I don't want to start a war about the ethics of this, I am just presenting what I have learned, if others want to try.

Sometimes it seem like these cars are forgoten about with most working on the W123's and early turbo W124's. But our engine seems particulary venerable to soot and crud blocking the intake manifold. Also non-turbos do not have as much HP and any performance benefit is welcome.

There are 3 parts to our EGR system.
1. The EGR valve it self and it's attachment to the intake
2. This model has a baffle in the intake, This baffle moves by vacume linkages to draw fresh air from the air box or exhaust gasses from the EGR (or a combination of the two)
3. There is a mechanical linkage that attaches from this baffle to the throtle linkage and helps hold the valve open under wide open throtle.

So what do we want, the EGR to remain closed. If we just plug the vacume line to the EGR it will not open, but because of the baffle we will still try and draw air from it, restricting airflow and hurting power.

I have worked out a way to make it all work, and it can be changed back in 5 minutes if you need to get an inspection

First block the EGR vacume line (the line going into the top of the EGR valve) with what ever fits. I used a bolt with the head cut off and shoved it into the line and then reconnected it to the EGR so it looks stock.

Next disconnect the rail that connects the baffle and the throtle, in a moment you will see why.

Next pop off the vacume regulator connection to the baffle, it will just sit there and move during operation but not affect the baffle.

Now I used some safety wire and fixed the baffle in the fully open position. Since the EGR will not open and the other mechanical methods of baffle movement are removed the engine always gets fresh air from the airbox.

I have included some pictures. I have noticed that the car has more pep under part throtle operation and does not have to downshift as often to accelerate or mantain speed on grades. I think it will make more difference once I remove my manifold and clean out all the crud that has built up. I think this may also work for the 98-99 turbo models but it may throw an error code because your engines have more electronic feedback.

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Karl B
95 E300 D
2006 Mazdaspeed 6
2001 GMC Yukon XL
1997 Contour SVT
Mazda RX-7 SCCA race car

There is a more simple removal method available for the non-turbo 606. Put a block plate over the exhaust port and stick a small filter on the end of the EGR (Or cut a hole into the clean side of the air filter housing and run a tube into there before the MAF sensor.)

It will put them into limp mode if any of the EGR parts aren't working. Something is needed to fool the MAF into seeing a reduction in airflow when the EGR is actuated.

The idea is to make it simple, and to be able to reverse it to stock. It is difficult to block off the EGR and to cut the tube to put on a small air cleaner. This technique works, is simple, and can be reversed in 2 minutes.

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Karl B
95 E300 D
2006 Mazdaspeed 6
2001 GMC Yukon XL
1997 Contour SVT
Mazda RX-7 SCCA race car

I saw this by chance and it sounds like it might be a better alternative to plugging the exauhst and adding the small filter to the EGR intake. This way the engine is getting a FULL supply of fresh clean air through the big intake throat ALL the time vs. a combo of clean air-box air & clean air through the small restrictive EGR port...

Racekar - Any update on how's this working out for you up to now?

That's if you have the MAF. Turbo models do. Mine does not.

After I plugged the EGR ('96 E300D), I seem to remember checking that flap and seeing that it is wide open with no vacuum, so I just put a BB in the vacuum line. But to be sure, I'll check when the wife brings the car home today.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I have been using it since I posted the thread. Works fine, I just changed my glow plugs and cleaned out the intake so when I check in 6 months the intake should be clean if this mod works. So far everything seens fine. I think that others have stated that it only works for 95-97 models.

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Karl B
95 E300 D
2006 Mazdaspeed 6
2001 GMC Yukon XL
1997 Contour SVT
Mazda RX-7 SCCA race car

Won't work on the turbo models - we've been around that tree before:

99 E300 Crankcase Vent

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Rick Miley
2014 Tesla Model S
2018 Tesla Model 3
2017 Nissan LEAF
Former MB: 99 E300, 86 190E 2.3, 87 300E, 80 240D, 82 204D Euro
Chain Elongation References

When I disconnected the EGR and cleaned out the pipes, I was flabbergasted at the amount of crud in there after only 250,000 miles and three POs. All that diesel soot had actually blocked the crankcase breather ports on cylinder #6. All of the intakes were blocked to some extent. Hopefully the last time I do that clean-out job.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

After replacing the #3 glow plug (an easy job, required removal of the crossover pipe only, the old glow plug came right out, no carbon deposits on the tip at all) I checked on the flap next to the EGR valve. Apparently I had thought it was part of the resonance flap mechanism and left it operational -- how wrong I was! Thanks, Racekar.

I "turned off" that flap by putting a BB in the vacuum line to its controlling solenoid, down under the main air pipe from the filter box. That way, the entire mechanism remains intact and looks stock, it just doesn't do anything. (I would have blocked the line at the flap itself but the rubber hose there is larger and my BB fit the small Y-connector better.) Going back to stock would require only removal of the BB.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I assume this "flap" that is being referred to is the one in the air intake? I plugged my EGR vacuum line and was looking at wire-tying the flap open but didnt know if it had any negative side effects.

I had the IM off to put a new wiring harness and GPs in. There was A LOT of soot especially on the first 2 cylinders- the CCV ports were completely blocked off on those. I suspect this may be a problem with the injectors and will have them pop tested in the near future.

To clean the IM and EGR assembly I soaked them in biodiesel for 2 days and scrubbed them as far as I could get into (I removed the 2 valves with vacuum assemblies first)

To clean the intake ports on the head I made sure the valves were closed for each cylinder by rotating the head- and used a wire pipe cleaner and then vacuumed out the port with a small hose. One port was 1/3 blocked with crud.

I started it up late last night and boy did it smoke! I plan on taking it out tonite and doing a good highway burn. I'm excited at the prospect of it running better now that its all cleaned out.

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1995 E300 diesel

Apparently none of these methods work on the '97. The '97 has different vacuum setup than the '95-'96. Blocking the hose that controls the EGR flap causes a CEL. Blocking the hose to the EGR causes a CEL. Installing a blocking plate between the EGR and the intake causes a CEL. Wire tying the flap open causes a CEL. Stupid computers.

Only option is to block off EGR at the exhaust manifold, then install a little air cleaner onto the egr valve itself.

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'98 E300 turbodiesel

This is one of the reasons I bought a 95! My car runs awesome now that it breathes easier, and I'd bet a dollar the emissions are far less running B100. Of course I'll never know because we don't have diesel emission testing here in PA....

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1995 E300 diesel

Yeah I should have done this EGR mod sooner. What a stupid concept this whole EGR thing. Introducing particulate matter into the intake, what's the point of the air filter if you're just going to foul the clean air anyways?

In VA we have emissions for diesel cars '97 and newer, but it consists only of an OBD2 readiness check. It's purely an OBD2 test; no codes, you pass! They don't actually test what's coming out of the tail pipe.

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'98 E300 turbodiesel

Completed my EGR mod tonight, thanks to some photos in an old thread (that I can't find now) by 97E300D.

I cut the EGR pipe in half (dremel with diamond cutting wheel), and on the exhaust side, flattened it in a bench vise and folded the flattened end over several times, like a toothpaste tube.

On the intake side, I first washed that half to get all the metal dust out from cutting it. I then attached a small filter from Autozone. It was only about $14 and looks to be surprisingly well constructed. I connected it to the intake half of the EGR pipe using a short section of 1 1/4" clear vinyl tubing from the hardware store, and two hose clamps.

The vinyl tubing has a VERY thick wall and is quite stiff. It fit snugly over the steel egr pipe and also over the filter without the clamps, but due to engine vibration, the clamps are necessary. I don't know how well the vinyl will hold up to the heat, but I'll keep an eye on it. Some 1 1/4" coolant hose is probably a better choice.

Here it is:

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'98 E300 turbodiesel