Valve cover leaks

Hot-rodding the Nash/Rambler 195.6 overhead valve six

18 June 2010

The valve cover design on this engine is fine; a groove in the cover holds a flattened O-ring type seal, and two screws clamp it to the head. The seals do age and seep in the back, but replacements are available.

But any tendency to leak is made worse by the oil dripping off the rocker shaft, onto the back edge of the seal, exacerbated on my engine with the higher oil volume from the blueprinted oil pump. Typical for front-engine cars, the block tilts to the rear about 5 degrees, causing oil to run down the length of the rocker shaft and exit of the rear end, right onto the bottom of the valve cover and seal.

A simple 5" piece of baling wire will cause that oil to drop onto the block and run down the rearmost pushrod hole. Twist a single turn of wire around the end of the rocker, twisting to make a short tail. See photo to the right. Then rotate the tail to point downward.

This provides a wet path for the oil film to follow, instead of running over the wave washer and onto the cover. Note how wet the wire tail is in the photo to the right. Simple! Cost: nothing. I twisted it tight enough to have a shape, but loose enough that it could never wedge itself between the rocker and washer. Even if it wears into two pieces they'll lay harmlessly on top of the head.

Note the top-down view in the third photo; this was taken with the engine running. Before this fix, oil puddled right to the top of the lip and much of it went over. It now runs dry; the oil flows over the lower casting in front of the rearmost head bolt, visible in photo two.

Last, here's a brief movie (AVI format) of it in operation.