I recently replaced the fluid in the front/rear differrential, transfer case and transmission on my IS250 AWD. I was reluctant to replace the transmission fluid since there's been conficting opinions on replacing and not replacing the fluid in the transmission. Since the transfer case and transmission uses the same fluid reservoir, I drained and refilled with Amsoil. I did the same for the rear differential and front differential. For the first day or so I had no issues but a few days later, I noticed that the front differential started to slowly leak.





The leak is not from the fill or drain plugs. Upon further inspection and wiping up the leak around the differential, I noticed the leak was coming from here:



Does anyone know if there is there a top breather on the front differentials on the 07 IS250 AWDs or are they sealed units? I may have overfilled the front differential and it's sloshing around and coming out of the differential breather. If it's a sealed unit, does the output shaft seal need to be replaced? Is that labor intensive to do on these cars? I searched high and low on the internets and couldn't find anyone with a leaky front diff. Thanks in advance!

 

All differentials have some sort of venting, to prevent pressure changes from the increase and decrease of fluid temperatures. Certainly possible that you overfilled, and it is now coming out of the vent. I have also heard of issues using synthetic gear oils after a lifetime of using conventional. Something about the synthetic fluid being too slippery, causing seals to leak. Dont know how much truth there is to that though...

 

I have the same problem. Have you found a fix?

 

I've done the repair, have to remove the Front differential and replace the seal on the oil pan. The ones I've repaired were leaking on the oil pan side not the Differential side. I guess because the oil is thinner in the oil pan.

 

Ok. Thanks

 

isfdude,

I'm trying to help out a friend who's front differential is fubar. You mention you've removed it to replace the seal. Could you briefly describe how you removed the front differential? Any help would be greatly appreciated.

Thank you,

MJB

 

Sorry to bring this thread back up but mine is doing the same thing. How long of a job is this and could you give a quick description of what needs to be done? Where did you get the seal, what is it called, and do you have a part number? Thanks.

 

Really? No one?

 

Your axle seals are leaking. since you changed out the old fluid, the new fluid is less viscous and leaks out of the worn seal. what grade gear oil did you use? try getting some lucas oil stabilizer and topping off with that. I am changing the axles on my GF's 07 is250, and just got the seals the other day. Ill have an OEM part number soon. and it took them 7 days to get from warehouse(my fault for ordering right before holidays)
is250 axle seal 90311-43005

 

was this a hard repair? would the shop charge an arm and leg? if it is oil from the oil pan, if i make sure my oil level is good always, do i have to rush to repair?

 

Hello,

I see that you have replaced the front def. Was that on the 07 IS250? if so, were you able to do it with the motor in the engine bay or did you have to drop the engine?