CLR Heater Core Flush

[qristofer]

My 2001 Chevy Suburban has been having intermittent heat. I barely got any heat from the front and the rear vents were a tard better. When temps dipped in the low 30s there was no heat to speak off. I decided to do do a CLR flush after watching a video on youtube. I do not have compressed air so I decided to use my garden hose.

 

Separating the hose from the heater core is a pain in the rear. It looks easy enough whereby you would just push the plastic fitting back, depress the tabs and it disconnects, but in reality it does not work that way. I did not want to break the tabs, so I decided to leave the connections intact and I pulled the hoses instead, the passenger side is the inlet and driver's side is the outlet. I cut off the screw-in part of the garden hose and pushed it in to outlet side of the heater core and turned on the water. I let it run for 10mins to clear out the coolant and then I used a shop vac to blow excess water out. And since I did not have 5/8 hose on hand, I just cut off a section of the garden hose, about 2' long, and plugged back on to the outlet of the heater core. I then poured an entire container of CLR into the heater core until it started spilling on the opposite end of the heater core. I attached the end of the garden hose back to the inlet side and I let the CLR do its thing for about 30 mins. I wanted it to let it sit in there longer, but the warning on the CLR container says that it is not supposed to be used with aluminum, so to avoid potential damage. I reversed flushed the system for 15mins. Nothing too dramatic came out like in the videos I had watched. Some foam came out initially, but after that the water came out clear. I flushed both sides for a total of 30mins.

 

I re-connected the inlet side of the heater hose and cranked the truck till coolant came out rushing from the outlet side, just to expel as much air as possible. I connected the heater core outlet and idled the truck for a few mins. It could be placebo, but the air coming from the front vents felt hot with the engine temp at approx 185, my normal operating temp is 210. The temp outside was 54, so I will have to wait till monday morning when the temps dip back into the 30s to really tell the difference. The rear vents seems to be blowing cool air whereas the front is blowing hot.

 

I will be flushing the rear by itself, but the plastic connectors are really a pain to get them to release. I hope this helps someone that is planning on tackling this project. It is an easy project, but it could be easier if you can get the the right tools to realeas the plastic quick connects.

[j13smiley]

Interesting...

[brainpause]

Isn't there a special tool for the heater hoses to make it easier?

[06pirate]

I think this is what you need:

 

 

 

http://www.amazon.com/OTC-6046-Heater-Quick-Connect-Release/dp/B000F5HUTE

http://www2.otctools.com/otctools.com/newcatalog/products/517917.pdf

[txab]

I think this is what you need:

 

 

 

http://www.amazon.co...e/dp/B000F5HUTE

http://www2.otctools...products/517917.pdf

 

 

Yep. That's the tool for the quick disconnect fittings at the core.

[hockeypro1411]

I went to my local Advance Auto and had them order me that tool for like 4 bucks. Mine didn't stock the tool, but i got them the Dorman brand part number and they had one for me the next day!

[qristofer]

Thanks for the info! I didn't even know you needed a tool. I might just get one before trying to flush out the rear heater core. The rear core in the suburban is upside down, so I doubt there is a way to let the CLR soak in there unless the connection are disconnected at the front (engine compartment), but that is a long ways for the chemical to travel.

 

I think the reason why you don't use CLR on aluminum is because of discolorization. Just my 2 cents