8 3/4 spitting gear oil out of breather vent

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There is no "valve" in the vent, there never has been. It's simply a hollow stud with a loose cap on it. Check your fluid level...if correct, pry the cap off the vent and wad some steel wool or similar on top and put it back.
 
The replacement ones have a spring and a rubber washer to throttle the pressure.
 
The replacement ones have a spring and a rubber washer to throttle the pressure.
Show me where, I've never seen one. Bought new ones as late as last year. Not sure why you'd want to lock any pressure in..
 
I probably pitched it. I had the same problem as the OP. Got mad and tore it apart, oh, it wasn't an orginal, it was a replacement. Got the cap off and there was a very light spring with a rubber washer in there. I agree about not wanting pressure, it's a vent. I have a new vent from Jamie at Mega Parts, I just haven't gotten around to installing it.
 
I just checked to see if I remembered to put teflon tape on the threads. I did not. I applied teflon tape to the threads and thought that would solve the issue. I took it for another drive and still have gear oil spraying out.
As Junkyard Hero has asked the question of the rear end being over filled. I put in the recommended 4.4 pints. The rear end was empty as I had just installed the new 3rd member. The car was on 4 jack stands on level ground.
After it happened the first time I checked the level again. I don't remember if at the time it was on jack stands or on risers. I took out the drain plug and gear lube barely trickled out the hole. If it is over filled, it can't be by much. I would think that as it blew out gear oil the level would eventually get to a point where it would slow or even stop spraying out. I could be wrong. I have been wrong before. Would it make that much difference if it were on jack stands, suspension unloaded or on risers at ride height?
I ordered a new breather vent since prevailing wisdom says the current one may be sticking and building pressure.
Thank you all for your responses. I will double check fluid level and make adjustments when I get the new breather vent installed,
Teflon tape is not tread sealant and belongs in the round file at the end of the work bench.

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Show me where, I've never seen one. Bought new ones as late as last year. Not sure why you'd want to lock any pressure in
Your not locking pressure in, you are keeping water, dirt, dust out.

Light spring allows pressure release like a rad cap
 
Wonder if the gears are running hot, boiling the rear end gear lube out the vent? No Backlash between Pinion and Ring Gear
That is a thought.

My builder said to take it easy for 500 miles.

I bought a Bluetooth temp probe and taped it on the the bottom of the pinion bearing part of the center section.

When I drove it I monitored the temp I kept it under a couple hundred deg, like 130 to 180.

Speed, load, etc increased the temp.
 
Get it level and pull the filler plug and see what comes out. I just fill mine until it starts coming out the fill hole and done. Never had an issue.
 
What was the brand of 80w90 gear lube you used?

Valvoline is good.

Want to make sure it is not an 80w90 weight lube that is a synthetic, that stuff is way thinner than the old school stinky 80w90 lube.


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If it's a Sure-grip, how much friction modifier did you put in on top of the 2 quarts of 80w90 gear lube? (making it over full...)
One of the Red Line gear oil already has modifier in it. I remember reading somewhere if you use the Ford modifier it’s like 1/2 ounce.
 
I remember smelling gear oil for a week after the swap and then again after the 1st oil change!

It's not a bad smell, just not a present one!

I would rather smell a feed lot over the gear oil.
 
I had a similar problem once.
I took the cap thing off, clamped a hose onto the stub, then hung the hose up higher on the shock crossmember, leaving enough slack for suspension travel. Problem solved.
 
I had a similar problem once.
I took the cap thing off, clamped a hose onto the stub, then hung the hose up higher on the shock crossmember, leaving enough slack for suspension travel. Problem solved
That's the way many Ford's do it back in the day. Also allowed you to get the rear fully submerged without getting water in it.
 
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