tool for rear differential

[lekmedm]

I've been itching to change the oil in the differentials of my new, used, high-milage Subie. What kind of fan-dangled square shaped tool do I need to open the drain and fill plugs in the rear? Do I use the same in the front?

 

Also, I'm tempted to completely open the rear pumpkin as it's completely wet and hasn't been out in the rain. I'd like to have a good look at what's in there and give it a good cleaning. Is there a special gasket under the cover, or can I just squeeze one out of a tube?

[1 Lucky Texan]

I've been itching to change the oil in the differentials of my new, used, high-milage Subie. What kind of fan-dangled square shaped tool do I need to open the drain and fill plugs in the rear? Do I use the same in the front?

 

Also, I'm tempted to completely open the rear pumpkin as it's completely wet and hasn't been out in the rain. I'd like to have a good look at what's in there and give it a good cleaning. Is there a special gasket under the cover, or can I just squeeze one out of a tube?

 

I dunno about opening it - I would make sure it isn't just some 'blowback' from an oil leak up front somewhere.

 

I've read here that most folks just use a 1/2" square drive breaker bar to take out the plug. You will likely need a 'cheater' bar too.

[kevinsUBARU]

Yes, just use a 1/2" square drive...just make sure you remove the filler hole (top) before you drain it. I believe the front differential takes a 18mm socket, and there is no crush washer on it.

 

By the way, what kind of ru did you get?

 

Kevin

[idosubaru]

regular out of the box 1/2" socket wrench on the rear and a regular socket on the front (just like draining your oil). i wouldn't open up the rear diff, usually it's wet from something up front leaking and blowing back....trans, diff, oil...anything. over many years doesn't take much to build up and gunk things up. no need to open up a diff and clean it. drain and refill with synthetic and be on your way. check the level from time to time. kind of tricky to do, but just add more fluid in after a couple months and see if it takes any. how the car sets has a lot to do with how much you get in there since there isn't much clearnace to pour the bottle in.

and yes the gasket sealant is out of the tube type.

[lekmedm]

...and there is no crush washer on it.

 

By the way, what kind of ru did you get?

 

Kevin

 

What's a crush washer??? I think I noticed a washer associated with the oil drain plug as shown in the owner's manual. Is that something that regularly needs to be replaced?

 

What kind of ru...? It's in my sig. I thought everyone could see it. I can. It's a 1998 Legacy Outback 2.5L ATX with about 137,000 mi on it now.

 

BTW, by 1/2" square drive, do you mean the square end to a 1/2" ratchet for sockets? I have a Mercury that uses a 3/8" square end ratchet to get out the ATX drain plug. Am I right in understanding it's the same idea?

[lekmedm]

regular out of the box 1/2" socket wrench on the rear and a regular socket on the front (just like draining your oil). i wouldn't open up the rear diff, usually it's wet from something up front leaking and blowing back....trans, diff, oil...anything. over many years doesn't take much to build up and gunk things up. no need to open up a diff and clean it. drain and refill with synthetic and be on your way. check the level from time to time. kind of tricky to do, but just add more fluid in after a couple months and see if it takes any. how the car sets has a lot to do with how much you get in there since there isn't much clearnace to pour the bottle in.

and yes the gasket sealant is out of the tube type.

 

 

Ah, thanks for the clarification. I see that in the time I was composing my last post, you were already replying.

 

Should the car be standing level when draining the rear diff, or can it be up on ramps?

[nickb21]

You can put it on ramps to drain it, just make sure it's level when you fill it.. I drained mine on the flat and got probably 90% of the oil out.

 

I believe there is a breather tube at the top of the diff, maybe there is a small leak there.

[beezer]

I would check the axle seals. If the diff. has a coating of oil and dirt on the sides and onto the axles that's probably what it is.

 

Pretty sure you can change the seals with the diff. still on the car. (I know you can on a '92, GRRRR). Just have to remove the axles and change the seal out.

[subie94]

I've read here that most folks just use a 1/2" square drive breaker bar to take out the plug. You will likely need a 'cheater' bar too.

 

yup that's how i did mine.remove lower one to drain' date='upper one to fill.

 

you can see them at the edge of the pic

[idosubaru]

ramps fine to drain, have flat to refill.

 

a good many people here ask questions about cars that aren't in their sig's so it's not a bad idea to post sometimes. i have 8 different subarus, 3 different models and forget to post which one i'm asking about from time to time.

[lekmedm]

Thanks for the advice, everyone!

[95Leg]

There's not much room to use a cheater bar if you don't lift the car.

 

I was able to get the rear drain plugs off easily by using a regular 1/2" socket wrench, and then using a floor jack (or you could use the scissor jack) at the end of the wrench. The car started to lift up a little and then the plugs finally broke loose.

 

Then of course a fluid pump makes refilling the oil very quick also.

[1 Lucky Texan]

Well, I haven't done a diff. but I've read some of them have magnetized plugs - so, be sure to wipe off any metal particles.

[BobBrumby]

when i looked at draining the oil in my rear diff the drive socket was about 1-2mm smaller than the square whole. did you guys have the same problem? i just dont want to do any more damage to them.

[avk]

The square hole in the plug is actually 13 mm, but in Australia, shouldn't it be a standard size instead of half-inch?

[1 Lucky Texan]

The square hole in the plug is actually 13 mm, but in Australia, shouldn't it be a standard size instead of half-inch?

 

Good question. maybe it's one of those things that could remain 'english' for a long time - like 1/4-20 tripod sockets for cameras.

 

I dunno

[ferret]

Subaru, as we all know, is a Japanese automobile. And being such uses Metric sizes. The Differential drain/refill plugs are no different.

 

They are 13mm square drive. We in the US use a 1/2" drive to remove them. 1/2"=12.7mm. This is why a 1/2" drive feels a little loose. On the job we use a combination of metric and ise spec fasteners. When it comes to a 13mm or 1/2" nut/bolt, most guys these days carry and have been using their metric sets. But when they need to hold the other side and that's the same size, they often force the 1/2" wrench or socket on the 13mm nut/bolt. Needless to say they are that close.

 

I've replace the differential oil many times. Opening the top first, (If you can't get that open, how are you going to refill it). Then open the bottom and let it drain into a pan. The plugs are 2 different sizes and the lower one has a magnet on it. Then clean the plugs and I use a non-adheasive sealer on the threads (I use locktite red non-adhesive sealer). Then replace the lower plug and torque it to 32 ft/lbs. Fill the upper hole until it drips. Then replace the upper plug.

 

All done without jacking up and on a level surface as not to overfill. Total time 30 minutes or less.

End of my $.02.

[Handtool]

There's not much room to use a cheater bar if you don't lift the car.

I was able to get the rear drain plugs off easily by using a regular 1/2" socket wrench, and then using a floor jack (or you could use the scissor jack) at the end of the wrench. The car started to lift up a little and then the plugs finally broke loose.

 

Great Idea! This is gonna save me a lot of cussing and time spent laying in the gravel.

[Setright]

Ferrit has it down.

[AlpineRaven]

Subaru, as we all know, is a Japanese automobile. And being such uses Metric sizes. The Differential drain/refill plugs are no different.

 

They are 13mm square drive. We in the US use a 1/2" drive to remove them. 1/2"=12.7mm. This is why a 1/2" drive feels a little loose. On the job we use a combination of metric and ise spec fasteners. When it comes to a 13mm or 1/2" nut/bolt, most guys these days carry and have been using their metric sets. But when they need to hold the other side and that's the same size, they often force the 1/2" wrench or socket on the 13mm nut/bolt. Needless to say they are that close.

 

I've replace the differential oil many times. Opening the top first, (If you can't get that open, how are you going to refill it). Then open the bottom and let it drain into a pan. The plugs are 2 different sizes and the lower one has a magnet on it. Then clean the plugs and I use a non-adheasive sealer on the threads (I use locktite red non-adhesive sealer). Then replace the lower plug and torque it to 32 ft/lbs. Fill the upper hole until it drips. Then replace the upper plug.

 

All done without jacking up and on a level surface as not to overfill. Total time 30 minutes or less.

End of my $.02.

 

I use 1/2" Drive to undo mine (yes down here in Australia), its easy and I don't need any extra tools.

Cheers

AP

[sid_vicious]

I use 1/2" Drive to undo mine (yes down here in Australia), its easy and I don't need any extra tools.

Cheers

AP

 

The 1/2" breaker bar works fine, but there is actually a socket called a pipe plug socket that is just a plain square. The retention ball on ratchets and breaker bars can get in the way a little, though it's not really a problem. I thought about finding a 1/2" pipe plug socket just because having the perfect tool for the job is a good feeling, but I don't think it's worth buying anything when a breaker bar fits so well.