"backflushing" heater core.

I've run two seperate loads of rad flush through the system and flushed the results out, but my heater core still seems to be blocked. I'm not in too much of a hurry to swap it yet as;

a) don't have the $$ to replace it.

b) heater core removal from RHD XJ's is not as easy as LHD ones.

Soooo. I'm thinking of

a) swapping the heater hoses from the block around so the flow through the core goes the other way, pushing the crap out.

b) draining the water and filling the system full of white vinegar for a couple weeks

c) both

Anyone done anything like this? any other ideas?

What is the problem? Are you not getting heat? It could be the heater control valve, or even a busted vacuum line. Start the jeep up and see if the little arm on the valve moves. I forget if vacuum opens or closes it, but if it isn't moving, that should be the problem, which is much easier to fix than replacing the whole heater core!

Here's another way to flush the heater core:

There are two tubes coming out of the heater core, through your firewall, and into your engine compartment: 3/4" and 5/8"

- Go to your local auto parts store and buy 3-foot sections of 3/4" and 5/8" heater hose.

- Go to a local hardware store and buy 2 garden hose repair kits -- the kit that allows you to mount a female garden hose thread onto a cut off section of hose. Get one for 3/4" hose and one for 5/8" hose.

- Install those two female threads onto your two 3-foot heater hoses.

- Remove the engine heater hoses from your heater core tubes coming through your firewall.

- Install the two hose sections that you just created onto the heater core tubes.

- Thread your garden hose into one of those hoses and run water through it for about 5 minutes.

- Then thread your garden hose into the other heater core hose, and run the water in the opposite direction for another 5 minutes or so. Keep it running, even after you stop seeing crud come out. Every now and then something will come out.

- After you do this long enough, your heater core will be thoroughly flushed.

Hope this helps.

I did this to mine when I swapped to the later cooling setup. It would run brown everytime I swapped directions and eventually ran clear. Major improvement in heat output.

I'll try that. Thanks.