Common Issues
Looking at buying a Astro/Safari van, or maybe you already purchased one. Here are some common problems/issues to keep an eye on.
In no particular order:
Turn ignition to run, listen for the Fuel Pump, look for check engine/brake indicator lights to turn on for a short period of time(to ensure bulbs work) and then they should turn off in a few seconds or after the vehicle is started. Often shady people will disable/remove the bulbs to hide the fact that there is something wrong.
Then scan the codes with an OBD adapter/reader and make sure all tests are completed and no codes are stored.
Cup holders missing from the center console/engine cover, without that black plastic/rubber piece that sticks up, good luck keeping a drink in there. Replacements and alternatives are available.
Vacuum hose leaks can cause multiple things, usually the first thing you notice is when the engine is working hard that the heater starts blowing from the defroster vent or to the floor regardless of where the controls are(it's only a few $ for the hoses so replace them all under the hood, one at a time).
Lower intake manifold gasket replacement on 96 and up is virtually inevitable, usually showing up anywhere over 100k miles. It's not a question of IF, but a question of WHEN.
Leaking oil cooler lines, even the replacements typically end up needing replacement, replace again or bypass/remove the oil cooler adapter for free.
ABS activation at low speeds - This is one of the most dangerous situations and there is a bulletin out about this one. Anti-Lock Brakes(ABS)
Engine mounts, these are a PITA to replace especially on the AWD models. On the AWD models it can cause damage to the oil pan when the mounts are worn as well make sure your oil pan is not damaged. See: Engine Mounts.
HVAC blower only blows on certain speeds or not at all. Make sure the A/C works, can be quite expensive to fix and they often leak at the compressor belly seal.
Check brake lines for rust, clean fluid, parking brake works, no warning lights.
Arm rests, drivers side door tends to be the worse, but so many of them are cracked, this is 'normal'. Depending on the year/type they can be easily replaced, others take more creative solutions. Plenty of people cover them with something else. Drivers inside flip up armrest being broken/limp is another common problem, easily fixed by removing the broken pin and replacing with a bolt, no welding required.
General tuneup, replacing the spark plugs and wires can be intimidating the first time, but with the proper extensions and techniques it can be easily taken care of, but often hasn't been. It's probably time for a tuneup. I have seen multiple vehicles where the easy plugs are replaced and still have the original plugs from the factory in the hard to reach ones.
2nd and 3rd gen - Pancake Distributor Disease, commonly leads to destroyed catalytic converter, easy and cheap to fix, but required paying attention to what you are doing when removing/replacing the distributor.
~3rd gen(vin X) piston slap, they shortened the piston skirts(for efficiency?) on the later Vortec engines, at higher mileage piston slap becomes more common, but can run a long time that way.
Water pump leaks are a common issue. Watch for water coming out of the weep hole at the bottom of the pump. If it's a small amount once in a great while, don't worry about it, but a large or constant leak is an issue. When replacing the pump, make sure to clean the mating surfaces well and install the gaskets dry. Keep an eye on your coolant level.
Rust on the front fender, radiator support, under molding, rocker panels, bottom of doors, around windshield, and at the rear hatch is common in the rust belt.
Worn out steering components, esp idler arms(these vans tend to eat idler arms, use quality idler arms or just get used to replacing them).
Missing lug wrench, jack, wheel chocks and the hook/nut that mounts them to the van.
Listen for groan, whine or clicking in rear end.
AWD, look for leaks, listen for clicking when you turn on ignition, check fuse and do tight figure 8s in parking lot. Sometimes on the 99and up vans the fix is as simple as a proper fluid change.
Inspect, inspect and inspect some more.
Things to bring with:
Large piece of cardboard or two
Old clothing or coveralls, and gloves
Couple of good flashlights, head mounted comes in handy as well as a nice bright handheld one. Using your phone can be an option but is often a PITA
Basic hand tools
OBD2 code reader(prefer with live data), scan for pending/stored codes, tests completed.
Cooling system pressure tester
Jack/stands/ramps
Water spray bottle
Once you have bought 'the one', it's time to do a few maintenance items. As you are probably starting without really knowing the history these are the things I would do to start a new maintenance history.
Replace all fluids and filters: Engine oil and filter, transmission fluid and filter, differential(s), transfer case fluid(ATF through 98, 99-05 Auto-Trak2 only), power steering, coolant, fuel filter, and brake fluid.
Replace all under hood vacuum lines, paying specific attention to the one that leads across the front of the engine and the one leading down to the vacuum storage ball. The vacuum check valve also is a common failure item and cheap to replace with your new hoses.
I would also replace the knock sensor on the older vans, they do age and there isn't a super accurate way to test them. You can always watch the live data to see if you are getting a lot of knock events. But I just replace them, cheap insurance, don't over torque them.
Inspect all rubber components and replace as necessary: Engine mounts, transmission mount, steering linkage dust covers, bump stops, belts, tires, hoses, etc.