[xj40] How can I check/replace the rear differential's oil

XJ40
1

My car is STILL making a loud noise from the rear, and the
only thing left is the differential. How do I locate where
to check the oil level? check the level of the oil? Drain
the oil? What oil to I buy to replace the oil? Am I better
off going to Jiffy Lube or some place like that?–
Tophatchef
Jupiter, Florida, United States
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2

In reply to a message from Tophatchef sent Mon 1 Jun 2009:

This is what you need to drain and re-fill the differential

http://www.jag-lovers.org/snaps/snap_view.php3?id=1145470011

First (repeat FIRST) remove the fill / level plug in the
back cover of the diff just to make sure that you can
remove it to re-fill the diff after you have drained it.

I find it essential to tackle that from below, so make sure
that the car is properly supported on ramps and / or axle
stands.

Drain the old oil by removing the drain plug in the bottom
of the diff (accessible through a hole in the rear ‘A’
frame). Pay particular attention to any metallic deposits on
the magnetic drain plug. If you see any substantial evidence
of that, the chances are that something internal to the diff
is badly worn and you may need a replacement differential.

You need 2.1 litres of differential oil. After replacing the
drain plug, you replenish the diff oil until it runs out of
the fill/level plug hole. It is a bit messy.

There are three main ‘noise generators’ in the diff - the
output shaft bearings (can be replaced with the diff still
in the car), the pinion bearings and the main carrier
bearings (the last two require the diff to be removed for
strip down to effect replacement - a BIG job, see archives)

I’m not familiar with the differential lubricants available
in the US - others will advise you on that score - but
replacing the diff oil will never cure the fault causing
the noise.–
The original message included these comments:

My car is STILL making a loud noise from the rear, and the
only thing left is the differential. How do I locate where
to check the oil level? check the level of the oil? Drain
the oil? What oil to I buy to replace the oil? Am I better
off going to Jiffy Lube or some place like that?

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
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3

In reply to a message from Tophatchef sent Mon 1 Jun 2009:

The product you need to refill the diff is Castrol Hypoy c80w-90.
John.–
John. Walsh. Purrrrr 89 vdp
bowmanville ontario, Canada
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4

In reply to a message from h s law sent Mon 1 Jun 2009:

So, wait, do I go in through the trunk?–
Tophatchef
Jupiter, Florida, United States
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5

In reply to a message from Tophatchef sent Mon 1 Jun 2009:

Just EXACTLY where is the differential plug? Under the car?
Passenger’s or driver’s side? Easy to see, or behind some
stuff? I’ve checked the two manuals I’ve got and neither
say anything about where the differential is.–
Tophatchef
Jupiter, Florida, United States
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6

In reply to a message from Tophatchef sent Mon 1 Jun 2009:

The differential has two plugs, level/refill plug wich is located
on the back side of the diff. and the drain plug on the bottom of
the differential. You can easily locate the bottom drain plug but
you need get underneath of the diff. to find the rear level/refill
plug. Using Bryan’s tool from the picture helps you undo the rear
level/refill plug quite easy. After draining the old oil and
reinstalling the bottom plug you need remove the trunk carpet and
find a hole that’s behind and almost above of the diff. I bought a
clear plastic tube that fits on to the funnel. Insert the other end
of the tube into the diff. level/refill plug through the trunk
bottom and pour the new oil into the funnel and let it go in to the
diff. Be patient and try not to scream if the oil pours out of the
diff. :slight_smile:
Joe–
'94 XJ40, CFA/AFW. Miles still under 100k. Naples, FL
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7

In reply to a message from Tophatchef sent Mon 1 Jun 2009:

Hi, Just in case you are not sure, and I don’t mean to be
telling you something obvious, but I am guessing you don’t
really know what the ’ diff ’ is ?
Just incase, it is the large ’ box ’ that is in the centre
of your car between the rear wheels. The prop shaft connects
to it at the front and the drive shafts to the rear wheels
exit each side.

Read the previous posts for changing the oil,with
particular attention to removing the filler plug first.

good luck.–
The original message included these comments:

Just EXACTLY where is the differential plug? Under the car?
Passenger’s or driver’s side? Easy to see, or behind some
stuff? I’ve checked the two manuals I’ve got and neither
say anything about where the differential is.

–
Casso - 1993 4.0 Sovereign.
Liverpool, United Kingdom
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8

In reply to a message from Tophatchef sent Mon 1 Jun 2009:

If you have a Haynes Manual, look in Chapter 1 on page 1.5
at the picture ‘Rear underbody view (typical)’ to see the
location of the differential. Then turn to Chapter 1 Section
9, ‘Differential oil check’ and then Section 27
‘Differential oil renewal’

Then take the car to your local dealer or Lube joint to have
the oil checked and changed.–
The original message included these comments:

Just EXACTLY where is the differential plug? Under the car?
Passenger’s or driver’s side? Easy to see, or behind some
stuff? I’ve checked the two manuals I’ve got and neither
say anything about where the differential is.

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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9

In reply to a message from Casso sent Mon 1 Jun 2009:

Yeah, I really didn’t know exactly where the diff is, but I
do now. I feel really silly because I forgot that in the
front of the Haynes manual they have an under car diagram
that I just ignored, and went right on to how to check the diff.

However, so much for doing it myself, I’m taking the car to
Eco Lube tomorrow. They said they’d do it for $25, and
since the auto parts stores don’t seem to carry the oil I
need, and Eco does, they are a perfect candidate.–
Tophatchef
Jupiter, Florida, United States
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