Johnly

It's been years since my 87 XJ heater has put out even a modest amount of heat. Got by using a little 12V heater that plugged into the lighter to defrost the windows. Just dreaded the thought of tearing into the dash to remove and replace the heater core.

Read another thread on the forum that suggested disconnecting the hoses going to the heater core and back flushing it. With little to lose I gave it a try last Friday before a cold weather trip. Rusty brown goo came out during the flush, so I did an additional forward and reverse flush and hooked the hoses back up, topped of the coolant and took it for a test drive. Magic! More heat than a person could want came out of the vents.

Thank you for the great advice.

John

JackJare9455

Glad to hear that you took some good advice and plunged in there yourself and got it fixed. Sometimes it just takes a little research and faith.

Chucks96XJ

ur lucky! i actually have to replace the core...its leaking...

cruiser54

It would be a good idea to eliminate the heater control valve since it will allow coolant to continually flow through the core and not stagnate. And don't worry about your heat being on always. It won't be as it's controlled by a blend door.

hoot619

Yes, the blend door works. When I did mine I never used the blend door til some time later. It is sure nice to be able to control the heat. As I am getting older I think my grey matter is turning to mush. A lot of help on this forum and people aren't afraid to tell you if you are screwing up. They will warn you not to try something if results could be bad. Thanks all Hoot

cruiser54

BTW Hoot, here's a little diddy about heater control valves.

HCV Removal

Well, you guys ponder all you want.

The heat is controlled by the blend air door. I've eliminated at least 10 of them here in Arizona and my AC always works perfectly.

Let's not have this thread turn into one of those where folks think theory and conjecture trumps actual field experience which has been proven time and time again, by numerous different people.

It flat works. Period.

I've already stated the other benefits of keeping coolant flowing versus being stagnant in the heater core and the dangers/disastrous results of having one fail unexpectedly whether you're poking around the engine bay or driving down the highway or trail.


Thanks to djb383 for this:

One thing you may want to consider, is removing/eliminating the heater control valve, if you haven't already. '96 down have the HCV, '97 up the Factory eliminated it.

During the warm months, with a HCV, (temp lever/**** never moved off cold) coolant sits and stagnates inside the heater core.....There's no fresh coolant/corrosion protection circulation through the heater core.

With the HCV removed/eliminated, coolant/corrosion protection flows through the heater core constantly when the motor is running, regardless of where the temp lever/**** is set.

Also, you don't have to remember to turn/slide the heat lever/**** when flushing/re-filling the cooling system because coolant is flowing to/through the heater core when the motor is running and the HCV is absent.

Be sure to plug/cap the small vacuum hose when eliminating the HCV.