I am in the middle of changing the gearbox in my 1999 XJ8 after getting the gear box fault message and clunking noises during shifts.

I went and bought a box described as in 'perfect working order' off ebay. However now I have the replacement box nearly in I noticed it is leaking oil from around the gear selector shaft. Having left it over night I see a small puddle on the ground. If I carry on I know it is going to leak some more and require regular top ups. Which is going to be a PITA if you look at the procedure.

Can the shaft seal be replaced without stripping the box down ? Something I did not want to get involved in.

I fear getting an ebay refund is going be tough, so I could do without loosing the £365 spent on getting it.

 

You can change the seal, but it's not normally a problem part. What concerns me is why the fluid level is high enough to leak from round the selector. If you have fluid leaking over night from there you have way to much in the box.
You say you have it nearly in, how have you filled it?

 

I agree! I've changed dozens of those transmissions and never once had a problem with that seal ever. What you could do is drain all the oil into a container that you could measure what came out. This is also a good time to crack that 8mm Allen fill plug loose if it's tight like they usually are. Also, hopefully you replaced the rear main seal and that cap seal above there as well....

 

Just been talking to 2 technicians in our workshops today and both say the same. The fluid should not be that high, so it sounds like its over filled as that shaft is 20-25mm above the max fill level.
There is a small o-ring seal in the housing on the outside case, but its more to stop rubbish getting in rather than hold fluid back. It is not a proper oil seal. Of course it won't let fluid out under normal condition as that area is not permanently submerged
How have you filled the gearbox as I think that is your problem here.
If you want to change the O-ring I can send you drawing, but I don't think that's your problem here.

 

I had the box supplied with oil just as it came out of the donner vehicle. Since the oil cooler pipes were cut and blanked off when it came I am fairly sure it had the normal amount of oil and none would have been lost. I was hopping to save not needing 5-6ltr of oil at £10/ltr.

Since the box is half in it is still dangling at an angle on the tranny jack. I did'nt get to finish putting in housing bolts and rear mounting bracket. So the oil will be sitting in the back end of the box.

The leak is not really bad I am worried that even at one drip an hour the level will be lost.

I didn't replace any seals on the box, it looks un-touched.

 

Having looked more closely the leak is actually from the selector switch side. Is it just an o-ring or is it a proper oil seal ? A press fit seal might awkward to prize out.

 

Yes that's just an o-ring that sits in a recess in the casing, but I think you are worrying about a problem that isn't real. If the box is full of fluid and hanging with the back down that would explain the oil level being around area you're talking about, but when installed the fluid level sits just above the sump line when hot, which is much lower. The O-ring seals are not designed to be a complete oil seal as that area should not be submerged and under pressure from the fluid.
As you sound almost there, I personally would install the box completely and after you've got the level right you won't have a leak, plus if that box has sat a bit of warmth with the fluid will soften any seals that have been sat a while.
Not sure how the box was removed with fluid, but if that was done at an angle the box probably has much more fluid in it than it should anyway, as the cooler will have drained back as soon as the first pipe was opened, so you may have a 2-3 litres extra in there at the moment.
Are you replacing the fluid? It can be costly I think we charge around £12 litre (Jaguar Dealer). Don't get talked into the wrong fluid by factors or eBay Mobil LT 71141 (used to be Esso). Even if you're not changing the box fluid you really must flush the cooler as I've seen new transmissions trashed after rubbish from old failed box is circulated round the nice clean new one and I don't mean to offend with that comment, but I've seen it happen in a main dealers with experienced staff.

 

Oh and the system holds 10 litres of LT 71141

 

When I drained my original box before it came out it relinquished 5 ltr. Some came out when the oil cooler couplings were they were un-done but not more that a cup full. So there must be another 4-5ltr still in the cooler ?

The replacement box is reported as coming out of a vehicle which had itself had this box as a replacement, it was then scrapped due to subsequent crash damage. So the box which I received is supposed to have low mileage (40k) and already a fluid exchange.

Perhaps I should consider completing the box installation, get it running to circulate all the oil. Then drain the box and refill. This should water down the old oil in the cooler with the newer oil in the box.

I have the proper Mobil LT 71141 oil and this was used when my replacement box was refilled last. The box supplier has some more he can sell me at a reasonable price.

 

Yes the cooler and pipes hold 3.5L and you will still have fluid in the torque converter as that won't drain from the sump, plus what ever else is held in the valve body of the transmission.

The 10L is total capacity filling from dry.

Hope this message isn't to late, but don't run the transmission with fluid from the old one in the cooler or you'll mess it up. You need to clean the cooler and pipes. We have a rig for cleaning them in our workshop, but you should be able to do without as long as you clean out the old fluid and flush the cooler through. The only thing you want in it when you connect and start running is fresh clean LT71141.

 

Box is in and pipes are reconnected now. I still need to do battle with the re-fitting the exhaust so its not been run yet. I did try to flush the oil cooler and pipes, not sure if I have done good enough job but this is what I did:
1. Hooked a rubber hose to the pipe on the right hand side (looks to connect to the top end of rad).
2. Shoved the air line nozzle in the rubber pipe and blew out all the old back oil in to a bucket through the pipe on the left hand side (seems to exit the bottom of the rad).
3. Kept blowing air though and did several times after until I was get little more than mist cumming out.
4. Pumped about a pint of fresh new LT71141 in to the right hand pipe and blew this through into the bucket.
5. Hooked up the left hand pipe and pumped another pint in the right hand pipe and quick coupled it up before it ran out again.

Is this good enough ?

 

Hi, I'm not sure I would of done it that way as you have not really cleaned out the cooler. Air isn't going to do much except push out what is in the pipes, it's not going to flush the system. Air is fine to dry out after a cleaner fluid, but it'll just take the easiest route out. You really needed to have circulated some cleaner (or the expensive and not so rigorous way flushing clean fluid through).
For warranty on these Jag & ZF insist on new pipes and cooler, or proof of decontamination with a rig like we use in our workshop.
You also don't need to prime the cooler or pipes as the box will do that as soon as the pump starts turning.

 

I did flush through with some clean fluid, it ended up coming out clean. For better or worse the box is back in service, it took 6.5 ltr to fill it to the correct level using the procedure. So hopefully the other 3.5 ltrs (Total of 10ltr) is what remained in the torque converter and not the cooler.

 

Hi just wanted to know if you got it finished and also do you know the correct method for checking the level as it's quite critical.

 

I think I got it right. I followed the procedure in JTIS and watched this video :
I had a similar handheld IR temp sensor so I used that on the bottom of the pan.

 

I really would suggest doing it reading the actual fluid temperature from the internal sensor the pan surface temperature is not the same. If you need a scan tool lend of SDD kit let me know. The chap in the video is working on a different transmission and he is not doing it the correct way.