round logo
Nat'l POC logo


Plymouth freeze plugs: When you’re hot,
you’re hot

By Pat Brost

The 1933 & ’34 Plymouth engine bocks have 3 freeze plugs, and the 1935 and later blocks have 5 plugs, due to the full waterjacket. These are supposed to be forced out if the coolant freezes and you forgot antifreeze.

Unfortunately, they decide to exit the block on their own on a nice sunny day when you’re going for a drive in the country.

I have a 1956 block in my ’33 convertible, and have had two of the plugs come out in the last couple of years. When the first one popped out, it was at night, and I tried to get as close to home as possible. In doing so, I ruined my temperature gauge. The large copper band in the back of the gauge (it has a name that escapes me) was damaged, and new ones are not available. I had a spare, and Bruce at Abbott Instrument was able to repair the gauge.

The second time a plug blew out, I pulled over and called a tow truck.
I have decided to replace all five of these plugs with the later ones that have a nut to tighten them. (NAPA part #600-4006.) While I had this done, I decided to replace the oil breather cap, also. This seems to be hard to find, so I used one that is close and looks good – NAPA part #703-1707.

The distributor body to engine block seal is cork, and probably only comes in an engine rebuild kit. It was broken in several pieces, and I found an “O” ring that fits tight but works. Seal Source in Portland has them: #MORN02500050 25mm I.D. x5mm thick. They have a ten dollar minimum, so I have 9 spares. See me if you need one.

While I had all five freeze plugs removed and the starter, distributor, oil pan & pipe, and generator removed, I also flushed the block to remove any sludge lurking in the bottom corners of the water jacket.

Stay cool, my friends!


"You're Grounded!"

By Pat Brost

These two words can strike fear into the hearts and minds of most teenagers, but when referring to our Plymouths, that's a good thing.

Some of the early 6-volt positive-to-ground cars connected the positive cable to the block or frame. If your car has never been restored or is an older restoration, you may need to check these connections.

Clean the metal surrounding the terminal and replace a bad cable or cables, and use a stainless steel nut, bolt, or lock washer.

The early cars that grounded their head- and tailllights through a grille shell or fender are especially prone to a poor connection.

Where possible, run a no. 16 wire (black or grey so it doesn't show) up into the headlights and solder or bolt to the socket base. Do the same for the taillights. Connect these wires and hide them in the car's frame, and then connect them together near the positive ground cable. Then run a larger woven ground strap from that wire connection to said cable. This might not be practical in all applications, but you will now have a good ground connection.

After doing this and you are working on your car and accidentally cause a short, your fuse will blow immediately instead of bubbling for 5 or 10 seconds while your wiring is burning. If you early car has no fuse, install one near your amp gauge.

If your car has been restored, sometimes too much paint can get in the way of a good ground connection. You may wish to add a medium-sized ground strap with an eye at both ends to the engine or transmission and then to a clean connection on the frame.

Another very important item is a large or marine-type shutoff switch in the battery circuit. This can sometimes be hidden, and will protect your battery from possible drainage.

Stay grounded, my friends!


Back to the list of stories.