Just wondered if anyone had any thoughts on how I might cure an annoying minor leak from the joint of the dipstick tube to the sump of the autobox on my 1994 AJ16 Convertible?

Ever since I dropped the sump in 2016, I've had a very minor but constant leak from the tube connection. And despite disconnecting and reconnecting it a number of times, I can't seem to stop it. Has anyone else had this problem?

The surfaces on the inner flare of the tube end seem fine, as does the tapered boss of the sump. The joint seems to pull up cleanly and the nut tightens well. But I still end up with a drip. So what can I do? Is there something that I can very carefully smear on the surfaces of the pipe flare and the sump boss to help them seal (that won't get into the box fluid and congeal)?

Tks

Paul

 

I'm sure there are several thread sealant products sold at your local auto parts store.

As for which works best? I'm sure someone will come by and give you their $0.02.

 

Paul,

There are flare sealants which are used in the HVAC industry. Here are some examples:

https://flareseal.com/

https://www.refrigtech.com/nylog-blue/

Cheers

 

Tks Guys,

I like the idea of both of those, Mac, as it's the flare that must be leaking, rather than the thread. I've used both PTFE and threadlocker on the thread but it still works its way out the back of the nut.

I particularly like that flare-seal product, never seen those before. I wonder how best to measure to see what size of flare is that connection?

Paul

 

My favorite thread sealing tape is Blue Monster. I learned about it from a water company service guy who said it works when all else fails. I'll be using it on my diff plugs, so you could try that as well.

https://cleanfit.com/blue_monster_pt...pe_70885.shtml

 

Concerning the subject of flare sealing (and many thanks for the two links guys) I have managed to seal double SAE flares very successfully when they started to leak, as explained below.

When udoing the P/S pipes into the rack and then refitting them, and also when refitting the trans oil cooler pipes to my GM400 box, I had annoying leaks from the double flares. Tightening more does no good as it just cracks the flare. The flares on the pipes fit into a circular V shaped groove in the female rack/box ports. In both cases I found a suitable O ring in my box of rings that fitted nicely into the groove, then reattached the SAE doible flared end and flarenut, just tightening it enough, not 'stupid tight' (copyright Grant Francis). I had no great hopes; but that was over 5 years ago and still bone dry.

So always worth trying, but will not work on fittings for single 'trumpet' flares though, as it needs the groove in the female fitting.

 

Paul,

Dealt with a few of them on the BW65/66 fill tube, same design as your ZF.

I found a THIN copper washer, that fit nicely into the female boss, then sat under that shade tree, and carefully filed the hole to suit the taper hole inside that same boss, offered up the pipe thingy and carefully tightened to suit ME, not that Garry Gorilla Fool.

FIXED.

When the X300 started the same nonsense, I had the fix, worked just fine, of course.

I like Gregs o/ring fix, and a suitable thick section o/ring would work also, with the same tightening care of course.

 

Tks Grant (& Greg),

Just so I understand correctly, are you taking about inserting a copper washer (or O-ring) that, when the joint nut is tightened. will distort to a matching flare shape, as shown in my rough diagram? Have I got that correct? Diagram doesn't show correctly but I'm guessing the hole in the washer should sit over the edge of the sump boss flare ie the hole in the washer is bigger than the leading edge of the boss?

Tks

Paul

 

Yep.

The copper or rubber forms a "new" face for the taper, thus eliminating the miniscule flaws that are the leak.

ATF is like Petrol, it will seep through where other fluids will not.

 

Hey Grant,

After a lot of head-scratching, I think I might try your approach first. I drained the box and split the joint last night and can't feel any cracks in the female dipstick flare, or any nicks in the male sump boss flare.

So does the copper washer need to be so thin that it deforms easily and provides a similar profile lining to the female dipstick flare when the nut is tightened? Or is it not that critical that it completely bends to match the original V-angle?

Tks

Paul

 

Paiul,

None of mine had feelable flaws, or visible either, and that was when I has 2 eyes that worked.

I had, and still do, have more hoarded stuff than Greg, lots of coffee jars with washers/screws/ dunno, of all sorts. I have thrown nothing away since 1968, oops the secrets out.

I tried ally washers, better, but still not 100%, then found (not lost just hiding) the copper washers, and some really thin fuel banjo ones fitted nicely.

Too thick and the "deforming" to create the seal may??? be harder.

If yours are too thick in your opinion, some 600 W & D paper on a glass surface, 2 beers, and simply rub them down. Finish with some 1000 and 2 more beers.

 

Well, I had yet another attempt at using PTFE tape on the taper boss of the sump as well the threads, carefully tightened it all up, filled the box, and.......it slowly drips again.

So tomorrow, I'm going to drain it again and fit either a rubber or copper washer to fit just over the boss sump taper before fitting the dipstick flare and tightening the nut. The measurement has to be pretty precise as the nut only just fits over the dipstick flare. So any washer has got to just fit over the first part of the boss taper.

I've carefully cut up a thin copper washer and then shaped it over a socket with approx the same flare angle as the sump boss. I've just got to decide whether to try the copper or the rubber one. It seems the rubber one would bend into the shape easier, but it might distort or slip and, once the nut is slipped over the dipstick flare, you can't see what is happening.

Any suggestions as to which one I try first?

Paul

 

You’re not grunting loud enough when tightening it! The nut is huge, you’re not going to strip it.

 

Well, I tried the shaped copper washer first and refilled box. Still dripping 24 hrs later.

So, I drained it, removed the copper washer and fitted the rubber washer and refilled it. Still dripping 24 hrs later. Drained yet again. As expected, when I drained the box and removed the rubber washer, it had slightly moved and distorted as I tightened the nut.

So with the box drained yet again and needing to use the car tomorrow night and at the weekend, I think I'll just have to put it back to normal, although it will inevitably leak. The only thing I can think of now is to very carefully smear some form of sealant on the small flare area of the boss or the dipstick flare before to try and seal them when tightening them up together. If I do it very carefully, it shouldn't get in to the box fluid.

I'm trying to think what type of sealant may work, maybe a loctite thread sealer or similar? Something readily available I can pick up at a motor factors tomorrow? Any thoughts anyone?

Cheers,

Paul

 

Paul,

Your copper version didn't look thin enough to work as crush washer, the FlareSeals that I mentioned are very thin and coated with something that also helps seal the micro crevices. I would look for a crush washer of the right diameter so it stays in place and don't pre-shape it, let the nut do the work.

Good luck

 

Paul
Try Loctite thread sealant. It is thin as water and you don't think it will work, but the stuff is magic. Put nit everywhere. Might help, and worth a try.
https://www.henkel-adhesives.com/fr/en/product/thread-sealants/loctite_5450.html

https://www.bearingboys.co.uk/Pipe-and-Thread-Sealing/Loctite-545-Hydraulic-Seal-50ml-862-p

 

Months later and I STILL have the minor leak problem!

After a lack of success with fabricated copper sealing flares, I then resorted to using sealants.

I tried Loctite 545, which definitely helped the connection joint to the sump but didn't seem to fully resolve the problem. However, I could see drips at the elbow of the dipstick tube, but I wasn't absolutely convinced it was coming from the joint to the sump. Slightly perplexed, I eventually tied tissue paper on both sides of the elbow and strangely, I still got a drip at the elbow but no stains on the tissue paper. So it SEEMS that the joint of the tubes at the elbow has a tiny split that is not obvious to the eye. Photo shows the elbow wiped clear of fluid drip.

I could clean it and use some rubberised tape or similar around the elbow to seal it, but I'd like a neater solution.

So, what do people think. Could I drain the box (for the umpteenth time!), rub off the paint at the elbow, and solder it? Or would it be easier to just try some superglue or similar and hope it seals the tiny split?

Thoughts gratefully received.

Paul

 

I recall buying a new tube to solve my leak. Check SNG that’s where I would have bought mine.

 

Paul
You would have to drain it and remove the tube, but epoxy, inside and out would do it fine.

 

Unfortunately the tube for the late 4 litre cars has not been available from Jaguar for many years, and I'm not aware of any of the aftermarket suppliers selling a reproduction part. So I feel I'm going to have to mend my original.

Paul