Welcome. Check out Sir Sam's NOOB guide. Let me say right off I don't have any problems with mine but it's low mileage; I have a light foot on the trottle; don't do off road hardly at all; tow is relatively light and on flat roads; and I like to be proactive on maintenance. Issues: 1) original factory turbo>intercooler>engine hoses tend to rot from excess oil - solution replace with SAMCOs or 2n gen factory and some do an elephant hose mode or provent to keep oil out of the hoses; 2) air box to turbo hose same oil rot at connection to turbo - dealer only item but cost is only ca. $60; 3) weak torque convertor - solution drive until it dies and replace with SunCoast or Euro; 4) EGR issues - solution get a GDE tune that essentially shuts off EGR and improves performance and fuel economy (22-24 in town, 32-34 hwy if light footed and hold rpms to ca 1800 on hwy; 5) F-37 shift points especially into top gear - solution get GDE TCM tune; 6) "fluid" problems - solution flush and fill as appropriate being sure to use ATF+4 tranny fluid, only HOAT antifreeze (Mopar or Xerex G-05, diesel rated synthetic oil); 7) oil dip stick markings are such as to encourage overfill which sprays extra oil into those hoses - solution don't overfill 6.3-.4 gts for standard filter fill 7qts for large filter fill;
marginal turbo durability - don't push it too hard and be sure to use proper oil + keep fingers crossed or replace with GDE turbo when available; 9) if near/at/over 100,000 miles timing belt must be done at 100K - some have been ok going a bit over but timing belt failure is not the be contemplated on ANY diesel engine, not just CRD, 10) air in fuel head - solution 2n gen fuel head and heater element pigtail, lift pump if needed and/or replace quick disconnect fuel fittings with solid hose, 11) ceramic glow plugs are not terribly durable if used a lot (not much of an issue in N. Florida) - solution factory kit replacement (kit cost ca $125) can be a DIY except for required ECU flash which can be part of getting a GDE tune or the viewtopic.php?f=5&t=62346 plugs being tested if priced right; 12) some have had fuel injector problems - solution be picky about where you buy fuel, use injector cleaner from time to time, don't skimp on fuel filter change intervals, if you have an injector problem find a good diesel injector service shop for cleaning and rebuild.#9 is EXTREMELY important if you are looking at a 125K CRD. If timing belt has not been done it needs to be done right now. About $1200-1500 give or take to have it done depending in part on whether or not you do the water pump. It's a tedious exacting DIY project but well within the capability of the mechanically inclined especially with the right tools, available for rent from GDE or on site use by those of us that have them, or equivalent. DIY cost is on the order of $500 for parts, again depending on water pump and what pulleys you decide to replace or not.