gushing noise 99 blazer
 

I replaced my heater core about month ago and all the hoses and radiator and water pump. not all at the same time but all in the last 30 days. the noise seem to be coming from the center of the dash. the only time I hear it, is quick take offs or while turning from a stop. I just got back from 1000 mile trip this weekend, it never ran hot and temp gauge stayed steady. I don't hear it at highway speeds only from stop and stop with hard turns. and not all the time. coolant is not low in the radiator nor the tank all at normal levels

park on a hill with your passenger front corner higher than the rest of the truck and let your truck run a bit. you probably have air in the system. with the front passenger corner higher the air bubbles will be able to work them selves out of the system into the radiator.

The water noise you are hearing is most likley air in the heater core. I ran my truck for about 30 mins with the heater on high passenger corner in the air and everytime I thought I got all the air out, a bit more would show up.

Good luck. it might take a bit of time, but its not to difficult to get solved.

Yup...that is def what you need a small hill and some time to kill.
squeezing the upper driver hose while doing this will help to.
if you get all the air out and the problem comes back you have a hose with a lose clamp...i had that happen...i kept getting air out and then it would come back month later...found out the hose on core return was lose enough to allow air in but it leaked so little it never dripped.

i was wondering about it being air, just figure since the system didn't have a control valve on the heater hoses it should flush out after a while and after 7 hours of driving under two different days the any air would surely flush out.

Nope....the air will stay in there till you work it out of the system...i fought it for months before i finally figured it out when i did my core couple years ago.

Yes! Your were right there was air in the system. I found a hill and got it to burp out.

thanks