New twist on the old diff breather problem

2304 Views 8 Replies 5 Participants Last post by 84hachi, Dec 1, 2020

Smileandwave

Discussion Starter · Nov 22, 2020

Hi guys,

Just want to say how helpful this site has been in maintaining my wife's 2007 RAV over the years. Still runs like a top. Thanks so much for your efforts in helping us all.

I've been aware of the clogged diff vent issue for years. Every oil change, I turn the car around, back it up on the ramps and squeeze my hands up in there to loosen the thing up.

Yesterday I discovered something new that I've never seen anyone talk about here: The vent cap itself has rusted away enough at its bottom that it will just lift off the base now. Just enough crimping left on it to grab a little but clearly not ideal.

With the cap off, I was able to get my fingertip on the opening in the vent base. It was clogged (of course), but couldn't have been that bad. In just poking at it, all the crud let go and fell into the diff.

Two questions:

Will the road grit and dust and dirt that fell down into the diff cause an issue? It let go so easily, couldn't have been more than a thimble full, if that. Will it just settle in the diff fluid? The options aren't pretty if it is an issue.

Second, to all you guys that have actually seen these vent contraptions up close, do you think I could buy a replacement vent, pry the crimped cap off and just push it on the base that's already on the diff? Pretty sure I could do that without dropping the diff. Seems a lot easier that the work involved in replacing the whole assembly. The vent base that's there seems solid, it was just the cap that started to rust away.

Thanks for any advice.

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kevcules46

· #2 · Nov 22, 2020

Well.....I don't know how you got your hand up in there? On my 08, I couldn't see or feel it.

My brother in law (toyota tech) advised me that I should change mine a few years ago when he said "are your axle seals blown yet?"

Yes, you can buy a replacement vent valve and it needs to be tapped into place. The original needs to be pried out. The way he suggested , instead of dropping the diff, was to remove the driveshaft and then loosen and lower the diff on the left side, so it droops down for better access. The you have enough space to pry out the old vent and tap in the new one with the right size deep socket. The vent doesn't always come out easy and then the diff needs to come out.
I would drain the diff fluid, then think about when to get in there and attempt the valve replacement.
There is another thread on here about this job and how DL175 I think re routed a hose to inside his rear fender for easy access, in case it's ever a problem again......good luck

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Smileandwave

Discussion Starter · #3 · Nov 22, 2020

kevcules46 said:
Well.....I don't know how you got your hand up in there? On my 08, I couldn't see or feel it.
My brother in law (toyota tech) advised me that I should change mine a few years ago when he said "are your axle seals blown yet?"
Yes, you can buy a replacement vent valve and it needs to be tapped into place. The original needs to be pried out. The way he suggested , instead of dropping the diff, was to remove the driveshaft and then loosen and lower the diff on the left side, so it droops down for better access. The you have enough space to pry out the old vent and tap in the new one with the right size deep socket. The vent doesn't always come out easy and then the diff needs to come out.
I would drain the diff fluid, then think about when to get in there and attempt the valve replacement.
There is another thread on here about this job and how DL175 I think re routed a hose to inside his rear fender for easy access, in case it's ever a problem again......good luck

Discovered that if you lay under the car with your head to the front and the diff over your chest, you can wriggle your right hand up the driver's side of the diff and get a finger tip on the vent.

On the passenger side, remove the suspension brace, and you can wriggle your left hand up and in.

Doing this, I can get a finger from each hand on the vent cap and keep it loose.

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Mikemnj

· #4 · Nov 29, 2020

Smileandwave said:
Discovered that if you lay under the car with your head to the front and the diff over your chest, you can wriggle your right hand up the driver's side of the diff and get a finger tip on the vent.

On the passenger side, remove the suspension brace, and you can wriggle your left hand up and in.

Doing this, I can get a finger from each hand on the vent cap and keep it loose.

Agreed just backed mine up on ramps and was able to snake my hand up the driver side on 2011 4cyl.to get two fingers on diff vent enough to make sure it wiggled and rotated around. It was def alittle rough but still functions!

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DL175

· #5 · Nov 30, 2020

If your breather vent crumbled then pieces could go inside the rear differential. As kevcules40 mention change the fluid. You should replace the breather vent because water and dirt will go into the vent hole. Also it is not an easy thing to do under the car to replace that breather vent.

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Mikemnj

· #6 · Nov 30, 2020 (Edited)

DL175 said:
If your breather vent crumbled then pieces could go inside the rear differential. As kevcules40 mention change the fluid. You should replace the breather vent because water and dirt will go into the vent hole. Also it is not an easy thing to do under the car to replace that breather vent.

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84hachi

· #7 · Nov 30, 2020

Supposedly part number 90930-03235 is an updated design to prevent the clog issues.

Had the front pinon seal fail because of that sucker getting clogged. Thankfully my friend who was helping me and had smaller hands than me was able to get the breather free and coated with a grease to repeal water.

But it took all this to get a hand back there. But the pinon seal needed to be changed anyway.

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DL175

· #8 · Dec 1, 2020 (Edited)

84hachi said:
Supposedly part number 90930-03235 is an updated design to prevent the clog issues.
View attachment 159829

Had the front pinon seal fail because of that sucker getting clogged. Thankfully my friend who was helping me and had smaller hands than me was able to get the breather free and coated with a grease to repeal water.

View attachment 159830

But it took all this to get a hand back there. But the pinon seal needed to be changed anyway.

Adding a coat of grease to the breather valve is a good idea and will slow down the rusting. The only thing is that there is little room on the top so maybe use a rag with oil and grease to some how move it around? Maybe use the double straw trick taped back to back and spray it?

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84hachi

· #9 · Dec 1, 2020

DL175 said:
The only thing is that there is little room on the top so maybe use a rag with oil and grease to some how move it around? Maybe use the double straw trick taped back to back and spray it?

I wont be able to answer that question since my friend and I were in the process of changing the pinion seal, so we had the room needed to free the breather and coat the area with grease. The grease I used was Hotchkis sway bar grease since it was the thickest and stickiest grease I had around.

Maybe a long spoon could get up there. All, I know is I don't have to deal with it for awhile.

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