So last year, I found out that I over filled my front diff and it started puking oil out of the vent tube until it reached the correct level, then it stopped. It hasn’t done it since.
Now, when I use 4WD, it starts puking oil out the vent tube again.
Why is this happening?
Is it still over full? Some vehicles automatically disengage parts of the front diff or driveshaft (like locking your hubs) when not in 4. Maybe 2wd sloshes overfull oil out and 4wd pumps it out with a spinning ring gear.
I don't think the vent tube is the proper fill level. Pull the plug that is used for filling it, when it stops leaking put the plug back in. That should cure it.
When in 4wd, you're likely making more heat in the diff. Fluid expands and overflows out the vent.
akylekoz said:I don't think the vent tube is the proper fill level. Pull the plug that is used for filling it, when it stops leaking put the plug back in. That should cure it.
The fill level is much lower than where the tube connects to the diff, probably by 4 inches.
rslifkin said:When in 4wd, you're likely making more heat in the diff. Fluid expands and overflows out the vent.
Yes, but it shouldn’t be doing that.
Robbie said:Is it still over full? Some vehicles automatically disengage parts of the front diff or driveshaft (like locking your hubs) when not in 4. Maybe 2wd sloshes overfull oil out and 4wd pumps it out with a spinning ring gear.
No, it’s where it’s supposed to be.
Is it clogged and building up pressure as it heats up? The pressure overcomes the clog and it squeezes past?
How did you overfill it in the first place? Serious question, not trying to be a dick.
TenToeTurbo said:How did you overfill it in the first place? Serious question, not trying to be a dick.
I thought it was to the fill hole (like everything else that takes gear oil) and according to the manual, it’s 1/4” below the fill hole.
ebonyandivory said:Is it clogged and building up pressure as it heats up? The pressure overcomes the clog and it squeezes past?
But what’s clogged? I pulled the vent tube off and blew through it with ease.
As a mechanic I have questions. Is there a hose attached to the vent tube or is it open to the atmosphere? Most 4x4s have a hose attached to the tube that vents 1-3 feet higher than the differential housing. I have found quite a few with missing or broken hoses.
outasite said:As a mechanic I have questions. Is there a hose attached to the vent tube or is it open to the atmosphere? Most 4x4s have a hose attached to the tube that vents 1-3 feet higher than the differential housing. I have found quite a few with missing or broken hoses.
It’s a GMC 2500HD, it has a hose that comes up right under the fuse box. Last year when I overfilled it, I made sure to blow that hose out and make sure the little plastic vent on the end didn’t have any crap in it. The hose is very much intact, but there shouldn’t be gear oil coming out of it.
Could you have water in there? Water at the bottom, heats up when 4wd is engaged then flashes to steam and pushes oil out the tube.
Just spitballing here...
In reply to RossD :
That could be a possibility. Well time to drain it I guess.
RossD said:Could you have water in there? Water at the bottom, heats up when 4wd is engaged then flashes to steam and pushes oil out the tube.
Just spitballing here...
If your diff was getting hot enough to boil water I think you would have other problems
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