In taking care of my dad before his passing, things got shoved down the line. After 5 years and an additional 13,000 miles (car has 155,000 miles on it), I have been meaning to change the fuel filters since I changed them 5 years ago, but haven't.


I want to spank myself. In any case, the car was running perfectly and also started instantly almost regardless of the weather. Also, the return lines coming off the tops of the injectors and are obviously leaking.


I replaced the fuel filters, but cannot quite start the car.


Any thoughts on a course of action?

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1983 240D low miles 156000, and yes, MB still gives out badges

Sounds like you didn't bleed it. It's air bound. Loosen one injector line at a time and crank it until the air bubbles stop. Have a helper watch the injectors until straight fuel is coming out with no bubbles. Also, next time you do it fill the fuel filter with diesel. It doesn't allow as much air to be introduced to the system. If there's a lot of air it may be wise to have a charger nearby.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

When I say loosen, just crack the lines. Also, I'd take care of the orings that are leaking on the injectors, you will start sucking air and make it harder to start.

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Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

Thanks for the input on air in the system. I will try that.


As far as I know however, there are no O-rings on a diesel 240D. There are crush washers separating the injector and the head, metal to metal. The fuel lines are also metal to metal.

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1983 240D low miles 156000, and yes, MB still gives out badges

I suspect it is the individual hoses on the returns of the injectors that may be leaking. More typical of the old rubber hoses on these diesels by far than any other leakage. At least in that area.


I do not know your 240ds year of manufacture. Over time components in the fuel linkage deteriorate. Any owner should periodically check to see if someone presses the pedal to the floor. That the lever on the injection pump goes as far as it should. My 1983 one has a deviish setup where there are two rubber inserts on a fork transmission universal joint. The actually rot and disentigrate with time. Allowing so much slop the lever on the injection pump is badly compromised in advancement.


As far as I know the two rubber sleeves may be the cheapest parts available for these cars at a dealer. There are no aftermarket. Around a dollar if needed for two should not put you in the poor house. Actually for the amount these engines really vibrate. To me is remarkable how long the linkage components stand up.

Does the leakage on the return lines cause a performance problem? Some of mine are soaked making tiny puddles in the injector sockets.


Your comments on the linkage are also interesting. I have some leaks in my door trunk gas actuators that cause run on at times. When I push the STOP lever on the linkage at the pump, I have to do so forcibly to stop the engine.


This car is in great shape, but when I started driving it regularly a number of plastic parts started to disintegrate. The linkage under the trans shifter (automatic), for example. There also is a plastic part (like a half moon on the long link (the half moon turns the up and down motion of the accelerator pedal to a circular one) coming off the fire wall and going to the injector pump. This half moon is hidden by metal, so you do not know it is there unless you unscrew its retainer off the firewall. When this gave out (after I did the rear brakes and master brake cylinder), it was a real puzzlement. How does doing the brakes keep the car from going more than 25 MPH with 0 acceleration.


You stated, "My 1983 one has a deviish setup where there are two rubber inserts on a fork transmission universal joint." What is and where is "fork transmission universal joint that these rubber inserts are located. I likely have the same issue.


I really appreciate you input.

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1983 240D low miles 156000, and yes, MB still gives out badges

Located beside the engine. You should see two little black pieces on the forks of that universal. It appears yours is an 83 240d as is one of mine with that joint.


So you should have it. Or you can grab each side of the linkage and hand twist one against the other section. It is an open cage rotating assembly to observe. You do not want to see excess slop.

One problem is those small sleeves rot and just fall off at times so they are no longer even present. In your mind when examining the joint they never existed in that case. So you are not expecting them to be there.


As for a driving indicator. You have no top end beyond around fifty miles per hour. Plus poor acceleration without them.

Depending on your background and what you have on hand. Heat shrink tubing might replace them if needed but it may not stand up.

Personally I really like these 616 engines. They will last a very long time if you become aware of where the issues are with them. Plus address them. Cheap to do as they demand very little really.

Not periodically checking and keeping the fuel system in good general condition. Makes a drop in available power and a noisier engine at speed. Plus a rougher idle sometimes. I still suspect it also damages the engine longer term.

Mercedes marketed their four cylinder diesel engines first. There are some small but important differences in comparison to the later five cylinder turbo engines. The lift pump for example is weaker but can be upgraded to the output pressure specifications of the later version. Simply by changing the lift pump pressure spring.

It is a very reliable type of fuel pump as well. Yet they are so old now. They should be rebuilt with a ten dollar or so kit. Or their output pressure gauge checked. Just to maintain if needed the reliability and pressure function they originally had. Adding the pressure spring from a turbo diesel lift pump at the same time to upgrade them. Is better than not doing it. Reduces the impact or resistance to flow of the secondary filter restriction as it contaminates.

Another area that I have been thinking about. Is stay on top of oil changes. I thought it always was a good ideal because of the rapid soot buildup in the oil.

Now to add to the list. The viscosity improvers in our multi grade oils wear out. So the running viscosity of oil not changed often enough falls. At the time these engines where marketed only single grade oils where available.

I have been looking for anything that may be other than running low fuel pressure. As the reason or a contributing reason to the eventual failure of the first rod bearing for a long time now on the 616 engines. Running multii grade oils too long without changing them may also be a factor.

Single grade oils may get really contaminated if left in too long as well. I suspect that they will still hold a better viscosity than the multi grades do. The multi grade enabler is a plastic additive that does wear out. Apparently the molecules increase in size as the temperature rises.

So my guess is that if two engines were operated for seven thousand miles. One with normal single grade oil and one with a multi grade. If you pulled a sample and checked the oil sample. Plus heated it for a viscosity reading. There may be lower viscosity left in the multi grade in comparison to the single grade oil. Just a suspicion at this point.

Yet we still have people suggesting that we can run multi grade oils for longer intervals if they are synthetic. Without a clue of what viscosity is still present at say 300 degrees F. As they get older. They both employ the same plastic viscosity additive I suspect.


Oil labs do this test I suppose. Reporting the viscosity of the oil is still okay. What is okay and what is it in comparison to the single grade oils? Okay is not a lab test result.


Perhaps the viscosity has dropped back to say 30 at high test temperatures. Thirty while adaquate or okay for most older engines is not enough for these engines.

Again just remember that the additive to make oils multi grade. Does wear out. So the oil will not thicken or declines too much at high operational temperatures as that additive deteriorates. Reducing the increased viscosity protection.

The lower engine blocks are built strong and operate at far less rpm than they could. Yet there are certain failures that Mercedes would have corrected if they were a design flaw existing.

So I am going to add that overdue oil changes may also be a small contributor. Yet still not the primary cause of the number one rod bearing failures on 616 engines.

I as an old guy want to pass one 240d down in our family. So it is important for me to keep it in good shape. I have one good spare engine on hand. These engines are not cheap to rebuild properly and good used ones will become really scarce all too soon.

No sense in not replacing the short leaking lines between the injectors anyways. In general you probably have a small accumulated pile of minor things you can easily do yourself cheaply.


It sounds like an example that is still well worth keeping up. I am an old guy now and remember when my dad told me. I should find a way to keep many of the odd older cars that were passing through my hands when really young. He was right.

As for the brakes jack each wheel off the ground and make sure you can turn the wheels fairly easily. You might have some semi seized calipers to deal with if the car sat around too much. Also if you encounter serious resistance to turning on a rear wheel you might have a seized emergency brake. Or did not put the transmission in neutral rather than park. Most times it will be the caliper though.

Generally whatever is found is not that hard to address with brakes. A test I do often that accomplished the same end. Is to drive the car for a distance of a mile or so and let it coast to a stop. No wheel should be hotter than any other. I use a temperature reader but saliva on a finger is good enough. In your case you may even smell a hot wheel.

Weeping fuel return hose is common. My new "Made In Germany" woven rubber hose started weeping after ~4 yrs. I replaced w/ 1/8" Viton hose on ebay, advertised for M-B and VW diesels. No leaks in ~2 yrs, so apparently authentic Viton (from China). Tygon hose works for some, but probably temporary. Silicon hose swells in a week. I mostly use Diesel HPR fuel, which is bio-derived so probably taxes hoses more than D2.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

I did a diesel purge, but I had to pump the pedal to start the car. In minutes, it was running great with very little smoke out the tail pipe. I put the lines back on and it would not start. It was idling ok, but probably about 50-100 RPM less.

I loosened the fuel line at the large fuel filter (the one that comes from the fuel pump to large filter), and the small fuel filter is still about 1/3 air inside after pumping the primer pump like crazy.


I removed the #4 injector line and almost nothing was coming out and I still couldn't get all the air out of the small plastic fuel filter no matter which way I tried to orient it. How much fuel should be coming out of the injector line? I had about zero. Makes me think it could be the IP fuel pump gone bad or could a loss of vacuum cause the problem. My car has 155,000 miles, so when do the IP fuel pumps go bad if ever?


Any further thoughts any one?

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1983 240D low miles 156000, and yes, MB still gives out badges

Everyone has a air bubble in the plastic filter. As long as you don't see bubbles flowing on down the line that is normal.

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84 300D, 82 Volvo 244Gl Diesel

Crack one line at the injection pump and crank with a helper. It's probably extremely air bound, so you may not see fuel for awhile. Crank for 10 seconds of time with a 20 second rest so you don't burn the starter. It will start again, have faith. The IPs barely ever go bad unless you pump WVO thru them.

__________________
Only diesels in this driveway.
2005 E320 CDI 243k Black/Black
2008 Chevy 3500HD Duramax 340k
2004 Chevy 2500HD Duramax 220k

hey rick - what fuel primer pump do you have on there? it could be leaking air if it's the old style that has a white top and you have to unscrew to pump it.

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'85 300D, 'Lance',250k, ... winter beater (100k on franken-Frybrid 3 Valve Kit)
'82 300D, 'Tex', 228k body / 170k engine ... summer car
'83 300TD Cali Wagon 210k, wife's car

If it ran well on the purge. This might eliminate some issues. To me although I might be wrong. The lift pump was working and the primer pump was not letting air get in.


You might disconnect the fuel line just after the lift pump. Crank the engine and watch for fuel coming out the lift pump. There is also a chance you have really bad fuel in the tank. That is a real long shot though.

Fuel tank strainer clogged maybe??

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2012 Mercedes ML350 Bluetec 91K (hers)
2005 Corvette 55K (fun car)
2002 VW Jetta TDI 231K (mine)
1998 Volvo S70 T5 Turbo 196K (kids)
1994 Ford F150 4WD 249K (firewood hauler)
1983 Mercedes 300D 376K (diesel commuter)