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Chevy Silverado and GMC Sierra Radiator and Cooling Questions

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Comments

  • Here's something to consider. I have an '01 GMC Sierra w/ 5.3, and experience the same "phanton" coolant leak.

    http://www.agcoauto.com/content/news/p2_articleid/148
  • Please help. I have a 98 z71 silverado. It has begun to overheat. I've filled the radiator, replaced the cap and the thermostat and it still gets warm. When the truck heats up it spills into the overflow container. The container actually sucks in like theres a vacuum till the cap pops and fluid spills from the cap. I have flushed the radiator and still no change. Does anyone have any ideas. Water pump next? I do not see any leaks. Any ideas will be appreciated
  • bowanabowana Posts: 9
    Hi,
    I would start out with a cold engine and take the rad cap off, start the engine and let it warm up. When the thermostat opens, you should be able to see the antifreeze circulate in the rad. If it does, I would then rule out the water pump unless it has very poor circulation.

    Nice thing about the water pumps is that they are inexpensive and relatively easy to change.

    Another thing to look at is the heater and if it blows hot air as it should. You could have a blocked heater hose or possibly a connection from the rad to the heater causing pressure.

    I am not certain that this would cause your problem, but it could be a head gasket but you should be able to see white smoke out the exhaust. Another thing is the rad hoses. They have wire in them to keep them from collapsing but you never know.

    A couple of google's should locate the problem as I am sure you are not the first with this issue. A call to a rad shop could also yield some answers.

    Nothing to say that the thermostat was good either and hopefully you did not put it in upside down.

    Good Luck.
  • i have a leak in a 1/4 inch metal tube that goes from drivers side to pass side and y's off and runs under the intake manifold does anyone know what it goes to and what it is called it is a pinhole leak and coolant is coming out of it also would anyone know where i can get a diagram that shows where this is and where it goes any help is great thanks
  • Had same problem. Was the intake manifold gasket leaking. Gasket only has a small bead of sealant around each port. Had gaskets changed and no more leaks
  • I have a 2004 Silverado and my engine temperature keeps changing between 205 and 235. I had a problem a while back and it was found that I had a stuck thermostat and bad radiator. Both were replaced then a couple months later the temperature gauge started showing my truck running warmer. Took it in and I was a gallon low on coolant. That was fixed and the mechanics said that it might have been caused by air pockets. About a month later my truck started doing the same thing and so I took it back in and they said my coolant was a pint low so they added a pint. They couldn't seem to find any leaks, and I haven't seen any leaks or evidence of a leak. My truck is starting to do it again, but this time it will get to close to 235 and then while I'm driving and I get to about 50 then the temperature goes back down to around 205. Does anyone know or have any idea as to what it could be?
  • obyoneobyone Posts: 8,065
    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?
  • akdrmrakdrmr Posts: 2
    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!
  • 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...
  • KCRam@EdmundsKCRam@Edmunds Mt. Arlington NJPosts: 3,496
    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

    KCRam - Pickups/Wagons/Vans+Minivans Moderator

  • sierratrucksierratruck Posts: 3
    edited March 2013
    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.
  • KCRam@EdmundsKCRam@Edmunds Mt. Arlington NJPosts: 3,496
    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

    KCRam - Pickups/Wagons/Vans+Minivans Moderator

  • Good idea, thanks for the help, I really appreciate it.
  • mtbouymtbouy Posts: 1
    my truck is doing the exact same thing did you ever figure out what was wrong with your. i have 2006 gmc sierra
  • ramnuttramnutt Posts: 3
    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.
  • ramnuttramnutt Posts: 3
    I have a 94 K-1500 Suburban 350ci, that we just purchased, it had a crack in the tank of the radiator. So I replaced the radiator, water pump, and thermostat. The original radiator was a single core, was replaced with a 2 core, that's the only one AutoZone had in a 34'' core (between the tanks). Problem 1:The thermostat I had bought didn't fit in the seat in the intake manifold (it was smaller and moved around a lot, in fact you could slide it to one side and there would be a gap that would allow water to pass), I took it back thinking that they gave me the wrong one, I was assured it was the correct one. Has anyone ever run into this situation with a thermostat? As I have never in my 20+ years working on cars.Problem 2: The engine doesn't want to get up to temperature, 180 degree thermostat. My guess it that the thermostat had moved allowing a gap to allow water to pass. The gap guessing would be maybe a 1/4'' or less, that just doesn't seem like a big enough passage to keep it that cool, it barely get off of the 100 degree mark. The fact that the radiator is a 2 core instead of a 1 core entered my mind, but the thermostat basically keeps the water in the engine until it reaches the proper temp that would allow it to open exchanging hot water and for cool water. And my experiences with over sized radiators not matching water pump volume usually causes an over heating problem. Your Thoughts
  • ramnuttramnutt Posts: 3
    If your are constantly having to add coolant, then its the heater core. Newer style climate boxes houses both the evap and heat cores with using an exchange door that opens and closes to allow heat or to block the heat to the cab area. So the both being housed in the same box this would allow for any heater core coolant leak to exit in the same drain as the condensation. One easy way to test for coolant leak at the climate box, is to run the engine with A/C off, heat on. If you see liquid coming from the drain at the firewall it is coolant.
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