Cleaned EGR Tube - PeachParts Mercedes-Benz Forum

sunedog · #1 01-23-2008, 11:00 AM

99 ML 320 with 207,000 miles. Had a CEL (P0400 code) for a couple of weeks. I took off my EGR tube and cleaned it out. It was solidly packed with black greasy gunk. There have been several threads on the subject, but none that really summed it up for me. Here was my experience:

I removed the air filter box lid, unscrewed the bolt holding the air filter snorkle to the engine and tried to open the funny looking arrow connector holding the snorkel in the back near the firewall. I tried pressng with fingertips and tugging and then resorted to prying with a screwdriver. It was 40 degrees at the time and the plastic broke. Oh well. Can't say I didn't expect it. Anyway, this allowed me to move the snorkel out of the way. It was only attached at this point by the wire to the MAF.

Used a 3/8" ratchet with a 2" extension and a socket (10mm?) to remove the two Torx bolts connecting the flange of the EGR tube to the rear of the intake manifold.

Used a small (about 8") Crescent wrench to loosen the large nut holding the other end of the EGR tube to the EGR valve. Then I could maneuver the EGR tube out of the rear of the intake manifold.

Went to the bench and was able to clean out the tube relatively easliy. The greasy crud was not very hard. I used a screwdriver and coat hanger to clean it out.

Tried at this point to remove the actual EGR valve. I was able to get the rear bolt out but could not get a socket securely on the front bolt because it is directly below the connector for a fuel injector and a rigid metal tube (which I think is a fuel rail). I tried with a universal adaptor and with a wobble adadptor but I couldn't get a bite on the Torx bolt and didn't want to risk rounding the corners over. Maybe a 12 point socket would work. I also tried to disconnect the connector to the fuel injector, but couldn't figure out which part of the connector to squeeze and which to pull on.

Any tips on removing this front bolt would be appreciated (for future reference).

I gave up and decided I would reinstall the tube, get the P0400 code cleared and see if the EGR tube was the only problem. I put everything back together and the snorkle seems reasonably securely positioned even with the broken arrow connector.

So far, so good. No CEL light and we'vew driven the truck 4 days since I cleared the code.

One other question: When I removed the EGR tube, I discovered a rubber connector directly below the intake manifold end of the EGR tube flange. This rubber connector had two tubes running into it and it seated in the intake manifold. One of the two tubes was disconnected. Don't know if I did that monkeying around with the EGR tube or whether it was already loose. What is that thing and could it have caused my P0400 code?

fingersandclaws · #2 01-23-2008, 05:05 PM

I just did mine today . . . needed to PB Blast the nut, was on there tight.

The gunk in my tube was rock hard. If it were an artery, it was 100% clogged!!! Took about 20 minutes to get all the crap out . . . used a coat hanger, to a screwdriver, to paper towels, WD-40, water, more WD-40 etc. Don't know what it does but seems like a blocked tube in your car is real bad!!!

sunedog · #3 01-31-2008, 10:20 PM

Finally downloaded this image. Here's what mine looked like before cleaning.

kwmccauley · #4 02-02-2008, 06:54 PM

The photo posted above looks just like the blockage in my 1998 ML320's EGR tube. I removed, cleaned and replaced mine today. The check engine light went out (after three engine starts and not detecting the fault). Mileage is at 190,500.
Thanks for the detail in this thread. It was a big help and good supplement to the WIS info.
Ken

v00ml430 · #5 06-25-2008, 10:30 AM

I have the P0400 code and want to clean the EGR tube (00 ML430). After I removed, engine cover, I removed the air filter box, MAF sensor, damper. I could not remove the remaining air intake pipe. I could disconnect it from the engine, but there is not enough room to take it out no matter how I twist it.

Did anyone remove and clean the EGR tube on a V8? Do I have to remove the coolant tank in order to have more room? Thank you.

Gene Horr · #6 06-25-2008, 11:22 AM

Removing the coolant resevoir is a great help. Be sure and either drain it into bucket or seal the bottom hose in order to save the coolant/prevent a mess.

kwmccauley · #7 06-25-2008, 12:10 PM

Please send me an e-mail and I will reply with two .PDF files that may be helpful. File sizes exceed the limits of this forum.
Ken

v00ml430 · #8 06-25-2008, 12:19 PM

Ken, I just sent you a PM. Thank YOU for all your help.

v00ml430 · #9 07-02-2008, 10:49 AM

Well, I cleaned the EGR tube but unfortunately the P0400 code come back. I actually have a set of 5 codes. The codes are: P0400, P0135, P055, P0161, P0141. The last four are related to O2 heater circuit. All O2s sensors are new and replaced when the cats were replaced about 3 month ago. Since I have 100K I also replaced the spark plugs. MAF sensor was replaced about 1 year ago due to P0170 and P0173 codes. The car runs smooth, no vibration, no other problems. Any idea why or what could trigger these codes?

Edit: 2000 ML430 about 105,000mi

lkchris · #10 07-02-2008, 11:57 AM

EGR system on M112/3 features an electric motor, and failure of this motor is often cause of the PO400 code.

v00ml430 · #11 07-02-2008, 12:29 PM

Thank you Kent. Any chance that you might have a part number and more details on its location? I took a look on the emmision system part list and did not see it. I noticed a pump air but could not find a motor.
Val

lkchris · #12 07-03-2008, 12:42 PM

The pump is an electric pump.

Wizo · #13 07-05-2008, 02:05 AM

sunedog

Could we get a pic of the EGR tube location?

74Stylez · #14 07-07-2008, 06:26 PM

I performed this service on Friday following Sunedog's post as well as with a lot of help from the PDF files from kwmccauley.

When I finished my EGR tube was whislte-clean, but I continue to get the P400 code! I was told by a Benz-mechanic that after he cleaned the tube if the Check Engine light came on again I would need to replace the EGR valve to solve the problem. Before I go there myself, is there anymore advice? Thanks in advance!

sunedog · #15 07-08-2008, 09:00 AM

Quote:

Originally Posted by Wizo

sunedog

Could we get a pic of the EGR tube location?

Located close to the firewell directly under the coolant resovoir. You have to take the plastic engine cover off to see it. It's the yellow plated metal tube with the accordian like rings around it.