bspark8613

I'm new to forums i wasn't sure if there was already a thread for this problem so i apologize in advance.

On my 90 3VZE i blew a oil cooler hose and after i filled the cooling system up again i had it in my shop idling for about 45 min and the upper rad hose was hot and the lower rad hose was room temp. as if no warm coolant even touched that hose at all. t-stat maybe?

j2the-e

Tstat hasn't opened. Did you try holding it at 1500 rpm with heater on and the cap off for a few minutes to heat it up and bleed all the air? Whats the ambient temperature?

bspark8613

No I didn't try with the cap off. The ambient temp is around 18 degrees Celsius

Slowey23

I noticed that on mine too after I replaced the head gaskets and thermostat, i was also concerned but took it for a good drive and that got the bottom hose hot, mines been running fine for a few months now, temp gauge never goes above half

Pat8942

The coolant flows out the top hose into the radiator, it's cooled and returned to the engine, so the upper hose should be hotter than the lower, all engines are the same, it doesn't matter where the stat is located, outlet coolant should be hotter than inlet or the engine would over heat.

j2the-e

Are you saying its normal for the lower hose to be room temperature?

Pat8942

Room temp doesn't mean much, it depends on one's definition, but as I said the lower will always be cooler, why are you losing sleep over it, if it's running at normal operating temp then everything is working properly, if the lower hose was as hot as the upper than you should worry.

Pat8942

This say's it better than I did.

The coolant follows a path that takes it from the water pump, through passages inside the engine block where it collects the heat produced by the cylinders. It then flows up to the cylinder head (or heads in a V type engine) where it collects more heat from the combustion chambers. It then flows out past the thermostat (if the thermostat is opened to allow the fluid to pass), through the upper radiator hose and into the radiator. The coolant flows through the thin flattened tubes that make up the core of the radiator and is cooled by the air flow through the radiator. From there, it flows out of the radiator, through the lower radiator hose and back to the water pump. By this time, the coolant is cooled off and ready to collect more heat from the engine.