Odd LR4 Noises

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richg

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So I'm a new owner of a 2012 LR4, 33K miles on it. Have noticed a couple noises that seem odd.

1. Have some ticking that is noticeable at idle and lower RPM (up to ~2K or so). It is NOT injectors and does not sound "normal", but haven't heard any other 5.0V8 LR4's to compare it to. Sounds valvetrain related based upon pitch and frequency. Doesn't matter if cold or hot, can hear either way. Took it to the dealer for this one, but they say the noise is too faint for them to diagnose yet. They don't feel it is timing chain tensioner related, as in their experience you hear that when cold and it makes a big racket. Basically told me to bring it back when it gets worse (still under warranty).

2. When sitting at idle with radio off, sometimes I hear what sounds like an electric motor hum noise coming from the passenger dash area. Goes for a few seconds then stops. Then happens again within less than 30 sec - 1 min. I tried listening at the engine bay to see if it was coming from there, but I couldn't hear it or it didn't happen while I was listening.

Anyone else experience these?

Thanks

Rich
 

cperez

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I hear the second sound you described fairly regularly. It is a two-tone sound with a duration of 1 - 1.5 seconds. For me it doesn't occur all the time but goes in spurts both while parked at idle or when underway. This is in a 2011 HSE w/67K miles.
 

jaguardoc504

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Sounds like what you are hear hearing is one of two mechanical fuel pumps in the front of the engine.
Given these are direct injection the fuel pumps run at about 2500PSI. I've had the "tick" since about 20K (2011 68K currently) on the clock. They can be very loud, and are expensive to replace. Which will only be done if they throw a code under warranty, not for a noise.

The other noise is called a HVAC reciculation valve. It basically takes the "pressure" of the interior and equalizes it to the outside air. can happen quite often or not at all. It because our interiors are so well sealed that the pressure equalization has to take place or we would feel the difference (think ears in an airplane, though not quite as severe)
 

samcarloso

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Yup, I get the humming noise quite frequently. It sounds like a cellphone vibrating in the glove box.
 

cperez

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Thanks JagDoc for the HVAC recirc valve theory. Without anything to go on my original thought was that it was HVAC-related but I wasn't aware of this valve. It did strike me as a "normal" (if formerly inexplicable) sound.
 

richg

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Thank you for the reply! I thought it might be something with the HVAC as it seemed to correlate when I had the HVAC going with fresh air coming in, I didn't seem to hear it.

Regarding the fuel pump, yea, I could see the noise being due to that. Where are the pumps physically located on the engine? I ordered the shop manual for the truck but don't have it yet.

Thanks again,

Rich
 

jaguardoc504

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Regarding the fuel pump, yea, I could see the noise being due to that. Where are the pumps physically located on the engine? I ordered the shop manual for the truck but don't have it yet.

Thanks again,

Rich

They are both on the right side of the engine under a cover.
Here is a pic from the workshop manual (circled parts)

Now that i look at the picture, i'm sure it's the tappet that is making the noise.
 

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richg

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Gotcha, cam driven pumps. The noise totally does sound like a bad valve lash adjustment or bad hydraulic lifter, and from the image showing the design I agree with you completely this definitely could be the source. I'll take a better listen in that area to see if I can confirm that is the source.
 

NASdiesel

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Richg, did you ever determine the cause for the 1st issue? I have a similar noise based on description. Rhythmic, with RPMs, disappears about 2K, but audible (very) at low RPMS.
 

richg

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Sorry for the delayed reply. Haven't done anything more with it (truck runs fine and have been sidetracked with other things). My warranty is good for another few months so I was going to wait it out a bit longer and then take it in. I do believe it is coming from the mech fuel pump though.
 

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