Heater core swishing

[HRV-LS1]

I have a 96 Chevy regular cab, 1500. About a year ago I replaced the coolant. Once and a while I can hear the coolant swishing in the heater core case under the passenger side dash. I remember topping off the radiator with the heater on full blast when I did the maintenance. Is this a normal sound or do I need more coolant? There are no leaks, no coolant on the oil, so the engine is fine. What do you think?

 

[TruckinAin4Sissies]

Just to eliminate the possibility: Remove the passenger side door sill plate (3 screws + seat belt removal) and see if there's water in the channel below the sill.

 

[scmsltn]

Check your coolant level...it is likely swishing because your coolant is low and when it gets hot enough it goes through the system. Or you have an air bubble.

 

[HRV-LS1]

Checked out under the sill, no water, little bit of rust but no water. The coolant level when its cold is full, I'll see when it gets hot. I'll add colant to the resorvoir tank when gets hot, if it need it. What to do if I have an air bubble?

 

[sewlow]

Put your truck on ramps in the front, or on a hill. Remove the rad cap when the truck is cold. Start it up & let it run till the thermostat opens. As this happens, the bubbles in your system will rise to the highest point, which should be the rad cap. Top up rad as required.

 

[Hezsus]

Put your truck on ramps in the front, or on a hill. Remove the rad cap when the truck is cold. Start it up & let it run till the thermostat opens. As this happens, the bubbles in your system will rise to the highest point, which should be the rad cap. Top up rad as required.

x2, i've never done it withh the ramps though. probably a good idea.