Somebody please help me diagnose the problem with this car before I go completely bonkers and they cart me off to the funny farm.

The car is a 1993 Mercedes 300 D, 2.5 diesel.

1) The car was running fine, no skips,cranked easily, no smoking problems, no problems whatsoever, prior to being parked.
2) After the car was parked for 2 days in the garage, it would not crank.
3) Checked the glow plugs–all 5 were working fine.
4) The battery was fine and I had it hooked to a charger to keep it 100% charged.
5) “Cracked” injector line to the 1st injector–not pumping fuel.
6) Changed pre & main filters–tried to crank, it was not pumping fuel.
7) Although there is an automatic bleeder valve on the side of the pump, I bleed all the lines at the injector pump and at the injectors–still not pumping fuel.
8) Checked the fuel pump mounted on the side of injector pump. Shop manual states it should pump approximately 2 oz. in 15 sec.-- it was pumping approximately 3 oz. in 15 sec.
9) Changed o-rings and seals on delivery valve holders.
10) Pulled the inspection plate off of the injector pump, the rack was moving freely.
11) Pulled the fuel pump off, cam was working properly and turning freely.
12) Pulled off the automatic bleeder valve on the side of the pump, cleaned and reinstalled it.
13) Continued cranking the car until it finally started.

NOW THE BIG PROBLEM!!!

Although the injection pump is pumping strongly to the first four injectors it is pumping nothing to the fifth injector.
I rechecked the fifth valve assembly on the pump and it was seated properly. Even swapped the fifth assembly with a spare, still no fuel on fifth injector.
The engine cranks very easily, but, of course, you can imagine the skip with no fuel reaching the fifth injector.
While I had the fifth valve assembly out, I noticed fuel trickling into the hole where the valve assembly was removed from.

Pull the IP cover off again to view the Rack. The Rack is supposed to turn part of the Element (the part that I would call the Plunger) to give it more or less fuel.

What you will be looking for is to see if the parts that move the Element that would be for the 5th Cylinder are following along the same as the other 4 Elements.

You also want to see if the Element (Plunger) is moving up and down and that the return spring is not broken or loose. If the Element (Plunger) is stuck or sticking the return spring will remain compressed or will not return as far as the other 4.

In the IP pic from the site below you see item #23 the Pump Element (I call Plunger and Barrel Assy.) that is 2 pieces the bottom portion (the plunger) moves up and down to deliver the fuel and is rotated to adjust the fuel by item #26 Sleeve and item #29 Clamping Piece that is attached to the Rack.
Moving the Clamping Piece will change the delivered Fuel quality. Also if the Clamping Piece is loose the delivered fuel quantity on that element will not be correct.

So you can have a Plunger stuck in the UP position, a cracked #26 Sleeve, a loose Clamping Piece, or a broken return Spring (item #32).

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=124130&M=603%2E912&GA=722%2E415&GM=717%2E433&CT=M&cat=503&SID=07&SGR=045&SGN=01

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84 300D, 82 Volvo 244Gl Diesel

I really appreciate the information you provided to me. There's no doubt that you're an expert in the field.

Although the injection pump is pumping strongly to the first four injectors it is pumping nothing to the fifth injector.
I rechecked the fifth valve assembly on the pump and it was seated properly. Even swapped the fifth assembly with a spare, still no fuel on fifth injector.
The engine cranks very easily, but, of course, you can imagine the skip with no fuel reaching the fifth injector.
While I had the fifth valve assembly out, I noticed fuel trickling into the hole where the valve assembly was removed from. With number five valve removed I could operate the rack and see the slot on the top of the plunger move counterclockwise about 30°.with the inspection plate removed and the motor cranking over I could see all five plungers moving up and down with about the same rotation. I could not see any springs broken or anything unusual on any of the plunger mechanisms.


If I remove the valve holder from number five valve on the injection pump, disconnect the fuel inlet hose and blow compressed air back through the plunger on number five hole, am I likely to cause any damage to the injection pump?
Since the first four valves are pumping extremely well and since the mechanical part looks like it's in order, I thought perhaps it might have a piece of trash blocking the hole in the plunger. I would appreciate your advice on the matter.

Thanks, Stark

Not an expert but those are some of the things that I remember I found when I rebuilt different types of Inline Fuel Injection Pumps in the past. There is another companies IP that uses a similar Clamping Piece and they can sometimes vibrate loose.

Concerning the above I guess it is possible for the fuel inlet hole on the side of the Barrel to be plugged. However you do not want to shoot 125 psi into the IP housing as you will be presurizing the low pressure part of the IP. Also if your Compressor Air is not filtered you could introduce something extra.

If you are going to shoot some air in remove the Over Flow Valve again and this will allow some place for the air in the housing to escape to. If you have a regulator on your Air Compressor turn it down to what ever you guess is safest. Or, at leas hold the Air Gun back several inches from where you are going to shoot the air in.

Before you blast some air into it try this it will add about 10 mim to your time. Remove the Delivery Valve Holder with the special Socket and remove the Spring and the center part of the Delivery Valve (as if you were getting ready to drip time the IP) just put the Delivery Valve Holder back in snug without the Spring and Valve.
Do not install the hard line and crank the Engine. If the Barrel fuel feed hole is open some fuel but not high pressure fuel should come out of the top of the Deliver Valve Holder.

It is not a good idea to rotate the IP with the Delivery Valve and the holder not screwed in as it is possible for the Barrel to loosen and rise up in the housing and rotate past the alignment pin (at least in the past the Barrels had a slot on the side and the housing had a pin so that when you drop the Barrel into the housing it would align the Barrel).

I wish someone else would also provide some suggestions as without being there ?????

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84 300D, 82 Volvo 244Gl Diesel

WARNING -- be careful who you are dealing with. All that glitters is not gold.

I contacted a Bosch authorized repair station in Forest Park, Georgia and talked to their shop foreman. This was before I got the car running on four cylinders. At the time I talked to him the car would not crank at all. I told the shop foreman the following:

1. The car is a 1993 Mercedes 300 D 2.5 diesel.
2. The car was running perfectly when it was parked in my garage.
3. Two days later, for no apparent reason, the engine would not crank although the battery was fully charged and the motor was turning freely.
4. I then checked all five glow plugs and they were all working properly.
5. I checked for fuel at all five injectors, no fuel was reaching any of the injectors.
6. I changed the pre-fuel filter and the main fuel filter -- still no fuel reaching the injectors.
7. I checked the lift fuel pump on the side of the injector pump, and it was delivering more than a sufficient amount of fuel according to the Mercedes specs.
8. I removed the inspection plate on the side of the injector pump to inspect the operation of the rack -- it was operating freely as it should be.
9. I removed the valve holders on the top of the injection pump and replaced the copper washers and O-rings.
10. I tried to bleed the injector pump at each valve and at the injectors, but the injector pump would not pump fuel to the injectors.
11. The vacuum and manual shutoff was working properly.

The shop foreman told me that the expert who worked for him was from Cambodia and rebuilt those injector pumps on a regular basis and no one knew more about those pumps than he did. As a matter of fact, the expert Cambodian owned three Mercedes and drove a 350 SDL himself. He said that he would let me talk with the expert and see if he could help me.

I talked with the expert and told him everything that I have enumerated above. He told me that he did not believe there was anything wrong with the pump and I probably overlooked some simple thing and for $75 he would come by on his way home and tell me what was wrong. (It was approximately 3 miles out of his way to come by my place)

After about 15 minutes of inspection and agreeing that the rack and fuel pump was working properly,he concluded that the injection pump was worn out and needed to be rebuilt, although it had been working properly only three of four days before. He would perform this service for me for $1000 minimum and more if it required any hard parts.

After a few more hours of frustration and education I finally discovered that the automatic bleeder valve was blocked with a piece of trash. I removed the bleeder valve, cleaned it and reinstalled it and the car cranked immediately, however, the fifth injector was not receiving any fuel from the injector pump. That's when I came to this forum for help. Diesel 911 came to my aid. He was extremely helpful and furnished me with information that made me understand how the injector pump operated. He also furnished me the key to correcting the problem.

THE BARREL HAD JUMPED OUT OF THE ALIGNMENT PIN WHILE THE VALVE HOLDER WAS REMOVED.
I talked with Tom at Yankee Diesel in Newtown, Connecticut, and he walked me through the repair. After I put the barrel back on the pin guide, the car cranked up immediately and ran perfectly. I really appreciate the help that I received from Diesel 911 and Tom at Yankee diesel. If any reader of this essay needs expert diesel work, you know who to go to, on the other hand, I expect, you know who stay away from.

So what do you think was the original problem?
I'm taking it that the barrel that jumped out of position was done during your troubleshooting???
I am looking for one of these cars, so I'm most interested in the solution to your original problem.
Both you and Diesel911 did exceptional work IMO!

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Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

("I finally discovered that the automatic bleeder valve was blocked with a piece of trash.")
Speculation: The piece of trash that finally ended up in the Bleeder Valve may have been blocking fuel feed/inlet hole in the Barrel of the one Element. The troubleshooting process caused the trash to move from the hole and migrate to to Bleeder Valve.

Where did the trash come from?

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84 300D, 82 Volvo 244Gl Diesel

To Jimmy L. and Diesel 911:

Diesel 911, and Tom from Yankee Diesel deserve the credit for this car ultimately being fixed, the only thing I provided was wrench turning and persistence.

I do not want to blame the Bosch "expert" for the valve jumping off of the guide pin but at some time when valve number five was out of the hole either he or I operated the rack control and I believe that it jumped off at that time. As I stated before, Diesel 911 diagnosed the problem, and Tom at Yankee diesel walked me through the repair.

The car was running fine when parked, two days later before the engine was touched it would not crank. I changed both fuel filters, and the washers and O-rings on the valve holders and the engine still would not start. I think it was just a fluke that a piece of trash got dislodged and blocked the bleeder valve. I really don't know how it happened. I do know that I have obtained quiet and education concerning injector pumps since this happened. Jimmy L., I wish I could tell you more but that's all I know.

I hope both of you have a Merry Christmas and a Happy New Year and remember the reason for the season.

I'll tell you this Stark: While getting good advice is a huge plus [and you got great advice] it also takes somebody who can both follow said advice and think their way through it at the same time. It is an added bonus when you can convey your questions and procedures as thoroughly as you did. Now all we have to do is get you to start snapping some pics......
I must say, I hope I never "have" to learn that much about injection pumps......
And yes, the reason for the season is not lost on me!!!

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

I've driven that road thousands of times and can't picture Yankee Diesel. I did a Google map and I know now where they are but still can't picture the place. Next time I go by I'll see if I spot them. What do they do there anyway? No web site (but there is a listing where you can write a review if you're so inclined).

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1985 300D Turbo
"Evolution is God's way of giving upgrades" Francis Collins

To Jimmy L.: thanks for your kind remarks.
To raslaje: I believe Tom owns Yankee Diesel and they are in the business of rebuilding injector pump's. I don't know what else they do. I do know that Tom teaches at a local college. Although I have never met him, he seems like a super nice man and was patient helping me with my problem. He has a vast knowledge of injector pump's and if I ever need to have one rebuilt, he will be the man I will go to. I understand his prices are quite reasonable.

Must go now, I hear a clatter on my rooftop. Sounds like a herd of horses up there. I have a strong suspicion of who it is although he is about 35 minutes early.

Have a Merry Christmas, Stark