Would appreciate any advice on what to do before starting a 300e that has been sitting & never startedin a heated warehouse for5+ years.

 

Remove all the spark plugs, put about a tablespoon of oil in each cylinder. Then rotate the crankshaft in the same direction that it would normally travel during engine operation-don't force things, so wait until the oil does its trick (at least a couple of hrs or overnight).

The old gas will be you biggest nightmare, unless it was all completely drained beforehand. Unless your gas tank has a drain plug, you're going to have to get it all out of there most probably by removing the tank, cleaning the tank and reinstalling.

Gasoline these days is a chemistry set of cheap, unstable ingredients. Yours will be completely 'varnished' by now (you can smell this BTW). Your fuel lines themselves could be completely varnished & plugged. They may require disassembly as well. The big thing is that you don't try and run that rotten gas through your engine. Of course, change the oil & filter at this time before starting it. I'd use a product like Techron in the tank after you get the car running-probably for the next two tankfuls.

Unless you took the battery out, chances are that it's toast, even after a charge. I don't know how mechanical you are but there's an old restorer's trick; if your oil pump is gear driven, most probably you can get a distributor shaft from a junkyard of the same model engine. Cut the top off the distributor shaft so that you can chuck it up into a powerful drill. Make sure you have changed the oil, put the shaft in place and rotate the shaft (with the drill), the same direction it normally travels (spark plugs OUT, as you're not trying to build compression here). This will oil everything in the engine just like it was running. Otherwise, your engine has had six yrs for the oil to drip back down into the pan and a lot of your bearing surfaces will be too dry-very risky potential start up damage. With a charged battery, you could do a compression and/or cylinder leak down test....I would probably do that as an extra measure and a check on engine internal status.

Probably be a good idea to replace your spark plugs as well. You didn't say how the car was stored, or if it was just shut off and left. A lot of what you do will depend on the storage procedures done six yrs ago. The heated warehouse will have helped against internal corrosion, but if there was indirect light and the car was exposed to air (not placed in a giant bag), tires will most probably have started to weather check and I'd be examining all critical rubber and synthetic rubber parts. It's possible that some of your engine seals have shrunk and possibly leaking, but the heated warehouse may have prevented that bullet.

You're probably gonna hear stories about people that have just charged their battery, dumped some fresh gas in and the engine started right up. That was just dumb, blind luck they had no immediate problems and most likely, they're not telling the whole story or repairs down the road. I wouldn't gamble with a MB engine...treat it with the respect that it deserves.

Kevin

 

I don't think you'll get it going again...I let a BMW 633CSi sit for 5 years in New Mexico (in a garage) and it would not start after much effort...I think the injectors were all locked up and I didn't have the motivation to fix it...just didn't care...I probably could have made it run fine again but I just didn't care at that point.. anyway,...good luck cliff

 

Varnished gas will be his bullet....unless it was all drained out. I had a motorcycle sit that long with two carbs. Put Stabil in it but that was good for maybe a yr and a half. The inside of those carbs looked like somebody poured syrup in there. Had to completely dismantle the carbs and soak them in sauce. Everything was fine after that-still going. I didn't care at first either about the MC....in fact I was gonna sell it. Got one carb going, but the other was dead. Finally got the other one cleaned and it was the coolest thing though....fuel pump filled it up and it started working and came back online with the correct idle & power.

Fuel injection though....major pain. Will have to be done in sections. This wagon I have had sat for almost two yrs, although in the beginning she did occasionally start it. I could smell varnish....I took a chance and it started. Actually ran pretty well, although I could still smell the varnish. Ran Techron for the first three tankfuls of gas and it was fine. I recommend though, that he get all that gas out and not take that chance-too many yrs.

Hell, those are ideal conditions-garage, New Mexico. Still when the gas is varnished in a fuel injection system, it's pretty much toast without cleaning everything. Real PITA.

Kevin