Just "acquired" an 85 300SD. 208K miles. Starts when it's warm, not so good when cold. Needs tons of work. What's the first thing I should do mechanically? It has what sounds like an exhaust leak at one cylinder. Also doesn't idle very smoothly. Compression check in order? I also heard the valve adjustment should be checked on this engine. Anyone got any advice? Thanks in advance...

 

I'm in a very similar situation. I don't really feel qualified to give much advise, but it certainly sounds like you're on the right track. I too just bought an 85 300sd. Mine has just over 150k on it, and though it starts pretty quickly in the cold, I still feel like there is much room for improvement. I too have read that a good valve adjustment is very valuable. Many also seem to be recommending a "diesel purge". I've found some DIY instructions HERE. I think I am also going to have my mechanic check compression.

If I come across any good info I'll be sure to pass it along. It doesn't seem that this section of the forum sees much traffic so if you happen to find a better forum on this subject please let me know. I can use all the help I can get.

Well...Enjoy the project!

 

Adjust the valves, change the oil, change the fuel filters, change the air filter. In short: do a complete tune-up. Fill the tank with fresh diesel. Drive through a full tank and then see how it runs and go from there. You don't need "diesel purge". It doesn't have anything in it that fuel from the pump doesn't. It's just even more detergent additive. It's snake oil. If the car runs a little rougher after changing the filters and running through a full tank, change the filters again. It's likely there's sediment in the tank.

Anytime you acquire a new vehicle, unless provided with recent shop receipts, you should assume the previous owner was the worst car owner on the planet and did no maintenance. Do it all and you'll never wonder about your car.

 

Unless you got it's mait history a good start is check/change fluids and filters. Glow plugs most likely cold start problem. http://dieselgiant.com/mercedes_dies...nance_tips.htmis a good resource for mait on your car. He has nice pic,s easier for you to look their then me type and you still look their. Any question after reading somebody will be able to help out. WATCH out working around the vac hoses they are probely britle. It doesn't hurt to take some close-upphoto's of the motor compartment for a refrence.