front diff under pressure?

[usnick1982]

I decided to do my 120K oils by myself today and it was all success with rear dif, transfer, engine oil even loosened kdds valves and lubed them too however really hit the wall with front diff. The moment I loosened the fill plug I heard a whiff of a sound and as soon as I removed it oil started to come out from the fill hole...?? Car was on front jacks may be 1ft clearance from tires to ground but still oil should not come out from the fill plug right? I could not loosen drain plug at all after multiple attempt with wd40, pb blaster and ended up stripping it... I could not fill any more oil into the fill as it was still at the opening level already.. I put the fill plug back and going to drive on it tomorrow. What should I do? How the hell dealler overfilled it ? supposedly dealer changed it at 30,60,90K.. Today diff was cold and I am thinking driving it and then try to chisel the plug. would it be ok to use butane torch to heat it up? I was a bit concerned with all the oil around making fire.

 

[CJ3Flyer]

Meh... I have seen several front/side fill diffs seemingly overfilled. Just a couple of degrees of “crooked” on a lift can get an extra oz or two in there. I wouldn’t worry about the overfill.

As far as the drain is concerned I’d get a new one and then whack it with a chisel.

As far as the whiff sound is concerned. Are you confident it was pressurized? Could it have been suction? I can explain a suction.

 

[Mogwai]

You can try the chisel but the easiest way is to put a hex socket in there with a couple spot welds, it will come out easily with a wrench and some leverage. Have a new plug and washer ready of course.

Re: pressure, I'd check your diff breathers, probably clogged.

 

[usnick1982]

yes I guess it could have been suction noise. I just assumed it was pressure as oil was coming out. No ability to weld but did have success with chisel on rav4 diffs. I specifically asked dealer to change oil every 30... thx! just ordered lexus drain plug with hex

 

[CJ3Flyer]

With persistence and a chisel and/or good ctr punch I am confident the drain will loosen. Don’t undersize the hammer or punch.


Show no mercy.

Some residual suction is not uncommon. On the vent lines they often install a check valve to ensure no water is ‘sucked’ in.

 

[bloc]

These do have a diaphragm valve at the end of the breather. When the diff is cool it can have a slight vacuum.

Be very careful chiseling on that thing.. they tend to lock up and get very tight, and you don’t want to mar the sealing surface of the diff. You can also try hammering along the threaded axis around the edge of the plug in an attempt to crush the copper gasket a little further.

Use the correct torque spec for the new lexus plug and it’ll be much easier in the future. It’s surprisngly little torque for such a large thread diameter.

Oh and front tires in the air one foot will definitely throw off the correct fluid level, and can explain oil streaming out. When filling either put the rear in the air as well, or go rear up only and go by the specified volume not by overflow from the fill hole. I’ve been using an incline and 150mL syringes for diff and xfer fills lately and had almost zero mess.

 

[coleAK]

Mine was stripped out when I went to do the fluid at 60k, the dealer must have stripped it putting it back in at 30k . I got it out by hammering a torx bit into the hole then using a 40” breaking bar.

 

[usnick1982]

To follow up: i got the old plug out with chisel and simultaneous torque on left over insert. I got a new lexus plug with hex 90341-24016. It is shorter 12mm vs 17mm. Diff drain hole depth is 20mm.
Do you folks think 12 mm minus gasket enough to hold it?

 

[usnick1982]

Also changed diff breather. Old on was a little tight to exhale. It was easy to reach from ledt wheel well taking one clip off small plastic panel on the right

 

[usnick1982]

Old breather had small amount of oil on rubber flap perhaps making a bit more difficult to exhale when i compared it to a new one

 

[bloc]

Thread length is more than enough given the very low torque for such a size.

The breather was likely just fine. Millions just like that have been in service on toyota diffs and transmissions for decades and a little residual oil is to be expected. More likely it had a light vacuum when cold as designed due to the rubber diaphragm and spring. This helps prevent leaks by the way.