My E320 A124 had a vacuum every time I filled up. Previous owner had paid for a replacement fuel tank sender unit….it was damaged by the tank deforming due to a vacuum! I replaced the valve as mentioned in this vid along with the charcoal canister, still not 100%. The vacuum solenoid in the engine bay was defective (should click when 12v applied). Replaced & all good. Always good to fix the problem & not the symptoms i.e. don’t fix the deformed tank & replace fuel level sender without finding why it occurred. Previous owner used a ‘specialist’ MB independent garage code for bodger!
yep an uncontrolled vacuum forming in the tank will be disastrous. Have had a few people mentioned blockages in the line up from the tank as well. Not something i have ever experienced here in Australia.Good idea to check for blockages in these lines while working in the area.
I replace this valve on June 2023, Ref. A124760432,, 25.66 € from Mercedes Arles in France because over pressure in fuel tank. Very easy to replace on my w124 260E.
My tank has pressure when removing the gas cap, but my w124 has a strong smell of fuel from the rear end of the car. Changed fuel pumps and filters. Do you think this might be the issue? heard that it could be stuck and letting the fumes release into the environment.
In my case... I have deafinitely overpressure going on. When tank is full, I drive 10kms and when I open the cap then, about 2-3 litres (!) of fuel with a lot of pressure is going out... So I think it's just blocked and not having any air that should go in (otherwise tank will deform or fuel pump will die). I'm wondering If I can just remove the valve and connect those hoeses together (going from tank to charcoal canister). Car runs better when fuel cap is off so there is no (or little) pressure. Also no strange noises from the fuel pump. Older cars didn't have the valve. They have little ventilation on the cap. So, my though is the pressure is NOT needed and actually can do more damage that no pressure at all. It was just done because of EU/US "eco" regulations
@@dustblowboro your fuel tank will rust out if the tank is not sealed from the atmosphere with slight pressure. You are better off finding and fixing the blockage. I doubt its the valve it is probably the line to the charcoal canister or the canister itself.
2 functions. It does not allow vacuum to form in the tank when the fuel is used or when cools down at the end of the day and the other function is to keep a slight pressure in the tank when it warns up.
Hi, I wanted to ask your opinion on a problem, my fuel cap is always damp due to petrol vapors and there is a certain overpressure when you unscrew the cap, I have already replaced that valve, the canister, the solenoid and the cap of the tank, all new and original... the problem remains, the next step will be to test the ventilation lines after which I really don't know what to do if it remains, is there something I'm forgetting? thank you very much and greetings from Italy!
there is supposed to be slight pressure build up, this is normal. What is not normal is if there is never pressure buildup, buildup is excessive (blocked lines) and has to vent via pressure relief in cap, or is system is so faulty the tank forms a vacuum and the tank caves in 😅
thanks for the reply, I agree that the pressure must be there but what seems wrong to me and what I'm investigating is the wetness around the inside of the fuel cap when you open to refuel it actually drips, never seen on any car :(
no, that's the strange thing, until the fuel cap is opened nothing comes out, so it means that the system never goes into anomalous overpressure, but always remains within its operating range... in any case last night ( yes exactly) I tested all the vent and vapor compensation lines with compressed air and they are all free, I ordered another ventilation valve (the white one) thinking that my new one might be faulty (I think it is almost impossible but for what it costs I want to try), and nothing ... the humidity of petrol fumes inside the cap when you unscrew it is always there, I think I'll have to live with it
@@CompaJake it is directly below the fuel tank on cars fitted with charcoal canister system. On cars without it theres just a bell shaped vent connected to a straight version of this valve.
I’m working on my car today and I don’t see the valve I checked underneath the car by the gas tank and the only thing that is the cover for the fuel pumps is it in there with the fuel pumps ?
I suspect the viton diaphragm being folded under is the result of dried fuel residue partially adhering it to its seat during a long period out of service. The partial adhesion caused non-linear movement when used again, causing the diaphragm to fold on the edge opposing the adhesion. I wish I could set your mind at rest RE: the fuel tank debris issue, but I’ve replaced a handful of Mercedes purge control valves and there was never a polluted tank involved even when the charcoal can was rotted out. And Most of the cars were exposed to salt air to some extent, being located in Newport Beach, Ca. One is my rescued ’88 300TE that was left to die in a marina parking lot. It was a dock box for 5 years, the poor thing. The rear muffler sat not 10m from the tideline and nearly rotted completely off the car. Your tank looked like someone ‘sugared’ it. I Haven't seen that in many years. Any A-hole neighbors with a grudge? Sure hope not . . Reds' a peach.
Red did indeed sit for a long time before I got it. it was someone else’s project that never eventuated. The tank was rusted beyond belief when I got it and the fuel pumps rusted solid. I think I tested this valve at the time of installing the new tank and didn’t think much of it and thought it was of no concern having it not work. In hindsight i was wrong. Regarding sugaring, this car never gets parked in public places and when I do drive it somewhere I am always nearby it. At my house it is locked securely away from prying eyes. I think the mud in the tank the first time came from the 60 year old fuel retailing station I filled up at last before the engine started stalling. Also in hindsight, probably not a bad thing as this also brought to my attention the badly rotting new fuel hoses. Red could have easily burnt to the ground if i kept driving it without that stalling incident.
@@MMWA-DAVE Old filling station tanks, affirmative. Else-wise hard to imagine an open vent causing water accumulation in a tank. Cars 1889-1966ish had direct vent caps and/or lines without that issue. I ordered a 3m long endoscope today that pairs with phone & ap. for $23 US. Out of excuses. I'll be sticking it wherever the sun don't shine . . sure, yea, like fuel tanks. 👀 Cheers -
Great explanation to something otherwise forgotten and misunderstimated.
Something to replace just based on age-- and while you're changing those two hoses, which really need replacing based on age!
My E320 A124 had a vacuum every time I filled up. Previous owner had paid for a replacement fuel tank sender unit….it was damaged by the tank deforming due to a vacuum! I replaced the valve as mentioned in this vid along with the charcoal canister, still not 100%. The vacuum solenoid in the engine bay was defective (should click when 12v applied). Replaced & all good. Always good to fix the problem & not the symptoms i.e. don’t fix the deformed tank & replace fuel level sender without finding why it occurred. Previous owner used a ‘specialist’ MB independent garage code for bodger!
yep an uncontrolled vacuum forming in the tank will be disastrous. Have had a few people mentioned blockages in the line up from the tank as well. Not something i have ever experienced here in Australia.Good idea to check for blockages in these lines while working in the area.
Seems like i probadly should get one as preventive maintenance.
Thank you for the information! Would you please provide the clamp stock number, if so available? Appreciate it in advance!
I replace this valve on June 2023, Ref. A124760432,, 25.66 € from Mercedes Arles in France because over pressure in fuel tank. Very easy to replace on my w124 260E.
"Easy to suck, difficult to blow" need this on a t shirt
haha
My tank has pressure when removing the gas cap, but my w124 has a strong smell of fuel from the rear end of the car. Changed fuel pumps and filters. Do you think this might be the issue? heard that it could be stuck and letting the fumes release into the environment.
How can I test this part .thanks
Part number for fuel tank valve 1991 420sel
In my case... I have deafinitely overpressure going on. When tank is full, I drive 10kms and when I open the cap then, about 2-3 litres (!) of fuel with a lot of pressure is going out... So I think it's just blocked and not having any air that should go in (otherwise tank will deform or fuel pump will die). I'm wondering If I can just remove the valve and connect those hoeses together (going from tank to charcoal canister). Car runs better when fuel cap is off so there is no (or little) pressure. Also no strange noises from the fuel pump. Older cars didn't have the valve. They have little ventilation on the cap. So, my though is the pressure is NOT needed and actually can do more damage that no pressure at all. It was just done because of EU/US "eco" regulations
@@dustblowboro your fuel tank will rust out if the tank is not sealed from the atmosphere with slight pressure. You are better off finding and fixing the blockage. I doubt its the valve it is probably the line to the charcoal canister or the canister itself.
In Germany the part costs at the Mercedes dealer 25,76€ with 19% tax
not bad, I think i paid 50% premium on this for postage but still way cheaper than our ripoff dealers locally.
I have a w124, it smells a lot of gasoline in my car, it might be because of this part?
you probably have a fuel leak. You should check the entire system. I have leaks at the pump area to address on my other w124.
What is the job of this valv
2 functions. It does not allow vacuum to form in the tank when the fuel is used or when cools down at the end of the day and the other function is to keep a slight pressure in the tank when it warns up.
Hi, I wanted to ask your opinion on a problem, my fuel cap is always damp due to petrol vapors and there is a certain overpressure when you unscrew the cap, I have already replaced that valve, the canister, the solenoid and the cap of the tank, all new and original... the problem remains, the next step will be to test the ventilation lines after which I really don't know what to do if it remains, is there something I'm forgetting? thank you very much and greetings from Italy!
there is supposed to be slight pressure build up, this is normal. What is not normal is if there is never pressure buildup, buildup is excessive (blocked lines) and has to vent via pressure relief in cap, or is system is so faulty the tank forms a vacuum and the tank caves in 😅
thanks for the reply, I agree that the pressure must be there but what seems wrong to me and what I'm investigating is the wetness around the inside of the fuel cap when you open to refuel it actually drips, never seen on any car :(
@@Piccio93 I have never seen that either. I wonder if you vent lines are completely blocked and the cap is doing the emergency pressure relief.
no, that's the strange thing, until the fuel cap is opened nothing comes out, so it means that the system never goes into anomalous overpressure, but always remains within its operating range... in any case last night ( yes exactly) I tested all the vent and vapor compensation lines with compressed air and they are all free, I ordered another ventilation valve (the white one) thinking that my new one might be faulty (I think it is almost impossible but for what it costs I want to try), and nothing ... the humidity of petrol fumes inside the cap when you unscrew it is always there, I think I'll have to live with it
@@Piccio93 what country do you live in? It might be the climate responsible for this phenomenon.
Hi , how can I get in touch with you ? Many thanks Tienie
Why? I don’t provide technical support to individuals.
Where is this located on the 1992 w124 M103 engine
@@CompaJake it is directly below the fuel tank on cars fitted with charcoal canister system. On cars without it theres just a bell shaped vent connected to a straight version of this valve.
@@MMWA-DAVE thank you !
I’m working on my car today and I don’t see the valve I checked underneath the car by the gas tank and the only thing that is the cover for the fuel pumps is it in there with the fuel pumps ?
I suspect the viton diaphragm being folded under is the result of dried fuel residue partially adhering it to its seat during a long period out of service. The partial adhesion caused non-linear movement when used again, causing the diaphragm to fold on the edge opposing the adhesion.
I wish I could set your mind at rest RE: the fuel tank debris issue, but I’ve replaced a handful of Mercedes purge control valves and there was never a polluted tank involved even when the charcoal can was rotted out. And Most of the cars were exposed to salt air to some extent, being located in Newport Beach, Ca. One is my rescued ’88 300TE that was left to die in a marina parking lot. It was a dock box for 5 years, the poor thing. The rear muffler sat not 10m from the tideline and nearly rotted completely off the car.
Your tank looked like someone ‘sugared’ it. I Haven't seen that in many years. Any A-hole neighbors with a grudge? Sure hope not . .
Reds' a peach.
Red did indeed sit for a long time before I got it. it was someone else’s project that never eventuated. The tank was rusted beyond belief when I got it and the fuel pumps rusted solid. I think I tested this valve at the time of installing the new tank and didn’t think much of it and thought it was of no concern having it not work. In hindsight i was wrong. Regarding sugaring, this car never gets parked in public places and when I do drive it somewhere I am always nearby it. At my house it is locked securely away from prying eyes. I think the mud in the tank the first time came from the 60 year old fuel retailing station I filled up at last before the engine started stalling. Also in hindsight, probably not a bad thing as this also brought to my attention the badly rotting new fuel hoses. Red could have easily burnt to the ground if i kept driving it without that stalling incident.
@@MMWA-DAVE Old filling station tanks, affirmative. Else-wise hard to imagine an open vent causing water accumulation in a tank. Cars 1889-1966ish had direct vent caps and/or lines without that issue.
I ordered a 3m long endoscope today that pairs with phone & ap. for $23 US. Out of excuses. I'll be sticking it wherever the sun don't shine . . sure, yea, like fuel tanks. 👀
Cheers -
How do you know that it’s faulty except by take it off and blow in it.
the fuel tank never pressurises. No hissing ever when removing the fuel cap, even on a hot day.
Thanks for the answer.
I had one start leaking from being cracked and weathered
❤❤❤❤❤❤😊😊ok
Pls I would like a favour from you