funny noise 2000 GMC 1500 P/U

Old 08-04-04, 10:17 AM
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funny noise 2000 GMC 1500 P/U

The truck is a 2000 GMC SLE 4X4 5.7 liter.

When I accelerate there is a noise that kind of sounds like running water coming form under the dash, it seems to follow the acceleration and then goes away?? It's nothing new and has been there for as long as I can remember. I wasn't sure if this was a thermostate issue or what. I have owned the truck from new and have had to do very little to it in the way of repairs. If anyone has any thoughts on this that would be great...>>
Old 08-05-04, 04:56 AM
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You've probably got some air in the cooling system in the heater core plumbing. You can try burping the system by parking uphill on a steep incline and removing the radiator cap (when cool). Start and let it run until warm with the heater control "on" (if the control has a valve to regulate the hot water; many vehicles flow water through the core at all times). You'll likely get some overflow out the radiator, so watch out for the spray off the fan. Eventually the air bubble should work itself out of the heater core/plumbing. Refill with coolant as neceassary.

There are also professional machines for doing the job by creating a vacuum in the system prior to filling with coolant, so if you can't burp it you can check with local shops.

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