Modestine

[DavidLaver]

I'm sitting here clenched thinking about you going for a drive with it making that sort of noise.  Times I've had engines making that sort of noise its been something pretty serious  and driving it could have resulted in a very big bang. 

Sometimes asking the question back the other way helps.   If you wanted to make an engine produce that noise, how could you do it?

Another thought is to post a clip on You-Tube for everyone to listen to.

Am sure you've been through all this but for the sake of it:-

= Is it possible to crank it over by hand with the plugs out and feel or hear anything?

= Does cranking it on the starter with the plugs out give a different noise?

= Put plugs back one at a time and crank and see if its compression force on a particular pot?

= Is there a way to test piston to valve clearances?   

= Any witness marks on the old piston tops or skirts?

= Were there any witness marks on the valves?

= One thought with that sort of noise is a valve stem "grabbing" and not wanting to come back up.  That could be either too tight in the guide or too loose.  That might show itself turning the engine over watching the valve gear.

= How is the petrol pump driven?  Might the drive cam be knocking on something every 7th turn or something odd.

= could the oil pump drive be skipping a tooth?  is the oil pump substantial enough to be a cause of the noise?

David

[DavidLaver]

Does the old head gasget give any clues?

Could a liner have moved?

Anything at the flywheel/clutch end that would act like cardboard against bike spokes?

Could a big end have come loose?

Are there any oil screens inside the crank case?

Could you put a paint mark on a pully and work out excatly at what point or the pattern of the noise?   If it was TDC on pot 3 or every 5th turn or something that would narrow it down.

David

[DavidLaver]

If I was wanting to install and annoying noise - lets pretend this is a 1970s BL plant with the red perils sabotaging the cars of the running dogs - I'd cut one of the billion bolts in half, say one of the ones holding the cam shaft down, so it would jump up and down hitting the cam cover.

Anyone else got some evil thoughts on how to make an engine rattle?  In general people are much more creative being evil.  There's got to be 101 ways at least - we just need to think like Gremlins.

http://www.imdb.com/title/tt0087363/

Been a while since I've seen those films, but I remember them fondly.

David

[Dilambdaman]

Thanks very much David for spending the time thinking and writing about my problem, much appreciated.

We don't get the rattle at tick over only when the revs are increased so the cranking tests don't help.

We've had a fibre optic camera through each plug hole and turned the engine over and all seems well.

My engineering friends dismantled the engine last time and checked everything thoroughly but found no unusual signs of wear or damage.

Petrol pump is electric.

Oil pump is driven with via a fork on the bottom of the distributor drive.

The head gasket gave no clues and the liners were all Ok.

I removed the clutch and gear box drive but still had he rattle.

The valves and guides have been checked but I will turn the engine over and have a close look at them operating. Will also see if its possible to put a mark on a pulley to see if there is a patern.

You-Tube I'm not used to date - I'll give it a go.

Thanks again David - Lewisham is not that far from me, come and have a listen!

Robin.

[Sebastien]

Quote:"It's a very loud noise bit like running an iron bar along iron fence railings is the best description I can come up with. "

Question, is it synchronous with engine revs? Does it happen when in gear, or also out of gear? As David said, something between flywheel and a fixed casting, or near the clutch? starter pinion rubbing against flywheel?  In an Aurelia, things can fall between flywheel and cover, and make horrible noises.

If no damage internal to the engine is seen, it should be an external problem!

Sébastien

[rogerelias]

Hi Robin. Just a long shot, difficult when not actually there to listen to, but here goes . Years ago i had an early mgb which had a dynamo, i had a horrible noise which increased with revs, how i found the culprit was, i took the fan belt off, and the noise was not there anymore, it turned out 1 of the 2 long screws that go right through the dynamo, had snapped half way inside, what was happening was, when on idle, i.e. slower rotation, the end of the screw nearsest the head of the screw would drop down and rub against the rotating part inside, but when the revs were increased the screw inside then got thrown about more and was bouncing off the rotating part and against the outer casing making a noise like you describe. As i say only a long shot, but sometimes its easy to overlook the simple things. Good luck. Roger.

[donw]

Robin

I had a noise like a machine gun in my Lambda engine which only came in as revs built up it was a valve guide loose in the head, the inner spring on later Lambda engines does not sit on the step of the guide.  I had to put a mole wrench on each guide as only the loose one turned slightly with some hand force when cold but became easier to turn as the engine got hotter.

Don

[Dilambdaman]

Sebastion.

Yes, it is synchronous with engine revs and not there on tick over. The engine has been apart 3 times recently and closely inspected for signs of wear/damage but nothing shows up. The engine has been run without clutch and gear box but still has the rattle.

Roger,

I will run it without the dynamo which is direct drive but I can't start it without the starter motor as the radiator was rebuilt at sometime and the hole for the starting handle doesn't line up with the dog on the crankshaft! Maybe able to tow start.

Don.

Interesting one that and not something we have checked so will have a look tomorrow.

Thanks all and please keep the suggestions coming, the withdrawal symptoms from not driving her are becoming unbearable!

Robin.

[Dilambdaman]

Well, another day of inconclusive tests and inspections. It really is looking as though the engine is going to have to come out and be stripped down again. Most frustrating, not least as we are off to France on Thursday for a month.

Robin.

[DavidLaver]

I guess you've done the "pulling a plug lead off in turn" thing...

That valve guide and the dynamo problem must have taken some finding. 

All this is reminding me of a previous life chasing software faults.   The kitchen radio amuses me at the moment by sometimes changing the volume up when I hit the down button.   The new digital garage radio infuriates me by taking three seconds to come on with no audiable "click" to give me faith that it will.  I can understand it needs to buffer and error check and so on but at least acknowlede the on button with some noise like a digital camera "shutter" noise.   

David

[Dilambdaman]

Having returned from a blissful month in France away from things Dilambda and with the AGM looming it was back to Modestine today.

Coxing her into life revealed that the rattle has not miraculously disappeared and if anything, seems worse! However, Tony from my local V&V workshop agreed to come and have another listen and pronounced the engine to be in rude health and the problem not to be too alarming. Having said that, he couldn't be more specific - maybe a con rod touching the liner, loose fly wheel bolt, starter pinion etc. He reckons that its better to leave the engine in situ and try and pin point the offending part by trial and error.

So, tomorrow I will see what I can find.

 Oh, and the clutch has decided to malfunction. Most probably I've assembled something wrongly, although you'd think by now I could get that right in my sleep. It doesn't bite until at the very end of the peddle travel and even then is slipping.  Fortunately it is possible to get at the clutch easily and indeed change it without disturbing the engine or gearbox.

Watch this space.

Robin.

[DavidLaver]

Trial and error sounds a bit harsh - lets call it "a process of elimination".   

You WILL get there in the end...

David

[Dilambdaman]

Not a lot to report from Saturday's investigations. Having eliminated external possibilities, off came the sump again to reveal - not a lot.

There were some witness marks on the six bolts that secure the flywheel to the crankshaft but they are more likely to be from being driven home during the rebuild, their being a very tight fit. Need to try and make absolutely sure that the con rods are not fouling the bottom of the liners, although this is difficult lying on ones back and given that on a V8 there 'aint much room and the angle makes it almost impossible to get an un-interrupted view.

Looking more and more likely that the engine will have to come out again.

Robin.

[ben]

Hi Robin
   Just been re-reading your tale of woe-Not sure how you havnt set fire to her by now!!!
   It isnt clear if you have had the main bearings attended to.Presumably they were not done when the first crank regrind etc was done byJohn Kirby as he did not have the whole engine.So were they remetalled and line bored by JEL? It strikes me that if some ot the mains had "run" you could be getting crankshaft whip or flexing as you increase the revs allowing some pistons to hit the head (or the valves).At one point you said the camera test showed a piston might be touching so they must certainly get very close.If the noise isnt there at idle it must come from something that flexes or distorts as the speed is increased.
   On the other hand if the noise is present at idle (but less severe) and builds in volume as the revs are raised I would suspect the valve gear.The business with having to add packing washers to get the outer springs to work properly sounds very odd.Are you sure the springs do not now get coil-bound? Or perhaps they are still so slack you are getting valve bounce.
   The other thought that occurs to me concerns the modified Ford pistons. Presumably the two pistons with the gudgeon-pin damage were replaced with "proper"ones as you did not mention a sourcing problem at the first rebuild. Also the top end noise was presumably not there when you did  the 20miles en-route to Swindon last year before you lost your oil pressure.So I wondered if the distance of the top ring below the top of the piston was less on the modified Ford ones. This could lead to the top ring hitting the wear step that is normally present at the top of the bores on an engine that has done a few miles.

[Dilambdaman]

Hi Ben, thanks for your input.

JEL re- metaled and line bored big end and main bearings and they all appear to be in fine shape.

It definitely seems to be something that is stretching or moving under acceleration

Tony from my local V&V workshop had a close inspection of the valve gear last week and reckons its fine. It was he who experimented with the washers and found that the valve gear became noticeably quieter.

At the first rebuild the two damaged pistons were repaired and re-fitted. The noise appeared following that rebuild, persisted after the JEL work and after fitting the modified Ford pistons. The cylinders had been bored when I bought the car and the engine has covered about 10,000 since. I've had the bores honed and there is no noticeable wear or step in them.

Another session with her tomorrow!

Robin.