Lower radiator hose cold

I initially noticed a cooling issue when it was running hot at stop signs. After letting it cool down I checked my coolant level and sure enough it was significantly low(added a half gallon). I let it idle at operating temp and the gauge did not increase. I assumed the problem had been resolved until I touched the upper and lower radiator hoses. Upper was hot like normal but the lower was cold. The truck was completely warm and had been running for over half an hour and it was about 65 degrees out side. Does this sound normal or should I just go ahead and swap the thermostat?

I also should add that I don’t think I have a coolant leak. I haven’t added coolant in probably 3 years so the significant loss is likely from evaporation.

 

Coolant does not just evaporate. You either have a high pressure leak from the radiator or hoses or water pump. Another possibility is the coolant is being combusted in one of the engine cylinders.

 

coolant evaporates out of the reservoir the same way water evaporates out of a glass. Thank you for your help.

 

check your oil and make sure its not milky! hope its nothing serious. keep us updated!

 

Lower hose cold is normal. Your radiator seems to be doing its job.

 

Never knew that regarding the coolant tank

 

does the reservoir cap help it at all from evaporating?
i try to keep the cap on mine snug and check it on most every tank of fuel replacement

 

If you're low on coolant you have either lost it via a leak or burned it off due to a leaking headgasket or something of that nature.

Do a coolant pressure test and check your oil to see of it looks like chocolate milk.

 

Agree. I live in AZ and the coolant evaporates from my overflow tank quickly. I know I don't have a leak because when I pull the radiator cap it is always full.

 

For 19 years in hot California I have never needed to add a single drop of coolant (until head gasket failed). Coolant does not evaporate from an overflow tank. There is a hose that sucks it back to the circuit when circuit needs coolant (leaking or shrinking). If you are loosing coolant from an overflow tank most likely you are loosing coolang from the circuit (read:coolant leak).

 

@RysiuM you may very well be right. I've never been able to keep that overflow tank full as long as I can remember though, and I have no signs of a leak. I filled it two days ago just below the full line (while cold) and now I'm at about half (while hot). I'll check it in the morning and see where it's at, I would expect it to be empty again.

 

Coolant doesn't evaporate, but the water in it can. But veeeeeeeeeeeeery slowly. If you're adding regularly it can only because of a leak.

If you're not seeing marks in the engine compartment, is probably coming out of your tailpipe.

 

1st gen gremlins
i am starting to write a book

 

Last time coolant was flushed and filled back in 2016 with new timing belt, water pump etc. Haven't lost any. Haven't had to add any. Evaporation would be not noticed if at all in a sealed system.