1991 350SD

The lower radiator host failed where reservoir connects to the hose. Lost coolant, and temperature wet up fast, but not too hot.

I replaced the radiator hose in the field and now the temperature is staying below 70C. It used to go to 85C. The temperature needle was also a bit jumpy at first, probably an air bubble.

When I filled the system I added 1 gallon of G05 antrifreze, and only about 1/2 gallon of water. I thought it would take at least 2 gallons. I am going to drain some coolant and add water.

Because the temperature is low, and rises slowly, my first thought is that the thermostat is stuck open. But, it could the the sensor be bad?

I filled the block and radiator directly from the top hose. I burped at the heater core line. The heater works with no gurgles. I drove it about 200 miles yesterday no problem. There are no leaks.

Could the >50/50 mixture cause the sensor to read wrong? (I would be surprised if it did).

Where is the temperature sensor? I want to make sure there are no gas bubbles there.

How can I test the temperature sensor?

I have a new thermostat and seal, should I just replace it?

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1991 350SD (updated rods)
Biodiesel B100 when I can find it.
Dino when really cold outside

Generally once the car warms up enough to activate the thermostat usually you can find space to add coolant. Exact mix should not affect temp gauge.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

When your coolant mixture is off, it's best to use a test strip, refractometer, or hydrometer to determine how much water or a/f to add.

You most likely have a problem with the thermostat. It may be that some debris is caught in the throat.

Where is the temperature sensor located?

I think there may be, or have been an air bubble in there based on how it was behaving.

__________________
1991 350SD (updated rods)
Biodiesel B100 when I can find it.
Dino when really cold outside

Also, is hose water so bad that I should replace the coolant now?

__________________
1991 350SD (updated rods)
Biodiesel B100 when I can find it.
Dino when really cold outside

It varies I think, some are right on the t stat housing, others nearby. The hose water is no emergency, change when convenient.

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Thermostat could have been damaged by the temperature spike I suspect. All of a sudden it had to open more than it usually did perhaps. I at least might suspect this.