Heater core hose leaking

2009_Suburban · December 27, 2023

I noticed a leak where a heater core hose meets the water pump on my 2009 Suburban. To fix this I am going to replace the hose and the clamp. What exactly is this hose called, and where do I buy a replacement? Rockauto has a bunch of hoses listed, but I'm not sure which is the correct one.

Here is where the hose meets the water pump

Here is where it meets the firewall

CamGTP · December 27, 2023

It's been replaced before, hence the worm gear clamp that is on it because that isn't factory.

Check your glove box for the RPO codes, I think you want to see the code C36. If you have that then you can just buy that GM hose with that RPO code listed on Rockauto under the heater hose section.

You can even measure your hose to make sure it matches the length that rockauto lists for it.

Edited December 27, 2023 by CamGTP

Bleepster · December 27, 2023

or - go to local auto store - they can measure and cut you one to length since that is not a pre-molded/shaped hose.

2009_Suburban · December 27, 2023

How can I find out what size the hose is?

dna9656 · December 27, 2023

BEFORE YOU GO THROUGH ALL OF THAT. Where is it leaking? Investigate while the engine is fully warm and running. AFTER IT COOLS DOWN (don't work on a hot engine; you won't like it) If it's leaking at the worm gear hose clamp, try tightening the clamp FIRST. Start it up, warm it up and check for leaks. If that fails, (after letting it cool down again) get a storage bin at Wal-Mart a shallow one, about 4 to 6 inches deep X 16" X 20" or so. Put the open bin under the truck below the leaking hose, this is to catch the antifreeze that will flow. Loosen the the clamp ALOT, pull it back onto the hose, pull the hose off, this might be tough, hoses stick. Apply some motor oil, petroleum jelly, grease, any ONE will work, do not apply all 3 just ONE; to the nipple where the hose was, this will make dealing with the hose easier the next time you have to do this. With a SHARP utility knife cut off 1 or 2 inches of the hose; reinstall the hose, the clamp and tighten the clamp, I pour the antifreeze through some cheese cloth to filter it if needed, or you can pour in new stuff. Start it up, warm it up and check for leaks. If it still leaks I guess you're buying that hose. You can take the hose off and take it with you to the auto parts store. With the make, model, and year plus the hose you should get a match. You'll need the drain bin, the hose will be full of coolant too unless it leaks out of course. You may have to buy some coolant. Most folks can't wait the week or so for the part, so you may end up at the autoparts store. You can call any GM dealer and with the VIN they can give you the OEM P/N and any auto parts store can use it to get you the right hose.

2009_Suburban · December 27, 2023

How much coolant will come out of the hose when I take it off? Should I drain it out of the radiator first? Does the radiator even have a drain plug?

dna9656 · December 29, 2023

There is usually a drain plug on a radiator, that does not mean it's going to drain a certain way, that's why you have a 2' square drain pan. The block (for sure) is going to drain and the radiator will too but not completely. You probably have a 20 qt (approx) system, you can look that up under capacities. I'd go get a Haynes Manual for your truck and follow their instructions.

Autocop · December 31, 2023

Like dna said, you'll definitely want to catch the antifreeze coming out, but I don't think you'll see a ton come out. There is a drain petcock on the bottom of the radiator, but your only gonna drain the radiator and nothing on the other side of the waterpump. IMO, you could do one of two things. You could just go to the parts store and get a section of 3/4 heater hose and replace the whole thing. It's not molded so you don't need a specific part number. Not saying they don'r make one for that application, but you're gonna pay less for a piece of bulk hose. If you don't want to do that, cut the hose right behind the nipple coming off the water pump, remove the bad section thats still attached to the water pump, and stick the fresh cut end on it. Make sure you replace the hose clamps as well. That end on the heater core looks like it could be a bear to get to so I would grab a pinch clamp as opposed to the worm type.

I would go with option 1.