I tried flushing my heater core but I'm still not getting enough heat and winter is approaching. I'd like to swap the heater hoses on the heater core side to reverse the flow through the core. Can I just swap them or are the host size differences too great. Any recommendations for the best way to do this?

I also purchased the parts to add a WIX inline filter. I'm going to route it to filter the coolant exiting the heater core as reversing flow should push some gunk out. Then when I put the flow back to normal it will filter before the heater core preventing future buildup. Does this sound reasonable (I understand I'll have to change ports on the filter mount to match flow direction)?

I'm not willing to do any more aggressive flushing as I am not willing to risk a heater core leak.

your thought process is good, IIRC the heater core pipes both in /. out have the same diameter.

They're different sizes unfortunately, one 3/4 and the other 5/8, so you'll need some step-adapters to make it work. Reversing the flow in the 95+ models is actually the "Engineering correct" way for the coolant to flow, entering at the bottom and exiting from the top. Not a huge difference, bleeds easier, and with the bean counters ruling the world now-a-days, ...

To help clean out the core, I used a pond pump in a 5 gallon bucket to pump stronger-than-recommended coolant flush through the core. I let it run for 24 hrs; seemed to make a difference...

If the heater core is corroded/compromised enough that multiple flushes isn't getting it done you're probably at the brink of springing a leak anyway...What makes you think it'll magically start working in time for winter by just reversing the flow if there's blockage now ? I'd keep the cleaning process going until you get to a better place with it and if it springs a leak it was going to happen anyhow...Or get the gloves out for the winter it's your choice...I'm assuming you've checked the blend doors for proper operation to get full heat ???

Thanks for the feedback. The heater in this XJ was never very warm since new. I don't think it's on the verge of anything different than it was the day mom took delivery from the dealer.

My thought process is it'll either push some debris out and slowly clean up (and into the Wix filter) or will do nothing and I'm no worse off other than a cleaner coolant system.

I have the part for the blend door and will be doing that as well (via a dremel, this is one part I'm not doing the proper way, I'm not pulling it all apart right now). Worse comes to worse my mom had one of those seat warmers that plug into the lighter in it.

Bummer the hose sizes are different. I need to splice in the coolant filter into one hose anyway, guess I will just splice both so I can mix and match.