now i wish i'd bought the F-150 instead of my car...it was at a car lot so idk the previous condition..i test drove it and the engine was strong but the trans had a shudder..it had about 150k on it...and a couple weeks later i found out he had to replace the trans...i instead bout an 01 cavalier Z24 i've given it a good run around it had 136k on it and i'm now at 152k in just over a year...i get junk for gas milage but you gotta pay for speed.....anyway my point is that newer technology has made engines more reliable...all i've replaced on my car is the plastic thermostat housing... i read an article that said in manufacturing the new mail jeeps they are built and equipped to run over 300k with just regular maintenance....sorry for the tread jack...just a little input.
I just turned in 2 98 expeditions with over 246,000 miles that's using rerefined oil, the only thing that went bad was 1 alternator, these were U.S. Military vehicles utilized for going to missile fields but the 5.4 is an excellent engine, and would have no problem buying a high mileage one
my 97 exped 5.4 just turned 167K and still going strong....great vehicles.
I have a 97 Expedition with 231,000 miles on it. It runs fairly decent. I bought it for $500, I've put about $800 into repairs and have a decent 4x4 that seems to have a fairl amount of life left. If not, I am not out much and could drop another engine it and keep on trucking. The body is great shape, the interior needs a few pieces and a good cleaning.
200K on my 2003 Expedition 5.4L
I have no money to buy another so I have to keep this one going. Oil and filter every 5K. Coolant and trans flush and new fuel filter every 50 K.
New plugs, cops and serpentine belt every 100K. Major problem was limited slip differential stopped slipping when turning from a complete stop. Ford rebuilt it. The clutch pack and friction modifiers had to be corrected and had to have a new ring gear. That was about $2K (of course it was out of warranty). It has been fine ever since. The vacuum hoses do get brittle and Ford has some neat little plastic vacum line pieces that can be discarded and bypassed with a plain old vacuum line circled around to make the bend. Ford designed a nice plastic cover to go over the intake and make the engine compartment look pretty. Snapping it on and off interferes with some of the vacuum lines so I have removed it and it is in the attic.
-Oil starvation: They can use a little oil when they age, and if run low, say goodbye. The higher the oil consumption just means more attention to keeing it full. Doesn;t mean tear it down for a rebuid, it will keep going.
-Lack of coolant maint. When you grab the hydrometer and it says you are protected down to -32 degrees and thats it for a coolant test.....say goodbye. 30-50k in 2-3 yrs is good for green. 75-100k in 4-5 yrs is good for motorcraft gold / g-05. Any other coolant, or any other interval is a death sentence on the cooling system / head gaskets.
If you measure electrolysis, and find it present in your cooling system, it is a matter of time before it attacks the head gaskets or aluminum head itself. It can happen at 130-150k but usually in the 200k it will work its way thru near the thermostat area of the head. Keep the electrolysis out by maintaining coolant change intervals from the start.
My wife's 2000 (My old truck, and still hunting rig) has 163,xxx on it and runs great. It did pop a plug about 30,000 miles ago, but I think it was my bad, as I had recently given it a tune up and used Bosch plugs... (I have since learned to use only the Motorcraft or Autolite platinums). It has a small oil leak near the intake manifold somewhere, so I have to keep an eye on the oil, usually adding a quart between changes at 4,000 miles.
I never replaced all the cops at once, instead replacing one at a time, as they go bad. I have replaced 6 as of now.
I put an Auburn limited slip in the rear ab out 7 years ago, and while I had it all apart, I went ahead and installed a new ring and pinion. It didn't need to be replaced, but I figured I might as well do it so it would last that much longer.
These engines are built for longevity rather then all out performance. Just look at the equivalent GM LS engines. Those make great power stock and respond better power wise to modifications then the modular motors do but how many of those engines do you hear going way over 200K? Not many. These mod engines are by far the best for longevity and for being workhorses. That is why you see them in taxi's, police interceptors, fleet trucks, vans and the service industry. A properly maintained mod motor should go over 300K if you have an owner that didn't neglect or abuse it daily. Not to mention they get decent mileage for being a V8. My 2002 Mustang GT with an auto gets 21-23 MPG routinely driving up and down the Cajon pass. These are good, solid engines.