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Engine clank


GBW
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A previous thread relates to my troubles with the crankshaft pulleys.

There was concern expressed that adding extra pulleys could unbalance the crankshaft leading to a possible failure.

Taking note, I became sensitive to NOISES.

In particular I believe I could hear a Clank every other revolution.  Must be a big end I thought.

MY very poor hearing has been of no help in diagnosis and the use of the screwdriver "stethoscope" likewise helped not at all.

Relating the concern to a friend, he remarked that sometimes a failing injector can sound similar to big end rattle.

 

I loosened the feed to the injector on cylinder one where I thought the noise came from and the clank disappeared.

 

I do realise that not allowing the cylinder to fire could have other consequences (e.g. in terms of bearing loading) but I am encouraged to believe an "engine out" may not be necessary.

 

Views please.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

scope" 

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14 minutes ago, GBW said:

A previous thread relates to my troubles with the crankshaft pulleys.

There was concern expressed that adding extra pulleys could unbalance the crankshaft leading to a possible failure.

Taking note, I became sensitive to NOISES.

In particular I believe I could hear a Clank every other revolution.  Must be a big end I thought.

MY very poor hearing has been of no help in diagnosis and the use of the screwdriver "stethoscope" likewise helped not at all.

Relating the concern to a friend, he remarked that sometimes a failing injector can sound similar to big end rattle.

 

I loosened the feed to the injector on cylinder one where I thought the noise came from and the clank disappeared.

 

I do realise that not allowing the cylinder to fire could have other consequences (e.g. in terms of bearing loading) but I am encouraged to believe an "engine out" may not be necessary.

 

Views please.

scope" 

 

If an injector is not atomising properly the fuel drops will take longer to heat to ignition temperature so you get a build up of fuel in the cylinder that all tends to ignite at once. All diesels do this but it is far worse with poor injectors. It is called diesel knock and has been known to scare petrol mechanics. So, is it a big end that only knocks upon ignition, or is it a dodgy injector. I think getting that injector or the whole set tested and overhauled might be the cheapest first option. If you do make sure the outfit knows it is a BMC 1.whatever to try to ensure the nozzles they fit are the correct ones.

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That was a rapid reply Tony!

I have a spare set of injectors for the replacement engine.  Their condition is unknown but, as long as they are identical, it would be interesting to swap.

 

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3 minutes ago, GBW said:

That was a rapid reply Tony!

I have a spare set of injectors for the replacement engine.  Their condition is unknown but, as long as they are identical, it would be interesting to swap.

 

 

Yes I was going to suggest swapping around the injector in the clanking cylinder with the injector from another cylinder then repeating your experiment.

 

If the clank changes cylinder with the injector, you'll have your answer. If the clank stays on the cylinder then yes its probably a knackered bearing. No particular hurry to fix it though, engines tend to carry on running for ages like that.

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4 minutes ago, GBW said:

That was a rapid reply Tony!

I have a spare set of injectors for the replacement engine.  Their condition is unknown but, as long as they are identical, it would be interesting to swap.

 

 

Just swap the one and if confident reverse the original on the injector pipe and crank the engine so you can view the spray pattern but stay well away from the spray and make sure there is nothing around to ignite it.

 

Ideally you would fit a new injector copper washer and crimped fire washer "down the hole" but for a test it should not matter as long as the inverted top hat heat shield stays in the head and does not pull out on the injector.

1 minute ago, MtB said:

 

Yes I was going to suggest swapping around the injector in the clanking cylinder with the injector from another cylinder then repeating your experiment.

 

If the clank changes cylinder with the injector, you'll have your answer. If the clank stays on the cylinder then yes its probably a knackered bearing. No particular hurry to fix it though, engines tend to carry on running for ages like that.

 

I am not sure the leaving it is particularly good advice on a 1.5, but I don't have much experience on the 1.8. The 1.5s crankshafts are known to not be the strongest so I would want to avoid repetitive shock loading. I do know they run for years with rummbley main bearings though.

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3 minutes ago, Tony Brooks said:

 

I am not sure the leaving it is particularly good advice on a 1.5, but I don't have much experience on the 1.8. The 1.5s crankshafts are known to not be the strongest so I would want to avoid repetitive shock loading. I do know they run for years with rummbley main bearings though.

 

 

Do we know its BMC? I scanned through the OP before posting but didn't see an engine model mentioned. I know I miss stuff like that sometimes.

 

It doesn't sound like a bad knock as the OP mentions only noticing it having been listening carefully to the engine for other reasons.

 

 

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1 minute ago, MtB said:

 

 

Do we know its BMC? I scanned through the OP before posting but didn't see an engine model mentioned. I know I miss stuff like that sometimes.

 

It doesn't sound like a bad knock as the OP mentions only noticing it having been listening carefully to the engine for other reasons.

 

 

 

It is in the BMC section, but I agree that the OP has not identified the engine. Given the locations in his profile is Gloucester it could even be a 2.x, 3.x or 5.7 BMC.

 

The way he described it is why I went for the diesel knock possibility.

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I wondered if causing the cylinder not to fire might ease the load on the crankshaft.  Is that what you are suggesting?

I was just beginning to take heart!🙁

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It is also possible that this is a small end knock, but that usually sounds more like a loose valve clearance.

37 minutes ago, GBW said:

I wondered if causing the cylinder not to fire might ease the load on the crankshaft.  Is that what you are suggesting?

I was just beginning to take heart!🙁

 

I suggest not a good idea on a 1.5, the firing impulses would be uneven. See if another injector alters it first.

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What I implied was that maybe the cessation of the clank was perhaps not due to the injector but due to some there reason due to the cylinder not firing.

Edited by GBW
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2 hours ago, GBW said:

What I implied was that maybe the cessation of the clank was perhaps not due to the injector but due to some there reason due to the cylinder not firing.

 

Yes, it might and as I said it might be a small end. No one knows, it could be a broken engine foot, something fallen down and resting against the engine, or loose engine mounts.

 

Of the possibilities it is now for you to decide how to diagnose further or to call the professionals in. I have given my opinion of the best next step but it is up to you, you could pull the engine out to have a look-see, but that won't tell you anything about an injector unless you have them tested.

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