1976 240D W115 OM616 will not start.

[Newtomercdiesels]

Hello.

I recently volunteered my electrical engineer/mechanically-inclined brain to a friend’s 1976 240D. I told her that the car wasn’t the best choice for a winter car driven by an elementary school teacher, but it was purchased anyway...and it broke.

Long story short, it decided to not start one day. From what she described, it was in the fall a year ago, and the symptom was a classic flat battery (womp womp womp from the starter).

She then took it to a local well thought of “30 year Mercedes master mechanic” to get it fixed. $2,000 later, it still won’t start.

Things this person supposedly did:
-Glow plugs/insulators
-rebuilt injector pump (big money)
-a few new hoses,”
-new main fuel filter (engine area, not sure about tank)

It then sat for a year. She got it towed to her garage. When I first looked at it, the valve cover, fan blades, and hardware were in the trunk(!!!!). Injector pump was out of the engine but hooked up.

What I did:
-Put the correct H8 battery in (new)
-confirmed glow plugs function (continuity check and dash filament lights up after 15-20 seconds, wires coupling plugs get hot)
-confirmed compression (300,260,310,340 psi 1,2,3,4)
-installed fuel injector pump and turned engine without fuel lines attached. Just before cylinder #1 cam lobes are completely off the valves, injector outlet #1 shoots fuel. I lined up pump timing marks and inserted pump into engine at what I thought was 25° before top dead center.

The car sounds like it’s firing weakly and I see white smoke and smell burnt diesel, but it will not catch and idle.

The first time I set the pump, I used the old factory marks. In this configuration, after liberal use of starting fluid with upper cylinder lubricant (I know, I know), it would eventually get warm enough and floored I could get it to run. The warmer it got, the further off the pedal I could go. Any further than about half, the idle hunted and oscillated between high and low rpm. Pulling my foot further off and the engine quits.

I reasoned that I didn’t get the pump installed in the correct time and that it was able to run off the remnants of the last injection at high rpms due to the amount of heat and increased compression.

This caused me to reset and confirm timing (as best I could) as I explained above.

It still will not start. I don’t have the drip tube and I figured if I was even close to the right timing, it would at least start and idle badly...but it refuses to catch and go.

Aside from blaming old diesel in the tank, I’m out of ideas.

Does anyone have any idea what is going on? Any help would be much appreciated.

The car is in awesome condition cosmetically and my friend is getting more and more discouraged that nobody can get it to run.

Any help would be much appreciated.

Thanks everybody.

[Newtomercdiesels]

Anyone have any ideas?

[Shortsguy1]

Sorry to hear about the frustrations. If you don't get enough feedback with this thread, you should start another one in the diesel section of the website. That is where you are likely to get the most help.

I have never removed the IP, so I unfortunately cannot help you there. It sounds to me like a problem with the injection pump (timing or internal malfunction) or a problem with the fuel or air supply. Have you removed the air filter and fuel filters to be sure nothing odd is going on there? If so, it could be old fuel (as you mentioned) or problems in the tank/lines (clogs or venting issues). You should try to run it on diesel purge, which acts as a supplemental fuel tank. That way, you isolate the actual fuel tank and can determine if the problem lies there. If you read up on diesel purge, there are lots of decent directions out there. Here is one:
Diesel Purge Mercedes diesel maintenance tips

My tank had black gunk "growing" in it, and I imagine it could clog up the fuel lines or filters pretty easily. It can be eliminated with startron or biobor or probably others, but it is a better diagnosis step to just eliminate any tank related issues by creating a small fuel tank with diesel purge up in the engine compartment. If it still runs poorly, I bet the IP has problems or the timing is off.

Good luck.

[Newtomercdiesels]

Thank you for your reply.

I have been watching videos by Kent Bergsma (the guy is extremely helpful both in literature/media/and parts) and I have come to the conclusion that my pump timing is most-likely completely off.

I can nurse it to life, as I said. Once it's 'alive', it will run full throttle, which tells me:

-fuel is OK (it can burn that year-old fuel)
-fuel flow is OK (it can deliver that much fuel and run fine)
-the pump is pumping (I confirmed this a variety of ways)

I reason that it is running on 'fumes' from the last injection in each cylinder. This explains strong diesel smell and smoke.

I think I am going to torque the engine over manually until I get a drip per second out of injection port #1 (I never followed this procedure, just trusted marks on the splined end and housing on IP). Then, carefully pull the pump, turn the engine to 24* BTDC (TDC is spot on both on cam and balancer, so engine chain is tight), and reinsert the pump being careful not to move the splined end.

I bet it'll fire normally if I do this procedure carefully.

I will definitely be writing up a tutorial or doing a short video on this if that is indeed what the problem is. There is/(hopefully was) a lot of confusion for me being a beginner with this sort of in-depth care maintenance regarding angles, methods of aligning things, the order in which steps should be done, getting to that d*** lower mount bolt on the pump, all of it.

I feel everyone's pain and will be going back and helping out where I can...that's what these forums are about!

I will let you know......and thank you.

[Diseasel300]

In the future, the "Diesel Discussion" subforum on this website is by far the most active page here for tech help. Usually your thread is answered in a matter of hours, if not minutes.

It sure sounds like the timing is off to me. Having been there, done that in my SDL, it'll run, but not well.

Make sure the alignment you do is based on TDC on the COMPRESSION stroke for #1 cylinder. You can be at TDC, but the Exhaust stroke. If that is the case, you'll be 180˚ out of time on the IP and you'll have heavy white smoke and 0 power.

[barry12345]

I am going to chime in. She paid about two thousand dollars. Did she get the car back running well? A Mercedes mechanic with even just one years experience from an early portion of his career would not get the pump timed wrong. It is almost unthinkable. Unless drugs or booze were involved.

Now the fundamental issue with amateurs is to get it timed on the right stroke. Both valve lobes of the first cylinder pointing upward with the crank mark where it should be. On the other stroke the valve lobes will be generally pointing downward. Then the engine is not at the intended power stroke in relationship to the pumps required injection point.

Remember the camshaft turns at half the speed of the crankshaft. So you rotate the engine once again 360 degrees if the cam lobes are downward tending to your crankshaft mark. They then will point upward of course. Restoring the injection point to the power stroke.

I would also want to see her bill and if it describes a rebuilt pump. There are ways to easily determine that. Number one is the pump should look very clean. Plus the new paint marks every rebuilder puts in the vicinity of the output lines from the injection pump to the injectors. Should still look pretty new.

Finally this is an older series injection pump and it has a self contained internal oiling system. There are plugs to drain and fill that oil supply. In your case that oil internally should be as new still.

Some other questions perhaps of some merit. Why are the fan blades off? Compression is enough to run on. So what is with a two thousand dollar bill if that pump is not a real rebuild. If it was returned to her in a non serviceable running state what was she told?

Symptomatically these engines will run timed properly on the wrong stroke. Producing fumes and smoke with no power and unable to sustain an idle. Hard to start also a given. Your best bet is you verifying what I have posted. correction here what another had posted earlier as well.

Initially I was not going to respond because I have had the misfortune of working on things really messed up myself. Then I thought why not give it a good shot. He posted for help.

Just maybe the mechanic never really worked on any Mercedes diesels made before with inline pumps or drugs or booze are now involved.

If you missed this you could work for days and find no resolution. Forgetting it is not a single stroke engine basically. If the pump is rebuilt you may prevail. Although more usually this tends to occur only if the head was removed. It still remains a possiblity in the wrong hands.

I am not a working mechanic and do not possess the intuitive qualities that can only be developed with years of experience. I work on my own cars simply because I find it relaxing when I get time. Plus I resent getting ripped off by commercial establishments. It is their systems not the mechanics themselves in the majority that are the local issue.

I will watch your post for any updates periodically. There are far better minds than mine on this site as well. So keep an eye on it. I was pondering just how to present this information for some time if at all.

I see now a previous poster had posted about the same information in a different way before I did. Since the poster was new. I was uncertain how to describe a potential issue in a way he could easily grasp and check it out. There remain so many questions. Like why the mechanic did not call the pump rebuilder. They would have told him what we are trying to do. This alone led me to question if the pump was really rebuilt.

He should have thought. The injection pump rebuild has a warranty and that it may be bad. The whole situation just does not fit well together. Not being the brightest myself. Can any member guess why the fan blades are off. Was someone playing with the timing chain? Even that does not fit. I just cannot visualize that part of the situation properly either. A Mercedes mechanic with 30 years experience?

I was once in a shop in Cleveland where they were all higher than kites and working on cars. We had just picked up the car and it was a long drive back to the east coast of Canada. They let me use a hoist and check all the fluid levels etc myself. This was ten to fifteen years ago and I wondered how they kept the doors open. So it is happening out there.

Friendly bunch of guys yet the situation was bizzare at the same time. I do remember getting some laughter after locating a five foot pipe to put on my power bar. Until they heard the snap of the rear differential plug release. On that one I almost thought a piece of the casting was going to let go first. They only did tires and alignments. The customer service out front people where sober. It did occur to me that these guys where also changing front end parts. Perhaps it was a slower day and they were just having a party. Who knows. Beyond all my conjecture give the suggestion a try.

[gmog220d]

Hey Newtomercdiesels,

I've got a piece of fuel line left over from cutting one end off to make my dripper tool. You're welcome to it if you want it. Send me a PM and I'll send it you for the cost of shipping.

[barry12345]

Originally Posted by Diseasel300

In the future, the "Diesel Discussion" subforum on this website is by far the most active page here for tech help. Usually your thread is answered in a matter of hours, if not minutes.

It sure sounds like the timing is off to me. Having been there, done that in my SDL, it'll run, but not well.

Make sure the alignment you do is based on TDC on the COMPRESSION stroke for #1 cylinder. You can be at TDC, but the Exhaust stroke. If that is the case, you'll be 180˚ out of time on the IP and you'll have heavy white smoke and 0 power.

I think you are or have been a working mechanic. Not sure. It appears the much later versions of the more modern but in many ways still similar Mercedes indirect injection engines. Will run not too bad with the in line pump on the wrong stroke.


One member drove one of them a long distance home. Unfortunatly the cylinder wall wash down or thinning of the base oil did some engine damage in his opinion.


We will in all probability start getting people asking for more help with those engines. It may be much harder to determine that they are actually probably on the wrong injection stroke when they describe the symptoms. At least the older engines will not run well enough to drive.


Or in all the cases over my many years on the site one never did.. Even the 603s two year only 1986 and 1987 I think run somewhat better with that situation. Yet remain not really drivable.


It probably remains their 606 introduced in the 90s that will drive. Not sure of their introduction date. I think I remember on the one example that I know of. His power was down but he still managed highway speeds. Some smoke but not really a major amount like the older engines. My memory is not perfect so perhaps another member remembers that case better.


Apparently it idled reasonably. I again think I remember that near the end of his long trip the engine was developing symptoms of internal issues. May have just been carbon buildup perhaps. In any event he posted no more about it to my knowledge at the time. Maybe he will catch this thread if he is still active on the site and comment. People come and go. I have been absent for some time myself as of late.


I have just been too busy especially at my age of seventy five to stay active on site.

[Newtomercdiesels]

Thank you ALL very much.

I have survived, in part, due to these forums. I have about 20 tabs open on my phone and another handful at my computer. Certain things were quite evident/clear after the first several hours regarding the topic of IP timing:

^Assume nothing.

^24* BTDC is the number for a healthy, tight-chained engine

^As mentioned, twice around gives the full 360* cam movement and indeed I can understand (and have observed) the fact that one could conceivably be 180* off.
(I thought through it as I cranked the engine one evening and simply made sure that both values were CLOSED (lobes both up), implying that the piston was indeed TDC.)

^Given the amount of mismatch between cam sprocket zero marks and the marks on the balancer, one can estimate chain stretch. Centered perfectly on the sprocket, the reading on my balancer is within the thickness of the line that denotes zero, which is pretty damn good!

^"Drip method" involves finding the point at which #1 injector outlet is at "start of delivery" for cylinder #1. This is done by using a curved tube and slowly cranking until 1 drip per second is achieved while maintaining moderately-constant pressure with the (new style on my IP) hand primer. Fun fact - apparently you have to remove a valve before you do the test. GOOD to know!

^Pump then needs to be inserted into the engine where the engine is 24* BTDC, at which point, engine and injector timing are in-sync.

It will be interesting getting the pump in without the splined end moving. Apparently even one or two teeth will cause performance issues.

I also read that swiveling the pump allows for advancing and retarding timing. So perhaps I set the pump and repeat the drip test with the engine in the proper position, confirming I still have 1 drip per second, and then crank down and get it all back together.

I have a new gasket and some other odds and ends on order from merc source and auto haus, so my plan is to tackle this Friday or Saturday, whichever day the parts get delivered.

Many thanks everybody. I will 1) keep everybody posted and 2) author some sort of detailed tutorial about this and post it on every forum I can think of. I know there are other people like me working on these things and I know they're frustrated...you get 95% there, and that one detail someone assumed I knew I did not...and it costs 10-20 hours of labor.

Updates to follow. Thanks again.

[Newtomercdiesels]

Originally Posted by gmog220d

Hey Newtomercdiesels,

I've got a piece of fuel line left over from cutting one end off to make my dripper tool. You're welcome to it if you want it. Send me a PM and I'll send it you for the cost of shipping.

Thanks! Sent.

[Newtomercdiesels]

@barry12345

Honestly, I have no idea what the previous "mechanics" have done. I approached it from the perspective "this just broke yesterday - let's fix it" and "I'm sure the pump is fine".

I hope the pump is fine - because if it isn't, it's going to be very expensive to remedy.

On a happier note, when I crank the engine with the fuel lines off, laser-like jets of fuel hit the underside of the hood. I also perform the "loosen the nuts and crank to see liquid seeping out" test at the injectors, and it does this.

I have no choice but to trust that they charged $1,500 and actually did what they said they did. The primer is new, and there is a new looking red breather cap. The pump did not have oil when I first began working on the car. It now has 0W-40, which I believe should be 10W-40. I will correct this WHEN (optimism at its peak) the car starts.

Thanks!

[Shortsguy1]

As you know, there is a likely contradiction between "I'm sure the pump is fine" and "the pump did not have oil." This makes me question the prior work significantly. I hope it is just the timing, but right now, I personally doubt it.

[Newtomercdiesels]

Originally Posted by Shortsguy1

As you know, there is a likely contradiction between "I'm sure the pump is fine" and "the pump did not have oil." This makes me question the prior work significantly. I hope it is just the timing, but right now, I personally doubt it.

Well the pump was out of the engine at the time, although your point is well-received.

I attempted to set the pump right (getting a better drip tube soon!) tonight and it sounds like it wants to turn over and go. I hear one or two cylinders burning diesel and I smell it. But the battery went dead before I could get it to start.

I also think I'm having issues (or underestimate) just how much air is in the lines. It just dribbles out. I have seen it squirt out before, which is why I am blaming air. Does it usually take the better part of forever to bleed fuel lines? Frustrating.

[bokepid]

Originally Posted by Newtomercdiesels

Hello. I recently volunteered my electrical engineer/mechanically-inclined brain to a friend�s 1976 240D. I told her that the car wasn�t the best choice for a winter car driven by an elementary school teacher, but it was purchased anyway...and it broke. Long story short, it decided to not start one day. From what she described, it was in the fall a year ago, and the symptom was a classic flat battery (womp womp womp from the starter). She then took it to a local well thought of �30 year Mercedes master mechanic� to get it fixed. $2,000 later, it still won�t start. Things this person supposedly did: -Glow plugs/insulators -rebuilt injector pump (big money) -a few new hoses,� -new main fuel filter (engine area, not sure about tank) It then sat for a year. She got it towed to her garage. When I first looked at it, the valve cover, fan blades, and hardware were in the trunk(!!!!). Injector pump was out of the engine but hooked up. What I did: -Put the correct H8 battery in (new) -confirmed glow plugs function (continuity check and dash filament lights up after 15-20 seconds, wires coupling plugs get hot) -confirmed compression (300,260,310,340 psi 1,2,3,4) -installed fuel injector pump and turned engine without fuel lines attached. Just before cylinder #1 cam lobes are completely off the valves, injector outlet #1 shoots fuel. I lined up pump timing marks and inserted pump into engine at what I thought was 25� before top dead center. The car sounds like it�s firing weakly and I see white smoke and smell burnt diesel, but it will not catch and idle. The first time I set the pump, I used the old factory marks. In this configuration, after liberal use of starting fluid with upper cylinder lubricant (I know, I know), it would eventually get warm enough and floored I could get it to run. The warmer it got, the further off the pedal I could go. Any further than about half, the idle hunted and oscillated between high and low rpm. Pulling my foot further off and the engine quits. I reasoned that I didn�t get the pump installed in the correct time and that it was able to run off the remnants of the last injection at high rpms due to the amount of heat and increased compression. This caused me to reset and confirm timing (as best I could) as I explained above. It still will not start. I don�t have the drip tube and I figured if I was even close to the right timing, it would at least start and idle badly...but it refuses to catch and go. Aside from blaming old diesel in the tank, I�m out of ideas. Does anyone have any idea what is going on? Any help would be much appreciated. The car is in awesome condition cosmetically and my friend is getting more and more discouraged that nobody can get it to run. Any help would be much appreciated. Thanks everybody.

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[strelnik]

Congrats on your effort:

I think an oïl chqnge to 0W40 will speed up the movement of the starter; so will verification of the current flow, very often the ground is not strong enough to turn the starter, in my experience.

There are two ground straps, I periodically replace both,

Have you also checked the main fuse in the glow plug relay?