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Coolant temperature in cold weather

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Rick60

Rick60

Senior Member
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Hi all,

on a lately trip with my BT7 (outside temperature around 32 deg F) I noticed the temperature gauge not showing more than 120 deg F.
I was not too concerned about it cause I know the PO had disturbed the thread where the temperature sensor is screwed in. A new thread was made in the engine block, but not the correct size. He screwed in a small tube, about 2 inches long, with the correct thread on the other end, where he screwed in the temperature sensor.

I think at that point you all got it. The sensor isn't located directly in the stream of the hot coolant leaving the engine and is exposed to the air entering the engine bay. The colder the outside temperature, the less temperature is indicated. On hot summer days I can get an indication of about 160 - 180 deg F.

Does anybody know a solution for this problem? Is it difficult to "rethread" the original thread without taking the engine out?

Thanks as always for your thoughts.

Regards
 
Rather than risking any further damage to the modified threads in your block, you may want to consider having a threaded piece soldered into the radiator. Any good radiator shop should be able to do this. Many of the smaller Austin Healeys (Sprite) use this method (with the same type of sensor and gauge. One note of caution: if you choose to do this, be sure that the sensor is located low enough in the radiator so that it is fully submered in coolant.
Another idea might be to replace the upper radiator hose with two shorter hoses. Joint them with a steel sleeve and put the threaded hole (for the sensor) in the sleeve. Some Renault cars use a system like this.
 
Hello Rick,
while not ideal, it is still registering. Your coolant temperature is likely to be down anyway due to the low ambient. You can either blank off a part of the radiator or get a higher temperature thermostat and see what readings you get. You can also check the coolant temperature by putting a thermometer into the radiator neck to see what your coolant temperature is.

Alec
 
[ QUOTE ]
Your coolant temperature is likely to be down anyway due to the low ambient. You can either blank off a part of the radiator or get a higher temperature thermostat and see what readings you get.

[/ QUOTE ]

I installed a new 180 degree thermostat this past spring but the car runs cool on cold days--today was a beautiful day with temps of about 45. I went for a long ride and temperature never broke 150, though the heater was putting out fairly well.

Cold in the winter and hot in the summer, but wonderful nevertheless!
 
Rick60;
Keoke, is just curios.Feel up under the radiator tank at the top and see if there is not a capped fitting there.This was used to locate the temperature sensor prior to it being installed in the block.-FWIW
 
[ QUOTE ]
[ QUOTE ]
Your coolant temperature is likely to be down anyway due to the low ambient. You can either blank off a part of the radiator or get a higher temperature thermostat and see what readings you get.

[/ QUOTE ]

I installed a new 180 degree thermostat this past spring but the car runs cool on cold days--today was a beautiful day with temps of about 45. I went for a long ride and temperature never broke 150, though the heater was putting out fairly well.

Cold in the winter and hot in the summer, but wonderful nevertheless!

[/ QUOTE ]
Michael,
I found a similar situation after installing a "super" radiator. It struggles to get the winter temp up to 160 even with the 180 thermostat. The heater serves as a very effective thermostat bypass. The 160 is ok, but I would like to have it hotter. Some of the big trucks have air shutters on the radiator for cold weather. I think I'll just live with it. Fooling with radiator blanking just doesn't appeal to me. I have tried it for cold weather & it does work. The benefit of the good radiator is that it rarely goes over 190 in very hot weather.

Aside - I don't really think that the old cars were designed to run at 200 plus like the newer cars are. Although many Healeys do run at high temp. with acceptable results, at least short term.
D
 
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[

Michael,
The 160 is ok, but I would like to have it hotter.

Aside - I don't really think that the old cars were designed to run at 200 plus like the newer cars are.
D

[/ QUOTE ]

Dave--

The oil coolers on most diesel engines are designed to maintain oil temps at or above 220 and I have read that it is important to get oil temperatures up high enough to cook out any moisture condensation. Plus, engines operate more efficiently when running at their designed temperature--whatever that is--and I think that's why a lot of trucks, etc. have shutters or shrouds over the radiators.
 
Michael,
You are kind of mixing subjects. Oil temperature is not very closely related to water temperature. After warm up it will be at a minimum of the same as water temp. & quite a bit higher if the engine is doing any work.

Since diesel engines are heat (compression) ignition engines they are designed to run hot & will benefit from it.

I agree with your second point, but just think that the older "designed" temps. were lower. New vs old gasket material compositions for instance, or newer & vastly different combustion chamber designs that tolerate higher engine temperatures on low octane fuel.
D
 
Well lets see,I think controlling the "Thermal Efficiency " in a diesel engine could be be accomplished by controlling the oil temperature sure aid combustion if operating at low temps.On the otherhand,the "Thermal Efficiency" of the big Healey engine was related to me to accur at a temperature of about 185 Degrees F. This point represents the practical limits of the engine and its oil. Having an extensively modified cooling system I miss this temperature point too unless ambient is up around 110 in the summer and the engine is under load.-FWIW---Keoke
 
Rick60, I had to study your post a bit. I do not think your engine is running that far off the mark given the temperature ranges you are running in.However, it seems that you only need to shorten the tube the PO installed . Oh say cut it down to about an inch and rethread it to be compatible with the thread in the block.That will put most of the bulb in the water and reduce the amount exposed outside the engine block. OH! use Pimans suggestion to verify the temperature.-FWIW---Keoke /ubbthreads/images/graemlins/cheers.gif
 
Rick, for a quick fix and to test your theory, try insulating the connection into the block. Tape it on well, you don't want it coming loose in the engine bay. It will at least give you an idea one way or another.
/ubbthreads/images/graemlins/cheers.gif /ubbthreads/images/graemlins/england.gif Bob
 
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