Technical 100hp driveshaft seal leak?

[dac69er]

The car has had a leak on the drivers side gearbox seal for a couple of years.

It's only minor, but decided to do it the other week. All went fine, but after a week it was pissing out almost like it had no seal!?

I popped the driveshaft out again, inspected it, tapped it in a bit further as I didn't think it was in as far as it should be (only went about another 1mm). It's hard to gauge when doing it on your back!

All seemed fine again until today and it's a little damp around where the joint goes in the box
Seems to be fine for about 150miles or some, then starts leaking!???

Any ideas?
I didn't use a genuine fiat seal. It was a febi branded seal and quality seemed ok.
Sealing face on the driveshaft looked good, no wear or anything. The snap ring was fine and the driveshaft held in ok

 

[DaveMcT]

You have probably ripped the seal lip with the snap ring. One they start to leak the only fix is a new seal. If your driveshaft has a wear groove from the old seal, you'll have to make sure the new seal goes in a little deeper so it stays off that worn groove. Hopefully the shaft seal area is smooth and good.

 

[dac69er]

The seal lip looked perfect when I removed the shaft as that is what I suspected!?

I would have thought it would leak straight away if I had damaged it!?
It was improved after I popped it out and put it back in after tapping the seal in a little further.
The driveshaft was surprisingly good with no wear lip evident.

I have purchased a genuine seal and will give that a go. It's a pretty simple job, especially now everything has been taken off before recently. Just a pain as it leaked before and it now leaking like it did with the original crusty seal

Will let you know how I get on

 

[dac69er]

Fitted a genuine seal. Triple checked the sealing surface.
Made sure everything was clean. Lubricated the seal lip before reinstall........

.......And it still leaks

Not badly. But it weeps a bit. No idea what else to do!?!?

 

[DaveMcT]

Is there any radial movement in the inner CV joint where it enters the gearbox? That would indicate a bearing issue. Obviously VERY not good but easy to check.

When you have it apart again, replace the spring clip on the end of the shaft. That might be catching on the seal and damaging the seal lip.

 

[dac69er]

No radial movement. All as expected.

The seal I removed was perfect, i 100% didn't catch the seal on install. I got my girlfriend to support the other end of the driveshaft so I could ensure it went in without touching anything.

It is a very slight leak. Most people wouldn't even notice as they wouldn't tend to reach under the car and wipe their finger where the joint goes into the box
It just confuses me why it still isn't quite right!?

 

[koalar]

I am at a loss to understand why it's still leaking

I only fitted cheap eBay ones in the past on 5 speed boxes and they always stay dry, fit and forget. So little drama fitting them I don't even remember doing them

I'd be very surprised if 3 failed two very soon after fitting

And the original lasted years only weeping


I would assume if the deferential bearing had failed, there would be

1/ it would be noisey
2/ it wouldn't leak immediately

Worth checking but I don't hold out much hope the cause lies here


On the backside of the seal there is a spring that can pop off if you have to hit the seal in. Rare but worth packing the groove with grease to hold it in place

Couldn't find a great picture of the 6 speed but looks like the seal is quite a way below the surface

There also looks like a join that could be leaking nearby

 

[dac69er]

I am at a loss to understand why it's still leaking

I only fitted cheap eBay ones in the past on 5 speed boxes and they always stay dry, fit and forget. So little drama fitting them I don't even remember doing them

I'd be very surprised if 3 failed two very soon after fitting

And the original lasted years only weeping


I would assume if the deferential bearing had failed, there would be

1/ it would be noisey
2/ it wouldn't leak immediately

Worth checking but I don't hold out much hope the cause lies here


On the backside of the seal there is a spring that can pop off if you have to hit the seal in. Rare but worth packing the groove with grease to hold it in place

Couldn't find a great picture of the 6 speed but looks like the seal is quite a way below the surface

There also looks like a join that could be leaking nearby

View attachment 421888

I have only fitted 2 seals. First one I removed the shaft after the initial leak and then tapped it in a bit further and this improved the situation. I have then tried a genuine seal to try and stop the leak completely, but no luck.
The original old seal was a bit more than a week, it had got to the point where it really needed to be done otherwise I would start getting oil drops on the drive.

No issues with the gearbox regarding noise etc, so doubt it is that.

Sseal spring is still in place (or it was on the non genuine seal when removed). I have no reason to believe it is that. It wasn't hard to tap in. It's quite easy to get a good straight tap on it as clearance is good.

I did wonder about the joint on the box, but that would involve splitting the box apart. As the oil makes its way to the joint and gets flung out, it's not that likely it is that imo.

 

[DaveMcT]

My shifter shaft seal (a small thing on top of the gearbox) leaked so much down the back of the gearbox, that oil was getting flung off the CV joint case. I really thought the drive shaft seal was leaking. That is on the left side but makes me wonder if you have another leak from higher up.

 

[dac69er]

My shifter shaft seal (a small thing on top of the gearbox) leaked so much down the back of the gearbox, that oil was getting flung off the CV joint case. I really thought the drive shaft seal was leaking. That is on the left side but makes me wonder if you have another leak from higher up.

I've done the shifter seal a little while back. It's not from any higher up. It's clean and dry above it.

I have improved the leak, which leads me to believe it is the seal. If changing the seal made no difference, then I would suspect elsewhere.

 

[bugsymike]

If you grab the inner end of the drive shaft and can feel any up and down movement as in wear in the diff, that is one place as has been mentioned. It can cause oil to leak from a shaft, old FWD Ford Escorts used to suffer from it, the first sign was no speedo as the nylon drive on the diff got chewed up which then turned into an expensive gearbox job.
I assume oil level is not slightly high as that can make worse.
If you do go to fit another seal, I would first grease it and then slide it over the drive shaft where it normal would sit to make sure it is a nice grip on the shaft to seal area, after first checking there is no roughness or wear groove as has been mentioned earlier.
Other than that is there any damage in the housing the oil seal fits in, for instance if a previous fitter has hammered a screwdriver in to pry out the old oil seal etc. If so it may be possible to put a little sealant around the outside of the seal where it sits in the housing to help.
Is there any damage to the shaft or the CV joint that could cause it to be unbalanced when running at speed, in effect throwing the shaft away from the oil seal lip and allowing oil out? I admit a bit unlikely but if you have checked all else?
Finally and not meaning to insult as I have seen this done in a garage, I assume the seal is the right way round.

 

[dac69er]

Just double checked for any movement where the shaft goes into the box and there is none.

Oil level is fine. It was filled on level ground.

I checked the seal fitment before installing and it felt snug, as I would expect it to be.

There is no wear groove or anything on the sealing face of the joint. Just a slight polished ring around it. Very good imo.
No damage where the seal goes in either. I thought it may be that, but it's nice and smooth with no damage.

Driveshaft is really good. I had removed it to replace a cracking CV boot as well as doing the seal. The rubber damper is good condition and still attached.

Seal is the correct way round. As per the original. I'm a maintenance engineer, so am sure about that one

Thanks for all the suggestions. It's not pouring out, so I may just have to keep an eye on it and put up with a minor weep. It's done 170k miles, so it's not the end of the world as the rest of the car won't last forever anyway.

 

[bugsymike]

Just double checked for any movement where the shaft goes into the box and there is none.

Oil level is fine. It was filled on level ground.

I checked the seal fitment before installing and it felt snug, as I would expect it to be.

There is no wear groove or anything on the sealing face of the joint. Just a slight polished ring around it. Very good imo.
No damage where the seal goes in either. I thought it may be that, but it's nice and smooth with no damage.

Driveshaft is really good. I had removed it to replace a cracking CV boot as well as doing the seal. The rubber damper is good condition and still attached.

Seal is the correct way round. As per the original. I'm a maintenance engineer, so am sure about that one

Thanks for all the suggestions. It's not pouring out, so I may just have to keep an eye on it and put up with a minor weep. It's done 170k miles, so it's not the end of the world as the rest of the car won't last forever anyway.

I wasn't trying to be personal, just put forward all the many causes I have seen over fifty years that I could think of that may cause the problem without seeing the vehicle, based on my experiences .
What do your instincts tell you, being there, looking at it logically?
Do you think with the 170K it is just a case of Anno Domini or what ever they call it?

 

[DaveMcT]

The shifter seal was an illustration. It can't be causing this problem - its on the wrong side of the differential. The gearbox joint between bell-housing and actual gearbox might be an issue but unlikely. The input shaft seal could be leaking but I'm sure you'd have had the clutch slipping by now. The last is radial movement at the CV joint splined shaft into the gearbox. Not the joint itself inside the rubber boot that's outside the box.

Last of all - how clean is the back of the gearbox? A leaking seal can make a horrible mess. Have you cleaned all around to rule out any source of dribbles?

 

[dac69er]

The shifter seal was an illustration. It can't be causing this problem - its on the wrong side of the differential. The gearbox joint between bell-housing and actual gearbox might be an issue but unlikely. The input shaft seal could be leaking but I'm sure you'd have had the clutch slipping by now. The last is radial movement at the CV joint splined shaft into the gearbox. Not the joint itself inside the rubber boot that's outside the box.

Last of all - how clean is the back of the gearbox? A leaking seal can make a horrible mess. Have you cleaned all around to rule out any source of dribbles?

I was just commenting that it is ok to rule it out.

That is what I checked, the movement of the joint where it goes into the box. There is a tad in and out as it moves up against the snap ring. Nothing up and down or side to side though.

The back of the box is nice and clean. I cleaned it all up with brake cleaner.

 

[bugsymike]

With the box all clean, is it possible to run it up with the wheels of the ground safely , but just for a very short time, so you can catch the first early stage of the leak?

 

[dac69er]

With the box all clean, is it possible to run it up with the wheels of the ground safely , but just for a very short time, so you can catch the first early stage of the leak?

It's not leaking that badly. It's only apparent after quite a few miles once cleaned

 

[bugsymike]

It's not leaking that badly. It's only apparent after quite a few miles once cleaned

Bit off the wall, but is the gearbox breather partly blocked.
I am thinking that if it takes a while to start to leak, maybe when oil is warm and thinner plus a little bit of back pressure, if breather not 100% I know it's clutching at straws but?

 

[dac69er]

Bit off the wall, but is the gearbox breather partly blocked.
I am thinking that if it takes a while to start to leak, maybe when oil is warm and thinner plus a little bit of back pressure, if breather not 100% I know it's clutching at straws but?

I did consider the breather. It's a bit hard to check tbh. The top hat of the breather is free and clean. I tried to spray some brake cleaner under the top hat, but I don't think that did much.

I would expect it to leak from the other seal that is older though!?

 

[DaveMcT]

The gearbox breather is unlikely to get clogged but is accessible with the battery tray removed. However, I have no idea how to remove it from the cover without causing damage.

On a dry day, gaffa tape a donut of garage cleaning roll to the gearbox case all around the seal and drive the car. When you get back check where the oil has soaked into your donut of tissue paper.