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Discussion Starter · #1 ·
Ever since I bought skid plates and started carrying a full size spare, I've been able to tackle some fairly aggressive terrain in my 2000 Subaru Outback.

One thing that I have been nervous about is water. I just don't know what could go wrong. In particular, I have heard about people installing differential breathers on other models of vehicles to avoid water getting into the differential.

Assuming I have solid ground (not mud) and the water is still (not going to sweep me away,) what is the deepest water that you can drive a 2000 Outback through?

Do people modify their differential breathers?
 

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Ever since I bought skid plates and started carrying a full size spare, I've been able to tackle some fairly aggressive terrain in my 2000 Subaru Outback.

One thing that I have been nervous about is water. I just don't know what could go wrong. In particular, I have heard about people installing differential breathers on other models of vehicles to avoid water getting into the differential.

Assuming I have solid ground (not mud) and the water is still (not going to sweep me away,) what is the deepest water that you can drive a 2000 Outback through?

Do people modify their differential breathers?
Yes people do. I helped my cousin modify the breathers on his 4runner. Simple process picked up a roll of cheap rubber fuel line and some hose fittings and simply ran a tube from the top of the firewall under the truck and all the way back to the rear diff. Then connected the stock breather tubes to this line. The stock tubes were led to the bottom of the body directly above the diffs. The OB is probably similar as all my other vehicles have all had diff breathers clipped to the bottom of the body just above the diff. Meaning any water to the floor boards and you risk the diff being cooled off by the cool water sucking water in via the breather thats under the water.

Simple and easy project not really that complicated
 

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The 2000 rear differential, like my 2007, has a vent at the top of the rear cover. There's no hose going up to the body, as subiesailor referred to on the 4Runner, and as there is on my 76 Suburban.

The vent is basically a tube screwed into the cover, with a "floating" cap on the top. The cap prevents dirt from getting in and is loose enough to allow the release of any pressure build-up.

I'm not sure if the cap can be removed and a hose clamped onto the tube. There's not much of the latter there.

(see attached)
 

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Discussion Starter · #4 ·
The 2000 rear differential, like my 2007, has a vent at the top of the rear cover. There's no hose going up to the body, as subiesailor referred to on the 4Runner, and as there is on my 76 Suburban.

The vent is basically a tube screwed into the cover, with a "floating" cap on the top. The cap prevents dirt from getting in and is loose enough to allow the release of any pressure build-up.

I'm not sure if the cap can be removed and a hose clamped onto the tube. There's not much of the latter there.

(see attached)
Thanks. That diagram helped.

And if the differential was submerged in water, I assume it could fairly easily get in and mess stuff up?
 

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Yes.

I'm not aware of anything in the vent that would prevent water getting in if the differential were submerged.

Water in the differential reduces the protection for the gears and bearings.

By the way, I wonder if the maximum depth the car could go through would also be dependent on the height of the wheel bearings. In this regard, the rear differential, and particularly the differential vent, is higher than the axles/wheel bearings.
 

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(formerly) 03 H6 OBW , (presently) 06 WRX Sportwagon & 2021 Honda CR-V
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I recently read a little about this and there's some good info on the forester forum.

I don't think the breather is 'sealed' into the case. That is, a replacement breather doesn't have threads, it seems to have plastic ears that snap it into place. Still, seems one persons mod was to just drill out the center of the breather and run a tube up into a rear fenderwell (IIRC).

To actaull seal a snorkel to the diff would probablly require tapping a hole and screwing in a nipple with some sealant on the trheads. Not certain and may be year/model dependent.

And I think regularly fording deep water could very well shorten the life of wheel bearings and maybe CV joints. Don't folks with boat trailers replace bearings often? Water is gonna rapidly cool lube and air inside of enclosed spaces, creating a pressure differential that may exceed what the seals are designed for. But I have no experience with that stuff - others here and probably over at ultimatesubaru.org do a lot of offroad wheeling and probably have some good insight for you.
 

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I recently read a little about this and there's some good info on the forester forum.

I don't think the breather is 'sealed' into the case. That is, a replacement breather doesn't have threads, it seems to have plastic ears that snap it into place. Still, seems one persons mod was to just drill out the center of the breather and run a tube up into a rear fenderwell (IIRC).

To actaull seal a snorkel to the diff would probablly require tapping a hole and screwing in a nipple with some sealant on the trheads. Not certain and may be year/model dependent.

And I think regularly fording deep water could very well shorten the life of wheel bearings and maybe CV joints. Don't folks with boat trailers replace bearings often? Water is gonna rapidly cool lube and air inside of enclosed spaces, creating a pressure differential that may exceed what the seals are designed for. But I have no experience with that stuff - others here and probably over at ultimatesubaru.org do a lot of offroad wheeling and probably have some good insight for you.
I recall talking to a jeep tour guy maybe in Hawaii who told me they had to replace the diff/gear oil in the diffs about once a month due to the high water they regularly crossed during the tours. So if your only doing a couple of crossings during the spring or summer and you just replace the gear oil you would probably be fine. But if you forget then do a big road trip the gear oil and water mix ='s bad stuff for the gears.

As for the wheel bearings the subaru bearings are super cool single sealed units if water bothers them chances are the bearing is already failing and the seal has failed for other reasons etc.

The CV joints if the straps are all intact and the boots are all healthy and not split should not be bothered by any sort of water - snow or mud etc.
 

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+1

Agreed. Seals are just that. Nothing out as well as nothing in.

Ingesting water in the breathers is the only concern I see about being in water. I live in WA and regularly cross puddles when I'm up in the mountains. Diffs only take about a Qt each so why not change it often.

I suppose MT would be a bit more. I had a thought once about lengthening the front breather hoses to higher up by the hood.
 

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I've read that if the radiator fans get in the water, they can be forced into the radiator fins possibly rupturing the rad.

Lot's of xtra concerns if you're gonna subject ANY vehicle to extreme use.
 

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wow. never thought of the fans hitting the rad. good call texan.

i have been as deep as the bottom of the doors before and serviced my rear diff with no contamination.
 

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I've read that if the radiator fans get in the water, they can be forced into the radiator fins possibly rupturing the rad.

Lot's of xtra concerns if you're gonna subject ANY vehicle to extreme use.
Yes recall reading a thread about the crazy Russians they put a manual switch on the front fans so they can shut them off when doing deep water crossings. I recall the issue was trashing the fan motor given they aren't built to pump water.
 
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