1986 300sdl...my new and first benz diesel

[DieselAddiction]

Hello everyone. I am new to this forum and am finally the proud owner of my first mercedes diesel. Am a young army veteran and diesel mechanic and love everything diesel. My brother has a newer 300 diesel with over 440k miles still running strong. I am now the proud owner of a 1986 300sdl. Saw the car initially about 10 months ago in a mans driveway out in the country on the way home to work. Stopped and talked to him and he said it ran good had some shifting and suspension issues but said would sell it for 800. Amazing deal but didnt have the extra cash til recently. Went out and test drove it, and car drove pretty well minus a really hard shift i knew from my brothers experience in mercedes was just usually vacuum related. To make a long story short...i talked him down to 700 dollars!!! You would not believe how clean this car is. Gold with brown leather. Paint is great minus some hood fade and the interior has no rips at all in seats. Have a ton of reciepts that came with it including the original window stickers, some 4000 in maintenance, as well as a reciept where engine was replaced in 1995 because of the unoffical recall. New engine has about 180k miles. Drove the car home and after changing glow plugs, some vacuum lines, tightening oil pan bolts, filling fuel filters with diesel cleaner and running it through system and replacing filters the car runs like it should and has great power again. Absolutely love the car and have less than 1000 in it so far. Only wish it had the reclining rear seats but for the price i cant be picky haha. Anyways...just wanted to introduce myself and look forward to getting into the diesel benz world more. Am looking to change ball joints and some other suspension while im in there, and possibly injectors later as it seems to have a rough idle when cold started but warms up well. Anyone have any idea what is the best direction to start in if i wanted to smooth out the cold start rough idle? Car runs and drives amazing otherwise. Cant wait to change ball joints as soon as i find a loaner tool.

[brandlj]

Welcome!!
I also have a 1986 300sdl. 125,800 miles. I am the second owner. My car always starts a little rough when cold. I have not replaced my injectors yet, as when it warms up my idle is perfect, I have good power, and I have been averaging 25-27mpg. I replaced all of my glow plugs this past fall and it starts much easier, but the idle when cold is a little rough. I think it is the nature of the beast combined with 26 year old injectors. I have used Lubro-Moly Diesel purge once a year and it helps a little. In later 350sdl's Mercedes went to a different glow plug system that actually kept the glow plugs glowing longer while the car was running based upon coolant temperature. On our cars, once the motor starts, the glow plugs are OFF. I know this can be retro-fitted to our cars, but since my car lives in a garage at night, I am not concerned.
These are wonderful cars. My sdl has the electric reclining rear seats as an option. They are extremely safe, and relatively easy to work on. Just completed a replacement of my Guide Mount bushings, as they were original and my front end was knocking. I am in the middle of my latest project which included a new A/C compressor, expansion valve and drier. Just replaced my original 26 year old vacuum pump with the latest design, new radiator, hoses, thermostat, and drive belt.
Welcome again. There is a library of information on this forum and some of the greatest Mercedes owners around. Good Luck!
John

[DieselAddiction]

Thanks for the info good to see some other 300sdl owners. Mine does the exact same thing runs great once warm. Did not know about the retrofitting of newer glow plugs very good to know.

[daw_two]

Welcome to the 300SDL owners club! Sounds like you got a super deal on that car! This forum has a wealth of information. Using Google to search this site usually reveals an answer to any question you might have.

Start a thread (maybe this one) on your car and post everything to it.

Good Luck!

[barry123400]

Those engines could be updated to the extended glowplug system I imagine to get rid of the cold hearted idle. You could construct a test to determine if it would be the answer.

External power applied to the glow plug circuit for a two-three minute period when cold starting should answer if the change would be worthwhile. The complaint is so common perhaps someone has already done this?

[DieselAddiction]

Thanks everyone. When i first got the 300sdl 2 weeks ago it was about 65 degrees outside and the glow plugs were so bad had to leave key turned over for nearly a minute. It starts up everytime now very quickly. So far have done just a few things for tune up reasons as i know the car hadnt moved in about 2 years. Bought all new fuel filters and replaced them after i ran diesel purge and auto trans fluid through the system. Blew a ton of carbon out and after the new filters i have a ton more power. The glow plugs, usual tuneup stuff such as oil change and all new fuel air and oil filters and she was purring like it should. Also replaced rear shocks this week car rides nice. Next on my list is lower ball joints, injectors as i know one is seeping a bit, and possibly some heavy duty rear springs. Has anyone ever installed heavy duty rear springs? I can actually get them a lot cheaper than stock ones so figured might as well. So far i love this old benz and is easier to work on than most anything else i own. Am looking forward to owning it for some time to come and am going to slowly bring it back to almost new condition.

[Grenadiers]

Congrats on the 'new' ride! We got rid of our precious, to me anyway, '85 Jeep Grand Wagoneer because of the bad fuel mileage. We have two dogs, and the Jeep, minus the rear seat, was great for hauling dogs, groceries, beer, etc. The Jeep was rust free, and I installed an aftermarket TBI system based on Chevy's late '80s trucks. Whaaaa, I said.

Anyway, we found an '86 300SDL with lots of miles on the body, but a newer '20' series engine had been plopped into it. Wifey detailed the interior to like-new condition, and the dogs have plenty of room in the back. Seats are a bit slippery at the moment, but a couple of blankets and they're good to go.

We've taken the car on a couple 1200 mile round trips, and it gets great mileage and has plenty of giddy-up. We'll be driving it back and forth from WI to AZ each fall and spring. I still miss the Jeep! Dave.

[Hit Man X]

Originally Posted by barry123400

Those engines could be updated to the extended glowplug system I imagine to get rid of the cold hearted idle. You could construct a test to determine if it would be the answer.

External power applied to the glow plug circuit for a two-three minute period when cold starting should answer if the change would be worthwhile. The complaint is so common perhaps someone has already done this?

I have had extended glow forever, I used factory parts from a W140 to retrofit my SDL. Works nicely.

[86-300sdl]

Hands down the best vehicle I've ever owned. And there have been many. Current barn has Hondas, GMC, Volvo, and the SDL.

I've had mine for 10 or so years now. Bought it from my Dad when it would not fit in his new garage. I'm in my mid 50's and travel Southern CA, Nevada, and Arizona on a weekly basis....this car is saving my older bones. 250-500 mile days are frequent and the car is so smooth those days are easy to take.

An old post out there referred the SDL as an "80 mph+All-Day-Long machine with 26 MPG and a 500 mile plus range...Absolute Super Highway Nirvana".

Just clocked over 445,000 on Wednesday while on a trip from San Diego through Phoenix, Tucson, AZ High Plateaus...Sea Level to 5,500 ft...70 mph to 85 mph for hours. These damn things just love to roll. City driving...well that's another story (LOL).

Just think of her as a Boeing Luxury 747...find a runway...point her...calmly spool her up...and "Enjoy the Glide"!

P.S You paid $700...fantastic. You'd be hard pressed to find a new vehicle with that kind of ride for under $70,000. Every time I look at the new car market I realize how valuable these things "really" are. I'm not looking to sell & make money...I need good comfortable transportation so if I got to put bucks into it...not a problem. Plus they are so easy to work on!

[Renntag]

congrats on the W126 SDL. We love ours too.
Share a picture of yours.

Best of luck and welcome to PP.com.

[300D85]

Originally Posted by DieselAddiction

I am now the proud owner of a 1986 300sdl

300sdl was only 86-7, cheers

[desmo]

I also own a great 86 300sdl. I take some long trips in the summer and load up the trunk.
Has anyone installed any type of air shocks to help with the sagging rear end under heavy or trailering loads...?

Thanks. Jmk

[JamesDean]

Sagging rear end might be caused by a number of things including bad/worn springs, differential mount, etc.

you can buy heavier duty springs and taller spring pads to compensate.

[jake12tech]

Congratulations on the SDL. Sounds like a great color combo too. The wreckers can be a great source of parts for these cars as there's a lot in the yards at the moment. There's an older gentleman's car who comes into the shop for regular maintenance. He has rolled over once already.