Hello- what was the thermostat that came with a 1939 P-8? I have it running and it is
over just about 4 notches on the gauge. Also- is there a coolant additive that might be suggested?
What Antifreeze coolant is recommended? Thank you!!
There are two different thermostats in the parts book for 1939. For a 160°F thermostat for the P8 it lists part number 645494. That was the one used on the standard and roadking models from 1936 (and maybe 1935) through 1939. The Deluxe models used a 650048 up through 1948.
I believe, but am not sure, that the standar/roadking models like the P8 did not have an external bypass. If that is true then you can probably run the same thermostat I have in my 1933 which I picked up at a local auto supply store and was listed for a 1960s Chrysler/Plymouth 318 V8. For example a NAPA THM 91.
But if you have the external bypass setup like on the Deluxe models then the thermostat for a later Plymouth like a P15 will probably work. That would be something like a NAPA THM 55.
See the parts section on my website at https://www.ply33.com/Parts/numeric and https://www.ply33.com/Parts/group7#7-41-04
The 1933 Plymouth owners manual lists ethylene glycol as a suitable antifreeze so that is what I use in my car.
Tod- thanks for the info-I didn't know about your web page- it's great!!
I am going to post again-this time about a carb issue (I believe)- it really
increases RPMs when the chock is 3/4 closed- when its all the way open- it stumbles
the temp continued to rise on the dash- so I shut it off.
Thanks
Dennis
I am not a carburetor expert by any means but it does sound like you have an issue there. What have you done with the carburetor to try to address is.
Regarding the temperature rising, there is something fundamentally wrong as these engines don't normally have cooling issues. You might try some of these:
- Flow test the radiator (instructions in the factory service manual).
- Pull the core/freeze/welch/expansion plugs on the driver side of the engine and route out all the sludge that will have accumulated over the decades.
- An odd one that got me once: Water pump impeller loose on shaft.
Also, bad ignition timing and/or incorrect mixture can cause overheating.
Quote from: DENNIS P NOLAN on November 16, 2023, 11:01:58 PMTod- thanks for the info-I didn't know about your web page- it's great!!
It's listed in the POC's helpful web sites list ;)
Third site down, I'll move it up.
https://plymouthowners.club/members/links.html