Keithb

Got my C320 Coupe Service A done yesterday. One of the issues I asked about was a ticking noise from the engine.

They said it was the purge valve and that this was normal. OK I thought... but, what does a purge valve do? Can't say I've ever heard of it before....

TIA

mleskovar

The purge valve returns unused gas to the tank.

Steve Clark

the purge valve is part of your car's emission-control system. Opened on command by the ECU while the engine is running,it lets fuel vapors that have been trapped in an activated carbon-filled container return to the fuel tank.The container is thereby purged of the fuel vapor it has caught,and is ready to collect more fuel vapor the next time the car is parked.
It does not deal with liquid fuel unless things are seriously screwed up.I can only think of two ways it might see liquid fuel- if you severely overfill the gas tank,and then park the car in a hot place so the fuel expands and goes places it should not,such as the canister controlled by Mr. purge valve.Parking your car on it's roof could also have the same result.,depending on the car's final resting attitude.Both methods will result in an expensive repair.
The noise you're hearing may or may not be the purge valve.My C32's engine always has a bit of muted mechanical mutterings, especially when it's cold.

mleskovar

I thought that's what I said? Maybe my explanation isn't as verbose as your's Steve but it's still accurate. It simply returns unused gas to the tank. Jeesh!

Steve Clark

"gas'" means liquid fuel,not gasoline vapor.Let's give credit for the misunderstanding to the English language instead of each other.

levelr123g

i beleive you are both wrong on this. the ticking is caused by a purge valve, BUT if you follow the route of the lines coming out of it, they go to the intake manifold, NOT the gas tank. NOW it may return fuel vaor to the intake manifold, but definately not to the tank. I posted a fix to this problem almost a year ago. It only moves air, not a liquid.

Steve Clark

It handles gasoline vapor,ie evaporated gasoline in air.Geez loweeze you make such a simple thing so hard. The air used to purge said vapors comes from the engine's intake sytem.
The ticking that was the cause for this string's creation may very well BE caused by the purge valve.It may also be caused by something else.There are a lot of potential noise-makers under the hood.DUH!.

Keithb

Thanks.

I haven't heard it since I picked the car up on Friday, so who knows... I originally thought the sound was more like a valve ticking, cuz it seemed to be more in time with engine rpms. Does the purge valve tend to work in a similar timing to the engine rpms?

Narcissus

Mine has been ticking for the longest of time, my SA told me this was normal, I heard that they can replace the brackets to stop the ticking sound.. Nov0798 you said you posted a fix about a year ago but I never seen it, tried searching to no avail. care to let us all know again ?

:

mleskovar

Here's the part that MB replaced when I complained of the problem: "mounting clip for purge valve - 001-995-56-65 clamp" I still hear it sometimes but it is muted now. Found this with search:
Purge valve is emissions , vac. operated valve between the charcoal canistor and the intake manifold. It is signaled by the ECU with short pulses so as not to affect the idle/intake vac supply.
The common problem is they get dirty and require cleaning or replacement .

"the charcoal canister is a necessary part of the
emissions system in our cars and its removal will cause your ECU to fault
(it will also void your emissions warranty and it may be illegal to remove
it). The fuel vapors that are routed to the intake manifold are calculated
into the air/fuel mixture ratio by the ECU and if the canister and purge
valve are removed, less fuel is introduced into the combustion process and
you may run a lean condition which will cause your car to detonate
especially if you have introduced more air into the cylinders via a cold
air intake and low restriction filter. Also since the charcoal canister
only collects and releases fuel vapors, it rarely wears out. The part that
often wears out is the purge valve. It gets stuck in the open position and
will cause you car to run a little rich."

I always thought the canister collected the vapor, turned it into gas ( Steve
) and returned it to the tank.....wrong!!

levelr123g

sure, just go to lowes or any other parts store and buy some rubber hose and cut it in half. take the pieces of rubber and cut them to fit under the original metal bracket. this will isolate the valves metal mount from the body and dampen he noise you hear. alot easier then taking it to the dealer and only about a 1.00 worth of parts, and 20 minutes of your time.

Narcissus

Thanks Nov, I'll try this soon.... It's really a minor nuisance but one nonetheless, I'll let you know how it works out

David N.

Keith, Narcissus,

I'm glad I'm not the only canuck who got that explanation from their dealer.

I had read many threads on here about American members complaining to their dealers about the purge valve ticking noise. As I understood it, MBUSA had a tech bulletin out to address the problem. To my surprise, when I went to my dealer looking for the same resolution they told me that the Canadian market is treated differently. We don't get replacement purge vavles if ours tick. My SA said the ticking does not have an impact on how the part functions, so I just left it alone.

David.

Narcissus

Yeah I know, got the same story when I complained about the windshield fogging up when the climate control was on auto, apprerantly there is a prolem with the vent directing too much air on the windshield, had to talk to them 3 times to have them finally fix it, my SA told me they didn't wanna sound like *sses but they're told by MBcanada not to fix these little issues, same with rattling sound apprently it'S only covered for 1 year here and I heard otherwise from southern owners.... Hope I can fix this little purge valve problem and maybe let my SA know so he can advise future clients how to fix it themselves....

I don't understand why there is so many differences between canadian and american models, they should merge both together, would probably be more cost effective and they could finally offer a single c240 model instead of having the classic and elegance trim.

David N.

I'm surprised they give you a hassle about fixing rattles, etc. They shouldn't do that. All that stuff is covereed under the MB Canada new vehicle limited warranty. I've never heard anything about a 1 year expiry on that. Try going to a dealer that is corporately owned. All the stores in the greater Toronto area are owned by MB Canada.

And yes, they should merge resources btwn the US and Canada. Both use different TSB databases. Sometime when I read about TSB's or fixes on here my dealer can't find them because they're not in our system. Rediculous...

As for the c240, the classic model is only offered in Canada. MB, and BMW as well, treat the cdn market more like europe. We get many of the lower end cars that americans wouldn't think twice about buying, like the 240 classic and 320i.

Narcissus

I go to 2 different dealers and as far as I know they are both owned by MBcanada, both gave me the same answer for the rattling sound, they asked me how many hours they wanted me to work on them and they would try to find as much as possible, theese were cahrged 95$ an hour, told him to get the hell outta there that I would do it for free, managed to get rid of 2 of the rattling noises, one was the passenger's headrest and the other was the wiring under the shiftboot knocking on the plastic part, couldn't locate the 2rd one that seems to be coming from the instrument cluster and very sporadically, over bumps or sometimes out of nowhere, it's a really dampered sound, I'm probably gonna take the cluster off soon i I'm planning on trying to fit a w211 clsuter in there wiht the help of a dremel and my steady hand

krinderhagen

There are apparently different malfunctions of the purge valve mine says its open

I am trying to learn how its suposed to work and what tells the computer to open and close it

Flydutch

Hi to you all from Flydutch. I am for more than a year struggling with a suddenly arriving vacuum problem on my fuel tank, resulting in partial collapse, cracks, many "Goop" repairs which failed, total removal of the tank and re-welding of the cracks. After all this the vacuum is back and wanted to do another collapse, which I couth in time as I was expecting it, and now I have drilled a hole in the filer cap to avoid the vacuum but it is causing fuel spill at cornering with a full tank.
A. Can this purge valve be the cause of the vacuum.
B. My 2003 German S55 AMG Kompressor has a stainless tank with the a normal fuel level sensor but also a round aluminium electric sensor on top of the tank next to the fuel level sensor which does not show on any Diagram I get from my workshop manual or the internet. At the bottom a fuel extraction point with a strainer and two pipes which of which one lead to one plastic one way valve and the other to a steel one way valve which has however a bypass which open and closes that valve. I am totally at a lost how the fuel system works and why it suddenly developed that vacuum problem. Your learned input is much appreciated.