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  1. #11

    Arrow Okay ...

    Quote Originally Posted by RayVoy View Post
    Sorry, it was slang for while the system is empty.

    The thermostat is a temperature sensitive dam that stops the flow of water while the engine is cold. When the coolant gets hot, the thermostat opens to allow circulation. The thermostat is designed to open at a certain temperature. They do wear out and start opening at lower temps.

    You can change the thermostat while the system is full, but some coolant will leak out. The time to change it is when the engine is being flushed.

    PS, I don't think it is a good idea to start the engine and run it until the system is flushed, all drains closed and the system is refilled (my 2 cents)
    I have to run the engine ... there is no other way to flush the heater coils ... The whole system has to be flushed and the water hose will be running along with the engine.

    Quote Originally Posted by Pikey View Post
    I have to agree. If you have had that coolant in there for 17 years then you mine as well change the thermostat while you are at it. It is bound to fail sooner or later.
    I don't know where the thermostat is located ... or how hard it would be to replace it, how can I find out where it is?

    Quote Originally Posted by 87silver View Post
    FYI, Dex Cool was designed to have a service life of 150,000. The issue with it was how it reacted with air within a cooling system for those who did not maintain the proper coolant level (or didn't know they had to). I have found that if you closely maintain the coolant level, you won't have the issue of premature deterioration of head gaskets, intake manifold gaskets and other associated intake components. I had about 90,000 miles on a 1993 Blazer before flushing/changing the coolant, but kept it maintained. Never turned brown; always stayed red. Never had an issue with the engine. If you have not maintained the coolant level, or bought your truck used, then it should be definitely flushed/changed.
    The coolant level, is pretty low, but the color is still red ... if fact it doesn't look bad at all ... I want to say if it ain't broke don't fix it, but it was been 17 years and I did buy the truck when it was a year old.
    96 Chevy S10 4cyl 5sp manual :great:

  2. #12

    Default

    Quote Originally Posted by spirittoo View Post
    I have to run the engine ... there is no other way to flush the heater coils ... The whole system has to be flushed and the water hose will be running along with the engine.
    Ok, I'll try this as politely as I can: The only thing a running engine can provide is a spinning water pump. The water pump can not pump water unless the engine is full, hot and running. If you feel the correct way to flush a heater core is to open the drain, run a garden hose into the system and then start the engine, I only ask that you seek at least one more opinion before you do it.
    Ray

    '09 Avalanche LTZ - Black
    '05 Envoy XL (sold)

  3. #13

    Default

    You only need to run the engine for the flush IF you are doing it with a thermostat in. If you have the Tstat out then you can get water to flow to the heater core. If it is in then you need to get the tstat warm enough to open and let the old coolant and new water flow out. We used to hose flush with the top radiator hose off, engine running, all the time when I worked in the garage. We just kept the radiator full with clean water and ran until the water coming out of the top hose was clear. Then drained the radiator and filled it with coolant.
    Last edited by Pikey; 10-17-2012 at 07:42 AM.

    1995 Silverado 4x4
    6" BDS Suspension Lift-3" Body Lift-Add A Leaf in rear -Trailmaster SSV Shocks-Duel Steering Stabilizer Kit -AirAid Cold air intake-
    4.56 Gears with Detroit Auburn Locker-Pro-Comp Traction Bars with duel shocks-Aluminum Skid Plate Kit-38.5" x 16.5" Mickey Thompson Baja Claws-Constant Dropping fuel gauge

    2005 Yukon XL Jet Power Programmer, Bilstein Shocks, Bilstein rear springs, Helwig Anti-sway bars, EGR Window Visors, EGR Hood Shield, Denali Headlights, Headlight harness upgrade, GE NightHawk Bulbs, White Night Rear lighting system, Russell Braided SS brake lines, PowerStop Brake pads, PowerStop cross drilled and Slotted Rotors, http://www.gmtruckclub.com/forum/sho...5-GMC-Yukon-XL
    2002 Silverado ext cab 2wd (Sold)
    2003 Yukon XL (Totaled)

  4. #14

    Default

    Quote Originally Posted by Pikey View Post
    We used to hose flush with the top radiator hose off, engine running, all the time when I worked in the garage. We just kept the radiator full with clean water and ran until the water coming out of the top hose was clear. Then drained the radiator and filled it with coolant.
    spirittoo, @Pikey's suggestion will work for you. The difference is that he is opening the system at the top, this keeps the engine full of coolant, let's the water get hot, lets the t-stat open. You need to keep water in the engine, or it will overheat.

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