• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

Normal operating temperature for a B20

spock345

Well-known member
Joined
Nov 3, 2016
Location
Livermore, CA
Does anyone know what the normal operating temperature is for a B20? Also when the ether-tube 122s gauges are out of spec do they tend to read warm or hot?

The car reads a bit warm at the gauge but I am inclined to believe it is the original gauge.
 
Get a non contact thermometer check all around the engine It would depend on the thermostat, If you cooling system is in good shape you can run a 195 degree thermo, the higher the thermo the better the cold incoming air will expand. On my V8 Wagon I run a 180 thermo some times that isn't hot enough when the weather is cool[radiator is too big].
 
Right now I am running an 82 C thermostat (180F). The gauge right now sits at the 90-ish degree mark at idle and drops a bit to what I assume to be 82-85 when moving. Judging by the tiny calibration marks at the top of the gauge.

The B18D that used to be in the car had a 70 degree thermostat for whatever reason and ran rather cold, a bit too cold for my liking. The engine came with what seems to be a 195 thermostat but the stamped numbers are difficult to read so I decided to start fresh with a new one.
 
I wouldn't really worry about what that stock gauge is doing. Maybe take it out of the engine, stick it in some hot water and double check it with a thermometer? They're usually wildly innaccurate unless they've been rebuilt/recalibrated at some point.
 
I have a 1971 B20E with the 82 C thermostat. The thermostat starts to open at 82C and is not fully open until around 90 C. Keep in mind that on the B20 the temperature gauge is located at the back of the head. As a result at idle speed the coolant temperature at the back of the head always runs hotter than the coolant at the front of the head where the thermostat is. My B20E has been retrofitted with Megasquirt so I can measure the temperature using the old D jet sensor located at the front of the head and I have a calibrated Speed Hut electronic temp gauge in the fitting at the back of the head. On a day when it is 20 - 25 C ambient after idling at a stop light for a couple of minutes there is easily an 8 C rise from the from the front of the head to the back of the head so if I am running 88 C at the front it will be around 96 C at the back. On really hot days at a stop light the front temp can bump to the mid 90s (my fan turns on at 92 C) and the back can be over 100 C and it all settles back down to normal as soon as the engine speed picks up after the light turns green. In the summer, when the car is moving at above 50 km/hr the coolant temp gauge is usually reading in the 87 - 88 C range.

Before I put the car away for the winter I was driving around when the temperatures were around 0 C. On the highway at 100 - 110 km/hr it was a struggle for the engine coolant gauge to reach 80 C with the interior heater going full tilt.

Assuming the temperatures in Santa Cruz are not 0 C, your temperature of 90 C at idle dropping to 82 - 85 C when moving seems to be reasonable for an 82 C thermostat.
 
I have a 1971 B20E with the 82 C thermostat. The thermostat starts to open at 82C and is not fully open until around 90 C. Keep in mind that on the B20 the temperature gauge is located at the back of the head. As a result at idle speed the coolant temperature at the back of the head always runs hotter than the coolant at the front of the head where the thermostat is. My B20E has been retrofitted with Megasquirt so I can measure the temperature using the old D jet sensor located at the front of the head and I have a calibrated Speed Hut electronic temp gauge in the fitting at the back of the head. On a day when it is 20 - 25 C ambient after idling at a stop light for a couple of minutes there is easily an 8 C rise from the from the front of the head to the back of the head so if I am running 88 C at the front it will be around 96 C at the back. On really hot days at a stop light the front temp can bump to the mid 90s (my fan turns on at 92 C) and the back can be over 100 C and it all settles back down to normal as soon as the engine speed picks up after the light turns green. In the summer, when the car is moving at above 50 km/hr the coolant temp gauge is usually reading in the 87 - 88 C range.

Before I put the car away for the winter I was driving around when the temperatures were around 0 C. On the highway at 100 - 110 km/hr it was a struggle for the engine coolant gauge to reach 80 C with the interior heater going full tilt.

Assuming the temperatures in Santa Cruz are not 0 C, your temperature of 90 C at idle dropping to 82 - 85 C when moving seems to be reasonable for an 82 C thermostat.

That makes a good deal of sense. My engine was once D-jet and I have another space for an auxiliary gauge (alongside volts and oil pressure) so I may put a water temp gauge in and install the sensor in the hole at the front of the head.
 
Back
Top