What's the ideal temp thermostat to be running in winter? I think mine's a 160 and the radiator is overkill so I don't think it really gets a hair above that, but I've yet to measure actual temp with a thermometer. Is that too cold?
Others will chime in soon But that sounds too cold. My 235 has a 180 degree. It runs great in our Hot summers and cold winters. As long as your cooling system is in top shape. -Todd
Tstats are not a precision valve. Look at the shop manual info. Opens @ 167 to 172. Another brand 157 to 162. You can go up to 180 but 10 miles down the road the wife may fuss that heater is not working.
"Adding CFM to a truck will only help at engine speeds you don't want to use." "I found there was nothing to gain beyond 400 CFM."
A thermostat sets the minimum operating temperature. Unless you live somewhere winter weather doesn't get much below freezing, a 160 won't get the coolant hot enough to make the heater work efficiently. Max temp is determined by the size and condition of the radiator, but unless you're pulling hard for a long time, a proper size cooling system in good shape should stay pretty close to the thermostat setting. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Does anyone know which thermostat will work with my 261? This one doesn't list 261 so I'd assume not. https://www.classicparts.com/1947-95-Thermostat-195-Degree/productinfo/89%2D032/ Hoping someone can point me in the right direction.
1950 Chevrolet 3100 (Ol' Roy) 1939 Packard Standard Eight Coupe (The Phantom) | 1956 Cadillac Coupe de Ville (The Bismarck) | 1956 Cadillac Sixty Special Fleetwood (The Godfather) | 1966 Oldsmobile Toronado (The Purple Knif) | 1966 Ford Mustang (Little Red) | 1964 Ford Galaxie 500 coupe | 1979 Ford F-100 | 1976 Ford F-150 (Big Red) | 1995 Ford F-150 (Newt)
high plains Use a 180 thermostat year round in 51 6400 (big radiator) runs 185 degrees highway or hot parade route year round good heater too that big radiator does good.
The link Gord posted is clear as mud, but I'm going to order this thermostat and see how it works. In my mind, it shouldn't matter if the bypass is open all of the time, even after thermostat opens, there should be much more flow through from the radiator to flood it and cool that smaller amount of antifreeze down right? Once I install it I'll know 100% if it still bypasses when engine is hot, once engine is warm, I can feel bypass hose and see if it stays hot. https://www.napaonline.com/en/p/THM155
You originally provided a link to a thermostat for a 235 so the intent was to warn you.
If the housing on your 261 was changed to a 235 housing, you would need a 235 thermostat. They do get changed - I have a 261 thermostat housing on my 235 and it was a PITA to get the truck cooling properly. There was no thermostat at all when I got the truck - I suppose the previous owner simply gave up. If the housing on your engine is a 261 housing, the thermostat you are purchasing looks right. I have a Stant 13928 180 degrees thermostat. Bypass has to be properly plumbed in or the temperature won't be steady.
The lower housing that was originally used on heavy duty truck applications with the 261 engine was intended to be used with an oddball "bypass valve" thermostat that hasn't been produced in decades. It had an extra threaded port for a large diameter bypass hose that kept the coolant circulating in the engine block during warmup. Once the coolant reached normal operating temp, that port was blocked by a flap valve incorporated into the stat. The diameter of the stat, the upper housing hose nipple, and the upper radiator hose was also larger than the one used on a 235 engine. Even if the correct housing can be located, the thermostat that works with it is unobtanium. If a heater core is plumbed properly, it serves the same purpose as the extra bypass hose, regardless of which size housing and stat is used, unless the flow through the heater core is blocked off by a control valve while the engine is coming up to temp. Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt! There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway Love your enemies and drive 'em nuts!
Gord I just meant that there's a lot of back and forth on it and it was hard to skim, once I went back and read through it I have it kind of figured out, thanks for the heads up!
Looks like the one I ordered will fit, doesn't look like it will allow any through to the bypass, ever, but like hotrod said, the heater will act as a bypass. The one that looks like a drain screen doesn't look like it shuts any flow to the bypass off. Does anyone know where the big thick O ring goes? It didn't come with one for the outside of the housing, the old one will work for that. Not sure how the new thermostat is supposed to stay together, it's split.
Thanks for the pic Gord, you saved my butt! The thermostat must have came apart in shipping. I easily pressed it back together by hand. Now I can see how it bypasses, just through the little slots.
The picture showing the housing was taken a few years ago. Since then, I removed the pipe plug and installed a hose adaptor. Originally, my heater did not have a shut off - it circulated the water always and I didn't want that during the Summer. After installing the heater shut off valve, I installed a hose from the new adaptor back to the pump so the bypass works properly.
I see, that's exactly how my setup is, when it's 110 degrees in the summer I don't need any extra heat coming off the heater... Thanks again Gord, off to install it now.
There is a thermostat sold today I would avoid. The name is "Fail-Safe". If your engine overheats, it locks permanently in the open position. I think you can figure out what happens next.
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end
The one that looks like a drain screen doesn't look like it shuts any flow to the bypass off.
There's a collar on the inside of the unit that moves down when the t-stat opens and closes the holes on the side. Put it in a pot of water on the stove and heat it up to see if it works. You can use the wife's cooking thermometer (as long as she doesn't see you doing it) to confirm opening and closing temps.
