A Buyer’s Guide to Old Diesel Truck Shopping

By HN’s truest truck aficionado, Maria Wachter.

1994 Dodge diesel. Photo by Maria Wachter.

Are you looking to buy an older diesel truck? Maybe you need another backup vehicle, or maybe you don’t want to shell out 70 grand for a new truck, or maybe you’re sick of your newish truck getting horrible fuel mileage (older diesel trucks get pretty darn good fuel mileage compared to the newer ones)… either way, there’s one thing for certain: if you have horses, you NEED a truck.

Here are my guidelines I use when old truck shopping to keep from getting burnt and keep from shelling out thousands of dollars in repairs to fix said truck.

1. BEFORE you turn on the truck, do a walk around and inspect underneath the truck.

• Look for rust, especially frame rust. A little surface rust won’t hurt, but if the frame has rust rot, PASS. You don’t want to hook up your horse trailer and drive away and half the truck and trailer are still back in the driveway.
• Check to make sure frame is straight and hasn’t been in an accident. Also, make sure title VIN matches VIN on truck.
• Any major leaks or puddles in the driveway or covered on the underside of the truck? A couple of oil spots aren’t going to be a deal changer, but if there’s a lake in the driveway, walk away. Oil leaks can be costly repairs, because half the time the whole engine needs to be pulled to get to the leak. Most older trucks will have a couple smaller leaks/drips. Not a big deal, you can always top off the oil between changes.
• Check how old the tires are. A set of four or six tires will cost you a minimum of a grand. Factor that into the cost price. If you don’t know how old the tires are, there is a four-digit number you’ll find on the sidewall — the first two digits are the week of the year the tire was manufactured, and the second two digits are the year the tire was manufactured. Anything over three years old and you run the risk of a blowout. Not fun, especially if it rips off your dually fender in the process.
• Pull off radiator cap. If the cap has milk chocolate-looking gunk on the underside, pass on the truck. It means a head gasket is probably blown.
• Check the oil dipstick. Make sure there’s oil still on dipstick. If dipstick is dry, either the engine leaked it all out, or it’s burning too much oil.

2. Get in the truck and turn it on.

• If truck won’t start, pass on the truck. The owner might say something along the line of the batteries being dead. If the owner can’t get the truck started, it could be something like a bad fuel pump, injection pump or fuel line leak. If that’s the case, move on.
• Once truck starts, look at the exhaust and see if any major smoke is coming out. If you see blue smoke, walk away. White and black smoke are OK as long as they clear right up. No smoke is best. Smoke means there’s an issue from sending too much or too little fuel into your engine. Normal causes are from bad injectors: injectors cost a lot of money. Most old trucks will belch out some black smoke at start up and then clear up, which is nothing to worry about.
• Listen for any knocks or ticks coming from the engine. If the engine seems to be “loping” or knocking, move on to the next truck you find.
• While engine is running, check for blow-by. To check this, you need to remove the oil fill cap on the engine block while truck is running. When you remove the cap there should be no smoke or little to no smoke coming out. If smoke starts pouring out, your engine has blow-by and it means the engine is wore out. Pass on that truck.
• While truck is running, see if it starts leaking. Sometimes trucks only leak when they’re running.
• Check heat, AC, and if the truck is an automatic transmission, check to see if your overdrive button works if the truck has one. Also check the radio, horn, windshield wipers and windshield fluid.

3. Take the truck for a test drive. Make sure you take the truck up to highway speeds. A lot of these older trucks do great around town and feel like they’re going to fall apart once you get up to 65 mph.

• See if the truck pulls hard to either left or right. If so, it might need an alignment.
• Does the truck have any wobbles or shakes? If so, front end is probably worn out.
• When you brake, are the brakes spongy or firm? Is there any shaking when braking? If so, your rotors need to be resurfaced or replaced.
• Does cruise control work?
• Does the truck overheat or not get up to heat? Could be a bad thermostat, radiator or fan.
• Does the transmission shift smoothly through all gears including reverse? (If you can, always go for a manual transmission in an older truck. It’s cheaper to replace that an automatic transmission; normally you get a few more horsepower and the manual gears really help you out when towing, especially down hill.)

If truck passes all of these steps, I’d say buy the thing, especially if it’s at the price you want. If it doesn’t pass all of these, and you still want the truck, pretty much anything can be fixed if you have the time AND money. You can always drop a new engine in the truck or a new transmission, but be ready to spend more than you might have bought the truck for.

Happy truck shopping! And go riding.