Odd Differential leak

[44DHR]

Following reading the "Diff output shaft leaks" thread by "Kingzetts", I was going to post a supplementary comment, by thought it best to start a new thread on a potential associated issue.
I am checking a Series 1 4.2 E Type as there is strange very minor drip coming from the near side front area of the differential tie plate. I initially thought this could be brake fluid from the "T" piece mounted on the axle cage in that area, but it is definitely dripping gear oil.
I can confirm there is no leaks from the diff cover, the front pinion seal or the diff output seals. There is no oil trace on the brake discs, yet when parked up for a day or two, there are a few drops left and appears from the front side edge of the tie plate.
My thoughts are now turning to a leak from inside the diff through the lower trunnions brackets mountings where they bolt onto the side of the diff, but I believe these are blind threads with no access into the diff internals.
A real strange issue and just wondered if anyone else had experienced this ?
Regards,
Dave

[mgcjag]

Hi Dave.....as these diffs are different this may not be correct for you case......my S2 2+2 has whats refered to as the 3rd type.....i know my output shafts are leaking but no oil gets on the disks....thus is becaus in the flange of the seal carrier that bolts to the diff is a groove to catch any oil that gets past the oil seal....at the bottom of tbe groove is a hole to a channel going back into the diff body..this channel apearing as a small hole both sides on the underside of the diff ...oil from it runs down tbe case and drips onto the base plate of the irs.....from under the irs with a good lamp and if the irs is clean you can see the small holes......could there be a similar set up on your diff.. Steve

[44DHR]

Steve,
Many thanks for your reply and this information on potential holes in the output shaft carriers.
I have several E Type diffs here - ranging from the early outer nut output shafts, the later one piece shafts and some XJS diffs, but I simply can't see any external holes on the undersides of the output shaft carriers on any of these. I wish I could as your explanation could give another source for oil escaping from the diff. I have worked on these diffs for many years and can't ever recall seeing such an arrangement on the carriers.
Can you - or any anybody else - direct me to any reference source of these holes or provide a photo showing their location ?
Regards,
Dave

[mgcjag]

Hi Dave, my ramp is in use so cant get the E up..heres a quick sketch.....of the underside and roughly where i remember them.....they are not machined round but roughly moulded....old grease/underseal will easily fill them..hope this helps...have a good poke around...Steve

[Bob.]

A little late, but this is the drive shaft bearing housing drain route - at least on later diffs.

From bearing housing

into diff casing

exit from diff above tie plate

[mgcjag]

Thanks Bob......what are you doing to yours....do not be tempted to change the bearings as i did....you can no longer get exact replacements and you will get constant leaks.....my o/p shafts are due for replacement when i can get the car on the lift..actually looking closer at yours they look a different type are they from your S3. Steve

[44DHR]

Steve and Bob,
Many thanks for this information and on further inspection I have located these holes directly under the bearing housings. I am slightly embarrassed as I have worked on Jag back axles for over 40 years - from my customising days when we narrowed them - up to later years when I have rebuilt the Powr-Lok internals or refitted different Crown wheels and pinions - yet I have completely overlooked the significance of these holes under the output shaft bearing housings.
Although they don't appear on the earlier outer nut shaft housings, now that I have looked at some later diffs I have here, these ports are now screaming out at me. I attach a few photos to show the differences in the escape channel moulding in a Series 2 diff and a later XJS diff where the holes are readily seen in the later diff.

E Type Series 2 Output Shaft Bearing channel moulding


XJS Output Shaft Bearing channel moulding


Very obvious - (now !) - output port picked out by flashlight on the XJS housing


The reason for my contrite reply is that this port is a really important issue to be aware of as a potential source of leak which is completely undetectable when assembled in the car due to it's location up under the bearing housing and shielded from direct view in situ by the brake disc and inner fulcrum distance tube. So you can have an apparently completely oil tight differential with no visible leaks from the obvious sources of the cover, pinion seal or output seals, but this minor leak can escape from this port and track unseen around the diff casing - and exactly as Steve stated - drip onto the tie plate to then drip onto the floor from no apparent source.
In the case in question, I will get my video borescope and track down the nearside port - which I am now convinced is the source of the very minor drip which started this post.
The question then will be - is it really worth pulling the diff to resolve it - with all the other potential issues - probably not as it is so minor at the moment and the source is potentially identified.
At least now through this great Forum- despite all our perceived knowledge, it again proves that we are always learning and I have almost certainly the answer to my odd leak !

regards,
Dave

P.S. As an aside, I have now nearly worked through my 180 plus Photobucket photos in my various posts on this Forum to replace them with Postimage ones and I'm nearly there - when I can gladly kiss Photobucket goodbye !

[mgcjag]

Hi Dave.....will be pulling my diff out again at the end of the year......for the 3rd time to solve my leak my diff is whats known as the 3rd type(later S2 as your 1st photo).....the first time i refurbed the diff 8 years ago i replaced the o/p bearings and oil seals.....refitted it but it still leaked , pulled it again and replaced the oil seal and rechecked the shims spacing that create the crush for the oil seal on the bearing...after chatting to Alan at http://www.ajsengineering.com/index.html re my problems he confirmed that replacing the o/p bearings was a bad move as the replacements are not the same as the originals and trying to get a leak free seal between the outer lip of the seal and the bearing was almost impossible.....the seal around the shaft is ok oil isnt getting past that but its leaking internally between the bearing and outer lip of the seal and getting into the internal drain channel......i opted for replacement o/p shafts from an xjs that he assures will be ok....still need to get the irs out but have a handbrake pad thats crumbled so 2 jobs at the same time.. Steve

[Bob.]

Dave - I took the third picture with the diff in the car and both exit ports were clearly visible, albeit with no exhaust present and a clean diff.

Steve - yes the pictures are of my S3 unit. Being the third generation it has bolt on driveshaft housings, driveshaft and flange as a single forging, no separate mounting flange for the brake caliper and a crushable sleeve to provide preload on the pinion bearings. Clausager quotes July 1969 as the date for introduction of this type from chassis number 1R35418 for 2+2 RHD, although I have no doubt that in reality they would have used the earlier type until stock ran out whatever the paperwork says.

This is the bearing I found fitted and have reused - supposedly renewed when the whole IRS/diff was rebuilt before I bought the car. I rejected SNGBs O ring seals which sit around the bearing as the cross section was the wrong shape and they were the wrong thickness. If I had used them during the rebuild there would certainly have been leaks.



As to why I have been deep into the diff, too long a story for Dave's thread, suffice to say that it started with finding fluid on the driver's floor mat last March and has kept me "entertained", off the road doing a complete rebuild of a supposedly fully rebuilt, newly plated and powdercoated IRS and diff unit and spending £££s all through summer while muttering "B*******y Classic Cowboys" at frequent intervals. (Hope to be on the road next week though to do my 41st mile since taking delivery 16 months ago)

[44DHR]

Bob,
Many thanks again for identifying that there are two outlet holes on the diff.
I am still a little confused looking at your third photo in your photos for the Sunday 13th post showing one of your outlet holes.
I can find my outlet holes way up at the furthest point inside the rear of the bearing casting on the opposite side to the external moulding shown in my first two photos which would be forming cover for the internal port that any escaping oil would follow.
Can you confirm that your holes are in the same position as mine as I can't recognise the "sharp" edge of the casting and the adjacent machined flat area to the right of your hole which appears to have a head of a bolt.
Regards,
Dave

[Bob.]

Dave - sorry, the pictures weren't very good. Two larger versions below, one for each side. These should enlarge by clicking on them.

The bolt is the lower caliper attachment and the images are taken looking up through the hole in the centre of the tie plate. I'm afraid that none of the ones I took when I had the diff out of the car show the moulding of the channel in the bearing housing from the drive flange side.
I've just checked and with the exhaust now fitted the exit ports are still clearly visible - or at least the elliptical holes that appear to come from channels of about 1/4" diameter and which I have just poked a wire at least an inch up, is what I have been taking as the drain ports!
My diff is third generation E type 4HU-004-25.

Hope this helps,
Bob

LH port - drain plug top left and LH brake caliper lower bolt on bottom right:



RH port - RH caliper lower bolt left centre, White dots are on driveshaft flange and bolt.

[44DHR]

Bob,
Many thanks - I fully understand now.
I had forgotten the visibility available through the central hole in the tie plate.
Best regards,
Dave