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diff pressure relief/blowoff valve, fix/replace

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Old Nov 7, 2010 | 01:19 PM
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Default diff pressure relief/blowoff valve, fix/replace

Other than having the mechanic do it, on the differential, how does one 1.) replace the blowoff valve 2.) fix the blowoff valve??

I think this thing is pressed into the case and is located on top of the differential so not easy to get at and since it isn't screwed in, how do you pull it out?

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Last edited by Padrino; Nov 7, 2010 at 01:23 PM.
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Old Nov 7, 2010 | 01:57 PM
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Yep it's pressed in, why do you want to remove it?
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Old Nov 7, 2010 | 09:02 PM
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Originally Posted by corvettebob1
Yep it's pressed in, why do you want to remove it?
I'd rather it just get fixed but it appears to be 'stuck' shut and it sounds from other posts this may be the root of the reason I and others have gotten blown seals.

In case the valve can't be 'fixed', then it needs to be replaced and thus the question on how with the implied, how difficult.

And then the other part of my question; how does one fix it?

Padrino

Last edited by Padrino; Nov 7, 2010 at 09:07 PM.
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Old Nov 8, 2010 | 05:55 AM
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VALVE is a pretty strong word to describe this thing. If memory serves, the vent is just a short tube pressed into the driver's side of the case, with a cap loosely crimped to the end. There's not much to go wrong that would require replacing the whole thing. If it's clogged up, degreaser would fix it, but doing it thoroughly with the diff together and in the car might be tricky. If there's fresh oil around it, it's probably still venting. What do you mean your seals are "blowing out"? Which seals?
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Old Nov 8, 2010 | 06:03 AM
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Originally Posted by Its_Go_Time
VALVE is a pretty strong word to describe this thing. If memory serves, the vent is just a short tube pressed into the driver's side of the case, with a cap loosely crimped to the end. There's not much to go wrong that would require replacing the whole thing. If it's clogged up, degreaser would fix it, but doing it thoroughly with the diff together and in the car might be tricky. If there's fresh oil around it, it's probably still venting. What do you mean your seals are "blowing out"? Which seals?
The usual, the left, driver's side. Going into the shop on the 16th to take care of it.
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Old Nov 8, 2010 | 10:57 AM
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Originally Posted by Padrino
I'd rather it just get fixed but it appears to be 'stuck' shut and it sounds from other posts this may be the root of the reason I and others have gotten blown seals.

In case the valve can't be 'fixed', then it needs to be replaced and thus the question on how with the implied, how difficult.

And then the other part of my question; how does one fix it?

Padrino
Remove the vent cap by prying it off then inside you will find a spring pressing a small rubber washer down inside the tube remove a discard both the spring and the washer.
Get a short piece of 3/8 X 6" hose and attach it to the vent pipe with a clamp.
Bend it forward and install a white plastic vent with a jiggle top and your done.
Now your diff will vent normally like it should and your seals will love you again.
Check your fluid level it should be just below the fill hole when cold 1/8-1/4"
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Old Nov 9, 2010 | 06:40 AM
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Originally Posted by corvettebob1
Remove the vent cap by prying it off then inside you will find a spring pressing a small rubber washer down inside the tube remove a discard both the spring and the washer.
Get a short piece of 3/8 X 6" hose and attach it to the vent pipe with a clamp.
Bend it forward and install a white plastic vent with a jiggle top and your done.
Now your diff will vent normally like it should and your seals will love you again.
Check your fluid level it should be just below the fill hole when cold 1/8-1/4"
Okay...is a "white plastic vent with a jiggle top" something like a which-a-ma-call-it? You have any idea where to find this 'jiggle top'?

I know the fix would work as it's simple. Kind of like a snorkel. But where do you get the part?

Also, I'm not sure I'd be using plastic down around all the heat that's going on in that part of the car. But I do like the idea.

Padrino
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Old Nov 9, 2010 | 07:48 AM
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Our friend CorvetteBob1 has got me thinking this thing through with his idea of creating a whole new snorkel.

If the 'check valve' is stuck and you can't get the unit out of the case without the whole thing out of the car, wouldn't a reversed PCV breather valve do the trick if it would seal over the vent pipe tube (3/8"??) and then you could tube the overflow off to where you desired?

Just blue skying a little on this with the little downtime I've got right now. You can tell I'm bored and can't wait to get home for a few weeks.

Padrino

Last edited by Padrino; Nov 9, 2010 at 08:38 AM.
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Old Nov 9, 2010 | 11:00 AM
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Originally Posted by Padrino
Okay...is a "white plastic vent with a jiggle top" something like a which-a-ma-call-it? You have any idea where to find this 'jiggle top'?

I know the fix would work as it's simple. Kind of like a snorkel. But where do you get the part?

Also, I'm not sure I'd be using plastic down around all the heat that's going on in that part of the car. But I do like the idea.

Padrino
Sorry don't have a P/N but you can find them at just about any transmission shop or any dealer.
They were used for years as a transmission or axle vent in most cars.
Don't worry about the heat that's part of what the hose is for it insulates the nylon vent from the axle heat!
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Old Nov 11, 2010 | 11:16 PM
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Is it easy to tell that the left seal is leaking and not that the vent is working? my left side leaked for awile -- I left it alone and it stopped.......my working diagnosis was that it was fluid FROM the vent.
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Old Nov 12, 2010 | 03:22 AM
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Originally Posted by scottsdalecessna
Is it easy to tell that the left seal is leaking and not that the vent is working? my left side leaked for awile -- I left it alone and it stopped.......my working diagnosis was that it was fluid FROM the vent.
Thanks for that. Yes, seeing where the leak is from is easy. My case, the seals. Question is based upon 'if the popoff valve is stuck shut will it blow the seals'. Just looking for a fix if that proves to be the case.

Padrino
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