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Cleaning

purge valve,If the code did not clear when you got a new gas cap,or flipped the gasket.Clean the purge valve,it is a little pump that sucks a vacuum in the tank and gas lines systems,so it sucks fumes into the engine so they don't get into the atmosphere.
it is located .....
pop the hood,look in the drivers side of the engine compartment,in front of the area where the brake master is you will see a little black can looking object.
Labeled ---MOT---
with the engine running you should hear it clicking like a little drummer.to check it's operation,just start the engine and put a screw driver tip on it and listen with your ear pressed on the handle-------cheap stethoscope------
you should hear it doing it's job.Sometimes they get gummed up,so lift it off the
W shaped mount and gently pull off both enter and exit hoses,get some maf cleaner(CRC brand) and put the tube that comes with the crc on the sprayer.Insert the tube into the hose and spray for a few seconds,repeat to the other hose and the the valve itself,let air out for 10 minutes and reinstall both hoses and put it back onto the W shaped mount.
Start engine and enjoy.
ohlord

some pics to help you
 

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Ohlord,
Any chance you can put this last post in a separate article and get the moderator to add it to the stickies? This is one of those fixes that is so simple to do, but which one can never find again if you need it.:D And I'm sure it will be needed more as the cars get older.
 

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I'm not the boss,but I will try

:)
-----------GREG--------,a request for a sticky on the purge valve cleaning.............
the CRC maf cleaner ,really dissolves the any kind of gunk and leaves no residue.
Just be sure to air it out,no reason to allow flammable solvent into a hot engine.
Let it sit and evaporate just like when you clean a mass air sensor.
ohlord :bowdown:
:thumbsup:
 

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purge valve,If the code did not clear when you got a new gas cap,or flipped the gasket.Clean the purge valve,it is a little pump that sucks a vacuum in the tank and gas lines systems,so it sucks fumes into the engine so they don't get into the atmosphere.
it is located .....
pop the hood,look in the drivers side of the engine compartment,in front of the area where the brake master is you will see a little black can looking object.
Labeled ---MOT---
with the engine running you should hear it clicking like a little drummer.to check it's operation,just start the engine and put a screw driver tip on it and listen with your ear pressed on the handle-------cheap stethoscope------
you should hear it doing it's job.Sometimes they get gummed up,so lift it off the
W shaped mount and gently pull off both enter and exit hoses,get some maf cleaner(CRC brand) and put the tube that comes with the crc on the sprayer.Insert the tube into the hose and spray for a few seconds,repeat to the other hose and the the valve itself,let air out for 10 minutes and reinstall both hoses and put it back onto the W shaped mount.
Start engine and enjoy.
ohlord

some pics to help you
Thank you. You are a life saver. I will check it out later. I've just flipped the gas cap rubber yesterday. I haven't driven the car because I just took out the air filters and cleaned it up. I would assume the CRC maf cleaner would be sold at Autozone or something?

And in case the gas cap rubber and the purge valve not working, should I tackle the crank position sensor next? I couldn't seem to find where the CPS located (was told to look at the rear bank driver side but found nothing after few attempts). Thanks again.
 

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Great photos and directions. I've all of a sudden started having the blinking fuel gauge light issue off and on. Usually doesn't occur till after some significant start and stop driving. I bought a new gas cap, flipped the gasket in the original then even swapped gaskets from the new cap to my old cap which seems to have a tighter fit. I've never overfilled my tank (can't afford to fill it period). The car drives near perfect and always has even with the blinking gauge and the CEL. What's weird is this started with a CEL 0400 egr code as I was prepping to get my car smogged and didn't want any last minute surprises, so I went to smog 90 days prior to my renewal date as a smog is good for that long. That's when I found the egr issue. Had read a lot about it most likely being one or more vacuum hoses cracked or loose or just giving the egr a good cleaning as well as the tube. I did all that and did find 3 cracked hoses, make sure to check the pressure sensor hoses (2) at front of engine bay, saw a youtube video on it and sure enough mine were cracked. Anyways after doing all the above I passed my smog with flying colors and ASS-U-ME-D that I was in the clear. A few days later the blinking issue and CEL returned. Codes were egr again plus some other emmisions/evap codes. Just for good measure when I had taken off my Maff I thought I possible got it dirty, so I cleaned it, checked all connections and all 5 codes and the CEL were gone. But blinky and CEL returned in a few days which is what brought me to your purge suggestion as well as others. I also read that the breather hose intakes can get pretty clogged up and throw similar codes, so I took off the one on the passenger side and the small one on the drivers side as I felt the larger hose would not be an issue. I used some combustion chamber cleaner and sprayed both the hoses and the breather cover intakes, which I guess has some kind of screen or something as the spray tube from the cleaner was blocked from going very far inside the breather intake regardless of placement, so I just spayed them really good. Didn't seem to do the trick so I tried you purge instructions and the gas cap gasket change to my original one, which by the way changed the way it sealed when I tightened it. Previously it always snugged up pretty good but never actually clicked at the end signifying a lock I guess. So, I took a long drive with lots of starts and stops and idling. The CEL is still on and don't know if it's just a cycle thing or somethings still amiss. The blinking issue didn't rear it's head yet and I'm holding my breath although as I say it runs great and my gauge works perfectly. I will say that by cleaning the purge valve, the mild vibration I had at red lights/stops, which I attributed to engine mounts and I'm am probably due and will do them soon, but that vibration was cut at least in half with the purge cleaning and my engine was almost purring perfectly, will probably make it a usual service with oil changes. Not sure what to try next if the CEL doesn't fix by a completed drive cycle, again it's driving great, accelerates great and kickdowns fine. Anyone with any suggestions, please feel free. I don't believe it's a fuel sending unit as my gauge works and no driving issues. Oh and when I took out my purge valve to clean it and the contacts, I saw a youtube video saying one check was to blow on the intake and outake and no air should go through, which it didn't, so I'm hoping that means the purge is good and I've never smelled gas fumes. There was another check I was unable to do, where the video connected a vacuum gauge to the out port and pulling and holding about 15lbs? without losing any air, then he applied power to the 2 contacts and the purge valve opened as it should and the vacuum gauge went to 0. Sorry for the long story.
 

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MrBoca thanks for the reply. Haven't gotten new codes since the last 5 I had cleared themselves, although I'm fairly sure with the blinking fuel indicator and previous egr codes that they will be similar, large and small evap leaks/egr, if drive cycle doesn't clear in a day to two and blinking reappears, I'll get new codes from the auto parts store, don't have a scanner myself. I'll will say that I do regular maintenance on my car for the past almost 4 years (just passed 200,000mi.) and never had a CEL until the 1st 0400 egr code a few weeks ago and since all 5 codes were cleared after cleaning my maff and checking the connection of all vacuum lines, most of the codes seemed unrelated or incorrect. I've cleaned, sprayed, replaced hoses and gas caps, so not quite sure what the issue/issues are especially being the car drives fantastic. The lights are more of a nuisance than anything at this point.
 

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You really need to get the fault codes, in fact, invest in a $20 bluetooth scanner so that you do not need to go to an auto parts store. If the CEL is turned on, and the fuel reserve is no longer blinking, who knows what the problems are. You may have fixed them but some other problem may have popped up. A code scanner with an app in your I-Phone or Android will do much more than reading and resetting the codes. It may help you diagnose the problems, as you can monitor some of the sensor outputs.

Flashing fuel reserve may be due to component failure (fuel tank gas pressure sensor, shut-off valve, canister leak, purge valve, or any of the hoses that connect them or to the intake.

If you worked with the EGR valve and the EGR pipe, you may have caused a leak where the purge valve hose is connected to the intake .
 

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mrboca, sincerely appreciate the advice/suggestions, like I said waiting for the drive cycle to complete and go from there and recheck codes. All of the possible causes you mentioned were never inferred/mentioned directly by any of the codes received and would in my opinion cause noticeable issues of which I have none, other than a CEL at this point. I've checked the purge valve hose that goes into the intake and there's not a lot to mess up there as the hose simply plugs into the top a T vacuum line and has a stop ring on it to prevent it from pushing in too far or leaving too far out, which I have checked several times and even took the added precaution of wrapping that connection to prevent air leakage and movement of the hose. I did already mention that I removed the purge valve, partially tested it, checked all the lines to and from it and cleaned it, the electrical connections and 2 hoses attached and did notice a very slight improvement in less vibration and smoother idling. Greatly appreciate all your effort and advice. I will share that I'm no novice or beginner with Mercedes, nor claim to be a master, but I have owned at least 6 and done tune ups, diff/trans/ps/coolant/oil and other fluid changes, replaced water pumps, cooling fans, pulleys/belts, fixed ac's, brakes and rotors, solved electrical issues, brake stop switches and dozens and dozens of other repairs and maintenance. I've also learned that codes don't always mean what they indicate or are accurate and that there are just gremlins, quirks and seemingly unrelated small tricks or causes for codes that make no sense. If I was smelling fuel, getting poor mpg and/or acceleration,or starting issues, etc, then the codes would make some sense but as I said, I just recently got a glowing smog check and even after that cleared 5 codes just by cleaning my maff and rechecking vacuum connections, and I never even got a code for the maff. I will get the exact codes and post them in the next few days and greatly appreciate and consider any and all comments regarding such codes, but if it ain't broke and it's maintained properly, maybe something's just rotten in the state of Denmark, or just the appearance of such?
 

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Well, post the codes after the CEL pops up, and we will take it from there. My car completes the drive cycle (all green) in one day. If it takes too long, there is an intermittent failure which prevents a particular test to be run and completed. If you had a scanner you would know which tests are pending to be completed.

There are many issues you get a CEL, and you think the car is running great. But your car is trying to tell you something.
 

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Follow up on CEL and blinking fuel gauge:

Didn't get the codes reread, turned out I didn't need to....yet? Having somewhat stubborn streak I have repairing things, which has paid off many more times than not, I just for the heck of it gave my MAFF another THOROUGH cleaning and took a drive. I noticed I was a little low on fuel and went to gas up. Paid for my gas and went to pump it and couldn't get my original Benz gas cap off, it was stuck at the point it should have released from the fuel neck. I could pull on it a little and it felt like rubber was hanging it up somehow. I didn't have any tools with me so I had enough gas to make it home and looked online for a solution but all I found were mainly answers to do with the fuel door itself not opening. Wary or doing so and possibly causing serious damage to my fuel tank neck, I took two flat head screw drivers and cautiously pried on both sides of the cap at the postition where it should open. After soiling my pants, I actually managed to get it off. I'm still not quite sure what the cause was although it appeared the alignment of the plastic and metal tabs on the cap were misaligned somehow. Luckily I had an aftermarket cap that I had already tried but didn't seem to work the first time. I put it on the fuel neck, started the car to take a drive and hoped for the best and voila, no more CEL for 5 bogus codes that I was previously working off of. It's been several drive cycles and all is still good. While I do believe that my very 1st CEL for an EGR issue was factual because after I cleaned it THOROUGHLY and replaced multiple cracked vacuum lines it was good enough to pass a smog test, I believe the others afterwards were gas cap and posssibly a still dirty MAF. The 2 morals to the story are 1. The blinking fuel gauge is 99 percent because of a fuel cap issue and if the 1st replacement doesn't fix it buy another before doing something expensive, the 2nd is just because you get 5 codes for a CEL, doesn't mean they're real and not just a simple issue like a new gas cap and/or a dirty MAFF. Happily Ever After...The End.
 

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Hello, can anyone help me with the purge valve vacuum line i accidentally disconnect the line that goes behind the ecu box. Thank you
 
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