How to check/ top off rear axle?

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c - 26 Sep 2006 06:42 GMT

Hi,

I have a new to me 1998 F-150. The rear axle pumpkin has no drain/fill
plug. The bottom gasket area is damp and I don't know if much oil has
leaked out over time. It leaves no drops on the garage floor...but how can
I check level? And...how do you refill one of these? Through the axel
shafts??? One of Ford's better ideas???

I must be overlooking something simple.

Thanks for some help, Chuck

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djdave - 26 Sep 2006 12:13 GMT

It has a fill plug.
It is a 3/8 inch square (use a rachet and small extension)
its on the drivers side of the differential, in between the
reinforcement ribs, pointing torward the transmission.
You remove the plug, and usually stick a clean pc. of vacuum hose in
there to get a reading. Level should be full to the plug edge. Fluid
should not be milky. Since your diff. is leaking, I would plan a
gasket/fluid change. 98 f-150 should use 90weight gear lube. The
bottle you buy to refill the diff. is usually tapred, but I find it
easier to hook a hose to the taper, and fill the differential from the
hose.

>Hi,
>
[quoted text clipped - 7 lines]
>
>Thanks for some help, Chuck

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Mountain Mike^^ - 26 Sep 2006 17:21 GMT

> should not be milky. Since your diff. is leaking, I would plan a
> gasket/fluid change. 98 f-150 should use 90weight gear lube. The
> bottle you buy to refill the diff. is usually tapred, but I find it
> easier to hook a hose to the taper, and fill the differential from the
> hose.

Interesting. My 94 F-250 just got changed. It called for synthetic 75-140W
and a pint of anti-slip diff additive. They sucked out the old stuff with a
vacuum, and it cost $150 to get it done. Wonder if it's because it's a
limited slip?

MM^^

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Marlin Singer - 26 Sep 2006 21:44 GMT

>> should not be milky. Since your diff. is leaking, I would plan a
>> gasket/fluid change. 98 f-150 should use 90weight gear lube. The
[quoted text clipped - 8 lines]
>
> MM^^

The friction modifier is due to the limited slip. He will need that also
if changing the fluid and has LS.

Djdave, my understanding Ford has changed it's recommendations for front
and rear diffs from 75w90 to 75w140. Pretty sure it is all years.

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djdave - 27 Sep 2006 12:45 GMT

Sorry, was unaware.
I have been running a fleet of vehicles on 90 wt., and have 70+
gallons of it on hand, dont think I will be following fords'
recommendation :-)

>>> should not be milky. Since your diff. is leaking, I would plan a
>>> gasket/fluid change. 98 f-150 should use 90weight gear lube. The
[quoted text clipped - 14 lines]
>Djdave, my understanding Ford has changed it's recommendations for front
>and rear diffs from 75w90 to 75w140. Pretty sure it is all years.

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