New Owner Trouble

My first post so bear with me here, about a month ago picked up a 2009 4x4 dcsb with 200k, my first (finally) tacoma, let alone own truck. Quickly started to notice the neglect and some maintenance here and there ive finally found myself dealing with this issue. Issue: leaky pinion seal on rear diff. Noticed gear oil caked on my undercarriage for who knows how long…took fill plug off rear diff and oil was sitting about 5mm below so thought everything okay(previous owner probably filled right before sale) i continued keeping an eye on it the gear oil level and checking for more leaked out oil, cleaned my undercarriage… leak got worse. Brought to a shop with original plans of only doing pinion seal, he drains my fluid and gives me a call saying a full rebuild should be needed, keep in my mind my knowledge is limited but immediately I asked why, says shavings are present in the drain plug. If i figure out how to include an image i will update it and attach it, image showed usual amount of shavings for a truck that was probably neglected and never serviced this gear oil for who knows how long. I asked did you inspect the teeth, he says no that would require the case to come off. I asked why no premature signs of wear, humming, grinding, loss of power, says big tires might block the sound. I asked if he ran it on the lift…no. All in all felt rushed to a 2900 rebuild quote so left, after being charged 120$ for a “diagnosis ” and the replacement gear oil. BS bc I could've drained it at home and told myself the same thing. He said would not replace only the pinion seal because the bearing had excessive play and the crush washer could damage it more after replacing. I took it to another shop where the guy immediately made time to drive the truck with me, said i feel no rear end or hear no rear end issues. Took driveshaft off and disagreed that bearing had went bad, Went back to the shop and recommended buying a yukon pinion yoke, and replacing that and the seal as replacing just the seal the leak might still be there. Now im here writing this post. Much rather would spend the 100$ ish on a yukon yoke and have that installed and get the most life as possible out of my rear diff, rather than jump to a conclusion of doing a 2,900 rebuild. Now im at the point where im looking for the correct part and struggling to find out the needed spline count for my truck. I narrowed it down to having an 8.4 open diff pretty sure, but am reading different things online about 27, 29, or 30 spline. And on yukon website it shows that a 30 spline is compatible with my truck. Thanks for any replies!

 

Here are 3 images, briefly shows leak on pinion seal and spray onto gas tank when driveshaft spinning faster(leak never pooled on floor, only collected on undercarriage) drain plug from rear diff with what appears to be a chunk, and then shavings. And a picture of the stamp on the dana driveshaft to potentially help show which yukon yoke is compatible. Thanks

 

You probably need a pinion seal and maybe replacement gears

 

Meh, I've seen worse on a magnetic plug. I'd run it as long as it's not making noise and shavings dont get worse in a few thousand miles.

But the pinion seal is indeed leaking. it's one of the more difficult seals to replace because the torque on the nut effects the gears. Most of the time you can pay very close attention to the position of the nut and make sure it gets back to that spot.

 

I was guilty of not reading OPs post on my previous reply. So I put in a couple carriage returns since that wall of text was difficult to read and quoted it.

Replacing the yoke makes things a lot more difficult with pre-load on the bearings since the pinion nut sets that. HOWEVER if there is a deep groove in the yoke, then it needs to be replaced since the seal will never be able to seal.
If you keep the existing yoke you can likely just replace the seal by putting the nut on the same amount. I did this to my 3/4 ton chevy a few weeks ago. It was even called out in the Chiltons repair manual. I am reasonably sure this can be done on the toyotas too. However if you replace the yoke you need to remove the whole differential 3rd member and reset the pre-load the proper way since it's a different part.

Sounds like that first shop it fishing for expensive work, I'd not go back there. That second shop sounds much more reasonable.

ECGS will sell you a complete third for like $750, plus core. There are a number of Toyota 3rds on my local marketplace too (but I am in a lucky market)

 

Just replace the pinion seal and move on lol. It's a wear part.

 

Agreed^ I would replace the pinion seal and just ride it out.

I could search around for some DIY materials if you’re in need OP. Just replaced my pinion seal a few months ago after I developed a leak after lift. i used a combination of info hear on the forum and YT videos.

previous comment about the proper tension on the nut is absolutely true. But it’s accepted that you can return the stake nut to the same position by counting the threads and aligning and such. In fact, my tension nut was well marked and it was easy to return it to the original position and re stake.

it’s a slightly ambitious DIY job depending on your skill level but I survived it.

my biggest issue was actually getting the new seal placed. Despite leaving it in the freezer, and lubing it with diff oil it was very tight. I had a mechanic friend recommend silicone lube to have on hand. I was cheap but you should have some. Any other lube may damage the seal.

 

Agree with replacing the pinion seal. I don't see any indication you need new gears.

 

Hm, okay thanks for the reply, that was a little bit of my frustration as the guy at the first shop never mentioned gearing or anything, just kept using the word rebuild, maybe an excuse to regear haha. Im gonna try a yukon yoke and seal and keep my eye on the shavings in the next miles im using the truck, thanks again
billy

 

Thank you for your reply, for my next posts ill work on narrowing down my info as it seems I took a large paragraph to explain what couldve been a few sentences. The problem with just replacing the pinion seal is that every shop around me has denied doing just that, the second shop said something similar to that if I can remember, a grove in the system will cause the seal to never seal, which happened after the first time replacing. He then mentioned the yukon yoke and seal replacement as a solution instead of a rebuild. Ill be to sure ask about the needed preload if this part is replaced

 

As much as I wish I could give it a shot, I wont be with this one because I just know something would wind going wrong, and with how I want to maintain this truck to maybe squeeze what life is left in it id rather hand if off to someone with way more experience. My DIY for now is topping off the fluid which is barely needed, I only drive the truck to work in the morning, no highway driving. I ordered a yukon pinion yoke as the guy at the second shop told me to do that since the original pinion seal replacement started leaking the next day after replacement. Should i just make sure the the preload and nut is set correct while this new part is installed, and if so everything should be somewhat okay?

 

Yeah i know, my long message of a bunch of words scrambled together has kinda stemmed and made this issue bigger in my head. Calling 20+ different transmission/differential shops, normal mechanic shops, not one wants to take a job for ONLY the pinion seal. Get reffered to one guy, call, and its a different excuse why they cant do the job. So now this guy that has reccomended the yukon yoke is the only guy willing to help me out it seems like.

 

and dealership quoted 937$ or something crazy

 

do you have any idea about pinion spline counts in these 2nd gens? everything online is just confusing me more. Yukon website has it saying a 30 spline fits my tacoma but dont want to get to the shop for install and be wrong.

 

OP, if you are reasonably mechanically inclined keep in mind you can get a brand new rebuilt differential for ~$800. If shops want to charge you $1,000 for a seal, this might make it easy to DIY it amd know you get a good setup.
https://eastcoastgearsupply.com/i-788575-tacoma-8-4-non-eld-t100-tundra-3rd.html

 

For replacing a seal? That's silly. This is two hours in your driveway with a good impact wrench and a seal driver (take the seal to Home Depot and find a matching PVC pipe). Measure the pinion nut depth before and after to maintain the same preload.

In 2020, I had to remove the drive flange to hammer back the dust shield that got bent on the trail, similar level of disassembly.