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Can axle fluid expand in extreme heat situations?

Avery4jc

Avery4jc

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I stopped in a parking lot the other day and noticed that I had a little bit of fluid coming up and seaping around the breather tube on my 14ff. Its been 105°-110° for about a week now so I was wondering if the fluid expands in these extreme temps?
When I filled the rear end up with fluid many of you may remember I did it when it was out of the truck and I tilted the yoke towards the ground and had it on jackstands then just filled it up so I know its extremely full...anyways just wondering...
 
If an axle is over filled the fluid can foam up causing it to push out of the vent tube. I would park it level and recheck the fluid. Take a cup or something with you to catch any excess.
 
When the fluid gets hot it also gets thinner and probably found the easiest way out. I'm sure it expands some too.
 
When I filled the rear end up with fluid many of you may remember I did it when it was out of the truck and I tilted the yoke towards the ground and had it on jackstands then just filled it up so I know its extremely full...anyways just wondering...
Click to expand...

You just answered your own questuion right there.

Filling the diff as you have it is extremely overfull. Not a good thing to have too much oil as it will airate and not lube properly.
 
Avery4jc said:
I stopped in a parking lot the other day and noticed that I had a little bit of fluid coming up and seaping around the breather tube on my 14ff. Its been 105°-110° for about a week now so I was wondering if the fluid expands in these extreme temps?
When I filled the rear end up with fluid many of you may remember I did it when it was out of the truck and I tilted the yoke towards the ground and had it on jackstands then just filled it up so I know its extremely full...anyways just wondering...
Click to expand...

I thought we suggested that you drain some of that out after you overfilled the crap out of it??

Either way it has prob foamed up and come out the vent...
 
4X4HIGH said:
You just answered your own questuion right there.
Click to expand...

I would have thought the same thing except I've been daily driving it since I did the swap back in December/January so we're talking about 7 months of being driven every single day and it just now leaked out a little (I only noticed it b/c it was shiny around the nipple that the vent tube attaches to so its hardly any fluid at all)...

Oh and as far as over-filling I heard mixed reviews so I made sure there was a little space and left it.

Ok thanks for the info guys...
 
Fluid will always expand as it heats up...doesn't have to be "extreme". Since the ambient temp. is so hot I'm sure it's heating up even more and thus expanding more.

There is really no reason to overfill. The manufacturer spends a lot of time determining exactly how much fluid the diff needs and sets the fill hole at that height, they just don't randomly decide where to put the fill hole. Overfilling the diff is the same as overfilling the trans or engine with oil.
 
Avery4jc said:
Oh and as far as over-filling I heard mixed reviews so I made sure there was a little space and left it.

..
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There are no mixed reviews, its either right or wrong and your's is wrong. Like 6.2 said the auto maker put a fill plug on the side for a reason, and they sure didnt design the axle to be filled through the open diff cover...
 
I guarantee any "mixed reviews" about this method has to do with pinion angle changes. If you raise the pinion, you change how it was designed to be lubricated.

I'd agree, stock pinion angle, fluid level to the fill plug height. Raise the pinion, that is no longer a valid measurement.
 
if there was no expansion or contraction then there would not have to be a vent tube in the first place
 
Avery4jc said:
I would have thought the same thing except I've been daily driving it since I did the swap back in December/January so we're talking about 7 months of being driven every single day and it just now leaked out a little (I only noticed it b/c it was shiny around the nipple that the vent tube attaches to so its hardly any fluid at all)...

Oh and as far as over-filling I heard mixed reviews so I made sure there was a little space and left it.

Ok thanks for the info guys...
Click to expand...

You've been driving it around for 7 months with the diff too full, end of story.

A 14BFF holds 7.2 pints of gear oil, thats just a nudge over 3.5 quaarts.
 
dyeager535 said:
I guarantee any "mixed reviews" about this method has to do with pinion angle changes. If you raise the pinion, you change how it was designed to be lubricated.

I'd agree, stock pinion angle, fluid level to the fill plug height. Raise the pinion, that is no longer a valid measurement.
Click to expand...

Bingo...plus who is to say mine is too full? I filled it through the open cover b/c I had it off inspecting the carrier, bearings and gears and I just assumed it was a little full after talking to people. Anyways I'll go pull the fill plug next time I'm out workin' on something and let it drain down to that level (if it even needs to, I've never had the plug out)...

I'll keep ya posted on how much drained out...
 
Avery4jc said:
Bingo...plus who is to say mine is too full?...
Click to expand...

I say its too full, you filled it through the diff cover with the pinion pointed down, its overfilled. Pull the plug and watch it drain
 
Gear oil expands big time when it gets hot, just come to my house after I have been driving on the freeway and I will let you crack open the SM 465...you'll see how fast that stuff comes flying out, even if it was below the fill line when cold...and it friggin burns, ask me how I know:doah:
 
so did you pull the plug or is this going to turn into a month long thread like your carriage bolt center pin did?
 
Mine is "over full" as you guys put it and has been that way for 3 years with no issues as in no leaks out of the vent due to expansion or aeration. It does leak around the cover though:doah: .

By the way I have over a gallon of fluid in mine. With the volume in the tubes it will cause a minimal change in fluid level at the gears. I purposely over filled mine to keep lube down on the wheel bearings. Yes the engineers designed the axle to carry the lube down there but they did not design the axle to do what we do with them. There is a big difference between highway usage and extreme off camber situations.

Dik
 
You came in here with your mind already made up. That you were not going to drain it no matter what anyone said. So why did you even make a thread asking this question if you are not going to drain it.:rolleyes:

I am going to have start calling you Homeslice for all the useless threads that you start
 
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