I have been experiencing leaking from the rear diff for about 2 weeks now, not a lot of leaking but enough to notice on the garage floor. I took the car to my mechanic and was told there was a leak but they could not identify where the leak was coming from. The cost to replace the gaskets, etc was $2400 and the cost to put in a new system was $3500. Based on my research in these forums and online, this cost seems excessive.

At this time, there is no noise, no grinding just some leaking. I would like to get the car fixed but before I take it to another mechanic would like to know what the "average" repair is and what is the "average" cost.

Thoughts and thank you.
Brett

 

Hi Brett,

Welcome to the forum! When you get a chance, please add your Jaguar's year, model and approximate mileage to your signature so others know how to reply with maximum specificity. Since you are posting in the X308 forum, I'm assuming your car is a 1997-2003 XJ8 or XJR.

First of all, don't walk, RUN from the mechanic who wants $2,400 to replace one or more differential seals. There are only four places from which the diff can leak, and all can typically be resealed without dropping the rear end (the "Independent Rear Suspension" (IRS), which carries the differential). The one possible exception is the rear cover of the diff - I'm not positive it can be removed, cleaned and resealed without dropping the IRS, but I think it's likely. Fortunately, it seems to be the least likely source of leaks. Output seals and bearings run about $50 for parts per side, the pinion seal should be less than that, and the rear cover is just sealed by RTV silicone, at around $5 for a tube. Add a couple hours of labor and that's what you should expect to pay to have any of these jobs done by a knowledgeable mechanic.

The seals at the output shafts, or axle connections, are common leak points. Since the rear axles form part of the Jaguar rear suspension, the diff output shafts are under more stress than in most other vehicles. Usually, when the seal begins to leak it's time to replace the bearing also (and since you have to destroy the bearing collar and remove the bearing to replace the seal, it makes sense to replace the bearing while you're at it). An X308 is slightly different from our '94 XJ40, but the photos below will give you a rough idea of what's involved:

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page

Another source of leaks is the seal on the pinion or input shaft that connects to the driveshaft or propshaft. A knowledgeable mechanic can replace this seal without dropping the rear end as long as the pinion nut is returned to its exact original location, or just very slightly tighter. However, if your pinion seal is leaking you should have the pinion bearings checked to be ensure there is no discernible play, which indicates excessive bearing wear that will require a diff rebuild (or replacement with a rebuilt unit).

All this to say, you really need to find the source of the leak so you can determine how to proceed. If you can raise the vehicle and clean all the old gunk off the diff with something like engine degreaser or brake cleaner and use a couple of old towels to wipe everything as clean as you can, top up the fluid in the diff, then check again in a couple of days to see where it's leaking.

Diffs usually get really noisy long before they fail, so as long as you keep the fluid level correct in the diff, you're probably not in any danger of imminent failure. But the leak will probably not be too difficult to fix once you know where it is.

Just to give you an idea of the parts of the diff, here's a link to the parts diagram:

Differential Assembly - Parts For XJ Series from (V)812317 to (V)F59525 (X308) | Jaguar Classic Parts UK

And here are links to photos showing the rebuild process on our '93, which is very similar to the diff on the X308:

Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page
Welcome to Jag-lovers - Members Photo Viewing Page

I don't have photos showing how the pinion seal is replaced with the diff in the car, but you may find some if you use the forum search function.

Cheers,

Don

 

First, clean the differential breather and refill with lubricant.

Many leaks have been caused by a clogged breather causing high internal pressures which push lubricant past the seals. Cleaning the breather eliminates the cause and the leak goes away.

 

THIS!!
I had a leaking pinion seal, caused by a blocked breather. I procrastinated on buying a new pinion seal kit, and ended up blowing the diff and buying a refurbished one for about US$2500, by the time it made it to this side of the world.

I would recommend cleaning everything, especially the breather, top it up with fluid, and then keep a close eye on it to see if that has stopped the leak.
Of course, once fluid has started to seep through a seal, the only way to stop it may be to replace it, but leave that until you can positively identify which one is at fault

 

My differential was leaking from 2 seals. On advice from this forum I cleaned the breather valve (top rear of differential) which I found clogged and stuck when I removed it. Both seals have completely stopped leaking after cleaning the breather - start here.

 

#3

 

Hello Bret....follow the advice regards the breather and suck out the old
diff oil (which will stink like hell if it's original) and replace with a good quality full synthetic GL5/6 75/90 oil and add to this a tube of leak stopper/seal reviver.
My car had a slight weep at the right sidxe output seal and I treated mine with the above and now it has covered over 200,000klm and nary a sign of a leak. ;o)

 

I had a leak on the front of the diff, replaced the input shaft seal about a month ago. Prop shaft rubber flange out from the 3 bolts, a 32 mm socket, it must be the long type (3-4 inches total length),to take the nut out, and a three legs extractor plus some heat with the gas torch. Once the flange and seal are out, a little more heat to take the metal part of the oil seal. No more leaks, the breather was clean. 75W140 oil inside.
1-2 hours work plus 50$ seal.

 

Hi flay,

Did you return the pinion shaft nut to its exact original position or just slightly tighter? The preload on the pinion bearings is critical for zero play and long bearing life.

Cheers,

Don

 

I would forgo any "leak stop" unless the requirement was proven.

The 75W90 may be a tad thin as the recommendation is for Shell Spirax Super TS90 which appears to be a straight 90W with LSD additive. The reason no one can ever find it is that it is not TS, it is "Thermally Stable" on the bottle.

Redline 80W140 is almost as cheap as anything else.

 

I couldn't refit the flange on the same splines, but the nut , having that squeeze part to prevent unwinding, was tighter than before, about 1mm on the circumference.I couldn't check with the torque wrench but it was tighter.

 

Look at this other thread about the fluid and capacity:

https://www.jaguarforums.com/forum/x...ax-ts90-54273/

Jim Lombardi

 

Just purchased this beauty for a song 100,000 miles. 2nd Jag I've owned. Took to my auto service for lube and they noted the leak in the differential. Not too bad but will keep track of leak each lube or 3500 miles. Quote for replacement of all rear seals parts and labor about $1000. Over all inspection was very good and XJ6 4.0 l. motor is one of the better Jag as made.
Will follow up with progress. Just joined the forum.

 

Welcome to the forum, but you should be posting in the X300 forum. If you go to the USER CP you can add your car and signature to your posts.

Please visit the new member area and introduce yourself.

New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum