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.