Topic: '39 thermostat, 160 or 180?


Classic1    -- 06-16-2015 @ 11:06 PM
  I am having trouble determining the recommended thermostat temperature range for a 1939 engine. I'm assuming that there are 160s in there now based on the fact that under normal circumstances, the temperature displays around the 160 mark. I'm also running a newer Walker radiator with a 7 PSI cap.

I am seeing arguments for and against the 160s. The most cited reason for not using 160 is that the engine temp never reaches sufficient temperature to burn off the crud. But it seems that at some point, Ford actually recommend using the 160s. Most of the thermostat discussion here is specific to 1940s vintage cars. I'd like to get information specifically for the '39.

Thanks!

Steve
'39 DeLuxe Fordor


TomO    -- 06-17-2015 @ 7:00 AM
  Ford recommended the 180 thermostats with permanent antifreeze and the 160 thermostats with the alcohol based antifreeze. My reference is the 1949-1951 Passenger car Shop Manual.

Either one will work fine in your car as long as you frequently drive it long enough to reach operating temperature and for at least another 30 minutes. 10-20 minute drives will not burn off the sludge forming contaminants, with either thermostat.

The oil temperature is what determines sludge formation. when it is too cold, moisture condenses and forms sludge. So the longer that you run your engine under load, the more moisture will evaporate and the less sludge will tend to accumulate.

Permanent antifreeze was pretty rare in the pre-WWII years, so the 160 degree thermostat was the only one that Ford installed in the cars in 1939. The 180 F thermostat shows up with an 11A prefix and a note that it was installed in about 10% of the 41 and 42 cars.


Tom


Classic1    -- 06-17-2015 @ 12:48 PM
  Is there any wisdom in using the 160 thermostats during the hot summer months when one tends to inflict parades and other torture to our old machines? Just wondering if the lower temperature gives a bigger cushion against overheat? Also, is 160 too low a temperature to get that good efficient burn in the engine?

Steve
'39 DeLuxe Fordor


len47merc    -- 06-17-2015 @ 1:22 PM
  Steve - I had similar questions to yours last summer, so I fashioned a temporary calibrated thermocouple and Fluke meter on my V8 that I could read from the interior while driving. In 95+ degree very humid weather, with 155 degree stats, the engine ran (on the road) 185-190 degrees throughout the rpm range. I changed the stats over to 180 degree stats and performed the same test, with the same results - 185-190 degrees and the same reading on the dash gauge. The car simply warmed-up more quickly with the 180 degree stats.

Bottom line, the only time the cooler stats make much of a difference is in cooler weather and for me even in cold (for NC) weather the heater temp is more than adequate with 155 degree stats. The dash gauge reads slightly above mid-point in the winter and slightly above 3/4 in the summer (170-175 degrees and 185-195 degrees respectively per my Fluke). Our motors run warm and basically, from my perspective, running either will still allow your vehicle to achieve the desired operating temp in warm/hot weather. IMHO 160s will not limit your engine to 160 degrees in hot weather - they only will open at 160 but your engine will continue to rise in temp to a designed temp, likely 185-195. In the winter the 180s will allow the car to warm-up more quickly and allow the engine to reach that temp in colder climates.

Put in the 160s and check your coolant temp after a good 30 minute plus drive in 95 degree weather (careful with the cap!!!) - you may be surprised by what you find and also have whatever concerns you have eased.

Steve


37 Coupe    -- 06-17-2015 @ 5:15 PM
  Good post from Len,basically what I found out and why I don't even run thermostats in the summer and I run about 180 degrees.


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