I am a new Jeep XJ owner. I bought in the spring of this year.

1998 XJ Limited, 169,000 miles, clean and runs like a dream.

I drove it across the country, did some trail driving, had it covered in mud, then back on the highway for another 7 hours of driving and it was smooth the whole trip!

I have two issues that I need help addressing.

1.) I have dirty gunk in my coolant (mechanic said it was "stop leak" that previous owner may have put in for a leaky water pump or something) I had him do a tune up and some maintenance but he was hesitant to do a full flush in case all the gunk was holding leaks in on the radiator. (At least until I had enough money for a full replacement in the worst case scenario) Anyway, I had a heater core go bad in my dodge dakota (another jeep, chrysler, dodge product) and similar issues are happening with my XJ. The heat is HOT (it's getting into the 50's here in Ohio in the morning so I have been running the heat a bit) however, the windows are getting that fog on the inside, and that nasty "sweet" antifreeze smell comes and goes through the vents ( I've also heard that this is toxic) so I roll the windows down. Anyway, mechanic said its $600 to replace heater core and is not optomistic that a flush will help anything... I called another mechanic and they quoted me $790 and also said a flush wouldn't help.
What are your thoughts? I know heater cores can go bad and corrode and so I'm fine with replacing it but wanted to get some insight from the guys (or ladies) who really know these XJ's

2.) I have driven in 4 wheel drive and everything seems to be working fine, no grinding, etc... What kind of maintenance or check can I do (or have the mechanic do) on the 4 wheel drive system? Winter is coming and I can't wait to not get stuck in my driveway!!! When I got new tires they told me a front wheel axle that is wearing out but is fine for a while (only affected by 4x4) Also, can I shift into 4x4 on the fly or do I need to stop, put it in neutral, shift 4x4, and then put into drive?

Sorry if these questions seem basic, I searched quite a bit before posting and am just getting started on my journey into the world of XJ's. I have been doing my own oil changes, did my valve cover gasket, installed a new hood, and some other basics, but the heater core and 4x4 system make me nervous...

Thanks in advance for any opinions or advice!

 

1) no easy fix on the heater core, its got to be replaced. Since they have to pull the whole dash I would probably go ahead and replace the a/c evap core while they are in there doing the heater core. It will probably add about $225 to bill for part and recharging freon but could save more than that if it wasnt replaced and started leaking next year and whole dash had to come back out.


2) tranny fluid drain and refill , transfer case, drain and refill, and differentials drain and refill. Grease driveshafts and u axle u joints. Those are easy things to do and you can do yourself in about 4 hours and save some $.