I was wondering if you could advise how to purge an air pocket out of the cooling system on my 2000, 4.3L Vortec Silverado. I have the water rushing sound behind the dashboard and can't seem to get it out.

The system is full and the temp maintains under half, but the water sound is an annoyance.

***EDIT: The heat works fine on the truck, and the coolant level is also good***

ideas?

Thank you

 

I just went through the same thing with my 98. I swore I did not have a leak, the heat worked great, but I kept getting the noise under the dash when taking off. I finally pumped the system up with a radiator pressure checker and got under the truck on my creeper with a flashlight and looked around. My issue ended up being a VERY slight seepage around the lower radiator hose where it connects to the water pump. It wasn't leaking enough to drip to the ground, but was enough to allow some air in the system and therefore make the swishing sound. A little tweak to the hose clamp, purged the system, and no more noise. To purge the system I always open the cap (with it cool of course) and start the truck and turn the heater on high. Let it run for a while and it should purge out all of the air. You need to wait for the thermostat to open. If you still have a noise after that I bet you have a slight leak somewhere.

 

Thanks for taking the time to answer this. I"m gonna try and get a pressure tester from the nearest autoparts store in the area. I'm hoping it's something small causing the issue, I"m not getting any leakage in the cab or outside the truck some I"m hoping it's something like this.

 

I'd like to reference one of your other posts about finding water in the oil. You typically won't get water in the oil just from driving it in the rain. And if a little gets through the air filter into the cylinders, it usually burns off. Maybe your water noise is due to a coolant leak somewhere into the crankcase. If you can't hold pressure when you test it, and can't find a visible leak anywhere, that could be your culprit.

 

Oh I didn't see the other post - if there is water in your oil that is your issue.