My RX-8 is all grown up now.
 

It's has its very first fluid leak. Awww...

So I took it in for an oil change, and the tech noticed the pinion seal on the differential (where the driveshaft enters the diff case) is leaking and spraying oil in a circle, including onto the exhaust. That explains the faint whiff of burning-oil smell I've noticed lately.

The indy shop says it's 7.3 hours of labor to pull the diff and replace the pinion seal. That'll be about $1000, not including the part which they can't seem to find from their OEM vendors. I sure hope my warranty covers this. I can't just let it continue leaking indefinitely, because I have no way of monitoring the oil level in the diff.

Hi M8....

How many miles on your S2 and how often did you renew Diff oil?..

I think you have a Manual?...can't remember, it would be good if you added some details about your car in your Sig (see User CP).

Anyway...I am almost certain you will need to go OE for the Pinion Seal.
I guess yours is LSD.

RA03-27-165A Pinion Seal Manual (LSD)
RA02-27-165 Automatic Trans

Wow, 7 hours, why are cars so complicated today, early RWD Mazda's from the 80's and 90's you could change Pinion Seal in less than an hour, no removal of Diff, just Prop Shaft and pop out seal, and whammo!

Good Luck :)

Interesting - I had my pinion seal replaced under warranty at 28k miles, with similar symptoms. I have a 2009 Sport Manual. 35k on it now and no issues since the repair.

Initially the dealer diagnosed the "leak" as residual cosmoline from the factory and told me the seal was fine... I won't let this dealer even change my oil now.

FWIW - My diff fluid was changed at 18k with Redline.

2009 Touring Manual, 28000mi/45000km. I changed the fluid at 5000mi to a group 5 synthetic, determined it was too slippery, and changed it again at 10000mi to Redline MT90.

Yes, it is a limited-slip diff. When I rotate one wheel while the car is on a lift, the other wheel rotates in the same direction, and the driveshaft rotates as well. An open diff would allow the other wheel to rotate in the opposite direction, and the driveshaft wouldn't rotate at all.

There is no way to mistake this for residual rustproofing from the factory; it's a fresh stripe of dark-brown oil on the underside of the car and the top side of the exhaust, surrounding the location of the pinion seal.

I figured I'd have to go OE for this part. Changing seals on rotating parts is generally far too much of a pain in the ass for there to be any reason to bother with possibly-inferior aftermarket parts, unless there is a known defect in the design of the OE part.

The driveshaft doesn't appear to have a universal joint at the diff end; instead, it appears to have a metal-reinforced rubber disc sandwiched between the end of the driveshaft and the attachment point on the pinion shaft. It might be easy to disassemble, it might not, but access to the pinion seal is nearly blocked by the structural support bolted to the bottom of the diff. So I'm going to guess, the reason why this job takes so long is because the driveshaft tunnel is reinforced for stiffness, and the reinforcements need to be removed.

Glad to hear your seal got replaced under warranty, 2nd_RX8. Hopefully my local dealer will be as cooperative.

Skill level B 5.1 hours/ MfgWarranty 6.8 hours/ Standard



The labor times from the repair manual are for removing the Differential Assembly
and setting it on the bench to replace the seal. There is no need to remove the diff assembly
to change the Pinion Seal. (1.4 hours @ $108 labor plus $9 for the seal.)

Any idea why they would want to remove the diff if it isn't necessary? Maybe having a firm surface to brace the diff on is helpful when seating the new seal?

Removing the diff assembly makes it easier to "correctly" reset the pinion bearing preload, prevent bearing failure, and gear whine. It also allows for the replacement
of the side seal( axle output seals) at the same time as the pinion seal.
--

Okay. Is there any reason I wouldn't want them to do it the best possible way, since I have no way of monitoring the oil level in the diff without putting the car on a lift?

Damn man that sounds like a pia! maybe try and use one of those seal cleaner things they make for dirtbike fork seals and see if that will work lol they're only like $6 I thnk lol

Not sure how a seal cleaner would fix a seal that's already damaged enough to leak. Driveshaft seals aren't like suspension fork seals on a dirt bike; they're exposed to constant friction whenever the vehicle is moving, not just intermittent friction when the fork compresses or rebounds, and the wear pattern is rotating instead of sliding. It's unlikely that dirt would ever work its way into a rotating seal, lifting the seal away from the driveshaft and allowing fluid to leak out, because there's no sliding motion that could pull dirt into the seal. The pinion seals on my car must've just worn out prematurely. Fortunately, that's what warranties are for.

Anyway, I took the car to the dealer on Thursday and just got it back today.

At first there was some discussion about whether the oil leakage was really coming from the pinion seal, and then I pulled my flashlight out of my pocket and pointed it at the burn-mark on the exhaust. They bought my explanation that an oil leak from the transmission couldn't have produced such a clear mark on the hot exhaust pipe, even though it might explain oil spatters along the length of the transmission tunnel. However, because of those oil spatters in the transmission tunnel, they determined that the transmission was leaking fluid too -- the seals at both ends of the driveshaft were leaking, one on the diff casing and one on the trans casing. Not sure if it was the Redline fluid that did it, or the even fancier stuff I tried before, or if the seals were just defective.

Both seals were replaced under warranty. I sure am glad I didn't postpone the oil-change that discovered the leak; my "everything but the wipers" warranty runs out on October 23rd.

God dammit.

I drove the car to work and back today, and I have several observations.

1) The shifter is no longer perfectly-centered in the console, but appears to be very slightly forward and right of the center position.
2) The shifter (and by extension, the entire transmission) appears to be tilted very slightly to the right.
3) 4th gear now pops out about 50% of the time after I upshift while accelerating.

#1 and #2 might be my oversensitivity, and they might be well within the range of normal positioning. It's only barely visible, and even then I could be imagining it. #3, however, is impossible to ignore. Someone has got some 'splainin' to do.

Took it back to the shop today, with the complaints I mentioned above. I also mentioned it felt like the rubber weather-seal under the leather shifter boot was binding. They pulled up the leather boot and adjusted some stuff underneath, and now it works right again. Here's hoping it stays that way.

I heard there are some special procedure to ajusting the 3-4 gear, I dont know to what extent but it could have been your probleme if they disconnected the shifter from the tranny

It might've been that, I dunno. When I got the car back the shift knob was crooked, so I know they had to fiddle with stuff under the shifter boot. It might've just been the weather seal they needed to fix, it might've been more involved, I dunno.

...aaand my battery died. It started acting weak on Tuesday and by Friday morning I had to get a jump-start. The alternator seems to be fine though, because the voltage while the engine was on was 14.5V. I have a few days left on my warranty, so Mazda covered the labor and 25% of the battery cost. There goes a cool $100.