Thump Thump Thump

On The President’s Tour in June I noticed oil was dripping rapidly from the U-joint / ball cap.  We completed the tour, about 50 miles, and since then I have taken the T on several outings. The oil is still dripping but maybe not as fast.  Even after all the driving oil still runs out of the top petcock, so I must have overfilled the engine at the last oil change.  This may have encouraged the drip.

Yesterday I took the Model T to Bowness Auto to pick up a rad hose for our T-bird and noticed a dull thud or thumping sound when the engine was under load. I emailed Harry about the problem and we independently came to the conclusion that the grease had been washed out of U-joint / ball cap by the oil drip.

I pumped grease into the ball cap until my arm got tired and took the T for a short drive. Problem solved, or at least the symptom is masked.

Here is what I learned:

The oil level only needs to be above the bottom petcock. My accidental overfill promoted the leak

A dull thumping sound under load may be emanating from the universal joint.

In addition to lubricating the U-Joint and reducing oil seepage down the driveshaft to the differential, packing the ball cap with grease reduces the thumping noise (which may be caused by a worn U-joint or perhaps the joint is loose on the driveshaft*).

* I am using a modern pinion bearing and did not pin the U-joint to the drive shaft)

Update August 6,2014: We drove the T over 1,000 km last week without incident.

Update September 14, 2014: the loose U-joint was replaced with an NOS joint and after a 100 km test drive the thumping sound has not recurred.



  1. Is that really a ‘properly’ greased u-joint? Seems with that amount of grease lt is to muffle noise and vibration rather than just lubricate. Color me as a novice making an observation rather than knowing what I am talking about.

    • Your right. The grease has three functions: to lubricate, to keep the oil that leaks from the engine from running straight into the rear end, and to deaden the sound. Before replacing the 4th main the leaking oil would wash the grease out in about 50 miles of driving. When the grease was gone I could hear the loose U-joint.

      To answer your question from my experience that is the way to pack the U-joint housing.


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