Packard Forum Index » Post-War (1946-54)

Follow Owens excellent advice.

The piston with the hole in the top just over the ring is either due to running too lean due to a bad head gasket OR some extreme bellmouthing (taper condition is different) of the cylinder.

Just because there is no ridge does not mean that hte cylinder is not bellmouthed severely. A previous owner may have simply cut the ridge and ignored any bellmouthing of the cylinder.

Bellmouthing (seperate from taper) occurs at the very upper 1/2 inch of a cylinder just below the bottom of the ridge. It is caused by continuously placing severe performance demands on the engine as soon as it is started. i.e. not allowing engine to warm up ANY before hitting the hiway at speed.

What an interesting combination of damage and failure. I really expected to see more damage to the piston with the 0 psi reading you reported. Very surprising that small amount of ring land / crown missing and a valve stuck open only that much would be that catastrophic.

I to would agree on replacing pistons as a set. One very good reason is it seems in most cases they are being equipped with modern rings. They are (in the case of my 320) smaller and more efficient. The result is much better performance, longer lasting, and less wear on the bore and rings themselves.

What ever way you go, Dave (O-D) has offered excellent advice.

Sorry to see you will have to replace the piston, but glad it was not worse.
Jim

I fear you will find that the cylinders are quite bellmouthed as PackardV8 mentions. I also fear that your upper ring grooves are much larger than the rings. #8 was merely the first to escape. Anyway take your time to do some carful measuring. The headgasket and the amount of oil in the cylinders shows she is ready for some serious loving. The pitting on the intake valve is likely due to some water getting into the cylinder from a seeping head gasket--but do look carefully for a crack.

Well, thanks for the advice so far, that's why I'm posting pictures and asking for opinions. I will look more into the kits from kanter or egge, and get some more measurements of the bores. I guess if one cyl let go, it makes sense that the others are not too far behind, and replacing things as a set if more expensive does seem smart.
Is it only reproduction pistons that have the dimple in the center, or were original packard parts like that also? I'll measure the bore to see if the engine has already been overbored, I thought the pistons might be an indication of a previous rebuild.
I plan on towing the car to a shop this weekend and hope to dig a little deeper. Summer is going by fast.
In the past the car wasn't much of an oil burner or smoker. I had run 20w50 for a few years, and one year I changed to 15w40 and the car smoked for a while, and then cleared up. Didn't think much of it. I at least warmed the car up pretty easily, can't say if the previos owners beat on it or not.
Cheers all! Tobs
I'll look into having things proofed for cracks when apart also. There are some good machine shops here, just not on every corner.

I have seen a broken piston above the rings caused by a broken top ring. If the top ring is broken that would explain zero compression. The top rings can break because of bore wear or hitting a ridge.

When I did a ring job on my 288 engine I got replacement rings for the factory pistons from Egge. They worked just fine.