Clicking Sound When Turning Rebuilt Motor Over

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thunderbolt

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I have rebuilt the motor for my '74 MK2 Roadster. I have just fitted pistons, rings, barrels and head. The motor is still on the bench. When I turn the motor over using the large nut on the end of the crank (drive side) to adjust the valve clearances I hear a clicking sound from the motor. Not particularly loud but there nevertheless.

I am thinking it is a pushrod not located properly, but I did check they were all in place in the rocker arms when fitting the head. At the present time it is difficult to see if ALL four pushrods are in place (obscurred by rocker arm shaft) and I cannot get my fingers in there to see if the pushrods revolve. All the valves and springs operate as they should when the motor is turned over. There is also the same amount of thread on each of the rocker adjusters.

P.S. I am using mushroom adjusters and am able to set them to the correct clearances of .006 and .008".

My question: When the pushrod does not locate properly is it usually in the rocker arm or down in the tappet (although the workshop manual does say "the pushrod cannot help but locate in the tappet block successfully).

The head will need to come off to resolve the issue (hoping it's not broken rings). Is it ok to reuse the cyl head gasket seeing as it has been compressed once already?

I have also read that the Norton motor can run and be ridden with a badly located pushrod but with the clicking sound at idle. If so why doesn't the pushrod move back into its correct position?

Thanks for any helpful replies.

Cheers Don
 
my inclination would be to slack each rocker off in turn when in valve closed position and have a wiggle .. if its sitting on top of tappet block it should drop in
 
oldmikew said:
my inclination would be to slack each rocker off in turn when in valve closed position and have a wiggle .. if its sitting on top of tappet block it should drop in
Click to expand...
Yes you can get the pushrod back into it's ball/ cup proper position by doing this . I gave mine a gentle tap with a screwdriver to nudge it into proper position. This avoids pulling the head to try it all again.
 
I had a similar sound when turning over my engine using a wrench as you did. It was the cam chain dropping onto the tensioner. I pulled the timing cover and verified this by watching the chain drop in conjunction with the click.

Slick
 
Well I removed the head and the pushrods seemed to be located ok. I checked the pushrods for any witness marks - none found. As the clicking seemed to be coming from the drive side exhaust rocker cover aperture I thought that the thackary washer on the rocker spindle might have been digging in to the end of the rocker arm. The noise seemed to be occurring when the valve changed direction of travel. I removed the rocker spindle and yes there were a couple of witness marks on the end of the rocker arm.

Clicking Sound When Turning Rebuilt Motor Over


One at 11 o'clock and the other at between 5 o'clock and 7 o'clock.

I am tempted to put shims on both sides of the rocker arm and eliminate the thackaray spring washer - I suppose that is ok to do?

Then I will put the head back on and see if the clicking noise has disappeared or not.

BTW does anyone know what the piston clearance in the bore of an 850 should be for a new Hepolite piston?

Thanks Don
 
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thunderbolt said:
Well I removed the head and the pushrods seemed to be located ok. I checked the pushrods for any witness marks - none found. As the clicking seemed to be coming from the drive side exhaust rocker cover aperture I thought that the thackary washer on the rocker spindle might have been digging in to the end of the rocker arm. The noise seemed to be occurring when the valve changed direction of travel. I removed the rocker spindle and yes there were a couple of witness marks on the end of the rocker arm.

Clicking Sound When Turning Rebuilt Motor Over


One at 11 o'clock and the other at between 5 o'clock and 7 o'clock.

I am tempted to put shims on both sides of the rocker arm and eliminate the thackaray spring washer - I suppose that is ok to do?

Then I will put the head back on and see if the clicking noise has disappeared or not.

BTW does anyone know what the piston clearance in the bore of an 850 should be for a new Hepolite piston?

Thanks Don
Click to expand...
I always shim the rockers to the centre of the valves ,I don't use the thackary washers
 
thunderbolt said:
.. a clicking sound from the motor. Not particularly loud but there nevertheless..
Click to expand...

Loose camshaft chain .
Are you turning the engine over with the timing cover in place ?
( or support for the intermediate shaft ..)
 
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Looks like you've proceeded to remove head. But I'll chime in and say it is possible to sort out a displaced pushrod with head in place. Ludwig has posted a great valve spring and/or guide seal replacement procedure including a
couple of simple homemade tools needed. I performed it recently on my 850 to swap new springs and fresh seals on intake. I did have an issue with one intake pushrod slipping out of position. Found I could visualize and maneuver it from the exhaust side only. With the springs compressed and the temp thin diameter rocker spindle rod in place, there's enough clearance to reposition the rod correctly.
 
I noticed the chain top run appeared to sag and tighten with the click. Worn cam shaft bushes can cause a similar click.
 
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