3b time to reach temp idling (1 Viewer)

[MTNRAT]

Well this 3b runs cold. Even after 20 min at 1500 rpm (hand throttle), the coolant is still only 135 degrees. That is with the front and rear heat on as I am trying to get the heating system working well for winter. Previous owner froze every winter. I found the front heater valve would only open a little and the rear was frozen shut and the rear blower did not work. All that is working great now, but the engine runs cool. Even put the winter radiator shield down. It has an aftermarket 82C thermostat that I checked in a pot of water with a candy thermometer. If anything it opens wide at about 90C. Either way the engine wouldn't get hot enough to open a thermostat anyway. It has a turbo as well. Any thoughts.

 

[dcruiser666]

I assume you have an aftermarket gauge because you recorded the actual temperature. Where's the sensor installed? Factory position can give low readings if your coolant isn't filled to the max or fully bled, as well if you don't use the rubber o ring around the thermostat it will run cold for longer because fresh coolant can move around the thermostat almost as if it wasn't there. That o ring is made for this but isn't shown on parts diagrams, I think it's absolutely necessary for proper cooling and possibly a Toyota mistake to omit it. There is also a feature on the factory thermostat that blocks the lower passage on the housing when it opens. I have heard of 3bs running cold because an aftermarket thermostat was used that fit fine but didn't have this part, see photo.
Oring-

1634156030 Toyota GASKET, WATER OUTLET, Price: 1.52$, Weight: 0kg - PartSouq - Auto Parts Around the World PartSouq Auto Parts Around the World

1634156030 Toyota GASKET, WATER OUTLET, Price: 1.52$, Weight: 0kg - PartSouq - Auto Parts Around the World PartSouq.com Auto Parts Around the World

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Is it still cold after you've been driving for a while? Also if you have the type without a viscous fan they take a very long time to reach temperature idling, in my experience.

 

[MTNRAT]

Actually don't have an aftermarket gauge. Even after running for 20 min at 1500 rpm I can still just take off the radiator cap or the cap on the thermometer housing and stick in a candy thermometer and measure the temp. There is no rubber o ring and the thermostat looks after market and definitely not like the one shown. See attached. Says 82C on it for temp. Put it in a water bath and it didnt fully open until over 90C.

 

[Squash]

Unfortunately at idle our engines will cool down quickly, a diesel needs to work in order to produce heat.
Next thing is to unclip the water control valve and manually move it through the range.
These valves are old and may not cycle completely because of gunk or cable adjustment at the firewall. Really pay attention to getting the valve fully open and make sure it's fully open when finally clipped in to the cab controls.
Another issue is the blend door under your glovebox. Again lay on your back, grab a light and check that the blend door freely moves from open to closed. Sometimes it's the cable and sometimes both the wire(cable) are gunked and/or corroded. If corroded spray your favourite penetration fluid and cycle everything manually because you will have disconnected the components.
I drove my 3b from Ontario to Alaska and the Arctic Circle during a ski jaunt, a 3b makes tons heat when driving.

 

[MTNRAT]

I have already taken the water control valve out. It was stiff as hell and I soaked it in sunlight and lubed the pivot point. It works very smoothly now and the rubber seal inside is in good shape. Will check adjustment. Did the same for the rear heater. Blend door is working easily and seals well.
I feel a little stupid though as I didn't say that the truck is just the chassis and drive train so the engine is wide open to the air. Might make a difference. No insurance, but we have been driving it up and down our rural road and it doesn't get very warm. The previous owner complained of poor heat, but we found the front water control valve was barely opening and the rear was frozen shut and the rear blower motor wasn't working. All that is rectified as well as the heater cores checked for flow, so I am sure when the engine temp issue is fixed we should have good heat.
I am going to get the proper Tstat and o-ring. Make sure the cooling system is burped properly an go from there. Oh and maybe put the body parts back on once they are painted. lol.

 

[roscoFJ73]

Diesels run cold at idle and will not get warm enough to heat the car in winter conditions. Either bump the idle up to 1000rpm+ or give it some rpms.
And yes, having the engine in an unenclosed engine bay is not going to help it warm up.
And try leaving the heater shut until the engine is warmed up. The heater matrixes are like little radiators and if open will keep the engine cooler for longer.

 

[AussieHJCruza]

Pretty normal for a diesel to not make much heat idling/no load running and IMHO it's not conducive to keeping the cylinders not glazed.

 

[MTNRAT]

Update. Put in the proper thermostat and all is well. The heat now works really well.