Here’s how I cleaned my diesel injectors. You can pay a shop to do the job for you but it’s actually fairly easy to DIY. Injector cleaning is a job that doesn’t get done as often as it should (at least every 100,000 miles, maybe more often). If you have a problem with rough idle, smoking, poor fuel economy, etc., one of the things that you might want to try is to clean your injectors. Folks who experiment with alternative fuels (WVO, etc.) should clean their injectors more often. Anyone buying a car that has run WVO should ask when the injectors were last cleaned.

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This is one of the injectors from my 1987 300D Turbo (W124, OM603). My engine now has a #20 head with inclined injectors; the original #14 head had different injectors. Other diesel engines will have still other injectors but they will all be similar so that you can modify my instructions to fit your injectors. Some injectors have needles with holes in their tips; my injectors don’t have that so I don’t cover that part of the cleaning process. Diesel Giant has a good DIY on his site for OM617-type injectors. Warning: don’t swap parts between injectors.

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First, pull off the little return lines. Don’t cut them off; you could damage the little barb connectors and cause a leak. Next, disconnect the metal hard line at the injector. In most Mercedes engines this requires a 14 mm wrench. A crowfoot adapter for your socket set allows you to get at the connector without damaging anything. Once you have the line free at the injector, use a cord to gently tie the hard line just far enough out of the way so that you can remove the injector.

The injector has two flats on the top half of the body and a hex on the bottom. Do not put a wrench on the flats; you might cause the top half to come loose. This gets done in the next step but now is not the time. Use a deep 6-point 27 mm or 1-1/16 inch socket and make sure that it will clear the little barbs for the return lines and not damage them. Mercedes has a special socket for this but I found one at a local store that worked fine. Once you have broken the torque the injector should come out easily.

Now is a good time to fish the old heat shield (“crush washer”) out of the top of the prechamber and throw it away. You’ll need a new one for each injector. Stuff a rag in the hole where the injector came out so that dirt doesn’t get into the prechamber. If you put a rubber cap on the end of the hard line you won’t lose any fuel and the engine will be easier to start when you are finished.

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Now turn the injector upside down (a little fuel may leak out) and put it in a bench vice. Use sheet metal to pad the jaws of the vice so they don’t damage the injector.

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You can use either a wrench or a socket to separate the two halves of the injector. A torque wrench and socket will be needed to reassemble the halves. The wrench size is the same as used to remove the injector from the engine: 27 mm or 1-1/16 inch.

Once you have loosened the two halves (they are tight -- the torque spec is typically 70-80 NM or 55 foot-pounds) you should be able to unscrew the injector by hand. The good news here is that there is nothing inside to go “sproing” and send parts all over the garage. However, you should hold the injector horizontally over a box lid lined with a shop towel so that anything that might fall out is contained.

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The above picture shows the two halves. All of the bits and pieces are still inside. You may be able to tip the halves over and the pieces will fall out but if the injector is badly clogged with French fry grease then you may have to do a little prying. Each half has three pieces in it. The one that I found hardest to remove was the shim (like a small fat washer, it puts tension on the spring to set the pop pressure of the injector). It tends to stick in the top half of the injector.

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Here I have laid out in order the injector halves and all their internal pieces, before cleaning. This injector was actually pretty clean and really didn’t need cleaning but I had already decided to do all six. As expected, the shim was firmly stuck in the top half of the injector body. I left it there, knowing it would drop out in the acetone bath.

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To clean all of the parts of the injector, I used acetone, because that was what I had in my cabinet. You could also use carburetor cleaner, gasoline, or some other solvent. Be careful using any of these chemicals indoors; consider doing this part of the process outside. Wear rubber gloves and eye protection. Keep the chemicals away from kids, pets, and fire. I put the parts and the acetone in a beaker and put the beaker in a small ultrasonic cleaner with water. If you use a plastic container, make sure your chosen solvent won’t dissolve it. You don’t have to use ultrasonic but it saves a lot of time. If you don’t have an ultrasonic cleaner, put the container of parts and solvent into a pan of hot water. Cover the container so the solvent won’t evaporate. Go away for an hour. When you come back, the solvent and the ultrasonic should have removed all of the crud from the parts. Take the parts out of the solvent and rinse them in alcohol, then allow them to dry. Without ultrasonic, you may want to soak the parts overnight.

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My injectors each have four surfaces that must be lapped so that they will seal properly (there are no o-rings or other rubber parts in the injector). All of the parts are metal and the sealing is metal to metal. The picture above shows the surfaces that must be smooth: the top half of the injector body, the two sides of the “intermediate disk,” and the top of the nozzle. These surfaces are bare steel and will corrode if water gets in the fuel. Corrosion causes an imperfect seal and the injector then will leak.

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You can use a surface plate if you have one. I used 2000 grit wet/dry sandpaper made for fine finishing. I cut a small piece and taped it to a flat glass plate. A piece of window glass will be flat enough. Use a little diesel fuel as a lubricant and gently rub each surface around in circles on the sandpaper until it is clean and shiny. Rinse in alcohol and wipe dry.

The needle and nozzle need a little special attention. Use a brass wire brush to clean the tip of the needle. Be very careful not to damage the tip. The end of the nozzle will have some carbon on it from combustion in the prechamber. Any that doesn’t come off in the solvent can be gently scraped off with a razor blade. The inside of the nozzle (where the needle goes) may need a little scrubbing with a Q-tip and alcohol. When you are finished, dip the needle in filtered diesel fuel and put it in the nozzle. Once the fuel has wetted the surfaces, you should be able to lift the needle up a few millimeters and it will slide back into the nozzle under its own weight. If it sticks, clean it again.

Now you can reassemble the injector. The pieces, now clean, won’t stick together like they did before so be very careful handling them. Make sure everything is clean and lint-free, especially the four sealing surfaces. The spring and the shim can go in either way but all of the other parts must go in facing the same direction as when you took the injector apart. The metal “pressure pin” on the end of the spring is especially difficult to keep in place. Once each injector half has its three pieces, carefully bring the halves together and hand-tighten them. You should feel pressure as the spring begins to compress for the last couple of turns. Make sure the “pressure pin” doesn’t slip out of place and end up sideways.

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Put the injector back in the vice and tighten the two halves using your torque wrench. The spec for my injectors is 70-80 NM or about 55 foot-pounds. Now the injector is ready to go back into the engine with a new heat shield or crush washer. The picture above shows the right and wrong way to position the heat shield relative to the injector. Of course you put the heat shield in the hole and screw the injector in on top of it. I photographed them on the injector because it’s easier to see that way.

Torque the injector to spec (most are 70-80 NM but a note in FSM for the OM602/603 engine says that inclined injectors should be torqued to only 30 NM, about 22 foot-pounds). This lower spec for inclined injectors has been questioned by some readers and needs further investigation. The lower spec is apparently because inclined injectors screw into the prechamber itself rather than the locking ring. Caution is advised.

Now reattach the hard lines (torque spec 20-30 NM) and the little rubber jumpers. Start the engine and check for leaks. If you haven’t lost much of the fuel in the hard lines the engine should start with only a little more cranking than normal. You may need to tighten the hard lines a little more if they leak.

That's all there is to it -- nowhere near as hard as I had imagined.

Jeremy

Fantastic job.

Would this also apply to a 1999 606.962 E300 injector

Thank you
 

I've never taken the injectors of my 606 apart but I would think they would be very similar . . . longer and slimmer because of how they fit in the head but otherwise the inside bits should be pretty much the same.

Why is your engine so dirty?;)

Did you pop test them before you put them back on the motor?

Pop! goes the injector
 

They were tested for pop pressure and spray pattern when I bought the head that contained them. At that time (November) they were OK.

Nice set of pictures - thanks - I'm inspired.

Nice job, great pictures, covers the whole process very nicely. The only thing I'd add is that once the injectors are back together, they should be tested for opening pressure and spray pattern. Bosch certified shop in my town charges about $15 per injector for this service, will adjust them if required so that opening pressures fall within a 5 bar range.

Good suggestion
 

Good suggestion. My local shop (Santa Rosa Diesel) wants $45 each :eek: but that includes cleaning. I should ask them what they charge for only test/adjust. I had the injectors tested there when I bought the head and they did a quick check of pop pressure and spray pattern for free.

Cheapo injector cleaning.
 

I use the info here to clean the injectors and nozzles and the result is night and day. The 300D used to shake at idle real bad and I need almost full throttle to start it when cold. Also I need to start it a few times because the engine would not stay on. This is what I did and it makes a world of difference.

1) I do not know how long have the injectors been in service but the car has 340+K miles. I can see the flat surface of the nozzle is pitted so it must have in use for a while. I do not have a pop tester so I scratched a mark between the 2 halves before I disasmbled it.
2) Soaked them in gas and cleaned all the parts well. Use compress air to blow out all dirt and reassemble them. I did one injector at a time making sure all parts were put back in the same orientation, including the shim.
3) Re-torque the 2 halves and make sure the scratch mark aligned. By aligning the mark, I presume the pop pressure should be very close to what it was before.
4) Repeat for all injectors.
5) Reinstall and replace all heat shields.

The difference is amazing. The car now starts first time every time with a slight touch of the pedal, idles well and accelerates smoothly. I cannot compare what the car would be like with new and fully balance nozzles but all the rough start or shaking are gone. The bottom line is that I am very happy with the result at minimum costs.

Great pictures, but for someone to ONLY do this as DIY, IMO isnt the smartest. Popping and balancing should be done.

Would opening the injectors like this effect the pop pressure?

Joining in with everyone else -- great pictures. Based on my experience, paying attention to the lapping process is critical to prevent leaks. A table vise and a good torque wrench is a must. I got a manual pop-tester from Mercedes Source and it works pretty good. Two sets of injectors, and they all popped between 2050 - 2100 psi. Dis-assembly did not seem to affect pop pressure as long as the injector parts are not mixed.

It can, especially when cleaning and lapping are done, also. Plus, any work on the nozzles has the potential to disrupt the spray pattern, which is probably of greater concern than a minor change is pop pressure. It doesn't take much to turn a "sprayer" into a "streamer."

In my experience, the affects of disassembly are rather unpredictable from one injector to the next. Reinstalling them without testing is a total crap shoot. You can get away with it some of the time, but not all the time.

don't forget that when you lap the surfaces, you are removing metal. this will bring parts closer together, and it will change the pop pressure.
test the pressure before you disassemble, then again after lapping and reassemble, I bet it's different.

And that is almost never a bad thing.


Been there, done that. A few thousand times.

A typical "old" 135 bar injector will typically pop at 120-125 bar. After cleaning and lapping, you might get a 1-2 bar increase. In most cases, the "delta" is in the right direction, but lacking in magnitude.

Nice job Jeremy! We should get together in SR or Napa one day (or the Windsor PNP) Just picked up a '75 w115 300d (nice car for 300.00!) and also have an '84 euro spec wagon and of course my trusty high mileage still beautiful 300sd.

I have a pop tester and have done this job. The injector tips wear out with B100 and I can only imagine what SVO does.

With homebrew B100 or SVO I would clean them every 12K miles. I put in new Monark injector nozzles and saw a huge improvement.

WVO/SVO I can understand... But B100 made reasonably well should have superior lubricity.

In general, IMO its better to run blends anyway...

Nozzle erosion?
 

That is interesting -- commercial or homemade biodiesel? My '87 300D Turbo (W124, OM603) ran on commercial B100 for about 6,000 miles and since then (another 20,000 miles) commercial B20. I noticed no tip erosion when I removed the #14 head.

The nozzles in the #20 head I bought from Sixto were dirty due to the WVO he was experimentally mixing into pump diesel but there was no erosion that I could see, even under a microscope.

I would think that the water in under-dried biodiesel would be the big killer.

Jeremy

To the person marking halves and re-aligning them upon reassembly: old alignment doesn't matter nearly as much as torquing to the right spec. Pop pressure is not so much preserved by the closeness of original shell alignment, but by the spring + shim length w.r.t. inside chamber length.

As people mentioned, when you lap halves you shorten the (internal) spring chamber length, which has the effect of raising pop pressure.

And when you lap halves, any alignment marks made on the two halves are immediately rendered even more meaningless.

Torque to spec, check pop pressure, and adjust shims accordingly, repeat until spec pop is reached. Or, just slap 'em back together and hope they're better than before and if they are, great!

I think it bears repeating that a BRASS brush is used to clean the nozzle area so as not to scratch the metal.

Clarification required: Jeremy did you remove the nozzle pin from the nozzle, then scrub the end of the nozzle, or did you leave the pin in and scrub the lot? And did you do anything special (brass wire?) about cleaning the nozzle pin hole through the nozzle?

thx

Unless I completely misunderstood how the nozzles were made, I didn't find any holes in the injector nozzles of either set of OM603 injectors. (From the #14 head and from the #20 head, the injectors are different.) Even under a microscope the nozzle tips appeared to be solid metal. I did read about holes in the nozzles of OM61x injectors.

I think we need some pictures so we don't talk at cross-purposes. In the 6th picture of my OP, I show all the individual parts. I removed the "nozzle needle" from the "nozzle" and cleaned both, as well as all of the other parts, separately. That included carefully scraping the front surface of the nozzle with a razor blade (after removing the needle), to get the carbon that shows in pictures 3 and 4 off of the nozzle. As you say, it's important to use a brass (soft metal) brush so as not to damage the tips.

When I looked at the nozzle needle under a low-power (20X - 50X) binocular zoom microscope, I could see no holes in the needle. I admit to being somewhat confused because other threads talk about holes in the tip. I concluded that the other threads were talking about OM61x-family engines. Did I miss something?

Jeremy

You're right, let's use same terminology, I'll follow the picture in this thread.

What I meant was, when you take the nozzle needle out of the nozzle, do you plunge anything down inside of the empty nozzle with any cleaning action?

The hole I speak of is very visible to naked eye, it's where the tip of the nozzle needle goes through the nozzle. Do you attack that hole (from the outside) with any brushing action (needle removed) or running a wire through the hole?

That's what I meant to ask.

I get that you removed surface carbon on the face of the nozzle/injector, but it's what goes on in that very tiny region of the hole that matters most.

Clarification
 

OK, I understand now. I cleaned all of the parts for several hours in acetone using an ultrasonic bath (parts in cup with acetone, cup standing in water in the ultrasonic bath). I scraped the carbon off of the face of the nozzle. I didn't do anything special to the hole in the nozzle where the needle seats, didn't even think about it. Should I have? (My first experience with injectors, BTW.) Whatever you stick into that hole has to be carefully chosen so that it removes crud/carbon/whatever with zero risk of enlarging the hole.

Jeremy

There are tools specifically designed to do that job.

Would you mind sharing it with the forum?

That is a lot like asking your dentist if you could borrow his drill so you could fill your own cavity. There is a lot more involved than just having the right tool.

Great write-up Jeremy. I am definitely going to do this on my 84 300D. My impression in the past has been that there are special skills and tools involved. There certaily are some skills here, but I can handle it.

Are those your hands holding the injector or is that a professional model? There is no dirt. Not even under the fingernails. :confused:

Richard

Oh sorry, I mis-read your post. What you meant was ??

"There are special skill and tools specifically designed to do that job"

My hands
 

I wear rubber gloves for the dirty work. Must have removed them for the photos.

Your '84 300D will have different injectors but the pieces should all be similar and likewise the techniques.

Jeremy

I meant to ask my dentist that the other day...


c'mon this is a DIY forum!

We live dangerously here by attempting our own fixes. Live and die by them.

Risk a little and share the secret sauce of what you know about these tools, and what to do with them, that is, if you know. Otherwise maybe point us to your dentist.

The problem, Scott, is not the I don't know anything about injector tools. The problem is that the Bacharach tools that I have are a bit "vintage" and are no longer available through normal sales channels. So I don't know how or where the typical DIY'er would obtain them. And for those DIY'ers just interested in fixing up a set or two of injectors, new nozzles are likely a more cost-effective approach than spending money on a nozzle cleaning kit. Even then, you are absolutely stabbing in the dark without a nozzle tester.

Special skill, special tools, stabbing in the dark ??
 

As a die-hard DIYer, I will try everything, anything to get things fixed without resorting to anything special. Improvisation is the name of the game, not so much I cannot afford them but adventure is fun. I hack Kilma relay, convert A/C, design electronic circuit and improvise. I am admit I am not good with engine or tranny. I will try anything as long as I do not put myself or other road users at risk. This forum has a wealth of info, all about DIY and there is no 'Special' about it. Just look at the ingenious methods some members came up to fabricate tools to get things done. That said, there are special MBZ tools that are needed but IMO not with injectors. Any backyard mechanic can service an injectors with ( may be without ) a pop tester.

We do not need a dentist with special drill bits.:eek:

That's great to hear. Now I don't have to feel bad about not sharing my tools!

In any case, ah-kay, I will help you. If you will send me the injectors that you have "serviced" yourself, I will be happy to test them for you. Let's put your theory to the test.

I will bookmark this thread and take up your offer.:D

The injectors I opened up and re-aligned afterwards are in use now. Actually, they are on their way to SFO to pick up my daughter returning from Machu Pichu, Puru in the 300D. They seems to perform OK, they HAVE to, as it is doing a 500 mile trip and the car will be left in Santa Cruz.

Homebrew B100
 

I like B100 better than diesel, but not even the factory-made B100 around here is ASTM tested. The homebrew stuff probably has free fatty acids, some methanol, a little water, glycerin, glycerides, and who knows what else in it.

From my first-hand experience homebrew B100 will eat your injector tips.

As for higher lubricity of biodiesel, some of it comes from the impurities.

B100 that has been distilled (colorless) will oxidize fast with no added antioxidants, all B100 will grow bacteria without the addition of biocide.

Degraded B100 will eat your injector tips.

When running B100 I always have spare fuel filters in the trunk.

I couldn't see the wear on the injector tips (just carbon), but when I pop tested them the spray pattern was ugly compared to my new Monark injectors.

I soaked my completely disassembled old injectors in carb cleaner and cleaned them with the brass brush and a little brass pick. Pop testing / balancing before installation.

Not a hard job
 

Rebuilding injectors with new tips and and re-balancing is an easy job. If changing the oil is a 1, and rebuilding your turbo is an 8, this would be a 2. Having a pop tester and a box of shims is key.

It's also not what this thread is about.

Balancing your tires is easy, too. All you need is a dynamic balancing machine and a box of wheel weights.

Rebuilding is easy, done that. I have a pop tester.

Cleaning is what I was asking about.

I have read the thread about making a pop tester and I may do that. Where does one obtain a set of shims. I recall reading a thread that discussed the difficulty of finding a source for these.

Richard

As long as we are talking about dentistry, I was wondering if a piece of dental floss through the hole would be effective in cleaning it? I would think that the unwaxxed stuff would work best to keep from leaving any wax in the hole.

Richard

Would that be the hole in the nozzle or the hole in the needle valve?

Either way, the answer is no. In the case of the nozzle, it's the valve seat that needs cleaning; the tool for that is a brass scraper machined to match the angle of the seat. The needle valve hole is usually cleaned with an appropriately-sized fine wire.

Not only are shims hard to find, buying a set isn't exactly cost effective at the single car DIY level.

PNP could be a source for the shims. I see a lot of diesel engines getting scrapped along with their injectors.

Charlie

Don't forget you can also sand down the spring to lower pop pressure.

Dental floss? What are you thinking?:eek: How are you gonna thread that in the small hole? A brass wire of the correct diameter is the tool to use.

Thinking outside the box.:cool:

If I had a brass wire of the correct diameter, I could push it through. :P

Richard

It is not rocket science.
 

Cleaning Injector and nozzle is well within the realm of DIYers. If you have access to a pop tester then you can calibrate it accurately. I do not, so I mark it and realign it to what it was or very close to it.

My observations:

1) Scraping the nozzle with wooden or plastic sticks will not damage the nozzle. It is made of stainless steel. You need to poke it million of times to see any noticeable damages.
2) I soaked it in solvent and blew all the hole with compress air to dry.
3) You can sand it with fine grade sand paper but it may not be necessary, a cloth would wipe most dirt off.
4) The injector are held together by metal to metal contact. So there is a limit on how tight you can 'tighten' it. What I find is that the original marking is almost as tight as you can do it.
5) All the injectors I opened up have only ONE shim inside. I did not measure the thickness.
6) The spring will be weaken over time so the pop pressure may vary but can only go down. This thread's title is about 'Cleaning' DIY, not recalibration DIY. If you put it back to the same marking then the pop pressure will be close to what it was. If the spring is weaken then pop pressure will stay low.
7) I have not done it myself but you can buy feeler gauge and cut it to shim size to adjust the pop pressure. It comes in many increments so you have a lot to play with and is cheap.
8) Sanding down the spring is to lower the pressure. I would not recommend it. The spring is weaken already so shimming is the only way to increase it.

My next project is to build a pop testers but it is way down on my list. My $0.02