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Hissing noise when accelerating then dies out

Flag Gibby

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It seems that the OP was referencing the lines going to the vacuum reservoir and others indicate it to be the check valve under the hood.
 


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snakester

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Fixed this with a new vacuum check valve. No guesswork.

Purchased for $10 here : http://www.rockauto.com/catalog/moreinfo.php?pk=380402&jnid=2&jpid=0

20150912_183316_zps1hxkv9xe.jpg

20150912_183446_zpskpofs8zx.jpg


It is located here:
20150912_183827_zps3wilpeoo.jpg

Just pull it apart and replace it with the new one installed in the same direction and its done. 5 minutes including the test drive.
20150912_184032_zpsgej6c1sx.jpg
 




sync58

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It definitely was a problem with the A/C Check Valve. I had a broken vacuum reservoir so the A/C took a while before turning on with the damaged part, once I changed it the dreaded noise came back! I replaced both parts and the hiss went away... thank you guys!!

Here are some instructions with some pictures
http://imgur.com/a/2guSo
 




David05Caliexplorer

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Nice now does anyone think not changing this check valve would make a.c.compressor give up and leak Freon everywhere right at the compressor is where it just blew out one hot California day.
 




Rcflyer330

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Nice now does anyone think not changing this check valve would make a.c.compressor give up and leak Freon everywhere right at the compressor is where it just blew out one hot California day.


No the check valve would not cause an ac leak at the compressor.
 




PotatoExplorer

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Ah, I finally found a thread with the exact part I was looking for!

Does anyone know what the A/C Check Valve actually does?

I was having some crazy hissing/wooshing every single time I touch the accelerator pedal. I checked all the vacuum lines under the passenger dash and behind the glove box, but didn't find anything. Then I flipped the A/C Check Valve around, drove it, and the sound was gone. I'm wondering if my A/C is going to explode and I should just get a new valve, or is having it reversed OK?

36753888610_db3c5f0702_b.jpg
 




Bill MacLeod

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The check valve (1 way valve) allows the vacuum reservoir to hold the heater control valve open at wot or heavy throttle. You need to reinstall it to original position, otherwise the heater control valve will not function. (no heat)
 




07EddyB

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I thought the check valve had different size connectors on each side?
Anyhow, prepare to replace it frequently.
 




PotatoExplorer

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The check valve (1 way valve) allows the vacuum reservoir to hold the heater control valve open at wot or heavy throttle. You need to reinstall it to original position, otherwise the heater control valve will not function. (no heat)

Well I learned that the hard way! After all that snow earlier in the week, the temps dropped and was crazy windy... yeah it was a nice and cold trip to and from work the other day. Luckily my commute isn't very far at all. The check valve seems to control the blend door if I'm not mistaken? With the valve backwards, I could jack up the fan speed/heat, but no heat was coming into the cabin. I flipped it back around and immediately regained access to the heat. I then immediately ordered one online. A little piece of $10 plastic...

I wonder why these check valves tend to break so frequently...hmmm.
 




WaltZ

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I've had this problem, like most of the problems mentions in these forums.

I went and bought the check valve. That ended up NOT being the culprit.

I want you to look at the picture at the top of this page with the red circle.

With may lack of technical jargon:

The black cylindrical doo-hicky to the left with the spark-plug-looking-cover-thingy on top was the problem. The spark-plug-looking-cover-thingy on top was not connected properly. A mechanic was in the engine area a few weeks earlier and must have forgotten to attach it correctly.

Good luck
 




Ravenloft

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I was going reading through this thread and I thought I saw a solution but I will post up my problem ..dont scold me if I duplicate.

I have a 2006 Mercury Mountaineer V6 AWD. The problem I'm having is when I'm driving -- over 50 mph I hear like air rushing or being sucked into something.. it is coming from under the hood. If stop on a hill and then try to start moving again it takes a looooong time to climb the hill, feels like it is struggling and does not have much power. I took it to the mechanic and some work was done on it... it was working fine now the problem is back again. Also when the problem was fixed the gas pedal was tight - I had to apply a descent amount of pressure on the pedal. When I pressed on the pedal the car would fly up hills even if I stopped and then accelerated from a stopped position on the hill. When the car was without the hissing sound driving on leveled roads highways and city was great. I was able to feel the power. This was great but short lived. With the problem back the gas pedal does not feel tight... by that I mean I press the gas pedal and it goes almost to the floor.

Also the engine light would come on when I accelerate fast and hard or if im going up a hill at a fast speed. The light would stay on for two to three days and go out. If I accelerate up a hill or drive on highway for a long way the engine light would come. Then three days later it would go out.....and this keeps on repeating..

I had Autozone check the codes for me... one time it was a P0193 Fuel Rail Pressure Sensor Circuit High Input
Another time the code generated was for a faulty oxygen sensor.
Then yet another time I took it to a mechanic and he said the code generated meant i needed a new Throttle Body.... So i'm hesitant to throw money and it could be something simple....

Anyone has any ideas??

I noticed someone mentioned the Vaccum Check Valve could that cause an issue like that? And if so would any generic Vaccum Check Valve work or should I try for MotorCraft?

I just starting to read and learn about cars so forgive my car ignorance.....
Thanks in advance!!
 




Rcflyer330

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A vacuum leak could cause that but usually with a vacuum leak the idle on the car is rough. The hissing noise from the check valve comes from the passenger foot well. Also a clogged fuel filter could be the problem. To diagnose any trouble code you would need a obd2 scaner with live data and preferably freeze frame data for when the code was set.
 




Mitchs07explorer

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I was going reading through this thread and I thought I saw a solution but I will post up my problem ..dont scold me if I duplicate.

I have a 2006 Mercury Mountaineer V6 AWD. The problem I'm having is when I'm driving -- over 50 mph I hear like air rushing or being sucked into something.. it is coming from under the hood. If stop on a hill and then try to start moving again it takes a looooong time to climb the hill, feels like it is struggling and does not have much power. I took it to the mechanic and some work was done on it... it was working fine now the problem is back again. Also when the problem was fixed the gas pedal was tight - I had to apply a descent amount of pressure on the pedal. When I pressed on the pedal the car would fly up hills even if I stopped and then accelerated from a stopped position on the hill. When the car was without the hissing sound driving on leveled roads highways and city was great. I was able to feel the power. This was great but short lived. With the problem back the gas pedal does not feel tight... by that I mean I press the gas pedal and it goes almost to the floor.

Also the engine light would come on when I accelerate fast and hard or if im going up a hill at a fast speed. The light would stay on for two to three days and go out. If I accelerate up a hill or drive on highway for a long way the engine light would come. Then three days later it would go out.....and this keeps on repeating..

I had Autozone check the codes for me... one time it was a P0193 Fuel Rail Pressure Sensor Circuit High Input
Another time the code generated was for a faulty oxygen sensor.
Then yet another time I took it to a mechanic and he said the code generated meant i needed a new Throttle Body.... So i'm hesitant to throw money and it could be something simple....

Anyone has any ideas??

I noticed someone mentioned the Vaccum Check Valve could that cause an issue like that? And if so would any generic Vaccum Check Valve work or should I try for MotorCraft?

I just starting to read and learn about cars so forgive my car ignorance.....
Thanks in advance!!
Just like @Rcflyer330 said a clogged fuel filter could be the culprit if you haven't already fixed the issue. My CEL kept popping on when I would drive over 60mph and the code it kept throwing was for a "small evap leak". I changed the fuel filter and it hasn't popped back on, I bought the vehicle at 72000 mi and changed the filter at 90k. I don't know if it ever had been done before that.
 




TroyNJ

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Been looking all over the place for this vacuum hose part # or diameter so I can replace.
Mine was brittle and cracked while flushing my heater core.
Does anyone know the part number for 2009 explorer v6? or even just the diameter so I can patch with some hose?
tube.jpg
 




phoenixs

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Been looking all over the place for this vacuum hose part # or diameter so I can replace.
Mine was brittle and cracked while flushing my heater core.
Does anyone know the part number for 2009 explorer v6? or even just the diameter so I can patch with some hose?
tube.jpg
On my 2009 the line was so brittle it kept breaking so I bought the whloe harness from Ford for $38
The part number is 6L2E 9E498CA there is another line in the harness that goes to the egr and it
gets very brittle also. I hope this helps
 




TroyNJ

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phoenixs

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Thank you I was able to find another part # 6L2Z-9E498-A from searching the part you gave me.

Tube Assembly - Ford (6L2Z-9E498-A) | NewAutoParts

and then found another thread with some additional information
Vacuum harness part number....need help!!! engine light on with wrench


I was able to do a quick patch job while I wait for the part to come. While I was fixing another line from the harness cracked :mad::mad::mad:
Yes that is the new part number the part number I gave you was off the harness and the part number you have is the new
number from ford. I had the same problem as soon as I touched that line it just kept breaking farther up and then the same kind of
line goes to the egr and it broke also so I just replaced the whole vacuum harness.
 




il66pony

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Just noticed the hiss today on my '07 Mountaineer with auto climate control. Will try the check valve and replace if needed. If it is good, I guess I will go under the dash. Does taking out the glove box make the work under the dash easier? If so, is it easy to get glove box out. I am no longer a contortionist.

Thanks
 




Rcflyer330

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Just noticed the hiss today on my '07 Mountaineer with auto climate control. Will try the check valve and replace if needed. If it is good, I guess I will go under the dash. Does taking out the glove box make the work under the dash easier? If so, is it easy to get glove box out. I am no longer a contortionist.

Thanks
I dont know if removing the glovebox will give any better access but if the check valve doesnt work and you want to try its really easy to drop the box door down. Open the glove box and empty it, now on each side of the glovebox there is a tab that you need to get past the dash and the box will drop down.To do this just press inward on each side of the plastic box and the door will drop down.

In all honesty if it was my car I would not even bother trying to test the check valve just replace it with a new one. It is a very common failure item and not that expencive. Plus thay can be hard to test by just blowing into it and seeing if air is escaping. What happens is they will pass the air test just fine but it is actually bad and needs replacement.

Hope that helps.
 


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il66pony

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I dont know if removing the glovebox will give any better access but if the check valve doesnt work and you want to try its really easy to drop the box door down. Open the glove box and empty it, now on each side of the glovebox there is a tab that you need to get past the dash and the box will drop down.To do this just press inward on each side of the plastic box and the door will drop down.

In all honesty if it was my car I would not even bother trying to test the check valve just replace it with a new one. It is a very common failure item and not that expencive. Plus thay can be hard to test by just blowing into it and seeing if air is escaping. What happens is they will pass the air test just fine but it is actually bad and needs replacement.

Hope that helps.
Thanks for the info. Actually, after I posted yesterday, I did buy the Motorcraft check valve off Amazon. $8.00 and will be here Sunday.
 




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