I recently posted that my rear wiper motor had ceased functioning. I stripped it down today to confirm my diagnosis that it was completely shot. There was significant water ingress through the spindle seal (what a duff design) the gearbox was clogged solid with corrosion debris, I duly cleaned and freed everything up, packed with new grease and guess what............still knackered (O.K Mr moderator?).
The moral here is that I believe this is a common fault, so take early preventative action and strip, clean & repack with grease whilst still running apparently o.k. My Croma was only 3 1/2 years old and 40k miles when this happened.

Seconded - it's an utterly crap design. There's nothing unique about the car - you'd have thought they'd have worked out how to seal a wiper by now. It's hardly a new feature.

Mine is also 3.5 years old, and it was thick with rust. Did you remove the shaft from the gearbox? On mine, the resistance seemed to be at the point where shaft goes through the gearbox case. There's only about 1mm clearance, so any bubbling soon stops it.

I'm not sure where the water is getting in - down the shaft or between the grommet and bodywork. I want to find a way of stopping this happening. Some thoughts - please add to or improve upon...

I've looked at my neighbour's Fiesta, and the grommet looks to be pressed hard against the body. Presumably there's a nut somewhere squeezing it. The Croma one just sits there - you can grab it and wiggle it to make a gap under it. Possible fix: Take it off, put a thin layer of clear silicone sealant on its underside, press it on and thoroughly wipe away the surplus with spirit. Then wax the surrounding area.

If the water's getting down the shaft, then presumably it's gathering on the wiper blade then dribbling along/down the arm and onto the shaft. I've yet to test this theory with some water. This could be why so much gets in there. Possible fix: Put a small black ty-rap round the arm near the bottom, just to the right of the grommet, with the fastener pointing down. This should stop the water flowing past it and make it drip off the bottom of it. It should be almost invisible, and the surplus length can be chopped off.

Well Doofer, I have examined the design in some detail and it appears that when the motor moves on it's isolator mountings the spindle distorts the large grommet on the tailgate, this allows water to get inside, couple this with a slightly worn O ring and there is a clear path for the water to get in. I think a water shedder consisting of an inverted cup fitting tightly over and moving with the spindle would cure the problem. When I get round to fitting the replacement motor I will try this fix, I will get our rapid prototype dept to knock one up. I did strip the assembly right down, the motor worm drive shaft had also seized in it's housing, I freed it with WD40 and lots of working back and forward with long nosed pliers- but as I said earlier it's a goner.

Well I don't have a rapid prototype dept, but I do have an aerosol lid!

I was just wondering whether the wiper arm was somehow directing water in. It seems to find a lot of it for such a small surface area. Alternatively, it could be water rolling down the back screen into the top of the rubber grommet. Hence my previous thoughts.

The o-ring on mine doesn't look worn... it's simply too small to seal. If it was thicker then it would be in with a chance of sealing, but you'd need a washing machine motor to turn it. But the idea of sealing a turning shaft inside a tube with an o-ring is ****** anyway. Whatever is inside the tube will have a head of water sitting on top of it, so it's got no chance. I agree with you that it needs to be kept out in the first place.

I'll have a good play with the hose next time I wash it. Please keep us informed of anything you find out. It's annoying that there's probably someone at Fiat paid £1000s who should have sorted this out years ago though.

Sorry, just re-read your previous reply (properly this time).

Is there a path for water to get under the grommet and then down the tube around the shaft? I thought the tube went up through the grommet.

If this is correct then the rust inside the tube must mean that the water is getting in from the centre of the shaft, not the edge of the grommet.

Thinking about it some more, it must be water getting under the edge of the grommet. The rust inside the tube must be from vapour or capillary action, aided by the turning shaft.

However, a moving cup won't help as it won't seal against the bodywork. Plus the wiper blade itself already has a flip-down lid over the end of the shaft.

Silicone sealant under the grommet might do it, until the motor rocking peels it away.

One possible idea...

Replace the plastic tube with an identically sized stainless steel tube that has an external screw thread at the top. Then a slim round nut screws onto it, on top of the grommet to squeeze it against the bodywork. There's probably a name for it, but I'm thinking of it being like a thick washer with an internal thread with cuts across it so you can tighten it with a special wrench or tap it round with a screwdriver. Perhaps the tube would also need some protrusions or another nut on the inside of the bodywork to give something to pull against.

I don't know if this would cause problems though, as it may stop the motor rocking on its rubber bushes. They must be there for a reason. It really needs the grommet to be fixed by something that doesn't rock with the motor.

The Croma's shape seems to pull a lot of water onto the back window. Otherwise I'd be tempted to do away with it and plug the hole up.

You could be right Doofer, I think what is happening is that the shaft is acting as a pump when it rotates back and forth, any water that had found it's way under the large grommet being forced down the spindle past the O ring. I see this type of thing all the time at work where all the testing in the world still cannot recreate real world conditions, time alone can harden the seals and grommets leading to a poor seal under certain conditions. The amount of water that found it's way inside my motor housing was incredible, but it could only have got in via the spindle as there were no water witness marks anywhere except where it had leaked from the gearbox lid joint onto the tailgate trim. I once owned a Rover 418 with a problem water leak inside the spare wheel well, after a rain storm it would have accumulated about 5cm depth of water, when I eventually tracked the offending hole down, it was no more than a pin sized hole in the seam sealer. I will keep this post up to date if I find a fix.

Yes, I guess gravity is largely irrelevant on the back of a car doing 70mph with all the turbulence and a wobbling motor.

If the problem is the plastic tube wobbling the grommet then perhaps there's a simple solution - to isolate it mechanically from the motor. Either cut it off shorter from its bottom end and/or (if space permits) put some foam-type material between it and the motor. The spindle iself would still be able to wobble inside the tube, but with little effect on the grommet.

This, combined with silicone sealant under the grommet, might just sort it. I'll have a play with the hosepipe and see what I can work out.

So far I have not had this problem, but can you drill a small drain hole in the motor housing? Not having looked at it, this may attract well deserved derision, but its a learning curve.

cjlar said:

So far I have not had this problem, but can you drill a small drain hole in the motor housing? Not having looked at it, this may attract well deserved derision, but its a learning curve.

Click to expand...

I have considered this option, I was going to drill a relatively large hole and bond a tube on to take the water into the door latch area, it may be worth a try, but even though you have not had this problem yet, I bet there is some evidence of water ingress, although I have seen reports of this problem on this forum, there have not been that many, I often wonder if it is one of those faults that people don't discuss, just accepting it.

This sounds like drilling a hole in your floor because the rain keeps dripping through the hole in the roof to me.

Probably better than some of my ideas though