Hi HMAC300. Excuse me for butting in, ... Again. This was a real common problem with a pretty easy fix. The rear heater hoses have plastic quick-connect fittings at the rear heater core. Those fittings have a rubber o-ring that shrinks and leaks in cold weather. Manufacturers always insist that warranty repairs be made with their parts. The engineers came up with a pair of superseded part numbers for this repair. Those had TWO o-rings in each fitting that shrunk and leaked in cold weather!
When the van is out of warranty, the less-expensive and permanent fix is to cut off the metal crimped bands on the front of the hoses right behind the cross member, cut those hoses off, then install two new rubber hoses from bulk stock. I can't remember the diameter or if both hoses were the same. The pipes in front and the nipples for the heater core are barbed, so just slide the new hoses on and use regular hose clamps. If you leave the original hoses in place, you can use tie straps to hold the new hoses to those old ones.
If you're made of money, you can install a pair of 3"-long hoses to the heater core, then a pair of 90 degree elbows from the hardware store's plumbing department. Attach the new hoses to those elbows. For the rest of us, just watch that there are no kinks in the new hoses. They need to make some rather tight bends right under the heater core.
It can take weeks of driving to get the rear heater core to burp the air out and start the coolant circulating. What I did instead was to build pressure in the cooling system, either with a pressure tester or by running the engine, use a hose pinch-off pliers to pinch one of the new hoses, then loosen the clamp on that hose at the heater core. Thanks to the pressure, the coolant was forced to flow into the heater core, and through to the loosened clamp. Any air trapped in there yet will work its way out in short order.
Monday, January 16th, 2017 AT 5:49 PM