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2012 Sorento LX 2WD V6
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39 Posts
Discussion Starter #1
I recently started to notice a low slow thump noise during cold warm up ? I start her up and during the first minute or two I can hear thump thump thump every 2 to 4 seconds for the first minute running? I also here a faster thump thump thump as soon as I shut her down ??? It is very low but noticeable, it's very hard to pin point but I believe it might be the fuel system maybe in tank or evap system. I know if I bring it in at this point they will think I'm crazy so I will wait and see if it gets louder ?

3.5 V6 2500 miles
 

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2012 Sorento SX FWD
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47 Posts
I have the same problem exactly as you described. First I thought it was coming from the speaker but later realized it was not.

So far I've been ignoring it without any problem.
 

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2012 Sorento SX V6 2WD Titanium/B&D leather
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309 Posts
",,,I know if I bring it in at this point they will think I'm crazy so I will wait "

Wait? Go when you can.
 

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2017 Sportage SX AWD
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34 Posts
I have the exact issue described here, i have even revived an old thread before i saw this one.
I have a 2012 Sorento SX AWD with build date of August 2011 which i purchased last week.

Thumping noise also happens on cold starts from the right rear end of the car. I already contacted the dealer which stated that he needs to keep it overnight and gave me an appointment for next Monday.

It is very weird for a brand new car. In meantime does anyone have any comments, i would appreciate it.
 

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2013 Sorento ex luxury, 2014 Subaru Crosstrek XV
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82 Posts
I'm thinking along the line of the exhaust system heating up, could be a clamp or hanger.
 

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2012 Sorento LX 2WD V6
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39 Posts
Discussion Starter #7
Maybe, but I can only hear it from the inside. From the outside you can not hear that noise at all.
Yeah exactly ! I tried to listen under the vehicle when my wife started it and heard nothing. but inside it is coming from the rear right of the vehicle ? very well could be the exhaust expanding maybe ???
 

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2013 Sorento ex luxury, 2014 Subaru Crosstrek XV
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Over the years I have found a few odd noises using a mechanics stethoscope, they are not all that expensive and handy to have.
 

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2017 Sportage SX AWD
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34 Posts
I read in another thread that it can be the fuel pump. They said that the sound will disappear if the fuel level is more than half on the gauge and will come back when the fuel level is lower than that.
I have filled up my fuel tank today and will check tomorrow and post results. I do hope that this is an easy fix because the noise is getting anoying. Now the challenge is to get the dealer to hear this thump noise and acknowledge it and find a fix for it.

Vctr,
Try contacting your dealer, two answers is better than one. Can you also tell me the manufacturing date on your sorento.

Is anyone else having this issue, i would really appreciate the feedback
 

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2017 Sportage SX AWD
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34 Posts
OK, so as an update to what i posted above, it does not matter if you have a full tank of gas or not, the thumping noise persists on cold startups. I tried it today with a full tank and sure thing, i can hear the noise.
Well off to the dealer on Monday and hopefully they can hear the noise and fix it. It just too bad for a brand new car to have these kind of issues.
 

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2011 sorento lx V-6 AWD
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71 Posts
This is due to a purge solenoid releasing air or AKA purging while in warm up. although the trans has a hard shift form 1st to 2nd which has not been fixed yet by kia.
 

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2017 Sportage SX AWD
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This is due to a purge solenoid releasing air or AKA purging while in warm up. although the trans has a hard shift form 1st to 2nd which has not been fixed yet by kia.
Thanks 09 sorento for the input.

Would replacing the solenoid fix the problem? It does not seem that this happening on all Sorentos.

In regards to the hard shift from 1st to 2nd, I did not feel that yet or at least did not pay attention to it yet. I will keep and eye and see if it happens in mine
 

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2012 Sorento LX 2WD V6
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39 Posts
Discussion Starter #13
copter7 My build date is January 28 2012.

Thanks for the info 09 Sorento, so the culprit could be a purge solenoid in the tranny ? Would this be a normal sound or could it be malfunctioning ?
 

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2012 Sorento LX 2WD V6
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Discussion Starter #14
I had my wife start the Sorento as I placed my hand on the gas tank and can confirm the thumping is going on inside. It's a very mild thump and I can feel the vibration on the outside of the tank. Why would the pump thump like that and I am a little more concerned now that this involves the fuel system ???
 

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2017 Sportage SX AWD
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34 Posts
I can hear the thump now sometimes when I am driving as well. It is lower then when on startup but can still hear it. It is kind of confusing, if it is really the fuel pump why in some sorentos only.
As I said, I will be taking it in on monday, I just hope I do not get the run around from the dealer.
 

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2017 Sportage SX AWD
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I am hearing the thump now more often, still mostly when cold but i can still hear it when driving.
I am now more convinced that it is the fuel pump and the relay solenoid.
The dealer postponed my appointment till tomorrow so he can get me a loaner. I will take it in tomorrow and see what happens.
 

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2012 Sorento SX FWD
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47 Posts
I am hearing the thump now more often, still mostly when cold but i can still hear it when driving.
I am now more convinced that it is the fuel pump and the relay solenoid.
The dealer postponed my appointment till tomorrow so he can get me a loaner. I will take it in tomorrow and see what happens.
please keep up updated. thanks
 

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2017 Sportage SX AWD
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34 Posts
Finally, i got a call from the dealership service manager and below is what he found.

He stated that the thumping sound is coming from the fuel tank itself, the fuel tank are all now made of plastic and it looks like the one in my sorento has a defect where everytime the fuel pump operate to suck in gas, it creates a suction strong enough to cause the plastic in the fuel tank to pop and make that noise similar to a vaccum effect.
Why can we hear it mostly on cold startup is because the plastic is still cold causing the thump to be louder.

He stated that he was able to replicate that thumping noise by puting his hand on the fuel tank and pushing it upwards, everytime he pushed upwards the plastic in specific places of the tank popped and made that thumping noise.

To be sure, he did the same thing on a sorento that he has in the lot and did not hear the thump. He contacted Kia and they told him to replace the entire fuel tank. He has ordered the tank which will not be in till Tuesday or Wednesday.

I guess i will not be sure until the tank is replaced and i test it myself. I will keep you all posted but for now if anyone wants, they can check their fuel tank by using the above method and give us feedback that will be great.
 

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2012 Sorento LX 2WD V6
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Discussion Starter #20
copter7
Thanks so much for keeping us posted on this. I will use that method and check out the tank when I get home from work today. Please let us know if this solves the issue.
Sounds like this should be a TSB since a few of us seem to have defective tanks, wonder how many others are out there ?
 
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