Transmission is out, good time for rear main seal replacement?

**Gaki** · 06-19-2013 12:11 PM

I figure it wouldn't hurt but mine isn't currently in bad shape. While the transmission is out, would you recommend changing it anyways or leave it if it's fine?

thanks!

**Fourplay** · 06-19-2013 12:15 PM

I'm of the school of thought that if there's nothing wrong with it (no leaks or damage), then leave it. It would suck to replace it and have it not seal perfectly and then have a leak where before there was none (having to pull the engine again always blows).

**17708** · 06-19-2013 12:16 PM

do it!
if you plan to keep the car for a while, i would do it now.
the part is super cheap, its the labor that costs an arm and leg.
if you have the trans out, its the best time to do that.

my wifes bmw is leaking out the rear main seal and the shop quoted us just for labor 9-10hrs @$120/hr.

**17708** · 06-19-2013 12:17 PM

Originally Posted by Fourplay

I'm of the school of thought that if there's nothing wrong with it (no leaks or damage), then leave it. It would suck to replace it and have it not seal perfectly and then have a leak where before there was none (having to pull the engine again always blows).

if you do everything right, it shouldnt leak.
use any sealants or whatever it asks for, and torque everything down,ect.

**waB5S4** · 06-19-2013 12:22 PM

Originally Posted by 17708

if you do everything right, it shouldnt leak.
use any sealants or whatever it asks for, and torque everything down,ect.

That would be the general thought process but we're dealing with the 2.7T here..

I did a lot of looking when I had mine out and decided against it.. If it isn't leaking now then you only have to worry about natural failure. If it is leaking now, you have to worry about natural failure on the new one AND properly installing it.

Either way you're looking at doing the labor some day. This is just one of those times I agree with the "if it aint broke, don't fix it" crowd.

**Fourplay** · 06-19-2013 12:24 PM

Originally Posted by 17708

if you do everything right, it shouldnt leak.
use any sealants or whatever it asks for, and torque everything down,ect.

The fewer things you mess with on a B5, the better off you are. Regardless of what is "supposed" to happen, Murphy's Law is king with these cars. Hence the let it be if it's not an issue (except obvious preventative maintenance).

Originally Posted by waB5S4

If it isn't leaking now then you only have to worry about natural failure. If it is leaking now, you have to worry about natural failure on the new one AND properly installing it. Either way you're looking at doing the labor some day.

This.

**8520** · 06-19-2013 12:40 PM

I faced the same decision about 4 years ago when I did ko4's. I chose not to replace the rear main seal, and I don't regret the decision. Mine has yet to leak.

**Sscott09** · 06-19-2013 12:45 PM

I did mine, hope it holds up!

**Scotty@Advanced** · 06-19-2013 12:46 PM

Although I'm a big proponent of "Do it while your there" seals are a different story. i don't like to replace a non leaking seal as there's a chance you can screw up the install and there is a chance that the seal could be defective from the factory (a rash of main seals for the 1.8t/1.9tdi were manufactured with a weak spring years back). Many people preemptively replaced the RMS with a clutch job only to find they had to do it again after the RMS started leaking.

**Matt Danger** · 06-19-2013 12:59 PM

If it's not leaking don't fuck with it.

**jturnbull** · 06-19-2013 01:03 PM

I have my engine out right now and I chose to replace it. I made sure to use a screw driver to gently get the lip to seal against the motor and not face out.

Wasn't too difficult and hopefully it will be fine (knock on wood).

**ilyafil** · 06-19-2013 01:13 PM

I ALWAYS replace the seal...but that's just me...

EDIT: But I have a lift...

**17708** · 06-19-2013 01:19 PM

looks like the OP is getting 50/50 answers.

i would look at it and if it looks real worn or feels brittle at all, replace.
if it still looks and feels fine, keep it on.

**somebody5788** · 06-19-2013 03:21 PM

Originally Posted by 17708

do it!
if you plan to keep the car for a while, i would do it now.
the part is super cheap, its the labor that costs an arm and leg.

You're obviously still learning these cars. There are more documented rear main seal failures from replacing then there are from natural failure. And technically you should do the whole rear plate like Audi sells it. That is not a super cheap part lol.

**inzunzar** · 06-19-2013 03:33 PM

I replaced mine when I had my engine out, it was not leaking and I regret it, had to take the transmission down two more times, don't mess with it....

**1illA6** · 06-19-2013 04:04 PM

^ same! Was not leaking, replaced it while its out, 300 miles in it's leaking & it's getting all over the clutch. I'll be doing it again next week.

**Sole_** · 06-19-2013 04:21 PM

I'm about to finish my K04 install also replaced the clutch. Did not touch that rear main seal.

**Halfbreed** · 06-19-2013 04:28 PM

Originally Posted by Fourplay

The fewer things you mess with on a B5, the better off you are. Regardless of what is "supposed" to happen, Murphy's Law is king with these cars. Hence the let it be if it's not an issue (except obvious preventative maintenance).

+1. Most accurate statement I have read on here in a while.

**01audia4** · 06-19-2013 04:49 PM

I read through so many damn rear main seal threads when my engine was out. I ended up replacing mine.

Hope its on there correctly. 189 miles and nothing yet. Lets hope it stays that way. While I believe in the "if its not broke don't fix it" I think a seal in a place like that should be replaced, imagine if you don't replace it and it starts leaking...You didn't even try.

**somebody5788** · 06-19-2013 04:56 PM

Originally Posted by 01audia4

I read through so many damn rear main seal threads when my engine was out. I ended up replacing mine.

Hope its on there correctly. 189 miles and nothing yet. Lets hope it stays that way. While I believe in the "if its not broke don't fix it" I think a seal in a place like that should be replaced, imagine if you don't replace it and it starts leaking...You didn't even try.

I'd be even more pissed if it had started leaking because I did it haha.

**Delmed83** · 06-19-2013 08:07 PM

EPL did my K04 upgrade back in January. Back then when they were working on it, I knew very little about the car. So I didn't even think of it while they had the engine out. A few weeks after getting my car back, I came across some RMS threads. I then said to myself....why didn't EPL recommend to replace it while everything was apart? I then realized that they agree with the school of thought....if it's not leaking, leave it alone.

It's 6 months later and still fine.

I vote to leave it alone.

**DiscoPotato** · 06-19-2013 08:30 PM

Originally Posted by Scotty@Advanced

Although I'm a big proponent of "Do it while your there" seals are a different story. i don't like to replace a non leaking seal as there's a chance you can screw up the install and there is a chance that the seal could be defective from the factory (a rash of main seals for the 1.8t/1.9tdi were manufactured with a weak spring years back). Many people preemptively replaced the RMS with a clutch job only to find they had to do it again after the RMS started leaking.

I'm the same way.. Main seals and cam seals etc I never touch unless they're leaking

**01audia4** · 06-20-2013 08:36 AM

Originally Posted by somebody5788

I'd be even more pissed if it had started leaking because I did it haha.

Well mile marker 189 of my K04 install I have a HUGE oil leak. I feel like it is too excessive to be the rear main. Maybe oil pan or upper(both looked fine when engine was out)

Who here had a leaky rear main? How bad was it..>I really hope I don't have to pull my engine again.

**Gaki** · 06-20-2013 08:52 AM

thanks for the responses guys!

**1illA6** · 06-20-2013 08:59 AM

Originally Posted by 01audia4

Well mile marker 189 of my K04 install I have a HUGE oil leak. I feel like it is too excessive to be the rear main. Maybe oil pan or upper(both looked fine when engine was out)

Who here had a leaky rear main? How bad was it..>I really hope I don't have to pull my engine again.

Mines currently leaking:( its bad enough to be getting all over the clutch.
Drips crazy. Not so sure about pulling the engine way to much work, trans will be getting pulled w/in the next much easier & takes what an 1hr tops?

**Tyler S4** · 06-20-2013 09:00 AM

Originally Posted by 01audia4

Well mile marker 189 of my K04 install I have a HUGE oil leak. I feel like it is too excessive to be the rear main. Maybe oil pan or upper(both looked fine when engine was out)

Who here had a leaky rear main? How bad was it..>I really hope I don't have to pull my engine again.

You obviously did NOT knock on wood lol. 16 hours ago you were saying you were good. That's a bummer man. Excessive oil doesn't really sound like a rear main to me. But I'm not really sure.

**01audia4** · 06-20-2013 09:06 AM

Originally Posted by 1illA6

Mines currently leaking:( its bad enough to be getting all over the clutch.
Drips crazy. Not so sure about pulling the engine way to much work, trans will be getting pulled w/in the next much easier & takes what an 1hr tops?

I don't know about an hour tops..I've herd its almost easier to pull the motor as a whole. Plus you'll be able to see what you are doing. Ill pull it again when I get back from vacation.

Originally Posted by Tyler S4

You obviously did NOT knock on wood lol. 16 hours ago you were saying you were good. That's a bummer man. Excessive oil doesn't really sound like a rear main to me. But I'm not really sure.

Obviously not..16 hours ago it was not leaking, guess it started today. Now I don't know if I am more pissed cause I replaced it and it leaks, or if I would have just left it alone and leaks. I retract my previous statement. IM ANGRY.

Seem like quite a heavy leak though, I almost feel too heavy to be the RMS but the oil is dripping right by the service holes on the trans/engine.

Maybe an upper oil pan gasket i'm thinking? How can I really tell. I had it up on a lift we sprayed it down but still couldn't see where it was coming from. Almost looks like by the starter. Could it be leaking out of the RMS and being spit out the starter?

**Fourplay** · 06-20-2013 10:01 AM

Originally Posted by 1illA6

trans will be getting pulled w/in the next much easier & takes what an 1hr tops?

LOL nope.

Some of the engine to tranny bolts are almost impossible to access with the coolant hard line on the rear of the engine in place (plus oil/vacuum/wiring lines in the way as well). I would budget 4 out and 4 in.

**fshowcars** · 06-20-2013 11:17 AM

wow, i was a don't read and post, but then read it... sucks. So yeah, i just had a 1/2 shift collar go, JHM rebuild and here we are... check the rear main seal, looks fine, put it back. I'm with these guys... seals, don't mess with unless you are prepared for the nightmare (sorry OP)... same with our S4's fuel filters... those fitting corrode on and you are smoked when you are just trying to do maintenance.

**Fourplay** · 06-20-2013 11:29 AM

Originally Posted by fshowcars

same with our S4's fuel filters... those fitting corrode on and you are smoked when you are just trying to do maintenance.

Yep, I've cracked the feed line to the fuel filter from the fuel pump that goes between the tank and the body. Huge PITA to fix. All because the lines corroded on and it took enough force to break it free that the line broke.

**1illA6** · 06-20-2013 11:44 AM

Originally Posted by Fourplay

LOL nope.

Some of the engine to tranny bolts are almost impossible to access with the coolant hard line on the rear of the engine in place (plus oil/vacuum/wiring lines in the way as well). I would budget 4 out and 4 in.

I guess I should have made it more clear, it'll take me an hour:)
Plus the allens at the bottom of the trans are gone, so all that's left are the 16s.
Rear of the subframe comes down, trans slides onto a tranny jack & it's out.
Does help to
Have a lift I suppose.

But yeah 4hrs then sounds about right.