Knocking sound in BMC 1.8

[velox]

Does anyone have a good guess of what could be making this sound on my BMC 1.8? Could it be loose timing chain, something with pistons, or something else? The sound is louder on the left side of the engine, maybe at the front but I'm not quite sure.

 

I just recently had fuel pump renewed, as it had leaked diesel into the oil during the winter. This sound probably has nothing to do with this, but it appeared at the same time.  

 

Edited June 28, 2020 by velox

[Bee]

Have to say it doesn't sound good.  Have you got an oil pressure gauge ? does that noise speed up if you increase the engine speed?  Luckily its not a hard engine to  work on but  I would suspect a big end. Others will be more knowlegable so fingers crossed.

[velox]

Oil pressure is very good, no problems with that. When increasing engine speed, the noise speeds up as well, and when running at around 2000rpm it isn't at least heard as clearly.  

 

 

[Guest]

10 minutes ago, Bee said:

Have to say it doesn't sound good.  Have you got an oil pressure gauge ? does that noise speed up if you increase the engine speed?  Luckily its not a hard engine to  work on but  I would suspect a big end. Others will be more knowlegable so fingers crossed.

A big end would IMHO create a much 'denser' harder knocking sound than that.

 

Have you had a piece of wood and your ear on the block to try and identify the cylinder it might be coming from?

 

You really need @Tony Brooks to have a listen to your vid.

Edited June 28, 2020 by The Happy Nomad

[Alan de Enfield]

Just now, velox said:

Oil pressure is very good, no problems with that. When increasing engine speed, the noise speeds up as well, and when running at around 2000rpm it isn't at least heard as clearly.  

 

 

 

Get a long handled screwdriver, mooring pin or similar.

 

Put one end (handle  end of screwdriver) into your ear (push fairly hard against your ear/skull.

Put the other end on the running engine (be careful of rotating parts, belts etc)

move the 'point' elsewhere on the engine, keep trying until you can FEEL the vibrations in your ear - at the 'loudest' (most vibrations) that is the point where the rattle is coming from.

[zenataomm]

Probably my cheapo speakers, but it sounded more like a 'sucking/chuffing' sound as if you've got an exhaust valve stuck.

If you remove the oil filler on the top and place your hand over it, how much blow by is there?

[Alan de Enfield]

Sounded louder when you were around the pulley - is the bearing OK / wobbly / oil leak ?

Edited June 28, 2020 by Alan de Enfield

[Man 'o Kent]

My first thought too was "big end"  but given a good oil pressure that would seem, while not impossible, unlikely.

 

You say that the fuel pump has been replaced and that noise does sound a bit "cammy" so I'm suspecting it might be something to do with the new fuel pump, It may be the pump itself, something to do with the way it was fitted or something that was disturbed during the process.

 

The point is that things were working "normally", (other than the leak), before the work was done so something to do with the change has to be the prime suspect.

 

Given that the biggest thing that you should put in your ear is your elbow might I suggest that for the screwdriver trick to work best you place the handle just foreward of your ear on the bone where your lower jaw hinges. The sound will transmit very well through the bone to your ear.

[ditchcrawler]

Aren't they fitted with a rubber pulley thing at the front. Looking and listening again are you sure that V belt is OK

 

[Tony Brooks]

It does not sound like a big end to me and it seems more distinct as the camera moves to the lift pump area. St first I thought the same as @zenataomm but as you get to the lift pump area it sounds more metallic. Its definitely worth checking the valve clearances just in case one has opened up but it does not sound quiet like that.

 

Unless the mechanic took trouble to fit the lift pump lever on the correct side of the cam it could well be a damaged lift pump - especially if the noise started immediately after the new pump was fitted. A typical narrow-boat can probably supply fuel to the injector pump transfer pump by gravity and I don't think fitting the lever on the wrong side of the cam would not prevent the priming lever operating. Before doing anything else check all the engine mounts are secure on the beds and also the fixing to the feet are tight with special attention to the left hand side. As its a 1.8 I can't see it being the very old rear top hat engaging mount bolts tapping on the bed because it should have a different flywheel housing.

 

After checking the mounts and what others have suggested I think I would make sure the two cam follower/side covers are square on the block and tight. Then check the valve clearances and finally take the lift pump off and see if the operating lever is bent out of shape. When refitting the lever needs to be carefully slid up the inside of the block side so it end sup between the camshaft and the block. Its all too easy to get it on the other side of the cam. When in the correct place it will not sit snug on the block but will do if you push it BY HAND against the block. If you need to force it against the block by the mounting nuts then the lever is on the wrong side of the can and you have probably cost yourself a new pump.

 

[magnetman]

I recently (two weeks ago) had a heavy knock on one of my pair of BMC 1.5D engines and after advice from Tony Dunkley on thunderboat forum I checked the tappets and it turned out several of them had huge clearances. Set them all at 15 thou and it's lost the knock. 

 

It was really loud I was well bothered by it. 

 

Not sure why they were loose but it had developed over time since I bought the boat nd I've only had the engine for about 200 hours. I think a previous adjustment left the nuts a bit loose. 

 

A bit odd. 

 

The reason for the knocking noise was that one cylinder was doing most of the work therefore labouring somewhat. 

 

Edited June 29, 2020 by magnetman
Double post error

[Alan de Enfield]

1 minute ago, magnetman said:

I recently (two weeks ago) had a heavy knock on one of my pair of BMC 1.5D engines and after advice from Tony Dunkley on thunderboat forum I checked the tappets and it turned out several of them had huge clearances. Set them all at 15 thou and it's lost the knock. 

 

It was really loud I was well bothered by it. 

 

Not sure why they were loose but it had developed over time since I bought the boat nd I've only had the engine for about 200 hours. I think a previous adjustment left the nuts a bit loose. 

 

A bit odd. 

 

The reason for the knocking noise was that one cylinder was doing most of the work therefore labouring somewhat. 

I recently (two weeks ago) had a heavy knock on one of my pair of BMC 1.5D engines and after advice from Tony Dunkley on thunderboat forum I checked the tappets and it turned out several of them had huge clearances. Set them all at 15 thou and it's lost the knock. 

 

It was really loud I was well bothered by it. 

 

Not sure why they were loose but it had developed over time since I bought the boat nd I've only had the engine for about 200 hours. I think a previous adjustment left the nuts a bit loose. 

 

A bit odd. 

 

The reason for the knocking noise was that one cylinder was doing most of the work therefore labouring somewhat. 

 

Did you post it twice because both engines were affected ?

[magnetman]

Phone error. Just the starboard unit.

[Slim]

Did the knocking appear immediatley after the lift pump was replaced? The first thing I would do is take the pump off and check for damage. 

[Tracy D'arth]

It sounds to be at camshaft speed so fuel lift pump [could the wrong part have been fitted?] or tappet block breaking up. Check the pump and tappet clearances first.

 

TD'

Edited June 29, 2020 by Tracy D'arth

[velox]

Thanks for many good suggestions! I came to my boat to inspect more, but will not start it now as it appears that there is again plenty of diesel in oil! The oil level has risen quite a lot from where I filled it yesterday, and oil viscosity seems to be very thin. Maybe there is also some other leak in addition to injection pump (which had definitely previously leaked, and should not leak now). Could this also explain the noise? 

 

Just to clarify: the previous problem I had was with injection pump, not the fuel lift pump, which also has been replaced couple of years ago.

 

 

 

 

 

[Bod]

Have you changed the oil/diesel mix in the sump, before running the engine for the above film?

You may have a fuel leak into the sump, should this become overfull then this mix, can be taken up into the cylinders, where it will cause a run-away situation.  The engine then runs extremely fast to destruction!!(and no, switching off the engine will have no effect.)

 

Bod.

[bizzard]

Check the lift pump, they're quite famous for dumping fuel into the sump when the diaphram gets perferated. Probably leaking a bit externally too from the wee hole underneath.

[bizzard]

Although they had petrol engines, the old Vauxhall Velox's had lift pump trouble too and they suffered from the odd broken valve spring, something else worth checking.

 Don't run the engine anymore until you've at least got the oil level down or fixed the trouble and changed the oil.

Edited June 29, 2020 by bizzard

[Tony Brooks]

52 minutes ago, velox said:

Thanks for many good suggestions! I came to my boat to inspect more, but will not start it now as it appears that there is again plenty of diesel in oil! The oil level has risen quite a lot from where I filled it yesterday, and oil viscosity seems to be very thin. Maybe there is also some other leak in addition to injection pump (which had definitely previously leaked, and should not leak now). Could this also explain the noise? 

 

Just to clarify: the previous problem I had was with injection pump, not the fuel lift pump, which also has been replaced couple of years ago.

 

 

Now you tell us. As Biz says it may well be a split lift pump diaphragm but I can't link that noise to the lift pump unless its falling apart but they should not fall apart in two years or so. Again why   a diaphragm fail after only two years unless it was not pulled fully downwards before tightening the body screws.

 

If its is a leaking lift pump gravity would keep it leaking 24/7 and not just when its running.