few years ago that sounded awful on and off and that turned out to be the flywheel bound up on the key and not fully on its taper.

[starman]

Very much a case of speculation without a closer inspection to narrow down where the noise in coming from but as Tim has mentioned before a good possibility would be a sticking valve (may only be momentary due to some dislodged carbon). Sounds like this may be likely if the smoke coming from the intake observation is accurate. You will need to narrow down where it is coming from a bit more for the folks here to help in more detail.

 

One other but possibly unlikely thing is a loose flywheel. I had one a few years ago that sounded awful on and off and that turned out to be the flywheel bound up on the key and not fully on its taper.

If a sticking valve the noise would be what - extra large tappet clearance, valve hitting piston? Hopefully the former!

Will dig my tools out and check the flywheel now - the thought of it coming off has made me go weak at the knees.

[martyn 1]

If a sticking valve the noise would be what - extra large tappet clearance, valve hitting piston? Hopefully the former!

Will dig my tools out and check the flywheel now - the thought of it coming off has made me go weak at the knees.

With the setup a JP has its more likely to be an excessive clearance type noise if its just carbon holding the valve off its seat. But it wouldn't be the first time I have seen valve shaped imprints in the top of JP pistons...... Although I will add with that comment that its normally been on engines where the valve has partially seized into the guide not due to a bit of carbon.

 

As I said, it's not likely the flywheel is loose but worth a quick check as it took me bl£$dy ages to figure out what was causing the noise on the one I was having problems with.

Edited June 3, 2014 by martyn 1

[George94]

I had a terrible noise from my engine a couple of years ago, and immediately stopped it fearing the worst - a broken crankshaft. As this was on the tidal Thames, it was a bit hairy. Obviously the anchor was deployed.

 

The cause was a tappet where the rod had separated from the disk which touches the cam-shaft. No damage done, and a new tappet solved the problem.

[RLWP]

I had a terrible noise from my engine a couple of years ago, and immediately stopped it fearing the worst - a broken crankshaft. As this was on the tidal Thames, it was a bit hairy. Obviously the anchor was deployed.

 

The cause was a tappet where the rod had separated from the disk which touches the cam-shaft. No damage done, and a new tappet solved the problem.

Scary!

 

Richard

[monkeyhanger]

About three months ago my JP3M suddenly started making a heart stopping clattering noise while running quite hard. The sort of noise that makes you think something 'orrible has happened. But there were no other symptoms; no oil pressure or temperature issues, no rod hanging out of block, no clouds of smoke or steam and, once I cautiously tried the engine again it ran perfectly.

And has continued to do so until a couple of days ago when exactly the same thing happened. Again, I couldn't see anything amiss, the engine continued to run fine (and still does), nothing seemed to be loose or broken.

 

It's an odd noise too: more a metallic clattering that sounds like something has come adrift and is rattling about outside the engine rather than a deep internal sound.

 

The only other clue is that Starwoman thinks she saw smoke either coming from or near the intake 'silencer' as they call it in the Lister book. She can't be sure as she was at the other end of the boat when the noise started.

 

It's a real mystery - anyone got any thoughts?

If it's a regular ticking noise, it could be the valves in your water pump. Mine do that from time to time, with no indication of why, or when for that matter. Get your crew to have a listen (Using a screwdriver or something similar) as you gradually increase the revs, to the point when it begins to be heard It could very well be the washer type valves hitting their seats.

[monkeyhanger]

About three months ago my JP3M suddenly started making a heart stopping clattering noise while running quite hard. The sort of noise that makes you think something 'orrible has happened. But there were no other symptoms; no oil pressure or temperature issues, no rod hanging out of block, no clouds of smoke or steam and, once I cautiously tried the engine again it ran perfectly.

And has continued to do so until a couple of days ago when exactly the same thing happened. Again, I couldn't see anything amiss, the engine continued to run fine (and still does), nothing seemed to be loose or broken.

 

It's an odd noise too: more a metallic clattering that sounds like something has come adrift and is rattling about outside the engine rather than a deep internal sound.

 

The only other clue is that Starwoman thinks she saw smoke either coming from or near the intake 'silencer' as they call it in the Lister book. She can't be sure as she was at the other end of the boat when the noise started.

 

It's a real mystery - anyone got any thoughts?

Have you identified where the noise is coming from yet? I assume that with no more posts, everything is OK now. I'd be interested to know the solution to the problem.

[Bee]

Personally I would think sticking valve. If smoke has puffed from the air intake it has probably got there from a badly seating valve or sticking valve stem. If the valve is not snapping back with the valve spring it could be the push rod clattering around when the camshaft rotates. I am not familiar with the JP engines but that would be my guess.

Edited August 29, 2014 by Bee

[starman]

Have you identified where the noise is coming from yet? I assume that with no more posts, everything is OK now. I'd be interested to know the solution to the problem.

Funnily enough the noise re-occurred yesterday for the first time in months.

I've absolutely no idea what it is despite trying (in vain) to track the source with a listening stick.

Again it happened when running quite hard. It seems to fade away of its own accord so maybe it is a bit of carbon temporarily sticking a valve.

[monkeyhanger]

Funnily enough the noise re-occurred yesterday for the first time in months.

I've absolutely no idea what it is despite trying (in vain) to track the source with a listening stick.

Again it happened when running quite hard. It seems to fade away of its own accord so maybe it is a bit of carbon temporarily sticking a valve.

Without actually hearing it, of course, from what you've said I'd still put money on it being the valves in your water pump.Therefore nothing to worry about.(we hope!)

[starman]

Without actually hearing it, of course, from what you've said I'd still put money on it being the valves in your water pump.Therefore nothing to worry about.(we hope!)

What makes you say that? What are they doing?

[monkeyhanger]

What makes you say that? What are they doing?

There are two copper discs,each a bit bigger than the size of a 2p coin, if my memory serves me correctly, which are held in position by weak-ish springs. These are the valves which open and close as the piston in your water pump goes up and down. I have a JP2 in my boat, and every now and again I get this tapping noise from the engine room, which I'm pretty certain is coming from these valves hitting their seats. Of course, when you're steering the boat, it's not the easiest thing to duck into the engine 'ole at the merest whim to have a listen. This noise can happen at any time and under any operating condition but more often when running hard. On my engine, I have blanked off the bilge pump part of my water pump, and I've often wondered if it's this that is causing the pump to make this noise, by causing extra suction on that part of the pump. It scared the hell out of me when I first heard it, but after 20 years of hearing it on and off, I'm a bit blase about it now. Of course, if I'm wrong.....................Can anyone help me? I've got a strange knocking noise coming from my engine.........

Edited August 30, 2014 by monkeyhanger