Hole in gearbox!

[kodakokun]

My Saab recently had a new clutch fitted by a garage, when the car came back there was judder, difficulty in getting into gear and then I discovered an oil leak. On taking the car back to the garage they discovered a hole in the gearbox ! The car still drives ok and no excess noise from the gearbox.

The hole is between two strengthening fins in the casting and appears to be a clean hole as if it had been drilled about 5mm diameter.

The garage said it’s possible that something broke in the gearbox and had enough force to pierce the casting. I’m surprised though, since if this had happened I would expect the gear box to be inoperable or at minimum rumbling, I would also have expected that the hole would be not so clean or even to have cracked the casting.

The guy that did the job has since been “let go”. The garage are going to take the box out, strip it down and let me know what happened. If it’s their fault they said they would fix it for free. If it’s not their fault I’ll get a big bill.

Does any one have any ideas what could have caused this, more importantly if this could be related to having the clutch fitted? – badly or otherwise !

Thanks

[nighthawk]

Without seeing the car or the transmission, my first guess would be that a bolt has come out of the clutch pressure plate.

That would give you the selection problems you've described, and then when the stray bolt has been launched for the home run by the flywheel, it's exited stage left so to speak.

Make sure you examine the box and get good quality digital photo's.

I wonder if the guy was "let go" because he was crap at tighning pressure plate bolts.

[busa_rush]

Nothing that comes out through an engine or gearbox casing under load makes a clean hole, it looks more like a paper bag that's been punched through. The chap they let go did something, or more likely things, seriously wrong. Get it examined by the RAC/AA - they will tell you what happened. Act fast though before the garage substitutes parts and makes it look like wear and tear.

[GreenV8S]

Is it the gearbox, or bellhousing? I don't think there's any realistic way for anything to knock a hole through the side of the gearbox itself unless there's a catastrophic failure inside the box, and I don't see it leaving a clean hole.

It doesn't seem likely for anything to punch a clean hole through the side of the bellhousing either, but it's more credible that there may be a drain hole or vent here. That wouldn't account for the problems you're getting, but it may just be a red herring.

[nighthawk]

I have to disagree on the No force and not a clean hole comments.

Over the years I've looked at a couple of transmissions with such defects.
The flywheel is capable of launcing stray bits of metal at silly speed, especially if the revs are up.

Be interesting to see the box though.

[kodakokun]

Thanks all for your comments.

I'm not sure if the hole is in the gearbox or bell housing but it's where all the oil drained out onto my drive from!

The good news is that garage have agreed to repair it but without accepting any liability. they will get the hole welded and they say there is no internal damage to the gearbox and the missing piece of metal is nowhere to be found !

I will try to get some digital photos of the damage. The gearbox in bits so i should be able to get a picture of the hole from both sides. I will post them on this forum.

[GavinPearson]

Nighthawk is absolutely right.

As part of my job I look at transmission warranty returns so I can work out what went wrong to engineer them better.

On vehicles with dual mass flywheels there is a retaining pin, which if it drifs out can put an incredibly clean hole through the bellhousing. On a car with a FWD transaxle the time when it is a problem is when the pin pierces the area coving the differential.

It sounds like this gearbox is easily repairable but I would have all the gearsets flushed through to ensure no debris was present to cause further damage.

[busa_rush]

OK, that's interesting, all the holes I've seen have been obviously punched through, eg conrod etc. I guess the high speed of the small part must be what causes the perfect hole ?