Hello!

I should probably start this off with a disclaimer: I'm an electrics man. Electricity and electrical components make sense to me. Mechanics on the other hand... not so much. I am hoping to learn, however, through rigorous maintenance and upkeep of my XJS. That said there may very well be an obvious solution here in the ROM or the oil leak sticky, I'm just lacking the vocabulary to adequately find it. I understand I should have gotten something like a beetle but the jag is sentimental to me and I quite like it.

That said, I'm trying to trace down a leak from the rear diff area. I read in 'the book' that the diff breather valve is the most likely culprit, yet, when looking under the car, I also see what like like fluid coming off the driveshaft if I'm describing that correctly. Since I'm working on the brakes as well, I'd like to ensure this isn't a brake fluid leak before proceeding to bleed the system. I couldn't find the source but perhaps there is a better way to check than my looking about. In sum my goal is to:

1. Figure out what is the cause of the rust/leak area on the driveshaft
2. Find out whether the oil/grease buildup from the rear diff area is cause for concern or not. I think I scraped about 4-5 pounds of the grease off.
3. See if my untrained eye is missing something that is crying for attention but I can't see it

I've attached a video of the area in question. Apologies for the shaky cam, it has been a long and hot day here. If the compression makes it unwatchable:
Any recommendations, literature, or ROM procedures would be very much appreciated. Just don't tell me to get a beetle!

 

OK,

What I have dealt with over too manyyears.

1) Breather, some, but a good thing to KNOW is not blocked.
2) Diff end plate, rare.
3) Output shaft seals, hell yes, and usually caused by #1 above. AND, stale old diff oil.
HUGE job to replace a $20 seal, so many steps prior to dropping that rear cage.
4) The Uni Joints of teh halfshafts are screaming for grease. Most have never been greased since they left Coventry.
5) Grease and muck in that area, sort of normal for the age.

Suggestion:
Clean it down, nothing stupid, NO hi pressure washing machines, simple degreaser, brush/scraper, and wash off with the garden hose.
Drain and refill the diff oil, simple.
Grease the Uni Joints, and the other grease nipples in the area, CAREFULLY.

Drive it, just drive it, and check back under in a few weeks.

That simple suggestions has stayed dry on most of mine. Only 4 needed surgery.

 

A brake fluid leak obviously must be contended with, pronto.

A differential leak, less urgent.

The differential oil will be thicker than brake fluid and have the characteristic nasty smell. Yuck.

I agree with everything Grant said.

My first Jag had some differential leaks. Not gushers, just a few drips. Since none of the fixes were easy I drove the car for years and years that way. The only concerns were A) keeping oil from migrating to the brakes and B) the diff running low on oil.

"A" was easily addressed by an every-six-months cleaning with aerosol brake cleaner when the car was being serviced...or whenever a good opportunity presented itself. This takes about one minute. "B" was addressed at the same time as "A" by simply checking the oil level and topping-off it needed....and it never needed very much. A quarter pint or so, at most, maybe once a year.

Sometimes a problem is just easier to live with than to repair. And I'm rather nonchalant about oil leaks .

Cheers
DD

 

Thanks guys, this gives me a good jumping off point. Going to start with a good clean and give everything on the aft side a good greasing. Is the rear suspension cradle a protective element? I.e. can I remove it give it a good clean? That is where most of the gunk has accumulated and reaching the topside would be much easier if it's safe to take off.

For the output shaft seals, would liquid gasket/leak stop products be effective to hold through until I build up some confidence to do the big job of replacing the seal?

And I'm with you there Doug, especially at my stage where it's always a question whether or not it will work when I put it back on!

 

Dropping that cradle purely for cleaning, NOPE, as there is a lot of work for a 1st timer, NO DISRESPECT INTENDED.

Wash as best you can, and then move along the steps as needed.

The breather, fresh oil etc, and it will be just fine.

The tin "tie plate" on the bottom can be safely removed.
8 bolts
8 Bolts and washers
NOTHING will escape, dirt and muck maybe, but nothing mechanical. Makes cleaning a lot easier.

When and IF that cradle comes out, there a few things that should be attended to, so lets leave that till the comfort zone kicks in, and the beer consumption stabilises also.

Stop leaks and such, NO WAY, please. Fresh diff oil jas worked to soften those seals many, many times for me.

Also remember, the oil leaks were a design factor for rust protection back in the day, so like Doug, we live with that at times.

 

Suggest checking where the driveshaft meets the input shaft of differential. Diff oil can leak slowly through splines of pinion and will be slung out between the two flanges.

Larry Louton

 

Cheers all for the inputs. I got a bit of time on the car today and most of the muck cleaned out.

It looks like a leak spot is on the aft side of the diff, below the breather:


I'm guessing this could be from a clogged breather? I'm pretty sure I saw some fluid seeping out of here while cleaning.

Hi Larry!
Is this the spot you are talking about? If I read the workshop manual correctly, there is also an oil seal in there as well and the procedure to replace doesn't seem too involved. Is that correct and is it something worth doing?



These spots plus the very bottom of the diff looked to be the sources of these leaks. I'm planning to clean the breather once I find a good procedure and replace the oil with GL5/6 75/90. I read a recommendation to add in some leak stopper/seal reviver as well. Figure it cant hurt. I'm can live with small manageable leaks so long as they don't cause bigger problems down the road.

Good news that it's not a brake fluid leak, at least from what I can tell. I did see some white corrosion near the LHS brake line near the cat on a mystery tube. Doesn't look like anything more than surface corrosion but for my education what line is this? Any ideas how that corrosion got started?


Thanks all!

 

Hello Life, The mystery tube is the fuel return line from the engine. Suggest a light scrubbing, Then a couple brush loads of POR-15. The input flange is slinging differential oil up and onto the brake pipes above the flange.

Larry Louton

 

Hello Life, Forgot to tell you to put sealant on fill and drain plug threads. Any vapor stains from vent is fact of life.

Larry Louton

 

And, as always, do NOT undo the drain plug until you've confirmed that the fill up will undo!

Cheers

Paul

 

Excellent! That confirms the leak spots then. Is a potential cause the blocked breather or are chances likely the seal has gone? I think just about everything except the tires are original on this car.

Thanks!

 

My crystal ball will not tell me about the seals.

Fresh oil, DRIVE the thing, look under in afew months,.

UNLESS there are drops of oil on the pavement, return to drinking status, and another area of the beast.

Lack of use, #1 killer of any Jag, especially the V12.

My S2 XJ12, just short of 700000kms, UNTOUCHED in any major way. Output seals were done at 280000kms, no oil on the driveway, dont bother me at all.
ALL fluids are drained and refreshed annually, no matter what.

Engine leaks some oil, HAHAHA, and at that mileage, it can stay as it is. I am not that brave or stupid to look into it. 1/2ltr between oil changes, so care factor is real low.

NO under car rust, trust me, that "Coventry Rust Preventative Program" is working real well.

 

Thanks! Sounds like a plan. Though I am currently working through brake issues and unable to drive the car, I will search for more 'upkeep' items until it's drivable and check the area again then.

Though I might run out of upkeep items. Surely that is a possibility, right?

 

HAHAHAHA, in your dreams.

My Red beast was off the road for 4 months (had a company car), engine/trans out, cradles out, interior stripped a fair bit.

Oil leaks, wiring, general rebushing (car was 12 years old and 100K kms), then reassembled with MY upgrades etc, ALL before Forums and Computers, sooooo, shade tree, BEER (lots of), German Sheppard for company.
Learnt whole new language, ha.

All done, took 18 months off from the work force, drove that car all the way around the Aust Coast Road, 25000kms, and most of it barely sealed roads, never ever had an issue. Only Gremlin was a weeping idiot light sender unit (OE unit), got a replacenment at a Toyota Dealer in Townsville, fitted in their carpark, and its still it there, and dry, today.

Maintaining ONCE its sorted, is SIMPLE, but you will never run out of things to do, just because.

 

Respect, that is something I could never imagine doing. Need to get past the fear of making something worse before sorting it out. Or maybe accept it will get worse before it gets better!

I very much look forward to getting past these learning curves and getting to the maintenance or the upgrades I would like to make. So far the car reminds me of a sick animal you are trying to take to the vet but it keeps fighting you... still love it but many choice words are had. Like today, set out to replace the front tie rod. Simple as undoing three nuts right? Well with herculean strength they were finally removed only to discover mystery dangling part behind them and a mangled tab washer that doesn't exist in parts diagram! Such is life I suppose.

 

Let me know if I should make a separate thread for this, but, after some hours of research, I cannot find any references or diagrams that sheds light on this.

In any case, here are some pics of the area in question that shows the unattached ring around the shaft that attaches to the inner tie rod. I did the other side tie rod a month or so ago and don't remember seeing this piece. This almost looks like it was welded to the tab washer. Is this supposed to be there, did it break off from inside the steering shaft? And are these tab washers available some place or usually forgone in favor of loctite? I'm a bit surprised they are not shown on the jag diagrams.

 

For any future visitors here with the same issue sourcing this part, the kind folks at jagbits were able to give me the part number for this tab washer: C39341. It's NLA and laughably expensive for what it is if you can even find it available. I'm going the DIY route and going to fabricate one out of a traditional washer. I'm also assuming the secondary ring piece was put on by the PO when he replaced the tie rod. My guess is he also had trouble sourcing a replacement and reused the old mangled one with this spot-welded to give it some additional holding power.