I need you ears. Slight Knocking sound on engine

[Mrtoast]

Hi guys.

 

So i finally replaced the cylinder head, injectors, plugs etc. All seems to be great but after a run this weekend i have this low knocking vibration coming from the engine. I'd say its getting worse. LPWs2. I've done a little video

 

any ideas?

 

Cheers

Chris

It's only when it's under load as well.

[billS]

Ssimilar symptoms on my engine turned out to be due to a worn driveplate.

[Mrtoast]

Jesus. That sounds like an engine out job.

[Alan de Enfield]

I've never heard an LPWS2 run so maybe not the right person to comment - but - if my LPWS4 sounded 1/4 that bad I'd be worrying.

 

It sounds a lot worse and more 'rattley' than an old petter dumper I had.

 

Edit - how can I make so many mistakes in so few words

Edited May 19, 2014 by Alan de Enfield

[Mrtoast]

I've never heard an LPWS2 run so maybe not the right person to comment - but - if my LPWS4 sounded 1/4 that bad I'd be worrying.

 

It sounds a lot worse and more 'rattley' than an old petter dumper I had.

 

Edit - how can I make so many mistakes in so few words

Sick off worrying! You know that feeling when you buy something but have nothing but problems! Grrrr

[Alan de Enfield]

I guess most of us have bought something thats been nothing but trouble so can sympathise.

 

If I may suggest getting 'someone' to look at it before running it anymore.

 

A poorly engine won't get better by using it.

[Mrtoast]

Yeah going to get someone to look at it. I will get out on me boat eventually.

[RLWP]

I would do a compression test ASAP

 

Richard

[Mrtoast]

What do you suspect Richard?

[RLWP]

It could be a couple of things. One is something to do with the hydraulic tappets allowing the valves to clout the piston, which isn't nice

 

I have an LPWS4 here that made a nasty noise like that, one of the crank journals is very worn (4mm undersize)

 

A compression test should quickly tell you a lot of things

 

Richard

[Mrtoast]

Not sure i know someone with a compression tester. Will see. This problem only shown after the head was put on. Hoping it's nothing lower down the engine.

[bizzard]

Not sure i know someone with a compression tester. Will see. This problem only shown after the head was put on. Hoping it's nothing lower down the engine.

Those engines are a bit rattly when done a few hours anyway. It sounds to be running on both cylinders ok though and I'd say compressions aren't bad especially if it starts easily from cold? The rattle is quite a light sounding rattle, so I'd say top end, possibly a lazy, slack or stuck hydraulic valve lifter, could possibly be a valve head tapping on a piston head but mmm a valve has not been bent I don't think as it seems to be running on both pots quite well although a bit erratically. First I'd take the valve covers off and check for any too slack valve clearance and for any broken valve spring.

[RLWP]

The valves strike the piston quite squarely, so instead of bending them they bend the pushrod, and the rocker, and even fracture the rocker

 

Richard

[MtB]

I note the OP says the sound started after replacement of the cylinder heads.

 

If a thinner than correct head gasket was used, especially with tappet gaps too small, could this allow a valve to kiss the piston leading to the racket?

 

Who refitted the heads?

 

MtB

[Mrtoast]

Those engines are a bit rattly when done a few hours anyway. It sounds to be running on both cylinders ok though and I'd say compressions aren't bad especially if it starts easily from cold? The rattle is quite a light sounding rattle, so I'd say top end, possibly a lazy, slack or stuck hydraulic valve lifter, could possibly be a valve head tapping on a piston head but mmm a valve has not been bent I don't think as it seems to be running on both pots quite well although a bit erratically. First I'd take the valve covers off and check for any too slack valve clearance and for any broken valve spring.

 

I have only ran it to do that video today. The problem has gradually got worse. It started more on higher revs in gear and now in low revs in gear. It's defiantly lacking in power (but that was put down to fuel). Engine sounds great out of gear. Nothing to do with mounts?

Oh starts on the button after a few seconds of plug.

[bizzard]

 

I have only ran it to do that video today. The problem has gradually got worse. It started more on higher revs in gear and now in low revs in gear. It's defiantly lacking in power (but that was put down to fuel). Engine sounds great out of gear. Nothing to do with mounts?

Oh starts on the button after a few seconds of plug.

Is your oil pressure ok? If its too low the valve clearances will increase willy nilly.

[Mickj]

when you stopped the engine and the revs dropped it sounded like you may have an injector blowing

[Mrtoast]

ah, ok maybe i forgot to mention a little issue that went on also. (sorry for the can of worms) When the head got put back on oil replaced to what the manual said. Had the engine running for about 2 hours at the moorings. Everything fine. Taken the boat out for a 2 hour cruise and had oil leak coming from front of the engine sprayed up alternator belt. In the morning i checked the oil level and he read bone dry. So i put another litre and half in and limped back to the moorings. Now I haven't lost any oil since (after running with cardboard underneath to check) and probably done another 12 hours on it.

 

I also have just found slight bubbles coming from one of the injectors. (bottom, near threads)

 

Yup, it's all fun fun fun!

[bizzard]

ah, ok maybe i forgot to mention a little issue that went on also. (sorry for the can of worms) When the head got put back on oil replaced to what the manual said. Had the engine running for about 2 hours at the moorings. Everything fine. Taken the boat out for a 2 hour cruise and had oil leak coming from front of the engine sprayed up alternator belt. In the morning i checked the oil level and he read bone dry. So i put another litre and half in and limped back to the moorings. Now I haven't lost any oil since (after running with cardboard underneath to check) and probably done another 12 hours on it.

 

I also have just found slight bubbles coming from one of the injectors. (bottom, near threads)

 

Yup, it's all fun fun fun!

There must have still been enough oil in it or the valve gear would have slackened off through no oil pressure and stopped the engine and possibly knocked the engine out completely too. What oil pressure indicator have you? Warning light or gauge.

[Mrtoast]

Warning light.

Seems to be fine though.

[bizzard]

Warning light.

Seems to be fine though.

Ok. A little basic rough and ready test of the oil pressure, but first I'd have those valve covers off to check all is well there. However run the engine up to normal running temp. Stop engine leaving ignition key switch switched on. Now the engines oil pressure should take a few seconds to fall to zero if the engines in good nick after being stopped therefore the light should also remain off until the pressure has dropped down to something like 7-10 lb sq'' or so and then come on. If the light comes on the very instant the engine stops, I'd say you have too low oil pressure. But of course your oil pressure sender might be a little lazy, but the test should give you a rough idea to oil pressure. Low or very low oil pressure can be caused by many things, faulty oil pressure relief valve, worn oil pump, worn engine main and big end bearings ect.

Incidentally you might be able to locate the noises with a listening stick plonked onto various parts of the engine with the other end jambed into your ear whilst engines running.

Edited May 19, 2014 by bizzard

[Paul's Nulife4-2]

Could it warrant the time to Try a 'Bump Test' Cylinder Clearance, & look @ the Lift rods ?.

Did you say it only happens under load ?.

It obviously starts and stops ok,

To be fair it needs looking at in person, sack of spanners and a cuppa maybe a Donut or two.

Edited May 19, 2014 by Paul's Nulife4-2

[Mrtoast]

Yeah starts and stops fine. I ran the engine for a few mins to check the oil light. Turned it of and waited a good ten seconds for it to go off.

Yeah agree needs someone in the know!