Recently I have noticed that when I start my truck I hear a gurgling sound that sounds like it is right behind the passenger's side firewall. I am completely stumped on what this might be; any clues will be greatly appreciated. At first I thought water had just made it into the blower fan but if the fan is off I don't hear it.

 

Air bubble in the cooling system.

 

There is air in you coolant system, you need to burp it.

 

^^ And add more coolant to the radiator.

 

Thanks guys, makes sense to me. Ill will do it this afternoon when I get off. Thanks for the quick responses.

 

Umm, this is a PG website.

 

assuming hoses and cap ettc are all good, how else is air gonna get in there? i know ive had to burp it several times.

 

Timing chain cover and heater core are pretty common due to the trucks age and mileage.
Get some UV dye and a black light then follow the instructions on the dye package if you can't find the leak.

 

Coolant is somehow escaping. Even though it's a mix of water and glycol, evaporation still falls into play.

 

yeah, i have never noticed the fluid level gettin glower. well, a little after a 2000km road trip. ive got it ll ripped apart right now, i think there may be one hose thats worn. ill keep an eye on it. never had any issues other than being annoyed by the gurgling. which wasnt happening yesterday