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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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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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  • 1 month later...

I have bought an injector tester and found that one of the injectors on my spare engine (yet to be fired up) had a seized pin and the other three needed adjustment.

Good reason to check those on the boat.

However, how do you eject an injector?

 

Gently tapping with the mallet has not worked.

 

Will running the engine with the securing nuts loosened be wise/effective?

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16 minutes ago, GBW said:

However, how do you eject an injector?

 

Having removed the securing nuts, I think you just lift it out with your fingers.

 

If yours is jammed in position this suggests to me the copper washer seal has been leaking for a long time and carbon have built up around the base of the injector locking it into position. I don't know much about BMCs specifically but find myself wondering if this is related to the clank you originally asked about.  

 

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23 minutes ago, GBW said:

I have bought an injector tester and found that one of the injectors on my spare engine (yet to be fired up) had a seized pin and the other three needed adjustment.

Good reason to check those on the boat.

However, how do you eject an injector?

 

Gently tapping with the mallet has not worked.

 

Will running the engine with the securing nuts loosened be wise/effective?

 

Personally I first try a pry/heel bar between head and injector flange but loosening the nuts a fair way up the stud ad spinning the engine may well work. I have always managed to get them out with a pry bar/ heel bar. You will need new crimped heat shield washers in the bottom of the inverted top hat heat shields that may well come out on the injector. If they do you need new copper sealing washers for them. You would be well advised to fit new copper injector sealing washers as well, but you could anneal them before fitting. Make sure that you fish the old crimped washers out to the heat shields before putting new ones in.

 

You will probably find the auxiliary spray holes blocked in the nozzles, they assist cold starting. You may find professional overhaul easier than trying to unblock the small holes. Unless you also have the Pintaux testing addapter it is not so easy to check the aux. spray hole, but you can do it if you push the test lever down slowly.

Edited by Tony Brooks
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3 minutes ago, Tony Brooks said:

 

Personally I first try a pry bar between head and injector flange but loosening the nuts a fair way up the stud ad spinning the engine may well work.

In the absence of a proper pry bar, a pair of spanners can be effective. Find the longest one you have which will fit under the flange, lift it and slide another one underneath (or a screwdriver) at right angles, to form a fulcrum (pivot point). If you can get it right up to the injector flange and push down on the outer end of the first spanner you get some pretty decent leverage and most things will move so long as they are not too stuck.

 

Alec

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25 minutes ago, MtB said:

 

Having removed the securing nuts, I think you just lift it out with your fingers.

 

If yours is jammed in position this suggests to me the copper washer seal has been leaking for a long time and carbon have built up around the base of the injector locking it into position. I don't know much about BMCs specifically but find myself wondering if this is related to the clank you originally asked about.  

 

It's that word "just" again!   I do wish to check the injector following Tony's advice.

 

30 minutes ago, Tony Brooks said:

 

Personally I first try a pry/heel bar between head and injector flange but loosening the nuts a fair way up the stud ad spinning the engine may well work. I have always managed to get them out with a pry bar/ heel bar. You will need new crimped heat shield washers in the bottom of the inverted top hat heat shields that may well come out on the injector. If they do you need new copper sealing washers for them. You would be well advised to fit new copper injector sealing washers as well, but you could anneal them before fitting. Make sure that you fish the old crimped washers out to the heat shields before putting new ones in.

 

You will probably find the auxiliary spray holes blocked in the nozzles, they assist cold starting. You may find professional overhaul easier than trying to unblock the small holes. Unless you also have the Pintaux testing addapter it is not so easy to check the aux. spray hole, but you can do it if you push the test lever down slowly.

I have tried to use a pry bar but the access is difficult.  I'll try removing some of the ancillaries to gain more space.

I had not realised there were more than one spray hole.  I can see two in the old injectors and the spray pattern is "bifurcated", but there appears to be only one in the new nozzle I bought.

I have cranked the engine with the stud nuts loosened without result.  That was without it firing.  Perhaps while firing would be effective or too dangerous?

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I've got a pair of 1.5s (marinised Austin J4 engines) in one of the boats. When I bought the boat the starboard engine was making a bad knocking sound. It was running alright and not smoking much at all. Just a bit loud. 

 

Investigation around the rocker shaft discovered the fact that one of the rockers had lost its oil feed and in previous use had worn right down into the rocker shaft so it was impossible to set the valve clearance as it was just flapping around. The wear is quite impressive. Another thing is that some of the ball headed screws were soft. 

 

I got a new shaft from an MGB parts place and replaced the rocker with a new one, renewed the soft screws and set it all up and it was quieter. Still not the same as the other engine so there might be something else wrong but the heavy knock did get quieter. 

 

I really thought it might be the bottom end but it seems not. Not that I know what bottom end noise sounds like ! 

Edited by magnetman
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47 minutes ago, GBW said:

It's that word "just" again!   I do wish to check the injector following Tony's advice.

 

I have tried to use a pry bar but the access is difficult.  I'll try removing some of the ancillaries to gain more space.

I had not realised there were more than one spray hole.  I can see two in the old injectors and the spray pattern is "bifurcated", but there appears to be only one in the new nozzle I bought.

I have cranked the engine with the stud nuts loosened without result.  That was without it firing.  Perhaps while firing would be effective or too dangerous?

 

Are you sure it is a BMC 1.5/1.8? They have Pintaux nozzles that have one large center hole in the center of a little raised bump with a pintle sticking out of it, plus  a very small hole in the side of the bump that you will probably need a magnifying glass to see. The pintle is a very small inverted cone stuck out the bottom of the nozzle. If you do not have one then you need a new nozzle. A matched needle comes as part of it. The spray patter when you push the test lever down firmly should be a hollow cone with no gaps in it.

 

As far as removing the injector is concerned, I suspect your pry or heel bar may be too large. I have known people to use a slide hammer screwed into the leak off banjo thread, but it is  a very fine thread.

 

As long as the nuts are full of stud I think it will be safe enough to fire it up, but please put a load of rag across the top and around the injectors because you may well get chunks of carbon flying about.

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7 minutes ago, GBW said:

Bought from ebay;-  Injector Nozzle BMC 1.5 1.8 950cc Diesel GENUINE Lucas CAV 5650350 RDNOSPC6651

Can you see that written on the side of the nozzle? It should be etched on the side.

 

Alec

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