1994 Mercedes-Benz 300 Series

3.5L Straight 6 Cylinder Diesel Fuel Turbocharged

Automatic

WDBGB34EXRA158531

This is a 1994, Mercedes S350 Turbo Diesel. The car has 231,769 miles and has had two owners. I've been the owner for the past 14 years. No kid miles since I've owned it. To my knowledge, the car has never been in an accident. It has received oil changes religiously every 3,000 miles. Let's not kid ourselves, this car is old enough to vote and has over quarter million miles on it. It's not show room perfect. At around 200,000 miles, the car had an oil leak. I was told it was a head gasket (not a cheap repair). It turned out to be a cracked head (an even more expensive repair). I decided to invest the money in that and other repairs and get another 100,000 to 200,000 miles. In the past two years, I have put nearly $10,000 into the car, and it needs more. Unfortunately, for me, the only thing that makes sense is doing most of the remaining repairs myself. I’m simply too busy to do that, so I’ve purchased another car. When the Mercedes is running good, it’s a great car. So here’s the good, the bad, and the ugly. The Good: The bad gasket turned out to be a cracked head (a well known problem with this engine). That was nearly half of the 10K in repairs I mentioned. The mechanic made a mistake rebuilding the engine, causing a catastrophic failure. This resulted in another new head, new cam, new lifters and as long as we were at it, I had a new cam chain installed. Incidentally, the oil leak was dripping on the alternator (which ruined it), resulting in a new alternator. While the head was off, I had the engine checked for another infamous problem, bent rods. It’s a long story but the 3.5 liter diesel was nick named the “rod bender”. A significant number of the S350s suffered engine failures due to bent rods, many of them well before 100,000 miles. The only sure way to check is to remove the head and make sure that all six pistons rise to the same height in their cylinders. This engine has no bent rods. If it hasn’t happened by now, it probably won’t. Other items replaced since the engine rebuild include several front end components, new shocks all around, new engine mounts, new radiator, new front bumper cover (non Mercedes), both front fenders (Mercedes OEM) replaced due to rust, new heater blower speed controller, new front suspension springs, new set of glow plugs, new injector lines, and rebuilt cruise control module. Other repair within the last 5 years include a new driver side window regulator, new driver side door handle (with IR keyless entry sensor), new door locking vacuum pump, new auto antenna unit (could use a new mast), and the heater blower motor. No black or blue smoke. Burns less than a ½ quart of oil in 3,000. Gets 21 to 22 MPG. Has never failed to start even in extreme cold weather. The tires are Michelin MXV4's with plenty of tread life left. The Bad: After the engine has been running long enough to heat up completely, it will exhibit a rough idle. Off idle, it runs fine. I took the car to my Mercedes dealer to have them check it out. They said it is most likely the injection pump (IP). The injectors are clean, and the compression in all six cylinders in even and near the upper end of factory spec. The IP needs to be rebuilt. Through Mercedes, $2,500+\-, remove it yourself and send it to Bosch, $1,500 +/-. Replace with a salvaged pump, $385 and up. It’s not a simple task, but instructions are available on line. The water pump has a leaking seal. It’s good enough to drive, but obviously needs replacement in the very near future. If you will be driving the car very far, the pump should be fixed immediately. It looks like the pump can be had for under $150 on-line. I will be glad to work with you in getting the pump replaced prior to pickup if so desired. There is a bad sway link in the front end, which causes a clunk on rough roads. Not a big deal to do yourself. The front driver side lower seat cushion has a broken frame and needs replacement. Driver side seat heater doesn’t function. Shopping Ebay, it looks like $100 to $150 to replace with a used cushion. In this car, the front seats are interchangable (no difference between driver and passenger seats). The front brakes are about due for replacement. I believe the passenger side caliper is dragging slightly causing the rotor to run hot and warp. This results in a slight shudder in the steering around 55 mph. I priced out calipers, shoes and rotors for around $400 on-line. The radio volume knob is erratic (a common problem with the OEM radio) and the CD changer has occasional “drops out” when playing a CD. The Ugly: The driver seat back cushion has a rip (see photo). There are two scratches in the hood (not through to the metal) and there are some other body dings, most of which can be removed using “paintless” dent removal. No one has smoked in the car since I’ve owned it; however, the original owner must have been a chain smoker because even after 14 smoke free years, you can still tell it was a smoker’s car. It doesn’t have that ashtray smell, but it does have sort of a pipe tobacco odor. I’ve tried to be as honest as possible here. The car needs work, but it’s in driving condition right now. If you are comfortable turning a wrench, it should be possible to get this car into excellent condition without breaking the bank. The pay off is that the W140 bodies were the last of the hand tuned bodies from Mercedes. When this car is running right, it’s a joy to drive. This particular model isn’t the quickest by any means, but it can cruise all day at 75 mph while getting better than 20 MPG. I won’t claim it handles like a sports car, but this 5,000 lbs beauty handles amazingly well. I put a lot into this car and now someone will have a chance to finish it off. If you’re into making your own bio-diesel, this is the car for you. By bio-diesel I don’t mean strained french fry grease (always a bad idea), I mean fuel from any of the various bio-diesel reactors rigs that are out there at a reasonable price. If you’re looking for a “kid” car, this car may be a good choice. It’s no hot rod and it’s built like a tank.