Differential oil blowing out

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John Trickler

John Trickler

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I have had troubles with rear end oil coming out the vent. Bob. Drive it a short distance and I leave a puddle of rear end oil on the floor. I took the little vent cap off and put on a hose of approximately foot and a half going up over the axle floor pan. Drove the car approximately 10 mi to get gas and still have oil coming out of the vent tube. Any ideas? I did the best I could at taking pictures of the event tubing.
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1000002869.jpg
 

Is it getting to hot? Or just over filled.

It looks like a new set up from the photos. It would not be the first time I have seen a tad bit more oil than it should have or assembled too tight and a rear end is over heating. Hopefully it’s just too much oil.
 
Is it coming out of the vent tube still or the end of the hose you added?
 
It is a new set-up. It is still coming out of the new hose I added. I do believe it might be gear set may be set-up a little tight. It is not over full, I do know how to do that. Worked at a Chrysler dealership on the lube rack back in the day. I plan on taking the rear end housing out in the fall and moving the vent. Just looking for any other ideas or insights. Also have a driveline vibration on deceleration. Will re-check my pinion angle. It is an RMS suspension.
 
John Trickler said:
It is a new set-up. It is still coming out of the new hose I added. I do believe it might be gear set may be set-up a little tight. It is not over full, I do know how to do that. Worked at a Chrysler dealership on the lube rack back in the day. I plan on taking the rear end housing out in the fall and moving the vent. Just looking for any other ideas or insights. Also have a driveline vibration on deceleration. Will re-check my pinion angle. It is an RMS suspension.
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Humor us and explain how you filled it and made the determination that it is full.
 
This housing was acquired by a Mopar friend of mine. It has not been modified. I believe some of the earlier designs had the vent there, then relocated. I know on the B-Body I owned, the vent was located farther down on the tube area. As far as the level, the rule of thumb was if it was level with the plug to 1/2" below, you were good. The gear ratio is 3:90-1 with a Gear-Vendors O/D. My plan is to pull the rear housing after the season, plug the current vent, and relocate it further down inn the tube area.
 
John Trickler said:
This housing was acquired by a Mopar friend of mine. It has not been modified. I believe some of the earlier designs had the vent there, then relocated. I know on the B-Body I owned, the vent was located farther down on the tube area. As far as the level, the rule of thumb was if it was level with the plug to 1/2" below, you were good. The gear ratio is 3:90-1 with a Gear-Vendors O/D. My plan is to pull the rear housing after the season, plug the current vent, and relocate it further down inn the tube area.
Click to expand...
Well, The old adage about filling until it runs out the fill plug is just flat wrong. They all have a spec in the service manual. I filled them for years the wrong way and trust me. It's wrong. lol It always results in too high a fluid level. Every single time. I personally have never seen a vent tube from the factory in the housing in the third member area. Never. Having said that, that doesn't mean a darn thing, cause Lord knows I ain't seen it all. I'd do the relocation first and see if that fixes it. I bet it will.
 
Looks like a triangulated 4-link, maybe they moved the vent for one of the top brackets. I have the same, but didn't have to move the vent. My '72 would puke oil out all the time, while waiting for a replacement, I used a brake line and bent a pig tail into it, leak stopped. I never have put the new vent in.
 
RustyRatRod said:
Well, The old adage about filling until it runs out the fill plug is just flat wrong. They all have a spec in the service manual. I filled them for years the wrong way and trust me. It's wrong. lol It always results in too high a fluid level. Every single time. I personally have never seen a vent tube from the factory in the housing in the third member area. Never. Having said that, that doesn't mean a darn thing, cause Lord knows I ain't seen it all. I'd do the relocation first and see if that fixes it. I bet it will.
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Plans are to move it, just not high on the list this summer.
 
Early Ford 7.5 and 8.8 irs put the vent in a similar location (curb side, in the bolt-on cover) but there are baffles inside similar to an oem valve cover.

No practical fix leaving the venting there. A big breather box would prevent leaks but would just collect all the oil pumped up the vent that needs to be in the diff, then drain back when you stop moving. Baffles in the housing would work but still need tear down and good welds so they don't let loose. I also think the brake hose manifold was moved for 4 link clearance. You could leave the manifold there, cap the integral vent and add a separate vent to the top of either tube.
 
CRUZE 418 said:
Looks like a triangulated 4-link, maybe they moved the vent for one of the top brackets. I have the same, but didn't have to move the vent. My '72 would puke oil out all the time, while waiting for a replacement, I used a brake line and bent a pig tail into it, leak stopped. I never have put the new vent in.
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I did not move the vent, that's where it was when I put the rear end in. I put the RMS suspension in. Is a mystery.
 
John Trickler said:
I did not move the vent, that's where it was when I put the rear end in. I put the RMS suspension in. Is a mystery.
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I’m going to catch hell for it, but I’m going to say a cheap (relatively) fix is to change the gear oil.

I don’t know what you are using, but cheap gear oils foam like jack the bear.

It may be just a simple oil change. It may not entirely fix it, but it may help.
 
Newbomb Turk said:
I’m going to catch hell for it, but I’m going to say a cheap (relatively) fix is to change the gear oil.

I don’t know what you are using, but cheap gear oils foam like jack the bear.

It may be just a simple oil change. It may not entirely fix it, but it may help.
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Not cheap gear oil, unless you consider Amsoil inferior. I pretty sure that I just need to move the vent.
 
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