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Larry T
User
Mar 29, 2013, 3:08 PM
Post #1 of 15
(2130 views)
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Strange car noise
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I have a 2006 Nissan Pathfinder 4WD, 4 Liter DOHC V6, with 5 Speed auto trans. Just under 79000 miles.
It started making a noise that is hard to describe. It sounds like a humming or rumbling noise with minor vibration. It reminds me of the noise when an engine lugs down. I don't think it is lugging down, because the grades are very gradual. Probably not more than 5%.
The noise starts usually at speeds between 30 and 40 MPH when moving at a constant speed and coming to even a very slight grade uphill. If I let off the accelerator or increase acceleration even slightly, the noise stops. Usually I let off the accelerator very brieflly and then resume very slight acceleration. Then the noise/minor vibration starts again. This happens mostly when the engine is warmed up, but not really warm. What I mean by that is that I am a courier and stop frequently, but not long enough for the engine to cool down. Dang, does that make any sense?
The noise started out slightly, but has been increasing in intensity recently. I don't think it is an engine noise, as it seems to be coming from the area under the front seats, or further back, but I am at a loss to describe it further.
I am concerned, but I get no trouble lights from the computer. I have never experienced this with any other vehicle.
(This post was edited by Larry T on Mar 29, 2013, 3:13 PM)
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Discretesignals
Ultimate Carjunky
/ Moderator
Mar 30, 2013, 3:01 AM
Post #2 of 15
(2054 views)
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Re: Strange car noise
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As it is making the noise, with your other foot tap the brake pedal. Does the noise go away?
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Larry T
User
Mar 30, 2013, 2:16 PM
Post #3 of 15
(2028 views)
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Re: Strange car noise
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Thanks for the reply.
I went out today and did what you suggested. First, the noise seemed to be slightly louder than yesterday. I first made a light tap on the brake pedal and there was no change.The noise remained constant. Next, I tapped harder. No change. Then I tapped pretty hard, but still no change.
There is about 1 1/2" pedal travel before I get a hard feel on the brake pedal, if that means anything. As I recall, there has always been about that much pedal travel before feeling a hard pedal, but the vehicle, has always, and still does does begin to slow before the hard feel.
I really appreciate your input.
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Discretesignals
Ultimate Carjunky
/ Moderator
Mar 30, 2013, 2:27 PM
Post #4 of 15
(2026 views)
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Re: Strange car noise
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The reason I asked that question was to see if it was a torque converter issue.
The TCC clutch will disengage if you let off the accelerator, your under moderate acceleration, or if you tap on the brake pedal which activates the brake switch.
You may need to have a mechanic ride with you to help determine and hopefully isolate the noise.
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Larry T
User
Mar 30, 2013, 2:29 PM
Post #5 of 15
(2020 views)
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Re: Strange car noise
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Thanks for the quick response. Have a HAPPY EASTER! I'll let you what I find out.
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Discretesignals
Ultimate Carjunky
/ Moderator
Mar 30, 2013, 2:41 PM
Post #6 of 15
(2018 views)
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Re: Strange car noise
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Happy Easter to you also. We'll keep the lights on. 
Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.
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Larry T
User
Apr 1, 2013, 5:23 PM
Post #7 of 15
(1963 views)
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Re: Strange car noise
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Went to see my mechanic today. He thinks from what I described, that isn't a serious issue. That made me feel good, but he wasn't able to drive the car today. I will go back tomorrow.
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Larry T
User
Apr 2, 2013, 2:43 PM
Post #8 of 15
(1939 views)
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Re: Strange car noise
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My Mechanic drove the car today and thinks it is a bearing, but will need to do further tests next Wednesday. He too thought it might be the torque converter, but pretty much ruled that out after the test drive.
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Larry T
User
Apr 5, 2013, 3:15 PM
Post #9 of 15
(1893 views)
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Re: Strange car noise
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Since I had my mechanic drive the vehicle, I recalled one thing that he didn't do. He never turned off the overdrive.
I have since driven the vehicle several miles and turned the overdrive off. It never makes the noise with the overdrive off. Could it possibly be that with overdrive off, there is never enough pressure to cause the transmission to go into a high enough gear that might cause the engine to lug down? The noise has always sounded to me like an engine that is lugging down.
One thing, that I am ashamed to say, I haven't done was to check the transmission fluid. If it is low on fluid, or if the fluid is dirty and needs changing, could that be the cause?
As you can clearly tell, I am not very qualified to diagnose this problem.
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 5, 2013, 3:39 PM
Post #10 of 15
(1890 views)
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Re: Strange car noise
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That is exactly what DS was trying to find out about with the tapping the brake pedal idea. It would have been a whole lot easier to just take it out of overdrive like you did.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Larry T
User
Apr 5, 2013, 4:18 PM
Post #11 of 15
(1880 views)
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Re: Strange car noise
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Hammer, If you read the entire post, it would appear that DS was thinking there was a torque converter problem. He didn't mention a fluid problem.
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Hammer Time
Ultimate Carjunky
/ Moderator
Apr 5, 2013, 4:26 PM
Post #12 of 15
(1877 views)
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Re: Strange car noise
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Don't worry, I read it. Locking up the torque converter is how you get overdrive. Taking it out of overdrive disables the TCC solenoid.
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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.
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Larry T
User
Apr 16, 2013, 11:53 AM
Post #13 of 15
(1826 views)
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Re: Strange car noise
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I had the Pathfinder in the shop to try to diagnose the problem. They were unable to duplicate the noise on the lift so they could get under it and try to isolate the noise.
I asked the mechanic if it might be a problem with dirty fluid. He said he checked the fluid and it appears clean enough, that there should be no problems with it. Then I remembered a letter that I got from Nissan indicating a problem with 2005-2010 Pathfinders related to a possible leak of coolant into the transmission. The mechanic said that he didn't see an indication of coolant in the transmission, but he also had not drained the transmission, or removed the pan. He suggested that I take the vehicle back to Nissan and have them check it. Nissan has increased the warranty period on the transmission to 8years/80,000 miles for this problem, due to a class action suit that has been filed. The warranty is increased to 9 years/90000 Mi. with the owner paying $2500 co-pay, and then to 10 years/100,000 Mi. with a $3000 co-pay.
The vehicle currently has 79738 mi. on it. I am leaving for the dealership as soon as I finish typing this post! I don't have much mileage to spare!
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Larry T
User
Apr 20, 2013, 1:47 PM
Post #14 of 15
(1798 views)
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Re: Strange car noise
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I got good news from Nissan. They are going to replace my transmission and radiator assembly under the extended warranty.
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nickwarner
Veteran
/ Moderator
Apr 22, 2013, 2:12 PM
Post #15 of 15
(1787 views)
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Re: Strange car noise
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An excellent result for you. Thanks for following up on the thread with us. I'm going to lock this thread now so that nobody but moderators can post to it. That way a year from now someone can't just throw on their own post which will put an e-mail notice in everyone's inbox who has ever posted to it. If you need to reopen this thread you can send a PM to any mod and it can be unlocked.
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