: Gurgling Sound/ Trapped Air in Coolant System

01-09-06, 03:14 PM
I am experiencing the gurgling sound of trapped air in my heater coil within my dash when I accelerate my 98 STS from 1600/2500 RPMs. This is after a water pump, thermostat, radiator cap, coolant replacement as a result of WP coolant losses.

The 3/8 purge hose running from the engine to expansion tank flows coolant freely.

I am not experiencing any indication of overheating from the trapped air (thankfully the thermostat has a steam release hole).

I am at a loss on how to proceed to eliminate the trapped air. Anybody have any suggestions?

01-09-06, 03:27 PM
You've probably got a pin hole leak somewhere that's pulling in air when the engine cools down.

01-09-06, 03:54 PM
Shortly after I replaced my water pump to fix a leak at the bearing, the water pump cover gasket started leaking. It wasn't a huge leak, but it could have been enough to suck in some air as the system cooled. I think replacement of the water pump cover gasket and thorough and careful scraping and cleaning of both sealing surfaces should be a required step when removing the cover for any reason. Careful retorqueing of the cover bolts is also important. Pinhole hose leaks could do the same thing. Have you carefully checked for a tiny spray from a hose when the system is at full temperature?

01-09-06, 05:07 PM
Thanks for the responses.

When the WP was replaced, the WP cover "snowman" gasket was also replaced after through cleaning of the cover and its grove and the mating surfaces of the housing. The purge hose was tested when the engine was at temperature.

I will go back and look for for pinhle leaks???? I'm not real sure of the best way to do so. There are no indication of any leaks as the system holds it pressure good.

01-09-06, 05:11 PM
I had the same problem in my '02 SLS. It sounded like a perculator. It occurred for almost exactly 24 hours, and hasn't happened since. I do not know what it is / was, but it was almost a year ago.


01-09-06, 05:51 PM
Was the cooling system work done just recently? I believe the heater core is a low flow circuit. If the work was "just" done, give it a day or so to purge the air.