Front diff leak - Requesting advice (3 Viewers)

[itguy]

I want to first say I've read all the posts I could locate on this subject

I recently purchased a 2005 LC with 220k miles. I installed OME 865 springs and cranked the T bars 1" to lessen the rake (still have 1.5" and droop is good) Shortly after this change the passenger side front diff began leaking at the axle. I located service records and it looks like this seal was replaced 3 years ago by the PO and the dealer noted if it begins leaking again, need to look at bearings?

I went ahead and replaced the seal and made sure it was properly seated per the posts on this forum. It was good for 3 days and then it began leaking again. It doesn't always leak if I run out for 15 minutes but it always leaks for longer drives.

I checked the diff breather and it looks like it was changed over the years. There was only a 5" piece of line and then the breather in a U shape. The breather was stuck. I read some more and decided this was a good time to redo the front breather. I purchased fuel line and a filter and ran it up to the engine compartment making sure the runs were vertical.

I've ordered another seal and will tear it back apart, but I wanted to check and see if there is something else I'm missing. I'm not comfortable digging into the diff so if there is something, I'd prefer to bite the bullet and take it to a shop vs me tearing it back apart and checking the seal.

No noise from the diff. Thoughts?

 

[2020 Rocks]

It took me three tries to get the drivers side seal to seat properly. Freezing the seal overnight prior to install may help shrink it slightly to ease tapping it in. It’s critical the mating surface is free of debris on diff tube housing. Inspect and make sure it’s nice and smooth prior to install.

 

[2001LC]

I've replaced more diff side seals, than I can count. Not one has leaked (knock on wood)

Keys:
Use only OEM seal & front drive shaft
Lube seal seating area and seal with gear lube, than install.
Seat level & square with inner lip of diff.
Apply grease on inside of seal and FDS, prep to install.
Use great care during install of FDS, not to knock seal out of alignment.
Seal all the way in, visually inspect and try and pull FDS out.

90 degree screw driver works to correct over-seating-in of seal on drive side only.

 

[Skidoo]

Check the CV shaft where seal rides for wear or roughness.

 

[jahawk]

It took me three tries to get the drivers side seal to seat properly. Freezing the seal overnight prior to install may help shrink it slightly to ease tapping it in. It’s critical the mating surface is free of debris on diff tube housing. Inspect and make sure it’s nice and smooth prior to install.

I've replaced cv's on two trucks and both times it took two to three seals per side to get them not to leak. I've had the best luck with Toyota seals and the worst luck with NAPA.

Jim

 

[flintknapper]

I've replaced cv's on two trucks and both times it took two to three seals per side to get them not to leak. I've had the best luck with Toyota seals and the worst luck with NAPA.

Jim

One of those OEM only items for sure. NAPA are guaranteed to leak.

 

[itguy]

Thanks everyone! We did use an OEM seal and I've ordered two more to give this another shot soon.

 

[thebeedeegee]

2001lc has good advice as always. I got lucky and mine seated first try. My original leak was from a clogged breather line as well I'm pretty sure. Doubt you ha e any serious issues just need to get the seal seated correctly

Is it common to need to replace that seal everytime you replace or remove the CV?

 

[2001LC]

2001lc has good advice as always. I got lucky and mine seated first try. My original leak was from a clogged breather line as well I'm pretty sure. Doubt you ha e any serious issues just need to get the seal seated correctly

Is it common to need to replace that seal everytime you replace or remove the CV?

Unless issue with seal, no.

I replace seal, when replacing front drive shaft FDS. If I'm just pulling and reinstalling same FDS, like for a boot job, I don't replace seal.

Just tapped in a couple more seals today, to go with new 2 new FDS.

 

[DuckLN]

Check the inbound axle shaft sealing surface (as stated above). I think that is an unlikely source but stranger things happen. And of course make sure the seal pressed all the way in but it sounds like you knew that. Weird, maybe there is some pressure building up from that breather clog.

 

[itguy]

Finally got around to checking the seal again. It was pushed in slightly on the right hand side so we pulled it out and installed a new one. It was installed perfectly level, lubed and we were very careful when reassembling everything. The short story is after 50 miles it's weeping again and I suspect it will continue to get worse like last time. It was perfectly dry the first two days and short 10 mile trips.

One thing I just thought about, and I may be overthinking the situation, while I did install a new vent line, I don't recall if I ever confirmed the vent tube/nipple was good. Is there an internal check valve in the diff? Should I open the fill port and then check to see if the air flows in/out through the vent line?

If all this checks out I'm assuming it's something inside the diff so I'll need to take it to a specialist. Unfortunately, the closest place that I found on this forum (Trollholes) is two hours away.

 

[flintknapper]

while I did install a new vent line, I don't recall if I ever confirmed the vent tube/nipple was good. Is there an internal check valve in the diff?

^^^^^

No it's simply open to atmosphere so the pressure can always equalize.

IF it had a check valve (it doesn't) then as the differential cooled it would create a vacuum, sucking IN air/moisture/water/other past the seals.

We don't want that. Worse still would be a 'plugged' vent line since it allows the diff to both BUILD pressure (pushing lube past the seals) AND to create a vacuum (perhaps sufficient to allow water/moisture in).

So...not a bad idea to check and see that your lines and the union at the diff are open.

 

[Skidoo]

Do you know if it is an aftermarket CV axle? Some of those are known to leak.

 

[itguy]

The union is clear so that's not it. On 2/17/17 the dealer installed two reman axles P/N 00016-A5185. The sticker reads "CTPD".

I do want to revisit the dealer replacing the passenger diff seal a month after the axles with a note "If the leak returns the diff bearing will need attention." That's why I thought it may be internal and beyond my capabilities.

You can see the line of fluid dripping past the drain plug. At this time it's not terrible, but I want to resolve.

 

[gatormark91]

Do you know if it is an aftermarket CV axle? Some of those are known to leak.

Before I gave up on them - because they are crap - I received a Detroit Axle CV that I had to send back because the seal mating surface had been machined too far. I knew because the dust seal would just slip on and off by hand. It never would have sealed up.

Maybe try swapping axles from one side to the other and see if the leak follows the axle?

 

[itguy]

Update - Replaced seal and swapped axle..still leaks on passenger side! I did notice the axle definetely has some play on the passenger side vs drivers. I'm guessing it's the bearing as the dealer commented a few years ago.

I talked to a couple local guys and they're telling me it should be a sealed diff/axle bearing that the axle slides into. I viewed the parts diagram, I'm not seeing a sealed bearing. I found part number 9036650001(Front diff case bearing). Is this the right one or am I looking at the wrong diagram? I'm not convinced I will work with them, but I would like to understand what bearing appears to have failed.

 

[itguy]

Well, I guess I'm confused even more now...lol After poking around some more it doesn't look like there is an axle bearing for the passenger side. What supports the axle on that side? Is it the actual "case/carrier" 41302F, since the axle slides directly into that piece?

 

[WiscoLC100]

I was just trying to verify what seals I need for the sides of front diff when my new OEM CV axles show up. Napa said they are the same part number and ordered me 3 (one extra) of these:
Differential Pinion Seal - Front Axle
Part #: OSN 27SS3715

But the Lexus diagram shows 2 different seals 43420H and 43410M

Lexus parts now shows part numbers 90311-47013 for LH and 90311-47012 for RH.

If Napa is wrong, my CVs can't go in this weekend and I the family can't leave for our trip.

Please help!

 

[flintknapper]

I was just trying to verify what seals I need for the sides of front diff when my new OEM CV axles show up. Napa said they are the same part number and ordered me 3 (one extra) of these:
Differential Pinion Seal - Front Axle
Part #: OSN 27SS3715

But the Lexus diagram shows 2 different seals 43420H and 43410M

Lexus parts now shows part numbers 90311-47013 for LH and 90311-47012 for RH.

If Napa is wrong, my CVs can't go in this weekend and I the family can't leave for our trip.

Please help!

They are NOT the same seal. One side is much larger than the other.


Also, the NAPA seals WILL leak on you. Even if not immediately....they will soon.

 

[GVegasG]

Does the new seal seating correctly? Should push in bit more?
Pics of new and old. Thanks