Things to check on a new-to-you Sprinter

Inspection tips for buying a used Sprinter T1N (At the Sprinter Source, click here to view, sign in to see pics)

2007+ sprinters are bad. Do not buy.
 2007-2017+ NVC3 Sprinter disclaimer:
If you're looking at getting a Sprinter, you need to know that 2007 and newer sprinters are unreliable and can be extortionately expensive to repair; both in parts and labor. 02-06 (T1N) Sprinters are much more reliable and can be expensive to repair too, but not anywhere near as expensive. I just do most of the work myself, anyway. Some T1N Sprinter owners have got over one million miles - See Zimaleta, a handy youtuber with great sprinter repair how to videos.


http://www.stephensservice.com/bluetec-diesel-issuesproblems/

https://www.linkedin.com/pulse/fatal-flaw-mercedes-benz-sprinters-tom-robertson

#1: Check oil level (Monthly once you own it). This is a $12,000 engine brand new. Improper/insufficient lubrication is the #1 cause of engine failure. If you have red dipstick, only check fluid when your engine is at 180F on the coolant temp gauge on the dash. If you have a yellow dipstick, check it when cold.

Pull off the injector cover to inspect for black death before you buy. You will need an allen key.

Check the intercooler hoses, from the intake manifold it looks like an elephant trunk, goes into the cooler, then out the other side from the cooler to the turbo. Any tiny spot of oil on this should be highly suspect as a leak and should be wiped off and inspected after driving more.
Mounted to the outlet of the turbo you will see a black teacup, the turbo resonator/muffler. It is known to develop a tiny crack on the top where the cap is glued on, allowing high pressure boost leaks at certain temp/rpm, causing limp home mode. If the sticker doesn't say Q5 or if isn't made by dorman, it will fail, replace it preemptively with the $30 dorman part or the aluminum eliminator. My Q5 resonator failed and was replaced by dorman, which has a perfect track record on the forums.
 
Get under the van and give the driveline a good shake. Is it solid or does it rock back and forth?

I'd recommend removing the three bolts that hold the EGR on, it's very easy. Disconnect the negative battery cable to avoid throwing a code. The valve fills up with gunk and will eventually cause random limp home modes or shut downs if it is not cleaned regularly, like every year or more often. All you gotta do is spray it with oven cleaner/solvent and make sure it has full range of movement. It's a very easy job just don't tighten the bolts too hard.

Jack up the two front tires with two jacks in the proper spot, or the bottle jack and a jack stand or piece of wood (don't use the middle of the transmission crossmember, can bend it). Have someone hold the steering wheel in place and move the wheels side to side with your hand on the tire. There should be little to no play if your ball joints, tie rods and steering rack are good

Check battery voltage, oil level, trans fluid level, coolant level, power steering pump level. Sprinters are very picky about the proper fluid, don't just put anything in there. You are dealing with a state of the art electronically managed turbo diesel with very small clearances, you can't treat it like your old Ford. You will need to buy a trans dipstick to check the fluid level unfortunately, and you can't leave it in the dipstick tube. Buy one, a $20 part to maintain a $4000 part is a no brainer. Beware of knock offs. I trust http://europarts-sd.com, not ebay, and not amazon. Dealer should have em too.

You may find that the P.O. has left round square o rings in the oil filter housing, these should absolutely not be there and could cause your oil to not be filtered. That's what I found in mine, they probably come with the filters, made for other cars. There should only be three O rings on the oil filter cap-spike, there should be no O rings on top and bottom of the filter. You won't be able to see it under the filter as it will hide in the oil so use a pick to check. See thread "How to properly seat your oil filter" on the sprinter source. You can remove the oil filter without draining or spilling any oil.

I recommend you have a thorough inspection done and read up on the sprinter forum about stuff that wears out, before you spend any money on a conversion. Also I recommend any sprinter driver to own a sprinter-specific scanner, like an Autel MD802, keep it in the van. (Be sure to get the "All systems/modules" version, not the 4 systems version)

When was the transmission fluid last changed? Should be done every 30K (or more) to keep it in good health. See my RSN fix video if it rumbles. I recommend dropping the valve body to clean off the conductor plate speed sensors whenever you change trans fluid (which must be the proper spec fluid). Easy job. When you do this the 13 pin connector holder on the transmission should be changed with a new one if it has orange o rings or just preemptively cause it can leak oil and mess up the wires or even wick up to the TCM, $13 part, twist and snap in place, very easy. Remember, this is a $4,000 transmission, and that is the rebuilt price. I do not recommend to pinch pennies on fluid that isn't listed on the MB BEVO aka approved fluids list.

Head to the sprinter source or here if the site comes back up and get yourself a free copy of the 2006 service manual, T1N_CompleteSprinterFaultCodeGuide, parts manual, transmission manual, troubleshooting guides, and more. I'd suggest loading it onto a phone or tablet that is always in the van.

Also I recommend pulling a fuel sample from the very bottom of the tank. Any sign of cloudiness/water or gooey debris (fungus that feeds on diesel) and the tank should immediately be dropped and flushed. Water, even just a tiny bit, is the #1 cause of injector failure and they go for $340 a pop. If the sensor on the fuel filter is unplugged, you will not get a water-in-fuel warning. On mine, the fuel filler neck is rusting. I give it a wipe each time I fuel up and it needs to be replaced.

Behind the fuel filter is a bundle of wires that gets cut on the flat piece that sticks out from the fuel filter. This can cause random shutdowns and very hard to solve problems. Use thick rubber hose and tape to protect it.
On top of the injector cover is the injector harness. The wires are directly on the bare metal and will eventually rub through, giving you injector fault codes. Add some soda bottle plastic or hi temp tape or something to protect them to avoid a nightmare of intermittent problems and random shutdowns.

Behind the headlights and under the drivers seat and on the firewall are very important grounds. They should be wire brushed/sanded till they are shiny, the ring connectors too. This will save you untold headaches.