Mercedes-Benz Forum banner
1 - 20 of 58 Posts

·
Registered
Black 2005 ML 500
Joined
·
1,662 Posts
Discussion Starter · #1 · (Edited)
So I just changed my second EGR valve at 100K miles. I am adding some photos and comments that may help some people who are changing their EGR valves/tubes.

First, amazingly my original EGR metal pipe was not clogged at all (Maybe Shell gasoline really keeps it clean..?) . Last time I changed my EGR valve, only, and not the EGE metal pipe.

One thing I learned is that the EGR metal pipe does no come with the compression washer and nut (that nut is > 22 mm), so you need to make sure you get it. I had to destroy my old EGR pipe to get the compression washer and nut since today is Sunday and the dealer is closed.

Always make sure your hose connections, near the EGR valve, are correctly connected and that the hoses are going through the right spaces. If they are not going to the right spaces, they may pop or come loose.

If the latter hoses pop out, then your ML will start and then die immediately or have a very rough idle. Even though, I was careful to connect the hoses, I did not route the hoses through the right spaces and the hose will easily pop out and my ML will start up and die immediately. Later, the idle was bad because the hose barely become loose again since I did not route the hose correctly.




=====================================================================================
ORIGINAL POST: AC_ML; 12-21-2008 at 12:09 PM

Finally I went ahead and changed my EGR valve today..

I took my ML for a routine maintainance and for the engine mounts to be changed, and the next morning I had an engine light P0400 which meant an EGR valve malfunction. It is interesting to note that when I checked my EGR valve, the nut securing the EGR tube to the valve was completely loose...!!!

Overall it took me about hour and a half and at an easy pace. It is a lot easier to change it once you understand what needs to be done. I had already removed many of the components a week or so ago, so I already new what was needed.

Don't have pictures, but these detailed words may be helpful too..

Instructions:

1.- Remove the engine protection plastic cover. Make sure your vehicle is cold and that there is no pressure on your radiator. Loosen the radiator overflow container cap to make sure any pressure is released. Then place it back in place and tighten.

2.- Loosen the fasteners to the air filter box and loosen the air box.

3.- Loosen the ring that secures the air tube/duct to the MAF and air filter assemblies. Remove the MAF electrical connector.

4.- Remove the MAF and air filter assemblies. Put a plastic bag cover on top of the air filter so that no dirt will accumulate on it.

6.- Remove the radiator container's overflow tube from the securing plastic holder. Do the same on the other side because you will want to relocate the radiator overflow container but can't be done correctly if your tubes are still on the the plastic holders.

7.- Remove the two nuts supporting the radiator overflow container, but do not remove the container all the way out yet. Leave it hanging. Though pull the container out for a second, in order to remove the electrical plug from the fluid sensor. Then place the container back into the supporting screws.

8.- Remove the radiator fluid into some other container so that when you put the container sideways, it will not leak too much liquid.

9.- With pliers that have wide sides, press the lock on the tube under the radiator container and slided back so that you can pull the tube out.

10.- Once the tube lock is out, slide the tube out and place the radiator container quickly on its side (try to put the removed tube high so that it will not drip fluid), to the right, so that it will not drip fluid. The connector where we removed the tube will be now on the top since we turn the container to it's side so that it will not drip too much. Don't worry if some liquid spills, it should be minimum.

The main goal here is to move away the radiator container to one side so that we can have access to the EGR area. By turning the container to the side, we do not need to remove all the other container connections and there will be little spill.

11.- There is a small black plastic container attached to the air tube going to the engine. It is not bolted and you can just push out the hose connecting to the air duct and remove it.

12.- There is one star bolt securing the air duck on the right side of the engine (on the side of the battery..). You need to remove this bolt which secures the duct.

You can use a plain socket that fits tightly into the star bold to remove them. I used an adapter, too, in order to use a larger wrench so that I can have more torque when loosening the bolts.

13.- Slide your hand down the air dcut all the way where it goes inside the engine. There is a tube that attaches to this duct. You need to loosen it.

14.- Now the only thing securing the tube is a plastic lock that connects to the aluminum engine. You will need to pull carefully the whole assembly back so that the duct will pop from the engine and from the securing plastic lock.

15. Once it pops out, you can manuever the duct all the way out.

16.- Be very careful because there is another plastic tube close to the air duct plastic lock that can pop out. You may want to spend some time making sure where are all the hoses connecting around, just in case.

17.- Once the engine air duct is out, you have complete access to the egr valve.

18. Look at your brand new EGR valve part and check how everything connects. This will help you understand how the old part will come out.

19.- Unscrew the big nut holding the EGR metal tube that goes to the engine.

20.- Once you pop out the tube and move it a little bit out of the way, you can remove the electrical EGR connector and then have access to the two bolts securing the EGR valve.

21.- This bolts are difference in size (bigger) than the one that was supporting the air duct.

22.- Loosen the two bolts that secure the EGR valve using a rachet and an extension to make it easier..

23.- WARNING: THERE IS A METAL GASKET THAT GOES BETWEEN THE EGR VALVE AND THE ENGINE. BE CAREFULL NOT TO LOSE IT WHEN YOU REMOVE THE EGR VALVE.

24.- Clean the metal gasket or replace it if you have bought a new one.

25.- Remove one plastic tube that connects the EGR valve to the engine.

26.- Now you can remove the EGR valve making sure not to lose the metal gasket,

27.- Clean out all the sorroundings and make sure everything looks fine.

28.- I did not take my EGR metal tube out, but this is the time to do it if you are going to clean it.

29.- Resintall everything in reverse order.

30.- For me I put the two screws on the EGR valve and slided the EGR gasket into position in between the screws. So the two screws are vertically down on the holes of the EGR valve and I am holding the gasket in place with my fingers.

31.- Now carefully position the EGR valve (holding the gasket in place) in the engine position. Still holding the gasket with your fingers, align the screws into the engine screw holes and once both are aligned, screw them carefully by hand a little bit so that they are in place. This is the only way I was sucessful on making sure the gasket installed correctly without moving out of place.

32.- Install back every thing back and make sure you do not forget to connect any of the hoses. Make sure you connect the hoses to the plastic holders, too. Otherwise, the hoses will move around and can touch engine parts and get damage or burn.

33.- Use your OBDII to reset the engine codes.

34.- If you have a good OBDII scanner, you can drive you vehicle around until you can see the EGR tests pass. This may take some riding and turning the engine off and on a couple of cycles during the riding around.

35.- In my case, I did not clean the EGR tube, which means that if I still have a problem, then I will need to go ahead and clean it. I did not do it since my ML only has 69,000 miles and I use a guided wire into the egr valve and could not get any traces of gunk or obstruction, so I decided to run the risk.

I put a thick towel on top of the engine to make it more comfortable to work laying somewhat on top of it. I had a stool so that I can easily reach the rear of the engine from the front of the vehicle.


Hope this note helps other owners too...

Regards,

AC
 

Attachments

·
Registered
'07 C280 4matic, '06 530i, '98 ML320
Joined
·
1,562 Posts
Overall, good write-up. It's just a little difficult to reach the area. Other than that, not bad of a job for DIY.

In step 12, the bolt is actually on the RIGHT side of the engine (however, you clarified by stating that the bolt is on the battery side. Battery side is RIGHT side of engine).

In step 24, you were reusing the old metal gasket. It is always recommeded that we replace all gaskets. This will ensure a snug fit. You don't want to have to remove the whole thing just for replacing the gasket some other time.
 

·
Registered
Dallas, Texas
Joined
·
12,198 Posts
Good writeup but poor diagnostics. Code P0400 is most of the time triggered by blocked or restricted tube. Tube gets clogged by product of crankcase ventilation. There are two ways to check EGR for function. Use component activation function of SDS or home method of vacuum pump connected to EGR valve. With 10 inches of vacuum idling engine needs to stall almost instantly.
 

Attachments

·
Registered
Black 2005 ML 500
Joined
·
1,662 Posts
Discussion Starter · #4 · (Edited)
Thanks, I edited #12 to show it is on the right side of the engine..

When I got home, after buying the EGR valve, I realized at that time that the box did not contained any gasket and that I had not asked to see if there was a need for one.. My fault..

On the EGR tube.. I slided, into the EGR tube, a thin snake wire all the way in and did not get any hints of clogging or carbon and/or gunk deposits.

From other posts I know that the EGR tube can be somewhat hard to remove (I have not try it yet), but now that I know how to easy is to remove the components in order to access the EGR area, it becomes very easy to later do the EGR tube..

I wonder if the dealer removes the EGR tube and clean it as part of the $600.00 changed for changing the EGR valve.. When they quoted me the $600.00, it did not sound like it was included..

Though it is true that maybe the first thing to perform is an EGR tube clean, before buying the EGR valve/gasket, and then reset the error codes and check if the P0400 error code comes back...

Thanks everybody for all the owner notes on the EGR valve/tube replacement/cleaning and on the EGR testing and working notes. The EGR valve replacement is really a DIY. The only issue is the somewhat awkward access to the area, but if you lay kind of on top of the engine, it becomes easier. If you put a couple of pillows on top, it will be even more comfortable... :D


AC
 

·
Registered
Dallas, Texas
Joined
·
12,198 Posts
Have you tried to check EGR function by applying 10 inches of vacuum to EGR valve? Maybe all is well. This test may trigger misfire codes.

Tube gets clogged at intake manifold end. Here are couple of shots.



 

·
Registered
Black 2005 ML 500
Joined
·
1,662 Posts
Discussion Starter · #6 · (Edited)
Thanks for the information Witek.. I tested the old removed EGR valve and it completely shuts, I guess that is why my idle was still smooth. If it was in the open position or semi-open position, then I have gathered that I would have had bad a idle and/or detonations...

There is a post on one other Mercedes model that suffers from clogged EGR tubes. The link is:

Mercedes-Benz Driveability Evaluating Electronic Engine Controls


They deviced a method to clean the EGR tube (Quoting below):

"We have now added a job to our 30K services on the M104 motor. We open the steel line at the EGR valve and feed in a long section of speedometer cable. We spin the cable with a drill motor and run it through the whole tube into the intake manifold. This is a simple operation, yet it prevents having to unbury the actual fitting when it’s really plugged"

I was using a thin snake cable, but it is a great idea to attach it to a drill... Though there would be nothing better than to completely remove the EGR tube and completely cleaning it. Though the idea seems very practical...

Thanks,

AC
 

·
Registered
Dallas, Texas
Joined
·
12,198 Posts
Thanks for the information Witek.. I tested the old removed EGR valve and it completely shuts, I guess that is why my idle was still smooth. If it was in the open position or semi-open position, then I have gathered that I would have had bad a idle and/or detonations...

There is a post on one other Mercedes model that suffers from clogged EGR tubes. The link is:

Mercedes-Benz Driveability Evaluating Electronic Engine Controls


They deviced a method to clean the EGR tube (Quoting below):

"We have now added a job to our 30K services on the M104 motor. We open the steel line at the EGR valve and feed in a long section of speedometer cable. We spin the cable with a drill motor and run it through the whole tube into the intake manifold. This is a simple operation, yet it prevents having to unbury the actual fitting when it’s really plugged"

I was using a thin snake cable, but it is a great idea to attach it to a drill... Though there would be nothing better than to completely remove the EGR tube and completely cleaning it. Though the idea seems very practical...

Thanks,

AC
The ultimate judge of this issue is result of OBDII EGR test.
 

·
Registered
Black 2005 ML 500
Joined
·
1,662 Posts
Discussion Starter · #9 ·
Well so far my ML is great and no light has come on, and my ML is running even smoother than ever.

I noticed that the trip computer's instant mpg reading is higher than before. Though the trip computer reading is always higuer than the real gallons/miles calculation, it seems like in the city I am doing 1+ mpg more. I have not gone in a long highway trip, but I had noticed that whenever I am on the highway I am getting a better highway mileage, too. I never have hit 19 mpg, with my ML 500, on the flat Texas highways, but now I think I may be able to hit it..

I wonder if it was the EGR tube cleaning that improve the mpg..? Though, finding out the EGR metal tube nut completely loose on the failed EGR may have caused a problem. Having this EGR tube nut complete loose blows my mind since I don't know how my ML would have worked fine for 69,000 miles. I think something may have happened on the last maintenance/repair the day before this EGR problem began to happen.

On the latter, what happens if the EGR metal tube is disconnected from the EGR valve. Will that cause an EGR malfunction error code or is the EGR system check on the other side of the EGR valve and this will not have been detected..?

Next time I mess with the EGR area, I am going to try the drill with the snake cable attached to clean the EGR tube, as described in the link below. I wonder what is the length of the EGR tube, anybody has an old EGR tube handy that can provide us with the measurement..? In this way we can cut the cable to just a little longeer than the tube..

Mercedes-Benz Driveability Evaluating Electronic Engine Controls

AC
 

·
Registered
Dallas, Texas
Joined
·
12,198 Posts
With clear EGR tube disconnected engine will not idle. It would act like giant vacuum leak and trigger CEL in short time with code for mixture deviation. After repairs car needs to be driven according to EPA drive cycle twice. Each time starting with engine cold.



After that you query ME for test results. This is screen shot from CarChip but any OBDII scanner that displays live data will do.

 

·
Registered
Black 2005 ML 500
Joined
·
1,662 Posts
Discussion Starter · #11 ·
I am getting too old..!! My 2005 ML 500 engine light is on again. I put my OBDII scanner and it is the EGR valve again..

Anybody remembers what was the wrench size of the big EGR nut that secures the metal EGR tube..? I forgot to put the size of the wrench, I used, in the instructions below.

I was looking for a crowfoot wrench but the ones I have are too small for the size of that nut. I was at Sears and Autozone, and it seems hard to find large metric crowfoot wrenches (22-28 mm).

Does Mercedes have a special wrench tool for it..?

Thanks,

AC
 

·
Registered
Black 2005 ML 500
Joined
·
1,662 Posts
Discussion Starter · #12 ·
Ignore my question below.. I will do it the same way I did it 2-3 years ago and will take everything out to get more space to work around and use a short handle wrench.

I was hoping to use the drill method to clean the EGR tube (with the snake wire in a drill) before replacing the EGR valve itself and the tube, and before removing all the other parts.

My computer is running Windows Vista now, and I don't have access to my W163 Maintainance/Service DVD, since the latter old DVD software version does not work on Vista, so I could not get the information I was asking for below..

Thanks anyway..

AC

I am getting too old..!! My 2005 ML 500 engine light is on again. I put my OBDII scanner and it is the EGR valve again..

Anybody remembers what was the wrench size of the big EGR nut that secures the metal EGR tube..? I forgot to put the size of the wrench, I used, in the instructions below.

I was looking for a crowfoot wrench but the ones I have are too small for the size of that nut. I was at Sears and Autozone, and it seems hard to find large metric crowfoot wrenches (22-28 mm).

Does Mercedes have a special wrench tool for it..?

Thanks,

AC
 

·
Registered
1997 W210 E320, 1999 W163 ML430, 2002 W203 C240
Joined
·
761 Posts
Could it be the gas you use that clogs the valve? I did the egr valve removal and when I sent to clean it It was already pretty clean. I cleaned it anyway but nothing came out.
I was told its the gas we use that clogs it up. I use chevron with techron. I also do the seafoam cleaning.

Best regards.
Detane
 

·
Registered
Black 2005 ML 500
Joined
·
1,662 Posts
Discussion Starter · #14 ·
I only use Shell highest end gasoline. I may change to Chevron, I always liked their Techron additive, though, there is not a Chevron near my house..

I wonder if Shell's nitrogen additive cleans the combustion chamber, very efficeintly, but creates lots of particles/gunk that get stuck in the ML EGR tube/valve on their way out..?

Maybe it will be a good idea to see what kind/brand of gasoline people that have continuous EGR problems use.

AC

Could it be the gas you use that clogs the valve? I did the egr valve removal and when I sent to clean it It was already pretty clean. I cleaned it anyway but nothing came out.
I was told its the gas we use that clogs it up. I use chevron with techron. I also do the seafoam cleaning.

Best regards.
Detane
 

·
Registered
2000 ML 320
Joined
·
14 Posts
My CEL is on and I've changed 3 cyclinders, spark plugs and wires. My 2000 ML320 was running smooth but the CEL never went out, took it to Benz mechanic and he said my EGR valve was bad and I needed an O2 sensor. Can someone tell me what are the symptoms of a bad erg valve. When I start my car the CEL blinks and then the car stalls and once the CEL stops blinking it drives fine but still rough at idle. Help Please
 

·
Registered
Black 2005 ML 500
Joined
·
1,662 Posts
Discussion Starter · #16 ·
I have not fixed yet my EGR valve, and my engine light is still on (EGR code).

I don't have any symptoms besides not getting the best mileage on the freeway. My ML starts and drives fine.

My understanding is that the EGR lets the engine reuse some of the exhaust gases to optimize engine combustion and maximize mpg.

I guess maybe depending how the valve got stuck (open or close) it may affect what the symptoms are?

In my case, I am sure my EGR tube is clogged, so I am sure there is no exhaust feedback back from the engine. I am still getting 15-16 mpg, but on the freeway, I am getting 16-17 mpg and not higher..

What are the engine codes, without that information, you don't have the information needed in order to know what is wrong with your ML.


AC

My CEL is on and I've changed 3 cyclinders, spark plugs and wires. My 2000 ML320 was running smooth but the CEL never went out, took it to Benz mechanic and he said my EGR valve was bad and I needed an O2 sensor. Can someone tell me what are the symptoms of a bad erg valve. When I start my car the CEL blinks and then the car stalls and once the CEL stops blinking it drives fine but still rough at idle. Help Please
 

·
Registered
1998 ML320
Joined
·
56 Posts
I finally took my car into the dealership for the P0400 code. I've had that code for about 9 months. My husband could have probably cleaned out the tube for me but he didn't want to do it. My car drove fine the whole time, even gas mileage seemed OK. But I wanted to take a road trip for the long weekend and my husband didn't want to take my car with the check engine light on (even though I have a little ODB scanner and I could check to see if any other codes pop up).

The total cost wasn't too bad - about $480 total for them to put in a new EGR valve, clean the EGR tube, coolant flush, and also topped off my brake fluid.
 

·
Registered
2000 ML 320
Joined
·
14 Posts
Question.... After cleaning the EGR tube and reinstalling, will the rough idle stop immediately if its the problem? Or do you have to wait for some magical moment? :( This car has given me sooooo much trouble. I haven't had a chance to enjoy it. Thinking about getting rid of it. Cleaned the tube and still the same codes mis fires on cylinders and code for EGR valve. ROUGH IDLE
 

·
Registered
1998 ML320 stock 318,112 miles 2000 ML320 stock 250,994 miles 2000 ML 320 270,224 miles parts car
Joined
·
913 Posts
re

how do you change 3 cylinders ? Or do you me you changed the spark plug and wires for 3 cylinders ?

just trying to be clear about what you were saying .

cnb



My CEL is on and I've changed 3 cyclinders, spark plugs and wires. My 2000 ML320 was running smooth but the CEL never went out, took it to Benz mechanic and he said my EGR valve was bad and I needed an O2 sensor. Can someone tell me what are the symptoms of a bad erg valve. When I start my car the CEL blinks and then the car stalls and once the CEL stops blinking it drives fine but still rough at idle. Help Please
 
1 - 20 of 58 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top