Heater Hoses - Which Is Which?

dukbludvl · February 1, 2011

Hey - I just replaced the water pump, belts and hoses on my 2000 Yukon this weekend. The originals had 215K miles and still worked fine, but I've had the parts for a while and wanted to get new ones in there.

I now have a whine in my dash when I give it gas -- the whine changes in pitch along with RPMs. I believe it is a rattle in one of the hoses running to the heater core -- maybe from the water restrictor that's built into the hose? Can anyone confirm this? If this is my problem, is the only good fix to just replace the hose? If so, which hose is it -- the one that connects to the left side of the heater or the right?

Also, I want to make sure that I've reconnected the two hoses to the heater core on the right sides. At the left side of the water pump, there are two hoses that come out:

1. A hose towards the front of the engine that immediately splits into one that goes to the heater core, and the other that goes tot he coolant surge tank. I've got this one running to the right side of the heater core.

2. A single hose more towards the back of the engine that runs up to the left side of the heater core.

Do I have these right? I'm getting heat in the interior like normal, but I want to make sure that the whine problem isn't due to me switching these hoses around.

If someone could shed some light on this, I'd really appreciate it. PM me if you like. THanks!

txab · February 1, 2011

you took pics and still are asking ??? holy crap

thx for playing Darral !! your out !!

anyone else want to play ????

I'll still play.

To my knowledge, engines with the pump style you have are routed as shown below. At least on small blocks that I've been around

According to the GM Service Manual, here is you hose config:

I don't recall there being any restrictors on the lines. Most aftermarket lines do not have the quick disconnects molded onto the hoses. So you can buy new ones. Reuse the old ones. Or just attach the hoses with clamps directly to the core hoses..

I would flush the core thoroughly then I would swap the lines and see if anything changes

Make sure you have all the air purged from your system.

dukbludvl · February 1, 2011

thanks for the diagram and info. Yeah, that's what all the diagrams show.. my Haynes, stuff I've seen online. It's so weird because they were reversed before I changed them. Here's a pic of the before. You can see (well sort of, but trust me, I still have the old hoses, so I'm sure that's the way it was) the hose connected to the back fitting on the water pump comes out and goes up under the other one and connects to the left side of the heater core.

I just don't get how this can be...

you took pics and still are asking ??? holy crap

thx for playing Darral !! your out !!

anyone else want to play ????

I'll still play.

To my knowledge, engines with the pump style you have are routed as shown below. At least on small blocks that I've been around

According to the GM Service Manual, here is you hose config:

I don't recall there being any restrictors on the lines. Most aftermarket lines do not have the quick disconnects molded onto the hoses. So you can buy new ones. Reuse the old ones. Or just attach the hoses with clamps directly to the core hoses..

I would flush the core thoroughly then I would swap the lines and see if anything changes

Make sure you have all the air purged from your system.

txab · February 1, 2011

Your hoses at the core should be reversed

dukbludvl · February 1, 2011

I've done some more research on this online today, and it sounds like it doesn't matter which hose connects with which fitting on the heater core. Does this sound right to you all?

Also, I believe the whine I'm hearing inside the cabin is due to a cracked or faulty washer in the inlet hose. Apparently there is a washer in there that serves as a flow restrictor. The flow of water over the cracks causes the whining sound in the cab. I guess the new hose I bought (which I've actually had laying around for 3-4 years), either had a faulty washer/restrictor when I bought it or I broke it somehow.

Anyone else have this type of issue?

ChevyTech77 · February 1, 2011

The plastic quick connects in the heater hoses, at the core, should have restrictors in them.

I would bet that reversing the flow through the core could cause weird noises on this truck.

Otherwise, it has air in it. Vac-n-fill it and it will go away.

dukbludvl · February 1, 2011

Can anyone confirm that this is right? I think based on the pics I took before starting the job that I have the new hoses hooked up the same as the old???

anyone have pics or can take pics of their truck and post just to confirm?