Jump to content
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble
Strawberry Orange Banana Lime Leaf Slate Sky Blueberry Grape Watermelon Chocolate Marble

Featured Posts

3 minutes ago, GrahamSop said:

 

Is it worth trying a bit of injector cleaning additive in the diesel, if only to see if it changes the knock?

Yes

  • Greenie 1

Share this post


Link to post
Share on other sites

Just a thought or two, and a bit late into this; 
A few years ago I picked up some diesel from a boatyard, and during that tank full the engine was noisier (diesel knock) and gave a different smell from the exhaust (not very technical, I know.) On filling up with fresh diesel form elsewhere, normal service was resumed.

Another time my (Vetus) engine sounded like a bag of spanners was when i lowered it 5mm for a new gearbox.The casting around the starter was touching the engine bearer. Have the engine mounts sagged? 
Have you checked the alignment on this engine/propshaft and what kind of stern gland is it? Those Vetus ones can make a noise when the alignment is out, and the shaft taps against the stern tube.

Share this post


Link to post
Share on other sites
10 minutes ago, catweasel said:

Just a thought or two, and a bit late into this; 
A few years ago I picked up some diesel from a boatyard, and during that tank full the engine was noisier (diesel knock) and gave a different smell from the exhaust (not very technical, I know.) On filling up with fresh diesel form elsewhere, normal service was resumed.

Another time my (Vetus) engine sounded like a bag of spanners was when i lowered it 5mm for a new gearbox.The casting around the starter was touching the engine bearer. Have the engine mounts sagged? 
Have you checked the alignment on this engine/propshaft and what kind of stern gland is it? Those Vetus ones can make a noise when the alignment is out, and the shaft taps against the stern tube.

Thanks catweasel, I guess it's possible it is related to my current diesel. It's also quite old now as I haven't been cruising much since christmas. I'll fill up with new diesel soon anyway so it'll be interesting to see if this changes anything.

 

At the moment the gearbox and also driveplate aren't even mounted on the engine so alignment can be ruled out.

  • Greenie 1

Share this post


Link to post
Share on other sites
23 minutes ago, GrahamSop said:

Thanks catweasel, I guess it's possible it is related to my current diesel. It's also quite old now as I haven't been cruising much since christmas. I'll fill up with new diesel soon anyway so it'll be interesting to see if this changes anything.

 

At the moment the gearbox and also driveplate aren't even mounted on the engine so alignment can be ruled out.

I would think that fresh diesel and as you suggest, a generous dose of diesel engine injector cleaner would be worth trying. Either way hope you get it sorted quickly and cheaply.

Edited by catweasel

Share this post


Link to post
Share on other sites
12 hours ago, Mike the Boilerman said:

 

Forgive me but having listened to the OP's recording several times over, it sounds to me like a perfectly healthy modern diesel engine. 

 

I'm really not getting what the problem is.

 

^^^^^^
Pretty much this.

Obviously I'm used to air cooled Listers that are significantly more than 50 years old, but my untrained hear can't hear much wrong with it.

Share this post


Link to post
Share on other sites
24 minutes ago, alan_fincher said:

^^^^^^
Pretty much this.

Obviously I'm used to air cooled Listers that are significantly more than 50 years old, but my untrained hear can't hear much wrong with it.

I thought it was just me...

Share this post


Link to post
Share on other sites

The engine is running light with no driveplate or gearbox attached, yes!   There is a slim possibility that because of this the engine is running at a slightly higher idle speed also with a lighter flywheel mass which might alter engine sounds.  If there is any eccess end float on the crankshaft this might cause a feint bumping sound against the thrust bearings without the driveplate and gearbox keeping it a bit sort of stiller. although there shouldn't be much end float, hardly any more than the specified correct amount, a couple of thou or so.  Unlike a manual gearbox vehicle where the pressure plate of the clutch when operated to change gear puts load onto the crankshaft thrusts and can wear them.

    Also not having the beerbox attached which would act a bit like a heat sink,  sound sink and absorb and spread some engine noise.

Edited by bizzard

Share this post


Link to post
Share on other sites

I added some injector cleaner at the weekend, including a slosh in the fuel filter, and for about 20mins after starting it sounded better. But the knock returned soon after. This makes me think maybe it is just stale/funny diesel, and it was happier running on the cleaner-diesel mix for a bit? I'll fill up soon with new diesel and see if this helps. At least based on this hopefully it is fuel related and not mechanical.

Share this post


Link to post
Share on other sites
On 25/04/2019 at 20:06, Bee said:

That is good advice for some engines but some more modern engines don't seem to follow that rule, the light on my Beta goes out the instant it fires and comes on pretty much the instant it stops, its done it from new. Same on my 1.5 Renault diesel car, I think it may be because of modern, thin oils.

Doesn't turning off the "ignition key" (to shut off the fuel) also shut off the power to the warning lights? Ditto  electrical type oil pressure gauges?  It does on my system. 

Older style mechanical gauges should show the pressure falling.

Edited by Stephen Jeavons

Share this post


Link to post
Share on other sites
On 13/07/2019 at 19:01, MikeH said:

@GrahamSop Hi, did you find the source of the noise? I have an Isuzu 38 and it sounds the same. Thanks.

Almost certainly diesel knock from poor quality fuel.

 

It yours does it top up with a few gallons of road diesel and see if it improves.

Share this post


Link to post
Share on other sites

I'm curious as to why Isuzu, the largest diesel engine makers in the world, have stopped supplying marine engines for canal boats.

They sound a little harsh to me, I can tell when an old Canaltime boat is approaching easily!

Share this post


Link to post
Share on other sites

Apologies for never following up this thread...😔

 

Back in April I tried the injector cleaner which seemed to improve the knocking after I put a slosh in the fuel filter itself, but it came back a few minutes later. After a fresh tank of diesel, there was no difference here either.

 

The knocking remained the same until yesterday when I rechecked the valve clearances after being advised on Isuzu engines they can easily create a knock even if one is slightly mis-adjusted.

Last night I took my time setting the clearances as accurately as I possibly could. When I started up the knocking was reduced significantly. It is still there slightly, but it is definitely not as bad. I guess a perfect valve adjustment would have the knocking all but gone.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.