After everything I've done to my daughter's car, it still doesn't start the way that every other 616 or 617 diesel that I've had started.

It will start in any temperature that we experience here, which means so far this winter about 15 degrees F. The problem is that she has to grind it for a few seconds, then a cylinder starts firing, she keeps grinding the starter and maybe one more kicks in, then she keeps on grinding 'til it's finally going. It's a good thing that I have a fresh starter on hand.

Evidently there is now no compression problem. The glow plug system is in perfect condition with new plugs. I have pumped the hand pump while she's trying to start it with no difference.

The injectors are not perfect and the injection pump might not be either. If I knew it were injectors or pump, I would replace them.

I'm at a loss,

PS: Thanks Bill Woods for the Diesel Discussion Forum. It does keep us from dripping black oil all over Tech Help. Great Job!

Just thinking out loud here Larry.

A) Is it possible you have air in the fuel system somewhere?
When you crack the fuel connection at the main fuel filter, while pumping the hand pump, do you get any air? Also, if you close the fuel connection on the main fuel filter,WHILE still pumping the hand pump, does your mechanical governor on the injection pump open up and rattle? Maybe your governor is stuck open.

Larry,
Mercedes diesels are self-bleeding.That's the purpose of the small rubber lines going from one injector to the other. It carries excess fuel and air back to the return line.The early MB diesels used a steel line for this purpose Can you remember them?
Your hard starting of your daughters 300D is most likely a compression problem.Normal compresion should be 320-350psi(22-24atu.).Minimum pressure is 220psi(3atu.).Permissible difference is 44psi(3atu.).To get the car in top shape,you may have to rebuild the engine,and I know you can do that.
If I listed all the Mercedes I have owned,it would take up too much space,let's just say I have owned a few.Most were diesels.
Bill Lewallen Lexington,Ky.

IN MY EXPERIENCE IN WORKING ON MERCEDES DIESELS, I WOULD ASSUME IT IS A COMPRESSION PROBLEM.
IF COMPRESSION IS GOOD, CHECK THE EXHAUST TO SEE IF SMOKE IS COMING OUT WHEN STARTER IS CRANKING THE ENGINE.
IF THERE IS SMOKE, INJECTION TIMING IS PROBABLY THE CULPRIT.
IF THERE IS NO SMOKE, REMOVE ONE INJECTOR FROM ENGINE AND HOOK INJECTION LINE TO IT. CRANK THE ENGINE AND SEE IF FUEL IS SQUIRTING OUT OF INJECTOR.

GOOD LUCK,

PAUL
'87 300TDT

__________________
1987 300TDT 165K MILES

I would say that it is most likely an air in the fuel problem. I saw one once where the main fuel filter was not tight enough and it would suck in air as the fuel system cooled. The weird thing was, it would not leak fuel, it would just suck air.

We replaced the filter and tightened it down and the hard start was gone.

__________________
Benzmac:
Donnie Drummonds
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS

Larry, hope you don't mind my getting into your post. I am having very simular problems with the 86 300. I have supposedly good glow plugs, a good battery, timed to heat for three hours before starting for work, and it does very much what your young lady's car is doing. I have concerns for the life of the starter if this continues.

R Opp,

Yex, I'm glad I have a fresh starter on hand.

I do believe that it is a fuel leak somewhere, or maybe the lift pump. I've not had decent weather to mess with it. We've been without power for a few days and now I have probably a cord or two worth of branches to get out of the yard. I'll let you know what I find. I have so far checked for connections to be tight.

Good luck,

Larry,

From the front page picture in the San Diego Union (of a residential street in Paris), I'm betting all your Benz's are having a slow start right now. Stay warm.

__________________
Mike Tangas
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72

'02 CLK320 Cabriolet - wifey's mid-life crisis

2012 VW Jetta Sportwagon TDI...at least its a diesel

Non illegitemae carborundum.

Larry,

Just wanted to add to my experience of air in the fuel sys to what Benzmac said. I recently changed the fuel filters & adjusted the valves on both cars & put new glow plugs in the 240. Week before last, I noticed that the SD was getting progressively harder to start. When I came home one night, there was a strong odor of #2 coming from under the hood. Even though I had tightened the primer pump when I changed the filters, there was a spray of fuel coming from it ... all over my beautifully painted engine I replaced it with the newer style primer pump, and it started-up effortlessly. I've always had to re-tighten the primer on the 240 every couple of months (it was a very minor leak), so I decided this past Saturday to replace it also. It improved the starting greatly. Although I'm certain I got all of the air out when I put the filters on, it looks like air was getting into the fuel sys thru the primer????? BTW, I got the primer for $14 from the dealer.

__________________
1980 Mercedes 240D
1982 Mercedes 300SD
1985 Mercedes 300D
1993 Dodge Cummins Turbo Diesel

And the winner is........... Benzmac!

Benzmac was right on with his diagnosis. I replaced the fuel filter as he said, but there was still an air leak. I pulled the injector return line, the small one from number one back to the top of the filter, there was no fuel. This was after it sat overnight. I trimmed it and put it back on. This didn't help.

I pulled the cigar hose, and the clamp had a dent in it, a v that was pointing in toward the hose. I trimmed the hose just a little, banged the dent out of the clamp and put it back together. Now, in the morning, you don't have to keep grinding the starter after it begins firing.

Thanks for everyone's patience on this.

The car is now up in very good shape except for the blow by. It uses a quart in 600 to 900 miles. My daughter is learning how important it is to stay after the oil level.

Have a great day,

TXBill,

You probably went about 700 or 800 miles. That's the same kind of oil usage my daughter's car is seeing. If you were driving hard, you would expect to blow a little extra. I've said before, as long as you can carry enough oil to get where you're going, you can continue to run a diesel without hurting anything.

It sounds like you have bad valve guides, accompanied by some blow by. Valve seals may help, but I doubt that they would help much. I doubt that a valve job with new guides would stop your oil usage, but it might. Have you done a compression check?

I say keep it full of oil and enjoy it until it gets so bad it won't start, then renew the cylinders and do a valve job.

I dont' think there was overlap of the R4 compressor on the same engine as loop type glow plugs. These type glow plugs usually don't really go bad like parallel ones do. You can pull them, inspect them and clean out their bores, which on your engine will probably be particularly cruddy. If there is enough junk in the glow plug bores, the junk will short a little of your glow plug current to ground.

Why are you asking the Harrison Compressor/Serial glow plug question?

My $0.02,

larry,
i'm very interested in this air in the fuel system discution. my engine will fire right up on the first start of the day, but stumbles a bit, and i often have to try twice to get it going smoothly. i'm thinking air. i disconected the small cap line on the last injector today to bleed it out. there was no fuel when i pulled it off. i pumped the hand pump, and it took about 5-7 pumps to get fuel to come out. it was very bubbley. eventually it smoothed out to a solid stream of fuel. but, i did notice that on the bottom of the hand pump (where the actual moving part screws into the rest of it between the two fuel line ports) there was a little fuel seepage. not much, but enough to look wet (could there be an air leak here?). i also noticed that if i pump the hand pump down (or in) hard and fast that i get a bubbley shhhh sound, rather than the smooth 'fuel only' movement/sound. what do you think? thanks so much guys

Bill,

Since the compressor is in an entirely different location, I doubt that it has been changed over. If the earlier engine were put in it's place, I THINK that the bolt holes are on the lower left forward part of the engine where the compressor can be mounted. My '80 Euro 240D that I bought as a parts car had an aftermarket air conditioner compressor mounted there and it was a loop type glow plug engine.

Bamboo,

A leak anywhere will result in air in the system given enough time. I have been referring to my leak as an air leak because the leak is at the highest point, so it shows no diesel leaking, it just lets in air. If the leak is low like the pump it will result in the same thing, but will show diesel fuel around the leak because it is low.

When pumping with the hand pump, the hissing sound is what you listen for to see if the system is primed. It's not really a hiss, it's more of a high pitched groan. That is normal for system that is fully hand primed.

Good luck,

Larry, I have the utmost respect for the MB starters. I swas having a heck of a time starting my 78 CD and for a long (8 months) time I was jumping it in the summer and grinding away far more mercilessly than seemed sane. The ole starter kept valiantly spinning away but I lastly, found out that it had been slow and not turning fast enough to develop the firing compression. I took it to the batteries Plus store and they tested it at 1350 amps of draw. the cables were glowing. But the sturdy MB starter STILL had not cooked itself to death. Amazing! A new starter surely did the trick, though. Taught me a thing or two about minimum cranking speed requirement. (I get by in my 240 by using 12 and 6 volt batteries in series for some real spin on this low-compression engine) Crank speed is king.
Sparky

I hope you have the rest of the electrical system isolated from the extra 6 volts.

__________________
RRGrassi


70's Southern Pacific #5608 Fairmont A-4 MOW car

13 VW JSW 2.0 TDI 193K, Tuned with DPF and EGR Delete.

91 W124 300D Turbo replaced, Pressure W/G actuator installed. 210K

90 Dodge D250 5.9 Cummins/5 speed. 400K