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

I was driving my car, a'39 Packard 6 with about 80,000 miles a few weeks ago and started hearing a strange motor noise. About then I had a valve start sticking causing a major miss so I have decided to pull the motor and go through it. It has seemed down on power and when I pulled the #4 piston, ring pieces came out with it. The cylinder is not scared and there is no ridge at the top of the cylinder. What could have caused this?

I had that happen on my 1954 Patrician's 359 which had been rebuilt with low miles. Turned out to be a defective replacement pistons and at least one other was found to be cracked too. Are yours originals or have they been replaced with modern ones?

That is a problem common to all long stroke engines and especially those with the very simple oiled mesh air filters. The rings wear thin in the radial direction so they have less contact with the piston lands. As they thin they begin to flex torsionally which eats up the ring lands and enables the rings to flex even more. Finally they break up into pieces. The engines still run sort of OK because the second ring maintains some compression. After a time of the ring pieces dancing around in the groove one of them will migrate out the top of the piston and get stuck under a valve causing a dead miss.

This is not just a Packard thing. We call it long stroke disease, and I have seen it in Packard, Chrysler, Dodge, and Buick. I am sure the other guys do it too, I just have not worked on them.

In Packard service literature they recommended rings jobs sooner than later for that reason. But when our babies were just cheap old used cars, no one was going to bother to do a ring job as long as the thing would start and get them to work.

As a rough rule, a set of new rings at 50 or 60k miles would hold til 100. With no new rings and high revs-as your car is likely geared--you pretty well made the maximum at 80K

Thanks for this info, it's very enlightening. I'll be putting in all new pistons and rings now, this motor will never get many miles on it now but just in case whoever is the next caretaker of the car is, it'll be ready.

Ring service used to include re-cutting or shimming ring lands on worn pistons, and pistons with worn skirts were sometimes peened or knurled to "re-size" them. Using too much choke was a common cause of excessive ring wear, as was poor quality gasoline and dirty or low grade oil. Chronic pinging or detonation would cause damage also. The Depression and WWII caused a lot of neglect of maintenance and deferred repairs. Dirt road operation was also a lot more common then than now, and in some regions, blowing dust was a serious problem during much of the 1930s. Ford used to suggest that piston ring service might be needed at around 10,000 miles for the typical Model T. A pre-war Packard today with good pistons and rings and modern oils could be expected to run well beyond 100,000 miles with no significant engine wear if maintained properly. Pistons and rings improved considerably in the late 1930s, and have been greatly improved in the years since around 1950. Periodic ring and valve work and carbon removal are no longer routinely needed.

New rings cannot perform well on worn pistons or in worn bores.

Is there a good source for improved aftermarket pistons and rings for this motor?

Egge Machine sells both. The piston rings are made by Grant.

And you will obviously need to hone the bores.