Leaky rear diff cover gasket, '97 impreza

[shannon]

Hi folks, a leak in the rear differential cover gasket was recently brought to my attention by the guy at the Vavoline drive-thru oil change joint. Being someone who owns and notices subarus, he related to me this being 'common on imprezas' He reffered me to a local subaru specialist I'd heard of but doubt I can afford right now.

 

It's a '97 imp. wagon, manual trans., 90k. I've enjoyed it for about 2 months now.

 

First, is this common and if so does anyone know of an aftermarket upgrade for this gasket so that this is the only time I need to do this?

 

Second, who's done this repair and how tough can it be? I've done about three front axles, so you get an idea where my skill level is.

[Bobby_boucher]

Is there an actual gasket???? usually rear diff. are just sealed with gray rvt.

[idosubaru]

sealing the rear cover of a diff is way easier than doing an axle change in my oppinion. drain fluid, remove cover, seal and reinstall cover. super easy...you will likely have to drop the diff down though but that isn't all that difficult, should just be three bolts to unbolt the diff and you might have to unbolt the driveshaft to let the diff come free, but it might just have enough play to come down on it's own. have somethign on the ground under the diff so it doesn't fall all the way to the ground when you remove it...like a jack maybe (but dont' let the jack get in the way of the diff cover.

 

it could just be *wet* from either previous leaks up front (while driving leaks from up front fly back and attach to things, like the bottom of the rear diff. and sometimes it could just be a very minor leak. i'd clean it off, change the fluid with fresh fluid and see how it does. or just reseal, can't imagine it's that hard but i've never done it.

 

post on the off-road forum of this site, those guys rebuild rear diffs all day long, they'll definitely know exactly what to do.

[dirtball]

Hey, all! First post. I have a 99 Legacy GT (160K) with the same leak. Looks like the rear diff gasket. I'm a novice mechanic and not looking forward to dropping the rear diff. It has those mounting studs from the rear cover that fit through the frame preventing easy access to the top bolts. In order to get those out of the frame to allow the diff to drop, you'll need the whole diff to come forward a good 3-4 inches at least. I'm concerned that I won't be able to get to the cover without completely disconnecting the diff from driveshaft and output shafts. Haynes manual makes it look easier than I expect it to be (those studs are Michiganified). Good news is the gasket is $5 from the dealer. I drained and replaced the fluid for now. Assuming I have to replace this part, anyone have pointers on how involved this will be?

[idosubaru]

nice job using the search function....

 

i'm not familiar with your exact car, but i'll try to help. the rear support (sometimes called the mustache bar) that the diff bolts into typically isn't very stiff material. once the diff bolts are out, it has a good bit of play in it and you'll be able to push/pull it a good bit. push the diff forward, rear support back. just be careful so the diff doesn't pop out and fall on you.

 

as a last resort if you needed more room to play with, just unbolt the carrier that holds the driveshaft from the trans under the car. don't unbolt the driveshaft itself, just whatever holds it to the underbody, typically a center carrier support that's only 2 bolts. remove those two bolts and the driveshaft will slide out of the transmission and give you all the room in the world to more it around....by only removing what is usually 2 14mm bolts (not familiar with the specifics of your model though). and the exhaust has always been avoidable by me, just move it a little if it's in the way of the driveshaft. you might not have to do this, just a last resort that only requires removing two bolts.

 

i've definitely dropped a diff by unbolting those two bolts you speak of, so it might be that simple. then there's usually one bolt above the diff as well that needs to be removed. it's usually a 22 or 24 mm bolt on the drivers side with a 17 mm nut on the passengers side and the bolt will only slide through one way, so if it doesn't seem like it wants to go it, install it from the other side. each model is different so this probalby isn't exactly true in your case.

 

with high mileage/age look at the rear differential bushing. they crack/break after awhile and while you have it apart/off is a good time to replace it if needed. i replaced mine a couple weeks ago at 220,000 miles. it was cracked all the way through, the rubber bushing.