I'm looking to buy a 1992 F-250 with a 7.3L IDI with a ATS turbo and only 140,xxx miles on it. What do you guys think? any advice? Any problems I
should look for etc.? Thanks!

 

Ask the owner if they have kept up with the SCA's (coolant additives), or it might have cavitation. That's the big one I can think of, other than normal used car/truck buying things to look out for.

 

I just bought a 1994 last week and I wish I had a checklist to go off of. I'm new to ford diesels but I'm a professional mechanic. I'll try to give you some pointers based on what I found on my truck during inspection.
1. 4 out of 8 of my glow plugs were bad. They were a pain to remove and replace. You can check them with a test-light. You can tell a few are bad if the "WTS" light only illuminates for a second or so and theres a clicking noise under the hood when the key is turned to "Run".
2. All my fuel-return lines were leaking and the cap o-rings were shot. Look for signs of leakage.
3. Make sure the truck is dead-cold when you show up to inspect it. A warm diesel hides a lot of problems like glow-plugs or smoking problems.
4. If you have dual tanks, try the switch during the test drive and make sure the truck doesnt die on you.
5. Pull off the ATS air-cleaner an reach your hand into the compressor then spin and wiggle the shaft. It should have zero axial play and very little lateral play (0.050 or less or so; other people may have different ideas of whats acceptable.)
6. Check the oil and coolant for signs of a blown head gasket.

 

Oh... check the Vin numbers too and make sure they all match. Drivers Door tag, Dash, Tag, bed-tag (attached to the front of the bed behind the passenger door), and frame stamping (located on top of the passenger side frame rail, under the firewall. You'll need a mirror, flashlight and rag to see it.)

 

If I understand correctly, the clicking sound is the glow plug relay turning the GP's on and off after the main glow cycle, to keep the cylinders warm. Once my truck finished its initial ~10 second glow, it clicks the plugs on and off until I start the truck, and for a short time after starting.

Anyways, for the OP:

The engines in these things are just about eternal. Insist on checking it out when the engine is cold though (and if you can get to it early in the morning, do it). Feel the engine before starting it to see if the owner started it up before you arrived. If the engine has a problem, it'll very often be related to starting.

Take it for a test drive and get it to its full operating temperature, and try and keep it there for a while. After the test drive, shut it down, do some exterior inspections maybe, and after a few minutes try and restart the truck. If it's hard to start when warm, that's a dead giveaway that the IP is going out. Not necessarily a deal breaker, but they ain't cheap.

Besides that, if the transmission is an E4OD, give it extra attention, they've got a bit of a reputation for being a PITA. They're mechanically very good, the electrics just sometimes cause issues. If it shifts fine at various RPM's and the fluid looks and smells good, you should be fine.

Besides that, usual stuff. Brakes, joints, rust, raccoons living under the hood...

 

Yes, but what was mentioned earlier is the glow plug's failing. If the WTS light only comes on for 1-2 seconds and the glow plug relay starts clicking right after that, then there are dead plugs. The clicking after a healthy 8-10 second WTS is called afterglow, and it's normal.

 

Inquire about SCA's as mentioned, if he doesnt run them its not a deal breaker, but you should add it.
Check for oil leaks... IDIs like to leak but some are harder to fix than others; pay special attention to the oil cooler (long round thing above oil filter)
Also mentioned, insist on seeing the vehicle before its been started. Glow plugs are easy to change but are $10 a piece. Air intrusion can be a bitch to track down. The diagnostic difference between the two: if it is hard to start, but is trying, GPs, if it starts then dies after a couple seconds, air.
The obvious things like check all fluids, but make sure there is no oil in the radiator when cold (it floats) and after its been running check the oil (water in the oil will settle on the bottom, therefore wont be able to see if there is any until its ran and mixes with the oil) make sure the oil is not over full and also that it doesnt smell of diesel.
If so equiped check for exhaust leaks pre-turbo, and check turbo play. Contrary to above, i was told "side to side" play is fine given that it is minimal, but you want zero end play (in /out) if you can see the compressor wheel, verify that it is not "dusted"
Last thing i can think of is go for a nice long test drive to get it fully warmed up and listen for abnormal ticks, knocks, smoking, flying parts, etc as you would with anything else.
Having a pyrometer is a big plus, (usually, not always, means that theyve taken care not to melt pistons)

 

Another MIA OP.