Thermostat performance

Lately, according to the water temp gauge, the thermostat on my Cockshutt 540 is opening at 220-225, whereupon it drops to 160-180, then repeats within several minutes. I don't know what temperature rated thermostat is in there, nor whether it's vented, but would consider
it more normal to open at a lower temperature and stay thereabouts. Time for a replacement, or is this acceptable performance?
 
Sound like it is going bad for sure. Hottest thermostat I have ever sen was 195. Any temp above 212 is to hot since that is the boiling point
 
(quoted from post at 10:46:52 11/10/19) Lately, according to the water temp gauge, the thermostat on my Cockshutt 540 is opening at 220-225, whereupon it drops to 160-180, then repeats within several minutes. I don't know what temperature rated thermostat is in there, nor whether it's vented, but would consider
it more normal to open at a lower temperature and stay thereabouts. Time for a replacement, or is this acceptable performance?

Sounds like the temp gauge may be a bit "off" if the radiator is not boiling.

As to the "hunting", the thermostat may be failing.

Also, erratic temperature control can be a sign of combustion gas bubbles entering the cooling system from a leaking head gasket or a cracked block or head.
 
Is this happening in the first fifteen minutes to half hour after being started or is it happening after running with a steady load for an hour or more? Starting up with cold coolant will cause any engine to cycle through a few large swings on the coolant temperature gauge each time a new slug of cold coolant moves past the sensor, especially in cold winter temperatures. After the engine runs a while, all the coolant eventually cycles through the engine, the coolant temperature evens out and the temperature gauge fluctuates much less.
 
How close to the thermostat is the temperature gauge sensor?

Possibly the temp gauge is heating up sooner than the thermostat bulb.

If this is something new, I would replace the thermostat. Be sure the replacement is correct for the engine and be sure it has some means of bypassing a small amount of coolant when it is closed. Most have a small hole or a v notch cut in the disc.

Does the engine have a bypass hose? Some do, it allows the engine to circulate coolant within the engine until the thermostat opens. If it's there be sure it is not kinked or the fittings restricted internally.
 
Thanks for the replies - I?ll run it longer, with a load, and see if it levels out. Initial observation was right after startup - and it is gettin? cooler around here (east central Indiana)!
 

Get a temp gun and check temperature in several locations (top of radiator right beside the hose on metal, not the hose, engine side of the thermostat housing, and back of the head) as it warms. You didn't say it was blowing coolant out or steaming so your gauge may be failing.

If you replace the thermostat and it doesn't have a vent in the valve, I have been drilling a hole, up to 1/8" diameter in the valve. That helps get the air out of the engine when you fill it with coolant and the small flow it allows to pass helps the thermostat respond better.
 
A 50/50 antifreeze mix raises boiling point to 223 deg
A 70/30 antifreeze mix raises boiling point to 235 deg
 
Also pressure raises boiling point, 3? rise / 1# pressure. Eg: 10 psi raises boiling point 30?, 15 psi raises it 45?.

Willie
 
Altitude also matter. Things at sea level boil at a different temp then some place a mile high like Denver CO
 
As was mentioned, drill a hole. I usually go for 1/16", but 1/8" will also work. That hole will release any trapped air under the stat during initial install. After that it allows a small amount of heat to get to the stat bulb and allow it to more smoothly transition from closed to open and back again. By reducing temp spikes, the engine parts are much happier and will last much, much longer.
See Head Gaskets for an example.
 

While there may be some good points to drilling a small bypass hole in a t-stat in an old tractor, for those of us who live where it gets seriously CCCOLD, even a small hole will delay engine warmup.

A LOT.

More than you might think.

BT,DT.

It's common on newer cars for the t-stat to have a rubber seal that helps it seal TIGHT when closed, for faster warmup, lower emissions, and a longer-lasting engine.
 
(quoted from post at 23:58:02 11/11/19)
While there may be some good points to drilling a small bypass hole in a t-stat in an old tractor, for those of us who live where it gets seriously CCCOLD, even a small hole will delay engine warmup.

A LOT.

More than you might think.

BT,DT.

It's common on newer cars for the t-stat to have a rubber seal that helps it seal TIGHT when closed, for faster warmup, lower emissions, and a longer-lasting engine.


Yes a 1/8" hole will flow four times what a 1/16 hole will flow.
 
(quoted from post at 01:58:02 11/12/19)
While there may be some good points to drilling a small bypass hole in a t-stat in an old tractor, for those of us who live where it gets seriously CCCOLD, even a small hole will delay engine warmup.

A LOT.

More than you might think.

BT,DT.

It's common on newer cars for the t-stat to have a rubber seal that helps it seal TIGHT when closed, for faster warmup, lower emissions, and a longer-lasting engine.

Wouldn't the heater hoses in a car create a similar bypass situation?
 
That is not correct.

The area of 1/8 is 3.87 times 1/16, so take square root of that or 1.96 times the flow rate.
 
(quoted from post at 12:46:05 11/12/19) That is not correct.

The area of 1/8 is 3.87 times 1/16, so take square root of that or 1.96 times the flow rate.

What in the world kind of math are you using?
 
(quoted from post at 12:54:28 11/12/19)
(quoted from post at 12:46:05 11/12/19) That is not correct.

The area of 1/8 is 3.87 times 1/16, so take square root of that or 1.96 times the flow rate.

What in the world kind of math are you using?

ha -- Nevermind, it was mentioned already by the time i posted!
 
(quoted from post at 10:24:54 11/12/19)
(quoted from post at 01:58:02 11/12/19)
While there may be some good points to drilling a small bypass hole in a t-stat in an old tractor, for those of us who live where it gets seriously CCCOLD, even a small hole will delay engine warmup.

A LOT.

More than you might think.

BT,DT.

It's common on newer cars for the t-stat to have a rubber seal that helps it seal TIGHT when closed, for faster warmup, lower emissions, and a longer-lasting engine.

Wouldn't the heater hoses in a car create a similar bypass situation?

Certainly heat is "lost" though the heater from the engine, but circulating coolant though the relatively small heater core isn't the same as circulating it through the BIG radiator, which likely has cold outside air being pulled through it, IMHO.
 
(quoted from post at 14:23:56 11/12/19)
(quoted from post at 10:24:54 11/12/19)
(quoted from post at 01:58:02 11/12/19)
While there may be some good points to drilling a small bypass hole in a t-stat in an old tractor, for those of us who live where it gets seriously CCCOLD, even a small hole will delay engine warmup.

A LOT.

More than you might think.

BT,DT.

It's common on newer cars for the t-stat to have a rubber seal that helps it seal TIGHT when closed, for faster warmup, lower emissions, and a longer-lasting engine.

Wouldn't the heater hoses in a car create a similar bypass situation?

Certainly heat is "lost" though the heater from the engine, but circulating coolant though the relatively small heater core isn't the same as circulating it through the BIG radiator, which likely has cold outside air being pulled through it, IMHO.

My imagination was off. Thanks.
 

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