I disabled the EGR on my OM611 car (same engine, only 4 cylinders) and it took ages to get warm from a cold start, and the MPGS actually went down.

I can believe that. I have read that the EGR system on the CDIs assists in warming the engine to operating temp. I note my CDI has reduced MPG during the warm up process according to the on board computer. Anything that would make the process longer, like lack of an EGR valve, would cut into fuel mileage.

__________________
-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991

While I'm not generally a fan of additives, I decided to continue the Opti-lube regimen (boosts cetane and lubricity) that the PO used for the last 100k miles. It's cheap, it can only help, and one of the ways I suspect it will help is cleaner intake, EGR, etc....

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 159k miles
06 E320 CDI "Rutherford", Black on Tan, 179k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 145k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 77k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

I cleaned the EGR when I got my CDI just because I'd read about it getting dirty and did a lot of "new to me car preventative maintenance." The car performed noticeably better.

My understanding however is the EGR cooler also gets clogged up, and just cleaning the valve obviously isn't cleaning the cooler out. I like to think my daily full boost trips to the redline in a gear or two is working to keep the EGR cooler blown out. I've read of people pulling the cooler and manually cleaning it but it is much more labor intensive.

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68 280SL - 70 280SL - 70 300SEL 3.5 - 72 350SL - 72 280SEL 4.5 - 72 220 - 72 220D - 73 450SL - 84 230GE - 87 200TD - 90 190E 2.0 - 03 G500

Nissan GTR - Nissan Skyline GTS25T - Toyota GTFour - Rover Mini - Toyota Land Cruiser HJ60 - Cadillac Eldorado - BMW E30 - BMW 135i

My 06 CDI is still in transit, when it gets here I plan on doing the

EGR Delete here

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1999 Mercedes E300TD daily driver sold at 238K miles 106K miles were mine, rust worm got it :-(
2006 Mercedes CDI new daily driver! 56,000 miles May 2016 now 85,625 Apr 2018 and Apr 2019 101,000 miles Apr 2020 109,875. March 2024 135,250, Dec 2024 145,000 miles

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'06 E320 CDI
'17 Corvette Stingray Vert

After 28k miles since my first cleaning, my EGR valve began causing my '05 E320 CDI to go into limp mode again. No codes on dash. After removing the EGR valve, I noted it was again full of dry carbon powder.

This time I just used a small toothbrush and some compressed air and was able to clean it completely this way. Instead of graphite, I applied a few drops of Mobil 1 5w 30 to a q-tip and lubricated the armature under the plastic cover of the valve until it sprung closed. It now is operating correctly again.

It will be interesting to see if the carbon mixes with the oil and stops the arm again.

I think that the EGR does not have to actually be removed. You can simply remove the plastic cover and vacuum the powder out and then lubricate the armature and replace cover.

I will admit I have not looked at the EGR valve since I cleaned it the first time at about 103k miles. But given not having to remove the entire unit, I will begin inspecting at every oil change.

__________________
-- Chris

'95 E300, 216k miles, Silver Surfer
'05 E320 CDI, 138k miles
'07 S550 4matic, 69k miles

Gone but not forgotten:

'76 300D, 350k miles?, SOLD in 1995
'75 240D, 300k miles, SOLD in 1991