Packard Forum Index » Pre-War (1899-1942)

This may be a wild goose chase, and hardly ranks with some of the issues dealt with in this forum. But here goes...

I have noticed a light mechanical ticking sound in the engine of my 1941 120 Club Coupe. Not very loud, but there from start up (cold) and perhaps a bit less as it warms up. Engine was rebuilt a while back. Tappet clearances and compression checked more recently (all ok). Oil pressure steady at 40psi. It runs fine, and I probably would not notice it except that these engines are so quiet!

Any idea what this might be? One suggestion is that it's the drive finger on the mechanical fuel pump. Could be.

Any other ideas? Has anybody else noticed the same thing? Not sure if I should even worry about it.

Cheers

Brian

wrist pin????

Tell me more...

Are the pins retained by circlips or press fit? If circlip, having one come adrift could do a fair bit of damage to the bore. Would the noise come and go as the loose pin moves around?

Maybe I should try the old-fashioned stethoscope trick to help locate it?

Cheers

Brian

A piston noise should change when grounding a spark plug and snapping the throttle open. A piston pin should be a lower pitch and change somewhat when grounding the plug during deceleration after snapping the throttle open. A sticking valve should change after spraying Gummout down the carburetor. A broken valve spring will show up on a vacuum gauge. Tappet noise will occur when a valve stem is not exactly parallel to the tappet. It will change when putting heavy oil or a feeler gauge between the tappet and the valve stem. Loose valve guides will show up after putting thin oil down the carburetor. That is, the motor will run better. An exhaust manifold leak will change during acceleration and become less loud after warm up. It can be checked by putting small amounts of thin oil down the carburetor with the exhaust routed outside the garage, or by using soap and water when the motor is cold. An arcing coil will show up as misfiring during full throttle acceleration. A belt will go away when tension is changed. A fuel pump will remain fairly consistent and be felt through the pump body.

Hopefully you can make up a list now and work through the possibilities. Here in engineering I get to put everything in writing and when something goes wrong I take out the paperwork.

Thanks Tim

That list will keep me busy for a while! I'll check the easy ones first, starting with feeling the fuel pump. The performance of the car feels fine. I can't hear it with the windows up, so will probably lose enthusiasm for chasing it somewhere along the way.

Cheers

Brian