So, I finally took the plunge, and decided to tackle new (Monark) injector nozzles for my OM602 (1992 300D 2.5 Turbo). A few questions and observations:

1) Maybe it's placebo, but the Diesel Purge actually seems like it helps. Engine seemed to idle a little bit smoother afterwards, and pull a little bit harder. Of course, it's not going to make worn injector nozzles like new again, but I can see it being a worthwhile thing to do going forward, once or twice a year.

2) The spin-on fuel filter is a pain in the ass! I mean, it's held in by one bolt, but trying to maneuver the old one out and the new one in is super frustrating, and seems to a guaranteed fuel spill. Why didn't the engineers design enough clearance for this thing? There doesn't seem to be any elegant way to do the R&R.

3) WTF didn't I remove the crossover pipe FIRST? If I had known how easy it was, I surely would have. Instead, I waited until I got every single injector out, except for #3, at which point I gave in and admitted that the pipe MUST be removed. Sure would've made removing the hard lines a lot easier, not to mention the return lines and every single other injector. Oh well.

4) Speaking of the crossover pipe, can I reuse the gasket, or do I need a new one? Do I need any kind of gasket paste? Should I do anything else while I have the pipe off? It's filthy inside.

5) My injector bodies are heinous and covered in surface rust. Can't wait to see what the insides look like. Heat shields are caked with carbon - no biggie, they're being replaced. But what about the prechamber, where the injectors thread into? Plenty of carbon and rust down ther as well. I tried my best to clean it out, with a bunch of Q-tips soaked in brake cleaner, but there's just no way it's going to be spotless. Is that okay?

No just need to bench test these suckers, then disassemble and soak in Chem-Dip overnight. Then beer!

1) purge is a good thing on these engines
2) you have a good 1/4 of an inch wiggle room. I remove bolt draw some diesel out through the bolt hole remove. Insert filter dry use a wedge under and a funnel through the bolt hole to refill. Bolt in your done no spills.
3) hummmm what can be said
4) if your gasket looks good reuse it no sealer required. I soak the cross over in diesel to remove the coke works good over night.
5) soak a rag in brake cleaner use a wooden stick it will clean up.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

Diesel Purge can and does make a difference if the things it resolves impact performance. If the system has never had it run through, it DOES get rid of varnish and buildup in the injection pump and DOES make a difference in power and operational smoothness.

The spin-on fuel filter is seriously a pain. I share your opinion of it 100%. There are plenty of other places they could have mounted the thing or moved something else to give clearance to get the damn thing out without spilling it everywhere.

I've reused the crossover pipe gasket more than once. As long as it isn't in horrible condition, you can likely reuse it without issue. If you think the crossover pipe is bad, you should see the rest of your manifold. If the EGR system is functioning, you've likely got a HEAVY buildup of carbon in the intake runners. If you pulled the manifold, you'd probably be surprised the engine runs as well as it does!

The outside of the injectors isn't that important. It's what's inside that matters. Ao long as they're clean inside and free of rust and corrosion, you're good reusing them. Make sure you have the sandpaper and glass handy to lap the mating surfaces or expect leaks.

A really good "solvent" to get rid of the carbon cake is gun solvent. It's sole purpose is to dissolve carbon, oil, and lead remnants. Soak a Q-tip and rub, it should just melt off. Clean up afterwards with your favorite spray solvent.

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Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

In case anyone is looking for a write up in addition to the above good info on injector rebuilding/replacing, take a look at the link below. If you have any additional questions, feel free to post a Comment just below the article and we'll do our best to give you specifics.

Mercedes-Benz W124 Fuel Injector Replacement | 1986-1995 E-Class | Pelican Parts DIY Maintenance Article


-Dmitry

Don't get too concerned about it, and do not try to clean inside the pre-chamber. Focus on the surface that the heat shield seals against, that's all you really need to worry about.

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Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC