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Remove / Replace heater core 98 Buick LeSabre


Some of you may remember my question from a week or two ago about heater problems with my Buick LeSabre. Well now I’ve concluded I need to remove the heater core to either replace it or have it flushed at a radiator shop.

My question is about removing the heater core. Do I have to take it out from inside the car? If so how much of the dashboard do I have to remove or dismantle? I saw some information in an online forum that seemed to suggest it could be removed from under the hood but I don’t see what they describe.

Any advice would be appreciated.


Dennis B

I don’t know what you have done or tested to determine that the heater core needs to be replaced or is plugged based on info you received on your other thread ( ) If it is plugged due to crud in the cooling system, do you HAVE to remove it to flush it? I’ve never had to do one on a Buick, but I’ve flushed several Tauri and Sables by introducing a 50% solution of CLR and water to the core through a heater hose. Find where the heater hoses enter and leave the firewall (therefor the heater core) and pull both of the OPPOSITE ends off of the engine. Flush the core with compressed air and run water from a hose through it to see if it is indeed plugged. The air and water may be enough to unplug it. If not, bring both ends up to equal levels so the cleaning solution will seek its level in both hoses and fill the heater core completely. Let it set for a bit, flush and refill it with the CLR solution. Twice has always worked for me. Then flush it again with water, blow it out and reconnect the hoses to the engine. If you have heat, you just fixed it. If not, you probably have another problem.

I would prefer flushing it as you suggest. Just one question, what is CLR? Is this an over the counter product or do I have mix it from scratch?

Thanks Again
Dennis B

3 easy steps to making your world better…
Step 1) buy a Haynes Manual. I will tell you things like how to pull a heater core.
Step 2) Try the flushing first (less than 10 bucks). Never heard of the CLR solution but I could understand how it might work. I like using a engine coolant cleaner such as Prestone. They make a “neglegted” engine treatment for when you don’t flush and fill on a regular basis (every 2-3 years). Dump the juice into the radiator and drive for 3 hours with the heater on. If you’ve never flushed before, Prestone also sells a flush and fill kit that allows you to insert a garden hose directly into the coolant system to flush out all the crud you just loosened up. Follow the instruction on the box and/or Haynes manual.
Step 2b) after the flush, I like to drain out as much of the water as I can and I fill the coolant system with 50% coolant and 50% DISTILLED water. Tap is OK but there are minerals disolved in it that can (in theory) precipitate out an start the whole clogging scenario over again.
Step 3) Tell me why you think that you need to replace the heater core? Do you have coolant mysteriously disappearing along with no heat? I replaced this on my caravan and it took me 1-1/2 days and required me to have a mechanic drain my A/C refrigerant, pulling the dash (and a bunch of it at that), replacing the heater core, re-installing the dash (it will squeek for as long as you own the car), and recharging the A/C. If you need to go this route, read the Haynes manual until you understand exactally what you need to do. Talk with some car freaks and be sure you aren’t getting over your head. Repair shops and dealerships (stealer-ships) love it when someone brings in a job they have to admit they can’t finish (did someone say boat payment?).

Good luck!