02 Expy heat problem

[braddaddy]

Hi everyone!

Let me jump in with my problem.

My Expy is having heating problems. The heat is "ok" when its 50-60 out but as the temps drop, the heat is less and less warm. Get to single digits and its barely warm though gauge in right in the middle where it should be.

This has been going on for 2 years. (I keep wanting to get it fixed but trying to DIY it)

I noticed my upper radiator hose is not pressurizing when the truck has been running for a long time....I can pinch it closed....

It doesn't overheat....I took a 5k mile trip last summer with no problems.

I replaced the tstat just because...no change.

I'm thinking its the reservoir cap....not maintaining pressure??

Thanks in advance for your responses!!

--Edit--

I replaced the rez cap today and ill see what happens.

I drove to the auto parts store and back (30 min) and when I got home I felt the upper rad hose.....it felt cold and as if nothing inside...no pressure.

I took off the rez cap and nothing... no pressure.

hoses to and from core were nice and warm... not hot....both felt the same.

Fluid in rez was a little low....but fluid was in there..... I added 1 gal 50/50 AF and water.

I have searched the forum and cannot find anything with my symptoms......

 

[stamp11127]

What temp thermostat did you put in? Usually warm coolant indicates stuck open thermostat, stuck on fan, too large of radiator or failing water pump. Usually with a failing pump one rad hose is hot and the other is cold.

Don't buy premix antifreeze - If you buy 2 gallons of premix @$12 ea, think of it as paying the same amount for one gallon of straight antifreeze and one gallon of distilled water - $12 for the antifreeze and $12 for a gallon of distilled water.
I don't know about you but that is stealing from the general public to me.

System pressure is used to increase the boiling point of the coolant. Higher pressures increase the boiling point. Not pressurizing is a second problem. I'd get the coolant temp up to where it needs to be first.

 

[purple_50]

I'm thinking plugged heater core myself, feel both heater hoses and see if they are both warm, if so its not plugged. If one is warm or hot and one is cold, core is plugged.

Sent from my HTC6435LVW using Tapatalk 2

 

[braddaddy]

Both core hoses are warm.....not hot.

I bought straight antifreeze... i diluted myself

Dont know temp of tstat....just went to autozone lastyear and bought what they gave me according to my vehicle.

Drove awhile now.....still barely warm heat.....

Upper rad hose cold and no pressure inside.... can squeeze like just got it off store shelf

both core hoses only warm and i can pinch them closed as well...

Oye

 

[BigJuicy02]

My 99 has the exact same problem. Replaced tstat with OEM 195 degrees. Twice. Replaced res. cap. Heater hoses warm, not hot. Both same temp. System will not pressurize. I drove it with my scanner on and the ECT goes between 190 and 205, exactly as it should but the cooling system is not working properly. No air in the system. Factory fan and radiator.

Any ideas on this would be appreciated. If I come up with a fix I will post here.

 

[stamp11127]

Warm heater hose is indicative of low coolant level (trapped air) among other things. You may also have a plugged restrictor in the heater hose, cutting flow to the core. It is about an 1/8 dia. at most and easily plugged.

I'd check the coolant level with the car parked facing up hill. The surge tank should be the highest point of the cooling system. Once the engine is warmed up, squeeze the upper rad hose repeatedly with the engine running. Any trapped air is moved to the tank.

As long as the cooling system isn't overheating it is working well enough for the conditions. As soon as it diminishes it will let you know with increased temperatures. Most of the failures I see on the trucks at the shop are in the surge tank (cracking), loose hose clamps or egr coolers. We have two of the three.....double check them.