knocking noise

[stay_upright]

I think I can hear a knocking noise from my 300 and am thinking maybe it's the piston/little end.

Is there anyway to check, if it's gone would I feel play when trying to move the piston up and down if I remove the barrel?

If it's gone will I need a new conrod as well?

I will do a compression test shortly - should that show it up?

 

[darren]

From my experience -
Rattle/chattering = Small end,
Knocking = Big end,
Rumbling = Main bearings.
If you remove your barrel hold the con rod still and try to move the piston up and down if there is play then you have found your problem.
Also hold your con rod and try to move that up and down to check the big end.
If it is the little end providing the con rod is not damaged or mis shapen you could get away with just a bearing and gudgeon pin.

 

[darren]

Also when you remove your cyl head, check the head and piston crown to see if the piston has been striking the head.

It would be worthwhile before stripping to check the stroke in mm to see if it differs from the book. If it is shorter then something has failed. (little or big end)

 

[stay_upright]

Measured compression today at 130 so it's lost some from the 150 originally.

Will continue to dismantle, hopefully just a new piston, rings, wrist pin and little end bearing should do it...

 

[Diddel]

Mounts to bloke.

 

[darren]

Mounts to bloke.

What???

 

[DaveJ]

Also hold your con rod and try to move that up and down to check the big end.

What if there's no movement up or down, yet you can rock the connecting rod side to side a few mm's?

 

[rpduc]

There are specs in the service manual for side clearance on the big end.

When I did my top end this winter my big end was "just" in tolerance by this measurement so I left it and no probs yet...

The only service manual available that I know of is the '06 one HERE