Breather valve (A0004762232) making whizzling noise
Hello!
Would anyone have an idea what is going on with my G? I have 1991 300GE.
I have tried to search the net for answer, but it seems I'm the only one having this issue?
The breather valve (A0004762232, below right hand rear side window, behind paneling. Also includes safety check-valve so that fuel is not leaking out in case of capsize) is making really irritating whizzling sound.
I thought it is faulty valve, and replaced it with a new one. But the whizzling is still there. I don't know why it is making this sound.
I understand that this valve is sucking fumes out of fuel tank to KE Jetronic (vacuum while car is running). Sound does not appear at idling, but immediately when RPM rises. And with higher rpm it stops. But at normal driving speeds of 10-100 km/h it is there, buzzing away. And you can hear it inside. And it is the valve making the sound, not hoses etc. I tried to blow into it, and it starts buzzing. Both new and old.
So what could cause the sound? Is there too strong flow through valve (too strong vacuum?) or something like that. When you blow through valve moderately, only sound is the flow of air, but with harder blow buzzing starts.
Picture Valve1: Here is the breather valve setup (valve is No 35).
Picture Valve2: Here is the breather valve connection to charcoal filter and further to KE Jetronic
Thank you for any help!
-Harry
Hello Harry,
The noisy breather valve can be a problem. I have replaced one for a new one and the valve was still noisy. I suspect the problem could be the fuel filler cap. The cap is supposed to be breathable as well, where the breather hole is; I do not know, I suggest firstly to remove the cap and see if the noise is present under that condition in which case you need to blow out the fuel cap's breather hole where ever that is.
I have sprayed some lubricant in the valve and the noise did not go away or it would return.
Or turn your Radio volume up a little.
Hi, yeah that would be very annoying! Without knowing exactly how that system is plumbed, it's hard to know where the pipes come from/go to, but could it be a blocked pipe beyond the valve? On your original post, it shows a looped pipe, does that go beyond the valve and to a higher point and what is item 29? Maybe blocked? If removing the cap makes no difference, then that indicates that the suction or pressure is coming from somewhere else not the tank. Do you have a diagram of the entire venting/fuel supply/return system?
I know on diesel 460's, (at least mine, a 250GD) there is a valve in the side as well, that joins to a pipe (breather) which goes down the right quarter panel, then along inside the bottom of the rear door/floor frame and exits about half away along, if that pipe was blocked, the tank would have to breath through the valve, which I don't think is it's primary function.
I'd check all pipes into/out of the valve are free.
Ok, maybe check hoses 25 and line to tank are intact/free
Harry
Do you have the chassis number / VIN that you could post / PM / email me so i can see what set up the truck is running and maybe get some proper diagrams?
Gav
Hello Pistonhead,
Unfortunately I already have tried opening the fuel cap. Does not have any impact.
When I first time removed the valve to inspect it, it actually got pretty silent (opened it and basically just played around to see if it is ok), but only for a day or so. Then the buzzing returned, and I figured what a heck, I'll get a new one.
Seems weird that merc would put the bugger inside the car, if there is tendency to start making noise. There would be space for it outside also, where it could whizzle as much as it likes without bothering anyone.
Have been already thinking of bypassing the whole valve, as you said, the cap is also breathing, so there will not be pressure building up in the tank. Or bypassing just the valve with piece of hose. Then the only problem is capsizing the car as far as I can see. Then the fuel runs to engine bay via hosing.
The sound is just so irritating and high pitched - like your own personal vuvuzela - that I'd rather get rid off it.