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Front Axle Blowing Out Fluid

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Old 01-14-2018, 02:18 PM
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Front Axle Blowing Out Fluid

I have a rebuilt front dana 44 axle on a '79 F250 frame and it is blowing fluid out of the vent hose. With over 700 miles on the truck now I thought it would eventually stop but it continues. I've had to tie a ziplock bag to the hose so I'm not wiping off the pumpkin it drips on every day. I figure I've lost a pint or more now. I wouldn't think the shop overfilled it and I haven't even used the 4X4. So what is causing the over pressure?
 
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Old 01-14-2018, 05:50 PM
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Pressure is caused by heat.

Rebuilt?.. Not by you? I bet it is in fact overfilled. With the axle cold, remove the drain plug and let it drain to find level ... and full.
 
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Old 01-14-2018, 06:59 PM
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Originally Posted by HIO Silver View Post
Pressure is caused by heat.

Rebuilt?.. Not by you? I bet it is in fact overfilled. With the axle cold, remove the drain plug and let it drain to find level ... and full.
don'y you mean remove the fill plug?
 
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Old 01-14-2018, 07:09 PM
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Technically they are one in the same. There is only one plug on the 78/79 D44 axles. Just remove the plug and in fluid comes out it was over filled! The second question is how long is your breather hose? Is it the original one that ties up to the frame?
 
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Old 01-14-2018, 08:41 PM
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Originally Posted by willowbilly3 View Post
don'y you mean remove the fill plug?
Yeah same difference.
 
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Old 01-15-2018, 11:05 AM
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Thanks for the input guys. I'll open the diff plug tomorrow and check. Just didn't think a company that specializes in axles would make that mistake, or that it was physically possible to overfill. In regards to the vent hose question, I did replace it and attached it back on the original clamp under the engine mount bracket. It is approximately 14 inches in length.
 
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Old 01-15-2018, 11:09 AM
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Locking hubs? Are you sure they're out?? If one isn't disengaging, it might be backspinning the differential, that'd make a pile of heat and really be slinging oil around in there..... Does it smell hot/burnt at all?
 
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Old 01-15-2018, 11:38 AM
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The fluid collecting in the bag looks very clean with no burnt smell. However I'll lift the front axle and check the lockouts, thanks.
 
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Old 01-16-2018, 10:38 PM
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I checked the fluid level and its about 1/2 inch below the fill plug hole, so that seems okay to me. Lifted the frontend and confirmed both lockouts are "free". Are there any other thoughts/ideas on my over pressure issue?
 
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Old 01-16-2018, 10:57 PM
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What KIND of fluid is in it? For sure 80/90 gear lube or possibly some thing thicker?
 
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Old 01-16-2018, 11:01 PM
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And no chance the oil is coming from somewhere else and simply hitting the end of the vent hose?
Reason I ask is that with nothing spinning in there, you should not have any fluid pushing out of the tube. Whether it's from splash, heat expansion, over-pressurization, or what, it only happens when something is moving. Stirring things up, so to speak.

If the vent was plugged, you'd get oil out of the axle seals and nothing out of the hose obviously. So over-pressurization does not seem to be possible. Unless...
You didn't happen to have an ARB installed by the shop, did you? If so, what about air coming in from the compressor?

Paul
 
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Old 01-17-2018, 04:46 AM
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With the hubs unlocked do you have the transfer case in 4x4?
 
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Old 01-17-2018, 07:23 AM
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With the tc case disengaged, and the wheel hubs disengaged, there should be nothing turning inside the differential at all. If everything is proper, and 4x4 is engaged and working, fluid should still not be fartin' out the vent. There should not be "pressure" if the vent is working and unobstructed. Maybe it is obstructed? There has to be movement inside the differential to create heat, so your hub(s) are engaged or your tc is, and the vent has to be obstructed to fart out fluid.

You made sure the hubs are disengaged by jacking it up and spinning each wheel and making sure the driveshaft did not spin. Now, verify that the transfer case is not engaged by turning it by hand.
 
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Old 01-17-2018, 08:22 AM
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The fluid I'm using I believe is 75/90 synthetic. Rechecked the lockouts and front driveshaft are free. The axle is stock, no ARB. Fluid definitely coming from vent hose as I have zip tied a bag to the end to collect the blow out. The fluid collecting in the bag seems to be slowing down. What is the minimum amount of oil I can get by with in the axle? I'll check the axle vent nozzle next for obstruction again.
 
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Old 01-17-2018, 09:20 AM
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If the vent is plugged I dought oil would oil would be coming out of it, it would be coming out somewhere else.
 
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