Temperature Gauge Help [Expired Topic]

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by jerseyfred, Nov 28, 2006.

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  1. jerseyfred

    jerseyfred New Member

    I just got a 1990 Suburban and notice that within 5 minutes of first driving it the temp. gauge goes past halfway towards 220, then immediately drops down to below the halfway mark and pretty much stays there. When it first happened I put the truck in park and let it idle...and it remained cool. I checked under the hood and I have plenty of coolant.
    Is this something I need to worry about?
  2. curtolson

    curtolson Member

    RE: Temperature Gauge Help

    How is the thermostat? If it does not overheat who cares. If your driving that 5 minutes and it goes past the 1/2 way mark turn your heater on. Now don't go sueing me I no motor head, But
    If it's not broken you may fix it until it is. I'm just a dumb real estate investor/ want a be motorhead. Thats my story and I'm sticking to it.
  3. TrailLeadr

    TrailLeadr Epic Member 5+ Years 1000 Posts

    RE: Temperature Gauge Help

    Sounds like your thermostat is sticking when it's cold. I would replace the t-stat, and see if that makes a difference.
  4. kknobl

    kknobl New Member

    RE: Temperature Gauge Help

    Definitely sounds like the T-Stat is sticking. Keep your eye on it, but I'd definitely get it replaced before the really cold weather hits.

  5. GaryL

    GaryL Epic Member 5+ Years ROTM Winner 1000 Posts Platinum Contributor

    My dad's 94 does the same thing. I think it is that the system is so big that when the thermostat opens it cools the coolant down below what it took to open the thermostat so the temp drops just a bit.
  6. jerseyfred

    jerseyfred New Member

    Thanks for giving me a place to start! I have a feeling that this truck and this forum will teach me about auto mechanics!
  7. ChevyFan

    ChevyFan The Sheriff Staff Member 5+ Years 1000 Posts

    I've seen my share of sticking thermostats, so that's my first place to start as well.
  8. jerseyfred

    jerseyfred New Member

    Please forgive my newbieness, can someone please tell me how to change the thermostat? Is it as easy as changing a headlight? I really want to learn how to work on this truck myself.
  9. unplugged

    unplugged Epic Member 5+ Years 1000 Posts


    If you can change a headlight, (sealed beam) you can change a t-stat.

    1. You may want to drain off a little of the coolant before you start. You can do this by opening the petcock at the bottom end of the radiator or loosen the lower radiator hose.
    2. Pull the top radiator hose by loosening the clamps.
    3. Remove the two bolts holding the thermostat housing. The tstat housing is the metal assembly that the upper radiator hose is clamped to.
    4. Pull the thermostat.
    5. Reverse the process to complete the project.

    Notes: Consider buying the best tstat you can afford. The better quality seem to be made in Israel these days. Avoid the made in Mexico versions, I have had trouble with those. Use anti seize compound on the tstat housing bolts to avoid future corrosion/binding. Use a gasket and silicone sealant to seal the tstat housing to the block. Clean the gasket surfaces on the housing and the engine. Consider replacing the housing if the gasket surface shows heavy corrosion.

    Good luck!
  10. TrailLeadr

    TrailLeadr Epic Member 5+ Years 1000 Posts

    RE: Welcome

    That's great advice. Considering the tstat is extremely inexpensive by comparison to other parts, it seems silly when someone opts for the $1.69 model from the local parts shack, which is likely to fail far sooner, just to save a couple bucks.
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