I acquired a 73 F-100 a few years back. After a few minor fixes such as replacing the four partly delaminated tires and such, it did yeoman service for us till just recently. We picked up an apparent drive-line vibration. I replaced the u-joints (pretty sad little devils) and then the center carrier bearing. The vibration changed. Now it is pretty harsh starting up, then sometimes smooths out a bit. Other times it just gets worse. Under load, such as when putting it back up on the ramps for the next tool-time go 'round, it makes a crunching or ratcheting sound like some kind of New Years noisemaker. This appears to come from about under the firewall, but could be from low under the hood. It doesn't vibrate as much backing. There is little vibration free revving, though I do not run it up too high. Needless to say, it isn't doing what it needs to be doing around here.

I pulled the inspection cover and cranked it over by hand, but noticed nothing immediately suspicious.

It is not stock. The VIN says it is a 240 six. It obviously had a manual transmission at birth. Now it is a 351 Cleveland 4V Carter AFB in front of a C-6 automatic. The engine runs pretty good. Oil pressure is near the top of the gauge. All fluids are clean. The unexpected good thing I found fiddling about was a fuel pump leak. That could have led to problems. I also did belts and hoses recently since I like to keep ahead of such things out here in the country.

Any thoughts? I really do like this old girl, and intend to get lots more life out of her.

Regards,

Yardpilot

(yup, that guy)