'01 EB V8 No Heat/Cold Running Temp

[ggomez2]

Hello all!
First day of cold weather out here in Denver, and go figure, I barely had any heat.
Recently replaced radiator.. did hoses, new thermostat at that time as well. Did the work about 1 1/2 months ago, and no issues noticed with running temp of truck between then and now.
Weather this morning was 39 degrees, and while I sat idling for about 5 minutes I realized there was no heat from the ducts. Usually this truck heats up fast. Drove about 5 miles home through downtown, engine temp needle never moved from cold. No hot air from vents. I also noticed the top radiator hose didn't feel all that hot, but also it was very stiff; I feel like when water runs through it it's hot but also a bit pliable. I did touch the two heater core hoses and they didn't appear to be all that warm, either. Coolant level seemed ok judging from the expansion tank. Over first few weeks after the radiator replacement, I kept an eye on the radiator coolant level and seemed fine.

Any suggestions? Thanks for your insight, in advance! Love this forum for all the information I've gotten owning this '01 for last 2 years.

 

[yavapaires]

LOOK IN THE RADIATOR. Sounds like you have no coolant in the engine, just air. Hopefully you have not caused any serious engine damage. How low temp did the coolant test to?.

 

[ggomez2]

Yavapaires, you said: "How low temp did the coolant test to?" Do you mean using an antifreeze tester? I've been using 50/50 blend this whole time, so I hadn't tested but I will run out in a bit to check. If this isn't what you meant, can you clarify?

 

[yavapaires]

That is what I meant. Also, you may check both sides of the heater control valve, to see if water is getting through.

 

[ggomez2]

OK, so here's what I've done to figure out the issue (which I've yet to)

1. 2 separate drives today, both about 5 miles in length (20 mins city driving 1st trip, highway mostly second)
2. 47 degrees out side for most of the day; air temp 109 degrees, measured from center air vent, with heater at high (climate control set at 90 degree), blower at high, using A/C duct temp gauge.
3. radiator hose (top) felt rigid, warm but not hot to touch after both trips, same with heater hoses
4. Radiator (when engine had sat for few hours) was full of coolant. Tested coolant and it was measuring at about a freeze point of 12 degrees,so evidently I need to redo the mixture.

NOt sure if this is related but I'm starting to think my MPG have dropped since the radiator swap, which is when I put in a new thermostat. Is it possible to get a dud thermostat? Really wasn't fun getting to it, if it ends up being that, not going to be happy.

 

[yavapaires]

Yes it is possible to get a bad thermostat. What is your water temp gauge showing? Just for the fun of it, unplug your a/c compressor, and see what kind of heat you are getting from the outlets. This probably won't make any difference, but it is something to try. Oh, where is the coolant level in the reservoir? If it is low, add some antifreeze. can't hurt anything, and you need to add some anyway.

 

[ggomez2]

Yes it is possible to get a bad thermostat. What is your water temp gauge showing? Just for the fun of it, unplug your a/c compressor, and see what kind of heat you are getting from the outlets. This probably won't make any difference, but it is something to try. Oh, where is the coolant level in the reservoir? If it is low, add some antifreeze. can't hurt anything, and you need to add some anyway.

Water temp never moved about "C".

Coolant level in reservoir was/is in the right place; tube is not plugged/clogged either.
Starting to think it is the thermostat. This sucks... kind of thinking I should have left the original in place..

 

[shooked]

I'd bet thermostat. Reason being my trucks went bad and it had the same symptoms you are describing. No heat and the temp gauge never moved off cold. Good Luck.

 

[gadourym]

When I bought my truck 2 years ago, it had a thermostat that was stuck open, so the temp never went all that high, and I had very little heat. Once I replaced the thermostat, it was fine.

Another thing to check, that is often overlooked, is the hose that runs from the top of the radiator to the expansion tank. A couple of months ago, mine was clogged, so the coolant level always looked fine, but the radiator couldn't draw from the tank. There must have been a small leak somewhere, because my radiator went dry, and the engine overheated and blew the head gasket while I was 250 miles from home! Somehow I was able to limp home, stopping every half hour or so to add 2 gallons of water to the radiator. Now the truck is at the shop getting a new engine (it's only costing $600 more for an engine with half the milage than just to do the head gasket anyway)!

 

[pitbulldell]

I vote for thermostat my truck did the same thing no heat and temp gauge barely moved , i have gotten several bad ones from Advance and Autozone , luckly they stuck open and not close, when i took them out the tab was ****ed sideways and never closed. So last one i got from Nappa.

 

[bobflood]

Another thing to check, that is often overlooked, is the hose that runs from the top of the radiator to the expansion tank. A couple of months ago, mine was clogged, so the coolant level always looked fine, but the radiator couldn't draw from the tank. There must have been a small leak somewhere, because my radiator went dry...

+1 for this!! Had this happen with my Maxima. The nipple the overflow hose fit on got cracked - coolant flowed out but not back in - radiator almost went dry. Luckily, caught it before it did any damage to engine.