Heater Core Flush Or Replacement - My Solution!

[jpt7779]

Facing a $900+ heater core replacement on my 1999 Silverado Z-71, I thought I would try one last ditch effort - glad I did!!

 

Symptoms were poor heat flow in cabin, all else worked fine. The IN line to the heater core was always hot with lots of pressure, but the OUT line was almost cool with little pressure. Clogged heater core with sediment???

 

Previously installed a Prestone flush connection on the IN line to the heater core, flushed system, new T-Stat. Still no luck. Purchased another flush connection kit and Super Flush fluid. Simply cut BOTH IN/OUT lines to heater core, blew 100 psi air into lines and clearly there WAS blockage!!! Poured in Super Flush fluid and let it soak inside heater core for 30 minutes, blew more air into hoses and it cleared the blockage!!!! I chose to install the flush connections on both lines so that I could verify the amount of coolant flowing in and out of the heater core.

 

Reconnected both lines, topped off coolant, and now have VERY HOT air cabin - VERY happy with a simple solution....

 

A fair amount of rust sediment was all over my driveway!!

 

Everyone with potential heater core blockage should at least try this, before you tear your dash out to replace the heater core!

 

Good Luck

[MikeNH]

Out of curiosity what is your mileage and have you ever had the coolant changed? Are you running dex-cool still?

 

Glad the truck is fixed- $1k repair bills are a tough pill to swallow for sure.

[jpt7779]

I now have 180,000+ miles and still runs very strong! Yes coolant changed about every 2-3 years with Dex-Cool. I changed all fluids at 100k and getting ready to change all fluids again, all Amsoil products.

 

We don't use the heat much in Texas, except in Jan and Feb............

[nickvrebel]

backflushing the heater core is always worth a shot, worse case scenario is you over pressure it and it blows, at that point, oh well, you were fixing to pull it any way.