JowettTalk

Now then here a mystery to unravel. Towards the end of last month I went to use the car after a period of about a month of no use. I started it up first of all wound the engine round a few times to get the oil around a bit. Started up, Good oil pressure 25-30 at idle and road running. and what could be heard was a intermittant knocking sound. Another pair of ears thought it could be something catching/clipping the block like a split pin or something

Stripped down the engine to the big ends checked all the bearing surfaces in the big ends. All clean and no gouges or scrapes of any kind. But did find in the timing cover was a piece of broken crankcase from a lug where the timing case bolts to. Fished that out as it sounded more tinny front end this appeared to be it. Picking up with the chain and hitting against the cover. So I put it all back together just checking all the con rods bolts for piece of mind none were loose. So all back together, finding a louder noise coming from tappets. Reset all the clearances and now sounded nice and smooth and even tick over and no knock.

But having taken it up the road a few times, it has now re developed a different knock. This knock is instantaneous from start up/cold. which can be heard from idle. and it then drops from being revved and goes away, as soon as warm it transforms into another intermittent knock but sounds bloomin; horrible on the near side. The oil pressure is still between 25 - 30 on the gauge. I have tried winding in the oil pressure valve in half turn and hasn't made any difference. But thinking more on it now as the engine increases/revs and the knock dies down, perhaps it could be a lack of pressure on that one side. Though Ive spent all morning with a stethascope, and it sounds more in the cam shaft/higher up area than a big end knock. I will try to get a video up. But its still a well pronounced knock.

a long shot but easy to do - are you absolutely certain that the flange on one or both pots is seating properly on the crankcase and tht the face of the flange and of the crankcase on which it fits are absolutely crud free. Then make absolutely sure that all the nuts securing the pots to the crankcase are dead tight as even a quarter turn loose can result in misleading noises that can be taken for big ends or other drastic things. There was a factory service bulletin to this effect and it appied to all the twins.There may be a copy of it on the gallery somewhere but I can't find it.

This is a long shot on teh basis you have only just reassembled the pots to the engine but you may even have a stud that loosens very slightly giving the same effect.

george

George:- Have you reset the time on your Profile?

Alan:- Have a look at your engine with George's comments in mind, then search 'Pre-war' for 'Engine noise descriptions' if all's well with the nuts.

A slight knocking on my Flying Fox engine turned out to be the wrong-sized split pin holding the camshaft sprocket nut in the timing case. It was too thin (should have been 1/8") which allowed too much end-float as the nut unwound a fraction.

I'm looking forward to the video, I remember with mirth the one of the oil-spurting tappets some time ago!

Tony.

Alan

I agree with what the others have said, but would add one more option.

When the engine is runing you get this knocking noise. Try depressing the clutch as though you are changing gear. If the noise stops I bet you a beer that the flywheel nut has come loose. You need to take the nut of and smack the flywheel onto the taper and then tighten the nut up. Just tightening the nut onto the flywheel will not be tight enough.

If you want a chat give me a ring.

Well here is the video.

http://youtu.be/SNL6UCnL4-w

(Its handy having your car at work, gives you something to do during lunch)

And looks like I owe a feel people a pints,

Low behold I tried all the the nuts on the pots again and they were all dead tight still. Then went onto Peter's suggestion. And there it was with the clutch pedal pressed, it dissappeard, and re appeared with the clutch pedal off again. I never would have pegged it to be that. As Ive had before the last time where the flywheel was loose you could move on its shaft a considerable amount, but with no knock. But Im convinced it is. So looks like engine out again or possibly gearbox. Not sure which is the best option really. But at least its not something horrendous and expensive.

In most cases I will use Loctite Threadlock on anything with a thread. But that is no substitute for using a torque spanner (or at least giving it an experienced tighten). If you use Loctite you can often dispense with using original locking mechanism such as tab or split pin but for belt and braces fit them anyway. Do not fall for winding the nut back or forwards just to line up the spilt pin. This can mean you over tighten or leave the fixing too loose. Washers often wear so the split pin may not align again in the same place.

Alan

Take the gearbox out it is easier. With the engine in place you can smack the flywheel as the engine is held firm. One point ensure the keyway has not drifted back against the bearings or you will have other problems.

In the end I took out the engine. had it out and the clutch/flywheel out within about 3 hours. I did notice the flywheel come off with relative ease. two wooden wedges and a couple of knocks and it came off. Thought the nut on the end did put up a bit of a fight. Strapped the engine down to the table and gave it a good hit back on. Also re loctited the nut back on. And gave it a bit of welly. Re assembled the clutch again and had it ready to put back in this morning. which I did before work and had it back in and running. (Early start) And no knock, which is great news, and she sounds nice and quiet, has this kind of soft sound when revved which I think is right. Now the only thing is I there is now no clutch. So id imagine this is down to re adjustment. It appears the fork does not depress fully to release it. Though I did reset all the toggle levers when I put it back in.

Alan:- I loved the video, and especially the tympanic accompaniment.

Peter:- Thanks for the input, I hadn't heard this before.

Alan:- We've been through clutch adjustment in some detail in the past.

Tony.