Heater Core Was Whistling?..not Dixie though

[swalt]

My cooling system was professionally reverse flushed about a year ago and I replaced the rad cap as suggested on this site. Had a problem with a whistle noise under the dash this week (sounded like vacuum) under hard acceleration or rpm's above 3000rpm's and then I started to hear the heater core gurgle. We reverse flushed the system again today as the reservoir was looking skunky again and the problem seems to have disappeared. We back flushed the core with a pressure washer before we backflushed the entire system with a professional backflush machine just to see if it was clogged and nothing surprising came out other than Dexcool. Has anyone every heard a core whistle when it became restricted or am I looking at a possible heater core on its way out?

[mike2004tct]

Originally Posted by swalt

Has anyone every heard a core whistle when it became restricted or am I looking at a possible heater core on its way out?

Can you humm a few bars?
I can name that tune in 3 notes, Allan!

Just my opinion, but I doubt if your core is going. They usually start to leak when they go, no whistling unless there's a steady stream of steam with it. The whistling is usually a sign of air in the system.

[DaveLance]

Do all of your vent controls work? The whistling could be a disconnected vacuum hose.

[swalt]

I drove the truck about 60km's today and no gurgling, no whistling. All the vent controls work fine. I didn't think the core was obstructed, but with the gurgling it must have been. The whistling must have just been an odd occurence with the partial blockage. Just something I had never experienced before, but it is gone now. Just something to think about for anyone out there doing diagnosis as I was ready to start going after vacuum lines and diaphragms.