No heat in cabin, ended up being foam stuck in heater core pump!

I wanted to post this in case it helps anyone in the future:

Got a sudden "no heat" situation on my 2005 Prius. Checked the basics with the coolant level, it had been properly bled when I replaced the water pump (and blew hot for weeks after that) and made sure the blend door actuator down near the pedals was working.

I foolishly threw a new 3 way coolant valve at the car thinking it might be that even though it wasn't showing any codes. After replacing that and bleeding again no dice.

The only thing I could think of being left was the heater core itself, since even if the electric pump to the heater core died it should still push heat into the cabin with the gas engine running.

After much searching both on here and Google I finally came across this post: Heater issue! No hot air. Read many forums. Heater core hose not hot! | PriusChat and found the exact same thing in my car. Black chunks of foam that had become stuck in the heater core pump. Looks just like the type of stuff that the foam pipe wrap to insulate water pipes in a house is made of. The only thing I can think of with this particular car is it was hit in the front left corner and damaged the coolant recovery canister. Maybe this is the type of insulation used in this canister and some broke free into the system before it was replaced?

Anyways, it's all back together now (what a pain to get to that pump...) and has been blowing good heat
since November!

 

Yes, the CHS (coolant heat storage tank) is what I was thinking, but I've never cracked one open to see what's inside it. My guess is it would be foam in between 2 layers of metal and when it got smashed that let the foam out. Unfortunately I never did an autopsy on it when replacing the tank.