06 Trailblazer EXT leaking coolant by driver side rear tire

[06_ext]

It's either the rear heater core, and it's running down the line as it enters the cabin, or it's an actual tear in the line taking coolant to the rear heater core (which I've read is in the frame and requires the body be lifted off the frame to replace). Either way, I just want to bypass it and eliminate the problem (and heat for my soon-to-be chilly passengers)

My TB EXT is equipped with the aux pump that helps move coolant to the rear, and I'm having a b**ch of a time tracing the coolant lines. Does anyone have an image of coolant diagram to include this pump. Or can anyone tell me the hoses to bypass coolant to the rear.

Thanks in advance.

 

[Mooseman]

I'm not sure about a pump but there is a bypass valve on the front passenger side. That vacuum hose that goes from the front of the intake manifold goes to that valve. Maybe try the online GM parts dealers for diagrams.

Have you tried going under and looking for the leak? I've had a bad heater core and it just leaked out on the rear passenger side. It could be at a connector somewhere. If it is a hard line, you might be able to replace it with rubber line from front to back. If a rubber hose is cracked, you could possibly splice it.

 

[06_ext]

Thanks for the response Mooseman. I know the bypass valve you speak of, but am hesitant to mess with it as I believe it also provides coolant to the front heater core. I haven't dug into the blower and heater core in the back so I'm not 100% sure exactly where the leak is.

 

[06_ext]

Over the weekend I finally had time to jack the vehicle up to crawl underneath and attempt to find the leak. I knew the supply lines (coolant and AC) ran down the driver side, so I started there, A section of the coolant line was slightly corroded. Right after the rear driver side door, the lines go up over a crossmember, right where a varmint had setup shop on top of the crossmember. I think the nest took it's toll on the aluminum coolant line. I was able to cut the line out, and replace with rubber heater hose. Problem fixed, with no loss to the rear heat

 

[DocBrown]

Good find and nice easy fix! Mine was leaking in a place I couldn't get at to repair it. If you ever need to by pass the rear, the return line comes in along the front frame on the driver side right behind the wheel. It's a standard rubber heater hose. I cut it and put in an elbow connector and a new heater hose and ran that across the top front of the engine to the outgoing line of the heater control valve. That one's easy to trace because it goes to the rear heater core along the passenger side.

Another alternative is to by a kit that replaces the entire metal line system. I think it's a couple of hundred dollars, and I can't recall who makes it. I think at least a couple of other members have installed it.