2008 is250 hum noise differential louder with speed
#1
2nd gear
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Join Date: Aug 2022
Location: Massachusetts
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2008 is250 hum noise differential louder with speed
Had this issue noticeably start over a year ago, since then I have had all 4 new tires put on, wheel bearings, recently both front axles which i thought could help but didnt. The hum starts softly at 30mph then gets louder with speed til about 65 on the highway then it's a constant pitch or tone that doesn't get any louder. Then its a loud road noise, not much if any vibration associated with it. My mechanic said it was hum coming from the upper differential which in this model is tied in with transmission. Sealed transmission at that so I changed the fluid, didn't help. Anyone experience this? Such an annoying noise, 180k on it now had it since 70k have taken great care of it. Is it a warning sign transmission is on its way? Any advice or feedback is greatly appreciated!
#2
Instructor
is it awd? did u change fluids on front, center and rear diff? and was it top up properly?
#3
2nd gear
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Yes is awd, the front differential shares fluid with sealed transmission that fluid was changed, I wasn't aware of a center diff and it having its own fluid? The rear differential fluid was not changed. I didn't know they had independent reservoirs. Drove it today now feeling a vibration with the hum. Even on deceleration in between 25-60 mph.
#4
Instructor
That's the first time I ever heard of differential sharing fluid with transmission. They are two separate units and both use different fluids to operate, WS fluid for transmission and 75W90 gear oil for differential. If someone put the same fluid in tranny and diff you're in trouble.
Might wanna find out exactly what went into your transmission and how much fluid was pumped in as this is critical in those vehicles.
Lots of info covered on the subject, use search window.
Might wanna find out exactly what went into your transmission and how much fluid was pumped in as this is critical in those vehicles.
Lots of info covered on the subject, use search window.
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2013FSport (08-15-22)
#5
Lexus Test Driver
iTrader: (2)
That's the first time I ever heard of differential sharing fluid with transmission. They are two separate units and both use different fluids to operate, WS fluid for transmission and 75W90 gear oil for differential. If someone put the same fluid in tranny and diff you're in trouble.
Might wanna find out exactly what went into your transmission and how much fluid was pumped in as this is critical in those vehicles.
Lots of info covered on the subject, use search window.
Might wanna find out exactly what went into your transmission and how much fluid was pumped in as this is critical in those vehicles.
Lots of info covered on the subject, use search window.
It's the first time we've heard of it as it's incorrect information!
The front and rear diff's are hypoid gears that take GL-5 (GL-4?) gear oil. The transfer case takes ATF as does the transmission.
I'd suggest OP find a new a new mechanic and get all the fluids changed ASAP with synthetic.
Too bad all that money was spent.
#7
Lexus Test Driver
iTrader: (2)
I bought used diff to keep the 350 RWD on the road while the original diff gets a dose of LSD.
The used diff sings under light load making a 'whirrrrrrrrrrrrr' sound at steady state cruise.
Light or hard acceleration, it's quiet. Minimal or maximum engine braking, it's quiet.
It had 93k on when pulled from the donor. It also runs about 60° hotter than mine before I pulled it (162°F vs 102).
I'm just saying, even a Lexus diff can go awry. Thankfully this is temporary use only.
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#8
Instructor
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I'd really lean into replacing the tires but that's me. I had the same process done (fluid changes for front/rear diff and transmission) , and also went to several Lexus shops and had them thoroughly check the wheel bearings - the last shop called it and told me it's my tires since they clearly checked all the possible parts that would cause it.
#11
Lexus Test Driver
iTrader: (2)
Your saying your own rig makes noise?
#12
Instructor
iTrader: (3)
No, I'll be doing it myself. Likely post it in my build thread with a write up. I've never done Yoda, but about 50 others. Only had one whine which was a used gear set to a different case. I bought off craigs list for drag strip use, and I'm guesting its prior life hosed it up.
Your saying your own rig makes noise?
Your saying your own rig makes noise?
#13
Lexus Test Driver
iTrader: (2)
That said, straight cut gears like in a motorcycle transmission do get louder and louder as the load increases. Well, to a point.
#14
Lead Lap
iTrader: (13)
Here's the information on the front differential.
https://www.clublexus.com/forums/is-...l#post10282976
Also the information on the transfer case combined with the AWD transmission.
https://www.clublexus.com/forums/is-...ase-fluid.html
https://www.clublexus.com/forums/is-...l#post10282976
Also the information on the transfer case combined with the AWD transmission.
https://www.clublexus.com/forums/is-...ase-fluid.html
#15
I'd really lean into replacing the tires but that's me. I had the same process done (fluid changes for front/rear diff and transmission) , and also went to several Lexus shops and had them thoroughly check the wheel bearings - the last shop called it and told me it's my tires since they clearly checked all the possible parts that would cause it.