d1deuce

I have a 99 ls400 and when I accelerate to to 40mph , there's a whining noise. But only a around 38-41 mph is when you can hear the noise, before or after that there isn't noise. But it gets loud if you stay at around 38-41 mph. What can it be?? It sounds like the noise is coming from the rear. Could it be a wheel bearing? I've not had a chance to lift the car up to see if the wheel has any play but will do so tomorrow. But if it is a wheel bearing, wouldn't the noise be consistant instead of only at 38-40mph??? Any help will be great!!

sam12345

iTrader: (1)

could be ro your rear end. Check rear end fluid level (differential).

Alexis-LS

Yep, sound like the rear diff.

d1deuce

I'm sorry but I'm a noob on changing the fluids on the differential. I would think it's just a bolt for the drain and a bolt to fill? Am I correct?? What fluids do we use for the differential??? Thanks for you help you guys!!!

JAndersson

Maybe this information from lextreme.com would help?
http://www.lextreme.com/differential.html

d1deuce

Thanks but I found out on a different site... Well, I went to the parts store and bought myself some 75w90 royal purple did the gear oil change and drove it around for 20 mins and the sound at 38-40mph went away. At first it the whining noise was still there at 38-40mph but after 20mins of driving it went away when I went up to speed!! Hopefully it's gone for sure!!!

JimsGX

Did you see any metal shavings on the magnet of the differential drain plug? If not, it may be just normal pinion wear and your all set.

d1deuce

No metal shavings, thank god!!!! Thanks again u guys!!!!

tromly

hey that's great news, you just saved yourself a bundle !

d1deuce

Okay, now today the noise started to come back. Dammit!!!! So would it be just the pinion that I have to change to make the noise go away? Or Should I do a whole overhaul and change the differential and everything else???

JimsGX

I'd bring it to a mechanic you trust and have him run the car up to the 38~41mph range with it all the way up on the lift. A good mechanic will have a mechanics stethoscope he can use to determine for sure where the noise is coming from. Please don't waste your time and money replacing parts until you do this. Been there, done that...

Jim

d1deuce

Yeah, I'm gonna take my car to the dealer to see what the problem is and to see how much it'll cost me. I don't know any mechanics that I can trust around here so the dealer is where it's gonna have to be...

d1deuce

Ok now the noise is on and off at times. I'm still gonna take it into Lexus to get it checked up to see what's wrong. Hopefully it's not anything huge...

B-b0y

iTrader: (2)

Keep us posted! I have the same problem on my '95, gonna change the diff fluid today and see where it takes me...

sam12345

iTrader: (1)

Could be the bearing also. Did you look at the fluid in your drain pan very carefully? Did you strain it to see if there was metal fillings or worse yet one of the teeth in it? Also from what I have read on differential fluids Royal Purple is not that good. Another cheap fix if you are sure its the actual differential is to put the thickest fluid you can in the back like 75W-140 may give you some more life from an old differential. (temporary fix)

Good place to research on oils and fluids

http://www.bobistheoilguy.com/forums/ubbthreads.php