Re: Engine Thermostats - Old vs. New

Posted by TxGoat On 2023/10/6 8:47:25

It would be interesting to compare wide open flow rates, at some specific pressure differential, between"modern" thermostats that will fit and the original style. I put a "modern" 180F stat in my '37 120 and it runs substantially hotter than it did with a 153F bellows type. It appears to have a more restricted flow capability, just looking at it. I drilled a 3/32" bypass hole in the flange to allow air to escape when filling the system. I suspect that my radiator is partially clogged, although water is not pushed out the overflow at higher speeds when the radiator is filled to the top. I have reason to suspect that both the car's temp gauge and my hand-held temp gun are inaccurate. The dash gauge can reach 200 F with no sign of boiling or afterboil in 100F weather. System is not pressurized, and coolant is plain water.
I got a reading yesterday of 245F on the crankcase area on the camshaft side, which I found implausible. Pouring water on the area showed no indication of boiling or excess heat. If the cast iron surface had been anywhere near 245F, it would have been immediately apparent. I would urge anyone to use the correct type thermostat in any application, and especially in old cars with non-pressure systems, and in any flat head Ford V8. The water tubhe on my engine has been replaced at some point,but I have not examined it. Water pump is a new Kanter unit that appears to be well-made and identical to the original. Elevation here is about 1200 ft. Radiator air passsages are clear. I can't see the top of the radiator tubes. The radiator does get hot all across and top to bottom.