160 Degree Thermostat

[Tom H.]

I saw in the responses to the overheating 57 that some of you are running 160 degree thermostats. I currently have a 190 that seems awfully hot. I was thinking of putting in a 160. Is there any downside to running a 160? My car is a single carb three speed.

Thanks

[Wayne M.]

Re: 160 Degree Thermostat

I saw in the responses to the overheating 57 that some of you are running 160 degree thermostats. I currently have a 190 that seems awfully hot. I was thinking of putting in a 160. Is there any downside to running a 160? My car is a single carb three speed....

I don't have the shop or owners manuals for a '57, but the P&A30 catalog for July 1965 seems to allow (for '38-'59 Passenger and Corvette) a 160 deg (poppet pellet type) # 3156260 (pic below). They also state '38-62 pass. & Corvette 170 deg #3156270, and for '38-'65 All, (incl.) Corvette, the 180 degree # 3156280 (all poppet pellet type).

So I guess it's whatever suits; but definitely the earlier C1 Corvettes were not shipped with 180 thermostats.

[John H.]

Re: 160 Degree Thermostat

I was thinking of putting in a 160. Is there any downside to running a 160?

Tom -

Excerpt from my "Beatin' The Heat" Corvette cooling article that was in the Michigan Chapter "Vette Signal" magazine in the goodie bag at the National last week:

Thermostat: This is probably the most misunderstood component in the cooling system; thermostats have absolutely nothing to do with controlling maximum engine operating temperature. Period. What does

If you have a 180 thermostat and your engine operates at 220, changing to a 160 with a 180 thermostat), changing to a 160 thermostat may result in reducing your operating temperature to 160, but this is rare except in cold weather. Furthermore, 160 is too cold; OEM testing has proven that the rate of cylinder bore and piston ring wear at 160 is double the wear rate at 180, and a coolant temperature of 160

[Stuart F.]

Re: 160 Degree Thermostat

My 63 L-76 had run a 160* thermostat soon after the day I took delivery (old school). I only recently allowed myself to be convinced by this discussion board to up it to 180* on my last drain and flush. The first 180* thermostat turned out to be a diaster in that it stuck closed causing a super overheat, pucking out all my new coolant (It was a Chinese made Robertshaw type, Mr. Gasket). Being an L-76 with by-passes, the engine suffered no damage. I since changed to a better made Robertshaw type from a noted Vette Parts vendor. It works fine, but I see very little change in the typical readings on my temp gauge - only slightly higher, but not at 180* full warm. My IFR gun confirms this as I do a complete spot check after every cruise.

Stu Fox

[Wayne M.]

Re: 160 Degree Thermostat

Appreciate the advances in chemistry since 1957 to 1965, but as a "restoration" organization (emphasis on the "R" in NCRS), shouldn't a sniff of the antifreeze be in order; to determine alcohol-base (TFP) or glycol ? [points deducted accordingly].

I see that during operations check [at least per the '65 TIM&JG], : "gauges checked for apparent proper function are .... temperature... (etc).... Unusual gauge readings ... should be noticed and scored."

Depending on ambient temperature of the judging field, I would not expect a '57 Corvette to read 180 degrees at the conclusion of engine-run operations.

Said only partly "tongue-in-cheek"

[Adam S.]

Re: 160 Degree Thermostat

170 is the best choice in Southern weather, motor is half way heated up over night in summer and very mild winters, Northern weather 180. What I have experanced is cooler climents need that thural warm up when batteling the cold to reduce ware as explained in detail thread from John.

[Alexander C.]

Re: 160 Degree Thermostat

I have a 180 in my '56, I wouldn't use anything else.

[Donald O.]

Re: 160 Degree Thermostat

Tom -

Excerpt from my "Beatin' The Heat" Corvette cooling article that was in the Michigan Chapter "Vette Signal" magazine in the goodie bag at the National last week:

Thermostat: This is probably the most misunderstood component in the cooling system; thermostats have absolutely nothing to do with controlling maximum engine operating temperature. Period. What does it do? At cold start, it blocks the flow of coolant out of the engine until the trapped coolant reaches the thermostat’s rated temperature, at which point it opens and permits coolant to begin circulating; this aids rapid warmup, which reduces cylinder bore and piston ring wear by bringing the engine up to operating temperature relatively quickly. Once it’s open, it modulates the flow of coolant through its calibrated restriction so coolant temperature never drops below its rated opening point, assuming the cooling system is efficient enough to cool the engine down to that level. During the winter, the thermostat modulates flow to ensure that the coolant stays at or above its rating point for optimal heater/defroster operation. In most cars, it’s essentially wide open all the time, and only the heat transfer efficiency of the radiator and the airflow through the radiator determine the engine’s maximum operating temperature.

If you have a 180 thermostat and your engine operates at 220, changing to a 160 thermostat won’t change your operating temperature one bit – you need more radiator, more airflow, or both, to reduce operating temperature. If you have an extremely efficient cooling system with more heat rejection capability than your engine needs (runs at 180 with a 180 thermostat), changing to a 160 thermostat may result in reducing your operating temperature to 160, but this is rare except in cold weather. Furthermore, 160 is too cold; OEM testing has proven that the rate of cylinder bore and piston ring wear at 160 is double the wear rate at 180, and a coolant temperature of 160 won’t let the oil in the pan get hot enough to boil off condensed moisture and blow-by contaminants, which then remain in suspension and accelerate the formation of acidic sludge. 160 thermostats were specified in the 1930’s for the old alcohol-based anti-freezes, which would boil off and evaporate at 185; there’s no other reason for them.

John,
There you go giving out facts and dispelling the myths. So many car enthusiasts have no clue as to what the T'stat does and believe all of the misinformation. Maybe they need an electric water pump flowing 500 gpm without any T'stat.....yeah, that should solve all of their overheating

DonO

[Stuart F.]

Re: 160 Degree Thermostat

Q) OK all you heat transfer guru's; if an engine in a typical Vette is run w/o a thermostat, why is it more likely to overheat?

A) The thermostat acts like sort of a brake to slow the flow of coolant through the radiator so that it has a chance to cool. If allowed to flow through the entire system at the high GPM of your hypothtical electric water pump w/o a thermostat, the coolant very likely will not spend enough time in the radiator to transfer it's heat. Even racers at least use an restriction orifice in place of thermostat to accomplish the same purpose.

One would be surprised how many commandoes have trouble with that concept.

Stu Fox