76 300D W115, I have no car experience whatsoever! Please Help! - PeachParts Mercedes-Benz Forum

StolenBaby · #1 11-08-2006, 06:08 AM

Hey there! This forum is super awesome. I've been prowling around it for a while now, and I thought I should finally introduce myself and my situation.
I've never owned a car before, and certainly never worked on one, but I recently traded a vintage drumset (circa 1972, worth appox. $300) for a silver 1976 300D. The odometer is broken, but it probably has over 200,000 on it. I went a while thinking it was a W123 (especially since the haynes manual for w123s was under the driver's seat), but finally realized it was a W115 when all the diagrams I looked at didn't match what was actually under the hood.
My question is pretty broad, but I couldn't think of a better place to come for help. The biggest problem seems to be power- uphill, with the accelerator all the way down, 15-20 mph is about all you get (from my estimation... the speedometer wavers back and forth uncontrollably).
I plan on changing the oil, oil filter, fuel filters, air filter, and maybe the battery, since, now that the car is in my backyard, it won't turn over (I'll be trying to jump it this weekend).
It has a slew of other problems- rust, so far found in the undercarriage and in the trunk (bad enough that you can see light through it), leaks- mostly around windows and in the trunk, left-rear door that doesn't open, lights don't work- probably needs electrical work, the list goes on....

I was hoping you guys could let me know where to start. Is changing the filters and oil the best thing to try first? Are there any really good resources online (besides the official service manual) for doing these procedures?

Also, how much do you guys think this car is worth? The body actually looks pretty good- it's a sharp car.

Thanks a bunch! I can't wait to learn more and more about this car.

rs899 · #2 11-08-2006, 06:26 AM

Did you read the maxim on here somewhere that there is nothing more expensive than a cheap Mercedes? I think you are about to test this theory.
$300 sounds about right for the value.

This sounds a lot like a parts car to me. I would change the filters and fluids as you suggest and see what happens then.

Questions-

Did the car start easily when cold?

Did the car spew great clouds of smoke? What color (s)?

Did the transmission shift gears ? How many times?

StolenBaby · #3 11-08-2006, 07:15 AM

From what I remember, there was a good amount of cranking before the car started up, and there was a pretty big plume of white/grey smoke from the exhaust. As far as the transmission, it definitely went from 1st to 2nd, but I'm not sure if it went to 3rd.
I was thinking that a possible reason for the lack of power might be a vaccum system acting up. The W115 300D does have a vaccum system controlling the automatic transmission, right?
I was guessing that two other possible problems might be bad compression (worn rings?) or maybe the accelerator linkage.
However, I really only started learning about cars two weeks ago, so I really can't say anything for sure.
I know that it sounds like a parts car, but I wanted to learn more about what makes cars run, and I kind of see it as a learning tool. I don't have much money, but I've got a lot of time and energy, and soon a pretty good set of tools.

Thanks for the response!

rs899 · #4 11-08-2006, 07:30 AM

I am not sure the W115 300D had a vacuum modulated tranny (someone help me). If it does, I would temporarily disconnect and plug the line to the modulator. The modulator controls the quality of the shifts.

Yes, check the linkage. Test the glow plugs. Check/adjust the valves. Change your filters and fluids and see if it improves. If the car does not have good compression, there's not much point dumping money on it.

RichC · #5 11-08-2006, 07:59 AM

.
Hello all

This is just what I do to an old car I buy that has been sitting for a while.

Dump the fuel from the fuel tank.

. Check for debris in the fuel coming out.
. If there is a lot of gunk, flush the tank well.
. Check for an in-tank screen or filter.
. Clean or replace it.

Check all other fuel filters and replace as necessary.

. Your car may have as many as three filters.
. One in the tank, one prefilter, and one larger primary filter.

Add some good clean fuel to the tank and prime the system.

. You may or may not have a small priming pump in line near the injector pump.

This should deffinatly increase your chances of getting your car started.

This and a good battery.

Have Fun

RichC

StolenBaby · #6 11-08-2006, 09:20 AM

First and foremost, Meatwad is the best.
Secondly, thanks for the advice! I'm pretty sure the car didn't sit around for very long, and draining the fuel tank sounds a bit involved. I'm willing to give it a try, but would the condition of the fuel filter let me know if my tank is dirty? Right now I have everything I need to change the oil and oil filter (apparently doing this is a pain on the w115), so I think I'll do that first before tackling the fuel system. (by the way, I ordered a new main filter, but I've seen pictures of little plastic "pre-filters"? what are those, and where do they go?) I'm pretty sure it's not turning over because the battery is dead. I got some jumper cables and I'm gonna try and get it started that way, but it probably needs a new battery, too.

brightbus · #7 11-08-2006, 10:46 AM

recently sold my 76 300D, but as memory serves me, it the tranny on the 115's are not vacuum modulated