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Chevy Silverado and GMC Sierra Radiator and Cooling Questions

79 messages,  Last post on May 03, 2013 at 8:11 AM

You are in the Chevrolet Silverado & GMC Sierra Forum.

What is this discussion about? GMC Sierra 1500, Truck

Messages Page 8 of 9

#68 of 79 Re: 2004 Silverado Engine Temperature Sporadic [scotty_3998] by obyone

Oct 31, 2012 (3:37 am)

Replying to: scotty_3998 (Oct 30, 2012 5:57 pm)
You state that they couldn't find a leak? If the leak is internal it wouldn't show up on the exterior of the motor. Any white smoke on start up? During idling?
 
If the coolant level remained the same and the temp goes down to 205 when driving on the freeway, it could be a bad fan clutch. At highway speeds the fan is less important to cool the truck.
 
A blockage in the motor could also cause overheating. When the radiator and thermostat was changed was the motor back flushed?

#69 of 79 Radiator drain or petcock. by akdrmr

Jan 23, 2013 (9:53 am)

#70 of 79 Radiator drain or petcock. by akdrmr

Jan 23, 2013 (9:53 am)

Does anyone know if my 2012 Sierra, 4 x 4, 5.3L has a drain or petcock on the bottom of the radiator? I have crawled underneath but cannot see one. Before I remove the plastic shield under radiator I'd like to know if there is a way to drain radiator w/o removing the hose. I just had my truck in the dealership to get free oil change and asked them to lower freeze protection to -60 from -30. (I'm in AK). The untrained service "advisor" in Wasilla wanted to charge me $140. I asked him why they couldn't just drain a gallon of 50% antifreeze out and add 1 gallon of undiluted antifreeze in. He didn't know if there was a drain or not and that they would have to make a "special" mix themselves. This isn't exactly higher math and you would think a dealer in AK would have run into this type of request before!

#71 of 79 Fogged Windows, No Leak In Cab, Evap Core Drain Leaking by sierratruck

Mar 09, 2013 (11:04 am)

Hi, I have something goofy going on with my truck. When I turn on the heater, the windshield fogs up and I can smell the coolant. However, there is no water leaking on the floor inside the cab - as I would expect if there was a leak in the heater core. Water does, however, leak from the evaporator drain located on the other side of the firewall.
 
Additionally, if I run the A\C, water leaks from the evaporator drain as well. It's more than condensation, as it will eventually drain all of my coolant.
 
I have several questions running through my head:
1) Could I have a bad heater core without it leaking inside the cab?
2) Could a bad heater core result in a leak through the evap. core drain?
3) Would a bad evap core cause the windows to steam up when running the heater or defroster without the A/C button on at the same time?
4) Without having to take it to a shop and pay their $120 diagnosis fee, is there some way an average guy - like me - can figure out for sure if the heater core is bad? Same thing with the evaporator core?
 
Thanks in advance. I've spent so much time looking for anyone that has these same issues online, but virtually everyone that has a bad heater core says it leaks inside the cab. Mine doesn't, but something definitely is going on...

#72 of 79 Re: Fogged Windows, No Leak In Cab, Evap Core Drain Leaking [sierratruck] by kcram HOST

Mar 09, 2013 (6:37 pm)

Replying to: sierratruck (Mar 09, 2013 11:04 am)
Sounds like a combination of heater and evap cores. The heater core could be ruining the evap with a coolant leak into the A/C system instead of the floor.
 
kcram - Pickups/Wagons/Vans+Minivans Host

#73 of 79 Re: Fogged Windows, No Leak In Cab, Evap Core Drain Leaking [kcram] by sierratruck

Mar 11, 2013 (1:01 pm)

Replying to: kcram (Mar 09, 2013 6:37 pm)
Thank you for the reply. I was scared that that was what you would say.
 
Naturally it couldn't be straight-forward and easy to determine. Is there any way I can test both of these cores?
 
It's about $1,000 to replace the heater core, which I don't have laying around, so I was going to spend a long weekend doing it myself. The thing that scares me is that I tear everything down, replace the heater core, put it all back together and find out the evap core it bad too (or it wsa the only thing bad in the first place). And, although I might be wrong on this, I think the evap core is quite a bit more than the heater core.
 
To test them, do I need to tear everything down, then pull each core and take it to a shop?
 
Thanks for your help.

#74 of 79 Re: Fogged Windows, No Leak In Cab, Evap Core Drain Leaking [sierratruck] by kcram HOST

Mar 11, 2013 (5:36 pm)

Replying to: sierratruck (Mar 11, 2013 1:01 pm)
I would definitely recommend having them tested before you swap out. If you can, take pictures and/or video of the leaking water before you tear down so that the mechanic testing the cores has an idea of what you're experiencing.
 
kcram - Pickups/Wagons/Vans+Minivans Host

#75 of 79 Re: Fogged Windows, No Leak In Cab, Evap Core Drain Leaking [kcram] by sierratruck

Mar 12, 2013 (11:30 am)

Replying to: kcram (Mar 11, 2013 5:36 pm)
Good idea, thanks for the help, I really appreciate it.

#76 of 79 Re: 2004 Silverado Engine Temperature Sporadic [scotty_3998] by mtbouy

Mar 19, 2013 (8:00 am)

Replying to: scotty_3998 (Oct 30, 2012 5:57 pm)
my truck is doing the exact same thing did you ever figure out what was wrong with your. i have 2006 gmc sierra

#77 of 79 Re: 1989 C2500 5.7 Water Pump Rotation [1989c2500] by ramnutt

May 03, 2013 (7:04 am)

Replying to: 1989c2500 (Dec 31, 2006 8:51 am)
If I understand correctly you replaced these items, and now it stays cool and doesn't get up to temperature. If this correct, replace your thermostat. The failsafe thermostat is stuck open. I had the same problem, and when I removed and inspected the thermostat it was in fact stuck open. Replaced with a regular thermostat.

Messages Page 8 of 9

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