hey guys, i am looking at buying another cummins and i want a 1st gen but i dont know much about them. what are some thinks to look out for when buying one?

 

mine (1991 with I/C) had been sitting for a while. It needed a lot of o rings replaced in the fuel system. They had all dried up from sitting.

 

make sure the oil isnt brand new I hate it when sellers do that. If the oil is over filled it could have a blown head gasket. be careful with trucks that may have had wiring hacked up I.E plow trucks, big sound systems, a bunch of chicken lights, winches, cb's. Id stay away from a automatic. Make sure the front end is in good shape. Ask what mods have been done.look at the trash and fluids in the truck like if there is 20 blown fuses in the glove box or a jug of radiator stop leak. check for blow by. check exhaust smoke.

 

RUST! Body rust, frame rust, floor pan rust, cab mount rust, etc. Plus what everyone else has given you a heads up about.
Bill

 

also check the steering box mounting plate on the outside of the frame rail on the driver side most are cracker from what i understand. mine had 2 cracks i had to box the whole plate with 1/4 inch plate also dont forget the kdp good luck

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most are CRACKED sorry

 

Be vigilant for frame cracking behind the cab.
The early 3/4 ton 2 or 4wd trucks, especially ones pulled hard and heavy with a gooseneck or 5th wheel, are notorious for this.

Bubbling and/or missing drip rail and roof skin above the windshield, along with floor pan rot means the roof leaked and rotted.
Don't ignore "light brown spots" in the roof skin, especially above the windshield, nea the drip channle, it's an indicator!

Hard to see, but a concern nonetheless, is severe cowl cracks.
Sometimes these present as "popping" noises when you drive at harsh angles, through ditches (one major contributor to the problem) or such.
Cowl cracks get severe enough that they also will cause leaks to the floor.

Bed supports can rust through, even though the bed and rear corners look great, the channels that run under the bed, from side to side, will hold material and moisture, then they will rust out, then it's only a matter of time before the floor is shot.

Injection pump leaks!
If you can let the truck run, drive it, let it get warm, then sit and fire it again, watch for even the smallest sign of wetness, because sometimes if it leaks then the truck sits they sort of dry and seal up.
It may take a bit for them to leak again, but when they do, this time they will POUR out.

Mark.