1HDT - Coolant Operating Temps/Lower Radiator hose (1 Viewer)

[Dilspec]

I tried searching for some information on here and the FSM, but wasn't able to find anything. Maybe some here can help me out.

The water-pump was replaced recently and I was burping the coolant on an incline and about 45 minutes in, I noticed the lower radiator hose never got hot. Despite that, the heat blew really hot and temperature gauge was in the middle. I heard these engines like to run on the "cooler" side and the top hose is supposed to be hotter than the lower one. In this instance the top was hot, lower cold.

I can't recall if my lower radiator hose ever got hot or even warm. After a 60KM drive or so, the lower hose was still cold and the temp gauge was still at operating temperature. The top of the radiator was warm but the lower section and fins were cold. Maybe I'm just overthinking this?

No coolant leaks, or overheating. Also I should add that the lower radiator hose has a circulating heater (It was installed when the truck was in Canada)

Thanks in advance

 

[roscoFJ73]

The thermostat is in the engine block where the lower rad hose fits onto the metal pipe and its probably not opening to let coolant from the radiator in.
This could be because the airflow through the radiator is so cold ,the coolant in the lower hose is not reaching the temperature required to open ,somewhere around 88c.

Or your thermostat is faulty .

You could put some cardboard in front of the radiator to slow the airflow and see if both hoses warm up.
Either way it deserves investigation.

There are thermostats that open at lower temps, 88c is a warm climate t/stat. I think cold climates t/stats open at 83c.

 

[Dilspec]

Thanks for the quick response. I think the thermostat could be the root cause, It's supposed to reach near 50F this upcoming weekend so it should open up. If it doesn't I'll replace the thermostat. I thought maybe it just took forever to open up since I never overheated.

 

[IanB]

With cool temps and the engine just idling, it may be that the t-stat won't ever open. I find you can leave these things idling in the winter and the temp gauge needle never moves, you need to put some load on the engine to generate any heat.

 

[Dilspec]

I agree with you, it takes forever to warm up. But after a 40 mile drive at highway speeds and in boost, i suspected that it would have opened but it didn't. I think I might try plugging in the lower radiator hose and see if that would help too... I ordered a thermostat.

For reference if anyone comes across this, the thermostat is Part # 90916-03089

 

[jurassic cruiser]

I got a madman ems1- was a pain in the ass to install but peace of mind has been great it beeps if anything gets too hot. Although it was hard to know where to set the tranny temp to

 

[Tapage]

I see my t-stat open ( complete different ambient temps down here ) consistently around 124F usually when your dash needle start moving up ..

 

[JOHN OF LONDON]

An old thread but still being read it seems. The Thermostat is housed in the engine block and reads the temperature of the water circulating in the block. When the water in the block heats up past the opening temperature it lets a bit of water in from the lower hose. Normally this is cold as the radiator is quite efficient. If hot, rather than warm, water is reaching the lower hose its the start of an overheating problem. Cold water in the lower hose is normal.