3B Running Cold - Thermostat or Gauge?

[zakthor]

1984 canadian bj60.

More than 6 years ago it suddenly stopped heating up at all. I had it at mechanic for something else and he swapped in a new thermostat and it showed heat again on the gauge. He used 'a standard toyota part'.

But... the engine still never really gets hot and heater is marginal. Its been that way since I bought it in 2012.

On the temp gauge its never more than 1/3 way from the bottom. I had a second bj60 and it showed higher on the gauge and its heater worked a lot better.

How do I actually check the temperature of the engine? I have an ir heat gun and an instant read thermometer, but where exactly should I measure? And what temp should it read when its warm?

Is there a specific thermostat that is needed for the 3b?

 

[duncanrm]

B and H series engines run either 82° or 88° Thermostats.. Get OEM ones. The 82° part number is 90916-03026, its readily available.

As far as measuring the temperature. I run an "EngineGuard" dual thermocouple device. This gives me a digital readout from a bolt on the thermostat housing, and a bolt on the back of the head. With your IR thermometer, I'd be checking the thermostat housing personally, it's probably going to give you the best idea of coolant temperature.

With regards to your heater being marginal.. have you give it a good flush? Sediment can collect in them over the years.

Also.. living in Canada - I hear it gets real cold there. Its not unusual for old diesels to have a pull down screen in front of the radiator that is deployed in Winter to improve heating.

 

[bj70bc]

get a real gauge, there a port on the thermostat housing you can thread the sensor into.
Stock gauge is shiiit, 1/3 is normal, by the time your gauge says hot youve gone chernobyl on the thing (like rebuild time)

 

[David*BJ70]

get a real gauge, there a port on the thermostat housing you can thread the sensor into.

It’s been a very long time since I last installed a mechanical gauge (on the left‑side port of my BJ42), but as far as I remember, the gauge kit includes—among the various adapters—one that matches the OEM thread perfectly.

It probably won’t be easy to remove the plug. It might be wise to take off the housing and secure it firmly in a vise before removing the square‑head plug.

 

[Eurasiaoverland]

It’s been a very long time since I last installed a mechanical gauge (on the left‑side port of my BJ42), but as far as I remember, the gauge kit includes—among the various adapters—one that matches the OEM thread perfectly.

It probably won’t be easy to remove the plug. It might be wise to take off the housing and secure it firmly in a vise before removing the square‑head plug.

View attachment 4085558

The plug is secured with thread seal, so heat it first. I have a 14 mm square socket just for removing/installing these plugs, but if you have you use an adjustable spanner, it's easy to round them off.

 

[Eurasiaoverland]

And the thread on that forward-most port with the square headed plug is 1/2" BSPT.

 

[David*BJ70]

(on the left‑side port of my BJ42),

View attachment 4085558

I'm rereading my message… «left-side port» was referring to the port on the left in the image. It might not have been clear…