New to the forum, but have found it to be very interesting! I hope that I can get some good advice regarding my situation. This is a long post (and likely incoherent) so I thank you in advance.

How does one safely bring a "hibernating" 300SE back-to-life?

I am trying to create a "plan of action" on a '91 300SE that has been sitting unused in a garage since 2001. It has about 55,000 miles on it, and it appears to be in excellent condition inside and out.

Now what? I can do things like change the oil,plugs,anti-freeze...but is that enough? What should I change or replace before the first turn of the key? It does have some gas in it. Is that jelly now?

People have told me to open the valve-cover and get some oil in, close it up and then crank it a little without the plugs in just to get the motor moving a little before fully starting it. I really don't want to damage anything by doing anything stupid!

Should I just flatbed it someplace?

Also, is this a good car? Should I keep it once it is running, or should I sell it? I know nothing about M.B.s. I'm not a mechanic, but I am not totally useless either. I can do the "basics" for the mopst part.

It is a beautiful car, and it is really my first up-close look @ a Mercedes and it is a very different car than the Nissan I use now! I would like to get it running and keep it for myself, but if the 300SE has a troublesome reputation, then it may not be worth keeping it.

What does everyone think?

Thanks!!!!!

Change all the fluids, and pay close attention to the drained fluid (especially the coolant). Any wierd discolorations or particles are a bad sign. Drop a teaspoon of marvel mystery oil in each spark plug hole. Also, change all belts and hoses when you get the chance. Inspect every square inch for rust.


The 300SE is probably the most reliable of the gas powered w126's. Very far away from a problem car. But the 300SE in question may be iffy. Make sure you get a complete service history, and make sure it runs fine before you pay. The gas may be bad, I don't really know anything on that subject. I can say that I let my 85 Toyota Pickup sit outdoors in the sun for two years with half a tank, and it started up and ran just fine recently. Only thing I'm scared to touch on that truck is 4 wheel drive... I don't think it's EVER been in 4 wheel drive mode, so the transfer case and front differential are probably glued together.

Good luck!

Follow Dans advice for starters.But unless a fuel stabiliser was added to the gas tank,the gas has gone stale and started leaving varnish deposits.Depending on the fuel,what addatives are in it.Summer gas or winter gas for example.Gasoline starts going stale somewhere between one and two years.If the tank is more then 1/4 full,I would recomend draining the tank.If it's 1/4 or less,fill the tank with fresh fuel before you start it up.And whether you drain the old fuel or not.I would recomend adding a fuel system cleaner to you'r tank right away to disolve those varnish deposits.I personally like Sea Foam brand.I've seen it do a better cleaning job then any other brands I've tried.But who knows,maybe one of the brands I haven't tried is even better?Once you've got it running,keep an eye out for oil leaks during the first week or so.Seals dry out and crack from sitting sometimes.And if the car sat on the ground without being moved at all for four years,the tires might need to be replaced.If they act like their out of balance when you get it on the road.Then the tires have developed a flat spot.Sometimes they'll smoth out again within twenty miles or so.If not,replace them.

Thanks for the tips! I was able to pull the plugs on it today, and 5 of them were just blackish, but the sixth one (closest to the firewall) actually had some oil on it. Whats up with that?

I also put in a new battery and turned the key to accessory mode. It appears that the gas tank has a little less than 1/2 tank. I did dump 2 bottles of the STP gas treatment that was in the garage in there.

Yeah, the seals I am worried about - I'll keep an eye on them, and the tires are an obvious concern too. Thankfully, they're only 15 inch tires and won't be too costly to replace if needed. The ones on there look like they have less than 10K miles on them. The wear strips are nowhere near showing. Its what I can't see that worries me!

I'm happy to hear this car has a good reputation! I hope that if I can get it running safely, I will bring it to a local shop for a once-over. I learned on this forum that there are 2 reputable independent MB shops right in the next town! Cool.

Thanks!

Hopefully the oily spark plug situation came from the car being partially pickled before it was parked.If I know one of my vehicles is being parked for more then a year,I slowly pour some oil through the intake while it's idleing untill I see oil smoking from the exhaust.Then I shut it down right away.Tape off the intake snorkel and tail pipe to keep out any possible rodents.Add fuel stabilizer to the tank.Disconnect the battery.And then put some of the lavender scented moth balls in the car and trunk to deter insects and rodents.This is the way I learned to put a vehicle into storage in the military.The Air Force calls it pickling.My addition to the process is the moth balls.Find out if they oiled the cylinders when it was parked.If they did,mystery solved.

say why it has been sitting fallow.

seems unlikely to have been pickled. usually when a car sits like this there is something wrong with it....why else would it be sitting?

the above posts about cover everything. the gas is amost certainly bad. unless it has stabilizer in it (unlikely). if it were a diesel th e chances of the fuel being ok would be much greater.

the 300se's drive very nicley. a lot of get up and go for a relatively small six in a big heavy car! not bad fuel economy either i believe.

good luck. i would trailer it home, but then i have a trailer. when i was younger i would have driven or tow bar'ed it home or if not too far...rope a doped it.

tom w

__________________
[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I've had this on both of my M103 engines. My guess is that oil pools up at the valve guides back there and get's a small leak in one of the valves, most likely intake. This never seemed to cause any noticable problems like smoking or oil consumption however it should be fixed eventually. It's probobly time to replace the valve stem seals. Replacing seals is easy on the M103 engine, I can personally do the job myself in 2.5 hours.

The M103 is a great engine and along with the 126 body, a very reliable package. I would highly recommend keeping that car with only 55K miles on it.

I would drop in some sea foam, fill the tank, change the oil and filter, change the coolant (Red! not the green stuff!!) Fog the cylenders and change the spark plugs, remember to gap them!

From here i'd drive the car for at least 100 miles and see how it runs.

__________________
Current Stable:
01 ML55 AMG
92 500E (a few mods)
87 300E (lots of mods)
00 Chevy 3500HD Diesel Box Truck
68 18' Donzi Marine
06 GT i-Drive7 1.0 Mountain Bike (with GPS!)

PREVIOUSLY OWNED:83 300SD, 87 420SEL, 88 420SEL, 90 420SEL, 86 560SEL, 86 190E 2.3-16V AMG, 94 E320

This is great information!

The backgroung of the car is basicly it was owned by a relative who could no longer drive due to illness. It was parked in the garage with him fully intending to drive it again. So, no "pickling" was ever done.

Unfortunately, the relative has recently died, and now it has been tasked to me to either fix it and sell it or fix it and keep it.

I'm wary of acquiring a "white elephant" so-to-speak, so I wanted some informed opinions before I got too attached to the car.

From what I have been reading, I think I am going to give it a shot and see how she likes me! Thanks so much for the tips! Maybe I'll post some pics now and then to show progress.

3 more questions: 1 What does it mean to "fog the cylinders"? 2: I don't know what oil was used, what's the safest quess? Dyno or synthetic? 3. I also don't have the owner's manual. Does someone know what the sparkplug gap should be?


THANKS!!!

The cylinder head is no doubt "dried out" which means a valve job may be in your future. At the very least, you'll need new valve stem seals. These can be done with the cyl. head attached to the rest of the motor. The valve guides may or may not need replacing. Only a talented MB tech could determine that.

As time goes on, you'll likely find yourself using oil. Consider the above.

The biggest problem of all with any car idle this long(not just 91 300SE) is all of the "electrical gremlins" that may start to haunt you.

I've gotten good service out of mine. Good luck to you.

PS - this site has been around since 1999. There have been tons of posts on the M103 motor your MB has. Search the archives.

__________________
Mike Murrell
1991 300-SEL - Model 126
M103 - SOHC
"Fräulein"

the cylinders is oiling them.There are also spray can of fogging oil you can find in automotive sections.If the engine has any leaking seals.Synthetic would make it leak even worse.I personally use synthetic oil in almost everything I own.Even my shop air compressor.I wouldn't consider synthetic cost effective though for people who trade cars every few years.I rarely ever sell or trade my cars.I usually drive em till they drop.And deffinitly change those valve stem seals.Can't help with the plug gap.If nothing else,call the local parts store.The gaps are listed in the spark plug catalogs.

Thought I'd post an update on the situation. Well, I followed most of the advice offered here - filled up the tank w/ 10 gallons of premium ($2.87 yesterday, $3.15 today jeeeeez), "fogged" the cylindars with fogging spray, changed the oil and filter, new plugs and battery.

Wouldn't ya know, it started right up with little more than a puff of grey smoke, then ran at idle for 1/2 hour as smooth as can be. I was very happy and honestly very surprised!

Thanks for all the advice!

I will need to bleed the brake fluid, but after reading some posts here I think I'll have a more competant person than myself do it. Also, the power antennae is shot, the radio-code is MIA, tha A/C is quite warm, but they are creature-comfort things I'll get to in time. I hope that I can still get an R-12 recharge now!

I did find a note that Quaker-State 5W-30 had been used at least once before, so I am assuming that dyno-oil was the oil used before. I suppose I will stick with dyno-oil and not use a synthetic on this car.

Again, thanks to everyone who helped this newbie out!

Just get prepared to spend money on a full valve job soon. That engine is apparently known for requiring a valve job prematurely. And with your having sat for so long, no one knows what will be the case with it. Then again with your low miles you're probably still in good shape.

__________________
1999 Mercedes-Benz S600, 103K miles - garage queen
1988 Mercedes-Benz 560SEL, 89K miles - daily driver
2007 Hyundai Sonata Limited, 31K - daily driver

Don't try and start it on 4 year old gas you are asking for trouble. You need to drain the tank and lines of the old gas and refill with some fresh stuff. If you can't do that in the garage and need to move the car hook up a 6 gallon outboard fuel tank and bypass the cars currant fuel system completly.

I was looking at the insides of a set of carbs off a Merc outboard the other day. 18 month old gas was enough to clog them up with varnish to the point the motor wouldn't run.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200