Hose size for backflushing heater core

[gooffeyguy]

I need to backflush the heater core on my 2001. What are the port sizes so I can pick up some tubing before doing it?

3/4", 5/8"?

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

 

[Doubeleive]

I would say go buy a cheapy garden hose and a clamp, then just cut the hose end off clamp it to the core inlet, connect it to the faucet and have at it. you can flush till the cows come home

 

[PG01]

I need to backflush the heater core on my 2001. What are the port sizes so I can pick up some tubing before doing it?

3/4", 5/8"?

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

3/4

I would say go buy a cheapy garden hose and a clamp, then just cut the hose end off clamp it to the core inlet, connect it to the faucet and have at it. you can flush till the cows come home

Yeah but, what size garden hose?



And where did the cows go?

 

[Doubeleive]

3/4




Yeah but, what size garden hose?



And where did the cows go?

regular size, it was just an idea to make things easier, you could cap off one end and throw in some of that citric acid cleaner and let it sit for a while too

 

[gooffeyguy]

So are the inlet/outlet ports 5/8 or 3/4?

I have OEM replacement "T" connectors that I'm going to install for good measure (206k miles on originals). Measuring the end of the "T" fitting it looks like 3/4, but it's a quick connect so hard to tell exactly.

I have some old 5/8 garden hose, but I was thinking of getting some of that clear tubing just so I can see what's going in/coming out better.

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

 

[gooffeyguy]

Looking at @kbuskill post about the Gruven heater core T fittings, looks like it comes with 3/4" pieces or hose to connect to the inlet/outlet fittings.

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

 

[mizzouguy]

Heater core itself is 3/4" outlet and inlet. Is it clogged enough to not heat up the air box? Be careful with the pressure you force through it, wouldn't want to cause a leak.

 

[PG01]

3/4

 

[gooffeyguy]

Got the hoses and fittings off.

The original OE fittings were still pretty solid and looked great except for the white one being discolored.

Flushed the core, both ways twice, switching back and forth hoping to loosen any crud and flushing it out.

After getting the new connectors on and buttoning everything up, let the engine get up to temp and topped off the coolant tank. Checked the temp coming out of the vents and it was around 160*.

We'll see in a few months if it helped

Pic of OE "T" connectors with 206k miles on them

 

[kbuskill]

Got the hoses and fittings off.

The original OE fittings were still pretty solid and looked great except for the white one being discolored.

Flushed the core, both ways twice, switching back and forth hoping to loosen any crud and flushing it out.

After getting the new connectors on and buttoning everything up, let the engine get up to temp and topped off the coolant tank. Checked the temp coming out of the vents and it was around 160*.

We'll see in a few months if it helped

Pic of OE "T" connectors with 206k miles on them

Just my opinion... and I could be wrong... but I'm willing to bet those are NOT the original T-connectors at 206k miles.

 

[HiHoeSilver]

Just my opinion... and I could be wrong... but I'm willing to bet those are NOT the original T-connectors at 206k miles.

Never know. Mine are at 155...

 

[kbuskill]

If they are then you are on borrowed time IMO.

 

[gooffeyguy]

Just my opinion... and I could be wrong... but I'm willing to bet those are NOT the original T-connectors at 206k miles.

They are. I'm the second owner. I bought it from my father in law (original owner) in 2007 with 65k miles on it. He gave me all the service records at the time.

Only things I've replaced on motor have been spark plugs, wires, drive belts and front O2 sensors at about 110k miles. Everything else is original still.

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

 

[HiHoeSilver]

 

[wjburken]

Just my opinion... and I could be wrong... but I'm willing to bet those are NOT the original T-connectors at 206k miles.

My ‘07 XL Denali had the original ones on it when I traded it in at 300K. As a matter of fact, it had the original O2 sensors.

 

[kbuskill]

They are. I'm the second owner. I bought it from my father in law (original owner) in 2007 with 65k miles on it. He gave me all the service records at the time.

Only things I've replaced on motor have been spark plugs, wires, drive belts and front O2 sensors at about 110k miles. Everything else is original still.

2001 Yukon SLT
2012 Yukon Denali XL
2011 Yukon Denali RIP 5/20/18

My ‘07 XL Denali had the original ones on it when I traded it in at 300K. As a matter of fact, it had the original O2 sensors.

Guess I would have lost that bet... I must say that I am surprised.

When I bought our Burb it had 154k miles on it and it has about 239k on it now.

I am not certain if the first owner ever had the plastic T-connectors replaced or not but I had one break clean off while I was pulling a trailer with 4 motorcycles in it up the side of a mountain in Sevierville, Tn.

It broke and dumped all the coolant out before I knew what happened. I was on a winding 2 lane road with no where to pull over for about a 1/4 mile. Thank God there was an old abandoned gas station that I was able to get into.

I pulled over and popped the hood and discovered what had happened. I ended up bypassing the heater cores and was able to get enough water out of my cooler to refill the cooling system... it's a big cooler... lol

So that was one time that I replaced them.

The second time I replaced them was when one of them developed a crack that was just big enough to spray a tiny little stream out and cause the windshield above the heater core to fog up because it was winter time.

The third time I replaced them I went with the Gruven billet aluminum T-connectors and I should never have to worry about, or fool with, them again.

Not sure why some people never have issues and others, like myself, end up replacing them several times.

 

[08grey]

People like me lean on them and dont realize when they are changing the spark plugs. They breal shortly later.

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