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Howdy,
Can anyone identify the part number for the correct thermostat for a 1933 model 33 roadster? My manual had a hand written note in it indicating the correct ‘stat was a Stant S-344-160. That is not a good number anymore. I also have a number CT-53878 but can’t find that one either.
Many thanks!
Chris MacAllister
If you enter in your Stant S-344-160 on http://www.autopartoo.com you will find interchange info to Gates 33386 and Stant 13446, both which are listed for sale on e-bay.
Hi Chris.
I was looking at the Stant part number that found and noticed that it is a 160 degree thermostat.
After living in Texas for 25 years, I am all about motors running cool!
That being said, you might want to increase the temperature of the thermostat to 180 degrees for better performance of the engine.
I too came across the need to change/replace the thermostat in our Series 33. To my surprise, a 195 degree had been installed years ago (..this would explain why we nearly always overheated when pulling long grades). After doing some research, the only Pierce-Arrow literature I could find that talked about the thermostat in a dual value six was for the Series 36. It stated to use a 180 degree.
The theory is the warmer the engine, the better the fuel with atomize through the carburetor and into the cylinder chamber giving a more complete explosion in each cylinder to maximize performance.
Interestingly for our car, the original type/style was discarded years ago. Somewhere in its survival a brass plate was fabricated which allows a modern thermostat to be soldered on. This is a nice feature as the price for this style thermostat is a few dollars and can be easily changed if there is a problem. Lastly, I drilled a small 1/8″ hole on the outside edge of the thermostat to allow a “by-pass” so there will always be some water the flows.
Our car is performing very well with the thermostat at 180 degrees. Plenty of power while watching the Motormeter rise and fall to the conditions of the road.
Enclosed is a picture to the front and back of the brass thermostat plate that was made for our car.
Ben Oakes
Ramona, CA
Thank you both for the information! I’ll order 160 and 180 stats and try them both.
Happy motoring!
Chris
Once the thermostat is fully open it shouldn’t matter what its temp opening is. If you are overheating pulling a long grade and the temperature is over 200 it should be fully open and doesn’t matter what temperature it became fully opened. The higher opening temperature just means it will delay the thermostat opening and get to the point of overheating sooner. Sorry, that’s confusing. I wouldn’t count on the water temperature having much influence on the temperature promoting atomization. The main advantage as far as I am concerned with running a hotter thermostat is reducing the wall quenching during combustion that leads to more carbon deposits in the cylinder. A study years ago indicated cylinder wear was significantly greater with 160 degree coolant than 180.
Probably a bigger factor in whether a thermostat helps or hurts overheating is how much restriction there is when it is fully open. It is a balancing act between more flow picking up more heat in the engine which the radiator must reject. If the amount of cooling air through the radiator is the limiting factor then more coolant flow increases the heat picked up by the engine that the radiator must reject with its finite amount of cooling air. The many discussions over the years in the PASB’s where members put restrictions into the water passage to reduce temperatures suggests that is often the case for Pierce Arrows.
Jim
Chris,
To dovetail on Jim’s comment, once the thermostat is open, the coolant temperature goes up to whatever the radiator allows as effected by load and ambient air temperature.
The 1925 P-A cars have non-pressurized systems, so the coolant temperature goes wherever it wants.
If you are running ethyl-glycol coolant, that could be the problems, as it FOAMS in non pressurized systems.
When it foams, it hits the overflow tube and then starts siphoning off.
When it siphons off, you can lose a significant quantity / volume of coolant, thus reducing the quantity of coolant remaining in the engine / radiator, ergo causing overheating.
On my 1925 Series 80, I run a combination of distilled water and NAPA-Kool.
The NAPA Kool inhibits corrosion and does not foam.
I can still run hot, but it is not as severe as in times when I used ethyl-glycol coolant.
I also flush my cooling system with water every year to remove CRUD and such.
I usually just use water for the flush, but that depends on how CRUDDY the old liquid is when I dump it.
I then refill with the NAPA-Kool and distilled water.
You may also have the original type water pump seals (grease and packing) and that can cause a problem, as the hot water melts the grease and it migrates to the bottom of your radiator.
If you have not removed and seriously flushed your radiator in years, or ever, you need to do it.
For that operation I bought many (6+) gallons of Commercial Grade Vinegar (20% or 30% acetic acid).
I put the radiator on a set of saw-horses, warmed the vinegar bottles in a tub of hot water, used rubber bungs to plug the various inlets, and then poured in the vinegar and let it sit for 20-minutes.
I then flushed the radiator with a garden hose (from the bottom inlet) for 10 to 15-minutes to remove all of the vinegar.
The car ran cool as a cucumber for years.
I also had my water pump and fan hub redone with sealed bearings so there would be no grease migration.
Think about it.
Peter
Since my car has no thermostat in the cooling system (1931, the thermostat is the shutter mechanism in front of radiator), I did slow the flow of the water. I would be driving at speed, and taking foot off the gas would cause water to overflow the radiator (velocity of water going to top tank versus amount being pulled away by pump?). I took a freeze plug the diameter of the upper radiator hose, drilled a 5/8 inch hole in it, and inserted at top of hose. This works great on my car.
I had a terrible foaming issue on one of the tours. If your car foams, the first thing to check is water pump. The grease in mine was basically gone, so air was being pulled into the system around the shaft. New water pump grease, and foaming problem disappeared.
Hats off to the fine comments on this subject. I know of a Model 33
that has been in the same family since it was new. It was a graduation
present. The car has been overheating since it was brought home and
P.A. service couldn’t cure the problem. I wonder if application of
some of this advice would effect a solution?
The original 160 degree thermostat used in the Series 33 was at that temperature due to the alcohol based anti-freeze used at the time. The alcohol would boil off at a temperature just about 160 degrees. Using a modern thermostat in my Series 33, there was a problem with the mushroom on the thermostat bending because of the pressure that the water pump put against it when the thermostat was closed. This was cured by drilling four 1/8 inch holes in the mushroom to allow some coolant to pass by while the engine was warming up.
Thanks to all for their input!
I just returned from a 3 day tour with the model 33 and it ran beautifully up and down the hills of western Pennsylvania! It did push some coolant out of the radiator going up steep hills but no more than a gallon. I would refill and it would push some out, etc. I suspect I had the radiator too full so that when the coolant expanded it went out the overflow tube. Since I did not have a thermostat I put in a restrictor plate with a 5/8th inch hole in it. This worked well. While testing the car prior to the tour it would push gallons out after a hard run. The problem was what David Coco suggested; air being sucked in through the water pump grease cups was “pressurizing”” the unpressurized system and forcing coolant out. Pipe plugs solved this problem in place of the grease cups. Fitting sealed bearings is the next step.
Do other model 33 owners find the brake pedal pressure required to stop quickly to be super heavy! My right leg grew 2 inches on this tour!
Many thanks for all your suggestions!
Chris”
I am wondering how much of this problem over the years is really from air entrainment or foaming of antifreeze. I have spent some time theorizing about the heat balance and the effect of a restrictor plate on making a car run cooler, but it occurred to me that it could be much more basic than that.
Pierce’s seem to be well known for having a lot of flow and pressure out of their water pumps. I put a thermostat with some small holes in my 845 for initial startup before the shutters are installed. The backpressure blew through the water manifold gaskets – first cork then silicone Ultra. I’ve never had this happen before.
On the flow side, if the Pierce radiator tubes were marginal in simply handling the design pump flowrate to start with when new, then any restriction in the radiator such as minor gunk coating or plugging of tubes, or tubes tied off to solve leaks, will back the high flow rate up into the upper tank and overflow. Once several quarts are lost less of the radiator becomes effective and overheating can result.
Just a thought.
Jim
It seems that Pierce’s engineering was to have a high flow waterpump pulling strongly on the bottom outlet pipe of the radiators, so that the upper tank would not fill up and overflow. It works if everything is new or in good condition.
However, if the lower radiator hose is soft, or was replaced and the anti-collapse coil spring not transferred into the new hose, the lower hose will suck flat, and starve the engine for any coolant flow. This happens often unfortunately.
The other problem created by the high suction from the water pump is that you can have a snug hose clamp on a hose such that it will not drip or leak coolant, but under the strong suction, will draw air into the coolant, the resulting mix of coolant and bubbles allows coolant to flash to steam when it goes past hot spots like around the exhaust valve seats and ports. The combination of expanding steam and air bubbles makes the volume of the mix too much for the top tank of the radiator, and the excess goes out the overflow.
The other source for air leaks is the water pump packing on the shaft, A similar situation with the ‘snug’ hose clamp: The packing may not leak or even ‘drip’, but will let air into the pump under strong suction. The correct heavy water pump grease often fixes this air leak.
Greg Long