Humming noise on 99 LS400
08-14-13, 03:04 AM
#1
Humming noise on 99 LS400
Tried doing some searches here and I couldn't find anything... Well this problem started this morning. Basically, when I started the car, I heard a "loud humming" I thought it might have been the engine and the belts still cold... But when the engine warmed up I still noticed the humming. When I drive I can hear the humming. The sound matches the revs in the engine... When Rpm drops, humming drops, when rpm goes up, the humming follows, you get the picture...
I'm stumped. I checked engine oil, it's fine. Thought it was transmission fluid, but that's fine. Checked power steering fluid, and that's good... It's too dark to check much else right now, and in planning to check in the morning, but I believe it can be a belt issue... Car has 97k on it. With the timing belt and water pump already replaced by past owner...
Any ideas guys??
I'm stumped. I checked engine oil, it's fine. Thought it was transmission fluid, but that's fine. Checked power steering fluid, and that's good... It's too dark to check much else right now, and in planning to check in the morning, but I believe it can be a belt issue... Car has 97k on it. With the timing belt and water pump already replaced by past owner...
Any ideas guys??
08-14-13, 01:06 PM
#7
http://i710.photobucket.com/albums/w...F442E50D32.mp4
Here's what it sounds like... You might have to turn up the speakers to get a really good listen to the humming...
I'm thinking its coming from the intake... But I might be mistaken... Doesn't seem like it's coming from the serpentine belt... The sounds is coming from somewhere in between the power steering and water pump.. That's my thought...
Here's what it sounds like... You might have to turn up the speakers to get a really good listen to the humming...
I'm thinking its coming from the intake... But I might be mistaken... Doesn't seem like it's coming from the serpentine belt... The sounds is coming from somewhere in between the power steering and water pump.. That's my thought...
Last edited by ItsMiles; 08-14-13 at 01:09 PM.
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08-14-13, 01:45 PM
#9
If it is the electronics on the throttle body, how would I go about checking that? Or repairing that?
08-14-13, 01:55 PM
#10
Pole Position
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i would have the car in park with the engine running and have someone rev it while your under the hood listening. i think the part was the throttle position sensor and it was on the right side of the throttle body.
08-14-13, 03:10 PM
#12
Lexus Champion
you can narrow down the possibilities very quickly by simply removing the serpentine belt (a one minute job) and then crank the car and also rev it (this is perfectly safe, you just won't have power steering, alternator charging, A/C, etc.) and then note if the hum goes away
reinstalling the serpentine belt is about a 2 minute job once you get the hang of it, but if you have never done it before, it could take 15
reinstalling the serpentine belt is about a 2 minute job once you get the hang of it, but if you have never done it before, it could take 15
08-14-13, 04:03 PM
#13
you can narrow down the possibilities very quickly by simply removing the serpentine belt (a one minute job) and then crank the car and also rev it (this is perfectly safe, you just won't have power steering, alternator charging, A/C, etc.) and then note if the hum goes away
reinstalling the serpentine belt is about a 2 minute job once you get the hang of it, but if you have never done it before, it could take 15
reinstalling the serpentine belt is about a 2 minute job once you get the hang of it, but if you have never done it before, it could take 15
08-14-13, 05:56 PM
#14
Lexus Champion
yes
if the noise goes away, then it is something the belt was driving - i.e. A/C clutch pulley bearing, power steering, idler, tensioner, alternator, etc.
if the noise is still there with belt off, then you just quickly and easily eliminated all of those items mentioned above!
if the noise goes away, then it is something the belt was driving - i.e. A/C clutch pulley bearing, power steering, idler, tensioner, alternator, etc.
if the noise is still there with belt off, then you just quickly and easily eliminated all of those items mentioned above!
08-14-13, 06:54 PM
#15
Pole Position
Sounds like a pulley to me. But hard to hear 100%. Like Cowboy said, take the belt off and listen if you dont hear it. I'm guessing the tensioner pulley, the bearings are a common problem. With the belt off (and car not running) reach in and try to wiggle and spin the pulley, see if it wobbles or makes any type of scraping noise.