W210 (606.962) E300DT Injection Pump Questions...

[E-Classy]

Hello fellow MercedesShop.com members...

I am currently replacing all six sets of both the black rubber o-rings and the copper "crush washer” seals in the diesel Injection Pump of my 1999 Mercedes-Benz E300 TURBODIESEL sedan. I have chosen NOT to replace any of the six original Compression Springs, at this time, because the new Springs (M-B part no. 001-074-34-93) I had ordered from the Mercedes-Benz dealership are shorter than the original Springs that came out of the Injection Pump.

Although I have been very careful to keep the work area meticulously clean (with both Carburetor Cleaner and Canned Air) and have only removed and worked on one Pressure Valve Holder at a time, I have noticed that, upon the removal of the Pump's Pressure Valve Holder assemblies, pieces of the original black rubber o-rings as well as fine metal thread particles have fallen into the holes of the Injection Pump that were exposed when the Pressure Valve Holders were removed. Primarily, this was caused when the original, deteriorating o-rings were stuck around the treaded part of the Pressure Valve Holders during the disassembly process. When ratcheting out each of the six Pressure Valve Holders with the Special Splined 1/2" Drive HAZET Socket, pieces of the failed and deteriorated rubber o-rings and fine small metal particles (from the threads of the Pressure Valve Holders themselves) rained down into the area where the Pressure Valves and Pressure Valve Carriers are held.

My question is concerning the possible contamination of the diesel Injection Pump. If these debris particles are forwarded along the fuel delivery valves through the injection lines (once reconnected and the car’s engine started), may these debris particles eventually find themselves imbedded in the fuel injectors? I've read earlier threads mentioning that the diesel injectors themselves are VERY expensive and replacing them, due to blockage and contamination problems, could be quite expensive. Therefore, the need to keep everything clean during the replacement process is paramount!

I was thinking about the possibility of flushing out or purging the pump BEFORE reconnecting the metal fuel lines that lead to the injectors. The only problem I have is how? And how effective would this process be? As all six Pressure Valve Holders have a VERY small and deep pin-like opening at the top (where the fuel lines attach).

I was also considering the possibility of placing clean rags over all six of the open Pump's Delivery Valves (without reconnecting the metal fuel lines), once all six seals have been replaced and each of the Pressure Valve Holders have been torqued down to the final 35 Nm value. Another idea I had was to attach six tightly fitting hoses to the threaded top portion of each of the open six Pressure Valve Holders. I would simply have all six hoses empty into a bucket when I "dry crank" the engine. In theory, any debris contained in the six Delivery Valves would simply be ejected and flushed out through the hoses (with fresh diesel fuel entering the Injection Pump) by the turning of the engine, which in turn rotates the Injection Pump. Even though the engine would not receive any fuel (during this process), would the turning over of the engine create enough pressure to evacuate any contaminated particles from the diesel Injection Pump’s Delivery Valves?

Thank you for reading my new thread, as I would really appreciate hearing feedback from some of the more experienced diesel experts on this!

[TMAllison]

You are on the right track. Torque the valve holders to 35nm (one time only BTW, the 3 step process has been revised) and then crank until fuel comes out to flush.

I'd probably reconnect the metal lines to the valve but not the inj and put a paper cup beneath each to catch the fuel.

Mine was a little clattery after doing seals. Two dp's of two cans each, two weeks apart, helped. I didnt flush mine and wish I had.

Do rinse the holders and springs in clean diesel before assembly.

Do you have the pdf for the job?

[E-Classy]

Hello TMAllison,

Thank you for the reply and the encouragement, I really appreciate it!

So, if I understand you correctly… I should reconnect the metal lines back to the diesel Injection Pump's Delivery Valves (once all O-rings and Copper Seals have been replaced, the Pressure Valve Holder torqued only once to 35 Nm and the collars reinstalled). Then disconnect the metal lines at the injectors?

I guess I will then have to place six empty cups on top of the engine's Valve Cover where I've disconnected the metal lines to collect the diesel fuel when turning the engine over.

As the engine is not getting any fuel from the Injection Pump (during this process), will there be enough pressure caused by the “turning over” of the engine's Injection Pump to force fresh diesel fuel through the Injection Pump and then out of the metal lines, just before the injectors?

I've also rinsed the Pressure Valve Carriers (paying close attention to reinstalling them with the machined grove/ridge at the bottom), Pressure Valves and Compression Springs in clean diesel fuel. I then dipped the new black rubber O-rings in clean engine oil - as I was a bit weary of using the NEW ULSD fuel, for fear of the Ultra Low Sulfur Diesel fuel breaking down the new O-rings prematurely; as I did not replace them with Viton!

Also, thanks for the link to the "diesel delivery reseal.pdf" file.

I have reworked and converted the original diagram to a new JPG file that is clearer and much easier to read and attached it below...

[nhdoc]

Your idea to flush out the delivery valves by cranking with the hard lines disconnected will probably get rid of any of the debris you described. It is common to have small pieces of the old o-rings and minute metal shavings in there. I had them and cleaned them out as best I could and didn't flush at all and the car hasn't suffered one bit, but that's not to say it wouldn't have been a good precaution to flush them like you thought...so do it and then reconnect the hard lines, crack them open at the injectors to fill them and close them up and start the car...all should be fine. You might need to jump it if you kill the battery with all the cranking, I know I did, but I replaced all my fuel lines too and it took a lot of priming to get the system full of fuel again.

Good Luck!

[TMAllison]

The fuel feed and return lines should still be installed unless you also removed them for another reason. They are both at the fuel filter. Feed is into the pre-filter and return is the hard rubber line comming off of of the main filter housing. You'll have lots of fuel, turst me.

I think pumping wiht the metal lines disconnected from the injectors would be cleaner than pumping out of the del vavles but both will work.
Dont take anything else out of the valve other than the washer and spring. The diagram is not accurate....the washer and spring will be on top and the sprring will fall and get lost if you arent careful when you lift the valve body off the IP. You dont want to mess with anything below the spring, bad things will happen.