What Have I Done? (W116 content)

FlexYJeeper

Well-known member
Joined
Feb 4, 2017
Location
Oak Harbor Washington
TDI
MKIV Golf
Hello Everyone!

An old Mercedes Diesel has always been a dream car that i wanted to own at some point in my life however i dont have much money but have a lot of time and patience. i like buying things other people would consider junk and fixing them. probably costs more in the long run but at the end i know what i have.


a few days ago i picked up a W116 off craigslist for very very cheap. this is what i was greeted to.


it was apparently running when parked 4 years ago

got it loaded up and realized its almost the length of my F150.


and finally home



today i was finally able to play with it. hooked up cables to my GTD and tried to fire it. wasnt getting power to anything. i pulled the battery mount out to find the negative ground to the frame was badly rusted and wasnt making contact. wire brush+sand paper+new bolt and i had power to the dash. however there is still no start. i pulled the downpipe off the turbo to get top side access to the starter where i found i was able to jump the solenoid with a screwdriver. when i did the motor turned over very slowly. unfortunately my volt meter is dead so i couldnt test the signal wire to the solenoid to see if it was getting power so im not sure if its a bad solenoid or fault in the wiring. the slow turnover also has me concerned. need to check voltage to starter. if the voltage to the starter is good i will pull the starter then tear it apart to give it a good cleaning. really dont want to spend money on a starter.



and thats where im at as of now. going to be busy until sunday but if anyone has any ideas for me post them up!
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Drags old MB home from the woods...

says "Don't want to spend money on a starter".

ROTFLMAO!!!1!!UNO!!!

You sir, have started my day with a smile. Thank you so very much.

As someone who has a few "cheap Mercedes", some of which I even drove home, I can tell you that you are in for a rude awakening very shortly.

But if you are still not done learning from your mistakes, I know where a straight, southern, rust free W126 diesel is.

Seriously, though, I wish you all the best. And I sincerely hope you can get the old girl running again. Neat car. :)

I would start with taking the glow plugs out and putting some thin oil down each cylinder and see if you cannot get it cranking faster with the plugs out. Chances are the fuel system is 100% fubar, and it will ALL need to be rebuilt. Do you have any idea why the car was parked there in the first place?
 
Last edited:

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
Wait until you see the price / options for getting the climate control system (yes, even the heater) working again in that car... (the Evil Servo strikes again! :eek: )

Fun tidbit about the W116 300SD: The 722.1 transmission in those cars moves off in 2nd gear from a stop in Drive. However, MB installed a little control unit in the dash that looks at vehicle speed and the brake light switch. While you're stopped, it leaves the transmission in 2nd gear. But when you lift off the brake (and the brake lights go out) it activates the kickdown circuit until some slowish speed, about 7 mph I think. That makes the car move off in 1st gear, while resting in 2nd gear (so there's less "pull" while stopped).

The W126 300SD does something similar... it rests in 2nd gear and kicks down to 1st at the lightest touch of the throttle. If you examine the throttle linkage on a W126 300SD you'll see it pulls on the transmission throttle valve cable before it starts moving the fuel injection pump lever.

-J
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
Oh, and if you go to pull the starter do some reading in the repair manual first. As I recall one of the bolts for the starter goes into a spot in the block that's super hard to access, and it's somewhat easy to break / strip it out.
 

otm646

Veteran Member
Joined
Jun 20, 2007
Location
Metro Detroit
TDI
1998 AHU Jetta.
To get to the top bolt you'll need 3' of extensions and a swivel (tape it so it has some rigidity). You'll go over the trans crossmember and up along the tunnel to the upper fastener.

That socket drive feature is often and easily damaged, have a replacement on hand.

Also be careful that starter is seriously heavy. I've put 3 of them in my w115, the O'riley reman units are not great.

If the starter solenoid is not engaging you can use an 19mm wrench to bridge from the upper connection going to the battery to the post on the starter motor itself...Don't ask how I learned this out in the middle of nowhere Iowa.
 
Last edited:

clacker

Veteran Member
Joined
Mar 29, 2000
Location
Oxford Mills, Ontario, Canada
TDI
2015 Golf Wagon TDI DSG Trendline, 2000 Jetta TDI auto, 2008 Mercedes R320, 2006 smart fortwo cdi
Wonderful old car. I grew up in one, learned to drive in it, still have it stored away now with 600k miles. 33 years we have had it I know it very well. Slow cranking check all wiring. Starter signal wires are in a junction box pass wheel well near the battery.
Not much is expensive to fix on these cars and most of it is serviceable. Expect to spend weeks of labor sorting it out not hours but weeks. Tons of info on peachparts forum. Before you spend money spend time checking basic engine settings and normal maintenance procedures. Check and adjust valves. Test injectors and compression. Measure chain stretch. Test vacuum system for leaks worry about the engine compartment only to start and tee off the rest with a golf tee. Remove and test glow plugs ream bores. Inspect turbo likely waste gate is seized and rubber hose is split.
Once you have the basics covered try to run it off a jar of fuel with some ATF and diesel purge. It will need a good boost off a running engine to get proper cranking speed and bleed the system. Once running do all the filters and fluids.
 

FlexYJeeper

Well-known member
Joined
Feb 4, 2017
Location
Oak Harbor Washington
TDI
MKIV Golf
Drags old MB home from the woods...

says "Don't want to spend money on a starter".

ROTFLMAO!!!1!!UNO!!!

You sir, have started my day with a smile. Thank you so very much.

As someone who has a few "cheap Mercedes", some of which I even drove home, I can tell you that you are in for a rude awakening very shortly.

But if you are still not done learning from your mistakes, I know where a straight, southern, rust free W126 diesel is.

Seriously, though, I wish you all the best. And I sincerely hope you can get the old girl running again. Neat car. :)

I would start with taking the glow plugs out and putting some thin oil down each cylinder and see if you cannot get it cranking faster with the plugs out. Chances are the fuel system is 100% fubar, and it will ALL need to be rebuilt. Do you have any idea why the car was parked there in the first place?
haha glad i could make your day! when i said i didnt want to replace the starter it was because on the W116 FB page it was basically "oh turns over slowly? buy a new starter first." when there are still trouble shooting avenues to go down like checking voltage at starter. and rather then replacing id rather tear it apart and clean it and if need be order a rebuild kit.

i will pour some oil down into the cylinders, think marvel mystery oil will do the trick? i'll start drenching the glow plugs with PB Blaster. still a little nervous to do it after watching a member here destroy an ALH head drilling out a broken GP

Wait until you see the price / options for getting the climate control system (yes, even the heater) working again in that car... (the Evil Servo strikes again! :eek: )

Fun tidbit about the W116 300SD: The 722.1 transmission in those cars moves off in 2nd gear from a stop in Drive. However, MB installed a little control unit in the dash that looks at vehicle speed and the brake light switch. While you're stopped, it leaves the transmission in 2nd gear. But when you lift off the brake (and the brake lights go out) it activates the kickdown circuit until some slowish speed, about 7 mph I think. That makes the car move off in 1st gear, while resting in 2nd gear (so there's less "pull" while stopped).

The W126 300SD does something similar... it rests in 2nd gear and kicks down to 1st at the lightest touch of the throttle. If you examine the throttle linkage on a W126 300SD you'll see it pulls on the transmission throttle valve cable before it starts moving the fuel injection pump lever.

-J

AC and heat are way down the list, i just want the thing to run haha. i can actually hear the climate control system trying to work with the key on though

Oh, and if you go to pull the starter do some reading in the repair manual first. As I recall one of the bolts for the starter goes into a spot in the block that's super hard to access, and it's somewhat easy to break / strip it out.
saw this haha you need 10mm hex and a lot of 1/2 extensions

Wonderful old car. I grew up in one, learned to drive in it, still have it stored away now with 600k miles. 33 years we have had it I know it very well. Slow cranking check all wiring. Starter signal wires are in a junction box pass wheel well near the battery.
Not much is expensive to fix on these cars and most of it is serviceable. Expect to spend weeks of labor sorting it out not hours but weeks. Tons of info on peachparts forum. Before you spend money spend time checking basic engine settings and normal maintenance procedures. Check and adjust valves. Test injectors and compression. Measure chain stretch. Test vacuum system for leaks worry about the engine compartment only to start and tee off the rest with a golf tee. Remove and test glow plugs ream bores. Inspect turbo likely waste gate is seized and rubber hose is split.
Once you have the basics covered try to run it off a jar of fuel with some ATF and diesel purge. It will need a good boost off a running engine to get proper cranking speed and bleed the system. Once running do all the filters and fluids.
peachparts has become a daily read for me the past few days haha. lots of checks in the boxes to go through
 

FlexYJeeper

Well-known member
Joined
Feb 4, 2017
Location
Oak Harbor Washington
TDI
MKIV Golf
last week i pulled the glow plugs, shot some ATF into it and turned it over a few times and threw them back in. i had Monday- Thursday off so Monday morning i disconnected the fuel lines and put them in a water bottle i filled with diesel. with a new 1100cca battery i began trying to start it. at first seemed a bit hopeless but then i got it to stumble a little bit, then it stumbled again. then with a huge cloud of black smoke she stumbled into life. (mind you it was open turbo and i was jumping the solenoid which is under the turbo with a screwdriver so said black some was into my face)

video:
https://youtu.be/5ZJgscZH4_M

Tuesday when i walked out i noticed that i hadn't plugged the fuel line and a lot of diesel leaked out. i was okay with this because it told me the fuel in the tank was not gelled, instead just a dark yellow. i hooked up the fuel tank back up and put the last 2 gals of diesel i had in it. and let it idle while i pulled all the throttle linkages apart and cleaned, lubed them (they were sticky) after that i moved my tools out of the way and drove it around the parking lot a few times to make sure it was going to be okay. after 15 minutes i jumped on the road and drove it to the gas station on base and threw $20 in it to help burn out that old fuel. i also topped off the radiator that was empty (no leaks so far) and drove it around base for about 2 hours

driving around:
https://youtu.be/6ojQxnQBe58

it was about this time i started thinking, "man that sounds like its knocking a little more then a diesel should" im beginning to suspect it spun a rod bearing. i did an oil change on it so it would have to be preexisting. ive heard that a clogged injector can sound like a sound rod bearing on these engines. i also get paranoid and hear things from time to time. so it could just be me. the way i see it if it is a rod bearing the motor is junk and i should just drive it into the ground. or if its a injector some diesel purge and some driving should clean it out. either way i'll drive it. either it blows up and i find another or it doesn't and i continue to have a cheap toy i have literally no money into.


few problem as of now:
1. sticky brakes
2. cant start car with key, can cycle glow plugs, and shut it down but not start. have to use screwdriver.
3.only the drivers door window works.
4. cant open trunk
5. fuel gauge doesn't work

that's what ive found so far. side note, this cars ride is incredible. takes bumpy roads like a champ.
 

oilhammer

Certified Volkswagen Nut & Vendor
Joined
Dec 11, 2001
Location
outside St Louis, MO
TDI
There are just too many to list....
Awesome. Yes, the big S-class is truly a nice driving riding car. And they handle twisty roads amazingly well... far better than their stodgy looks would suggest.

The old iron inline 5 diesel has a pretty distinctive diesel knock sound to it (as does the old inline 4 engines based on the same design). However, it could also be poor injector spray patterns too, but usually that would be accompanied by a lot of smoke.

These also have solid lifters than need periodic adjustment.
 

FlexYJeeper

Well-known member
Joined
Feb 4, 2017
Location
Oak Harbor Washington
TDI
MKIV Golf
Awesome. Yes, the big S-class is truly a nice driving riding car. And they handle twisty roads amazingly well... far better than their stodgy looks would suggest.

The old iron inline 5 diesel has a pretty distinctive diesel knock sound to it (as does the old inline 4 engines based on the same design). However, it could also be poor injector spray patterns too, but usually that would be accompanied by a lot of smoke.

These also have solid lifters than need periodic adjustment.
there is a large amount of white smoke. i want to run the rest of this old fuel out, change the filters and run some diesel purge through it and see how it does. i did start to adjust the valves after the #1 exhaust valve i decided to save it for another day when the injectors arnt in it. they make it a pain in the ass
 

clacker

Veteran Member
Joined
Mar 29, 2000
Location
Oxford Mills, Ontario, Canada
TDI
2015 Golf Wagon TDI DSG Trendline, 2000 Jetta TDI auto, 2008 Mercedes R320, 2006 smart fortwo cdi
Diesel purge, atf, seafoam combo with a bit of diesel fuel-do the so called hot soak-run it up to temp on this stuff, shut down for a few minutes to let it do its thing and then start up again. I highly doubt it would start on its own power if a rod bearing was bad, seriously diesels are hard to start with good bearings a bad one makes them miserable to get going (experienced it once).
Whatever the sound is in the video that is really bad, check the timing chain, injectors and compression. Something is up, does not sound like a bad injector but more mechanical in nature but a really bad spray could cause all sorts of different things...it is not a normal diesel sound for those engines the hammering clank. It sound just have a mellow diesel noise and quiet down under throttle.
Drop the filter screen in the fuel tank and clean it once the fuel is low or empty, replace the hose on it and check the metal lines carefully. Do the filters (kit form is best as it has the crush washer and orings needed) and look carefully at the hoses in the engine bay (injector return lines, end plug, cigar fuel return hose, clear hoses from lift pump to filters and pump). Injector nozzles are cheap probably worth throwing a set in ($20-25 per) and adjusting the valves. For starter power start checking the wiring and seeing if a power signal is coming out, it is rare for an ignition switch to go bad, more likely something is rotten or poor contact.

What a wicked and rare color combo, very cool. They ride rough roads super well, speed bumps mean nothing and gravel washboard is not a problem. Wait till you drive it fast...the engine roar, the feeling of the road if the steering is decent is something else. Very very solid cars.
 

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
The fuel gauge is likely a dirty level sender. A float rides on a bar, and has contacts that touch 2 nichrome wires. Take the whole thing out and clean it. While you're in there, clean the fuel tank strainer too.

Pulling the injectors is easy enough. Have a local shop test them, or make / buy your own tester. Bad injectors will blow torch their way through the glow plugs, and if left long enough the whole prechamber.

-J
 

nokivasara

Veteran Member
Joined
Jan 25, 2008
Location
Sweden @ Lat 61N
TDI
Tiguan 4-motion, Golf mk7
Nice find, is the engine a OM617? My thought on the knock is that I wonder if the timing is too advanced? Maybe the advance mechanism is sticky after sitting 4 years...I think that advanced timing in a diesel will give white smoke too, and of course that marbles in a can sound.
Timing could be advanced due to a streched cam chain too.
I didn't know that the w116 was sold with a diesel, we only got gas engines in them over here, they are a common subject for a diesel swap though, as is the w126.


I like the old MB's, I've had a w114 250CE, a w115 220D (with the odo broken at about 650k km or so) along with some more modern w201 190 2.5D and w124 300TE and 300CE.
The 220D and 190 2.5D were daily drivers, the others were more of that too-good-of-a-deal-to-pass kind :)
 

hey_allen

Veteran Member
Joined
Nov 25, 2006
Location
Altus, OK
TDI
2000 Jetta TDI
I seem to remember that the W116 would have come with an OM616 engine, but my memory could be playing tricks on me.

I do know that my W126 300SD would often have visible smoke until the engine warmed up a little bit, though doing the tune-up and new injector nozzles did help.

I will suggest that if the OP ends up chasing fun times with the transmission shifting hard, make sure to check (and likely replace) the little plastic fingers that are between the vacuum valves and the throttle linkage cam under the black cover on top of the valve cover.
Those parts sliding on the two ramps of the cam will slowly wear down and change the simulated throttle vacuum applied to the transmission, and alter the shift behavior.

edit: Never mind, I double checked that, and the OM616 was only in the smaller cars (W115 and W123), the W116 would have had an OM617, from 1978 onward.
 
Last edited:

compu_85

Gadget Guy
Joined
Sep 29, 2003
Location
Springfield VA
TDI
... None :S
The 1978 W116 300SD was the first vehicle to have the OM617 Turbo engine. (and the first car with a turbo diesel engine)

The W115 240D 3.0 (europe) / 300D (usa) introduced the OM617 (na) a few years earlier in 1975.
 
Top