Gear selection

I’m wondering if you can shed any light on an ongoing issue with my girlfriend’s 2005 Astra H 1.7 CDTI. The problem first arose on a run from London to Harwich. As she approached a roundabout she couldn’t get any gears at all, so she coasted to a stop. The car still wouldn’t go in gear, so she turned off the engine. A few minutes later, she restarted the engine and all was well. The exact same thing happened on another run from London to Stansted Airport.

Driving on her relatively short runs to work (12 miles), everything has been fine up until recently. Now it is struggling to engage fifth gear on a regular basis. Even switching off the engine will not allow you to engage fifth, but at some point it will start working again.

The garage checked the gearbox oil level and it was half-full, so they topped it up, but said if that didn’t work – it hasn’t – it would be the gearbox itself. This advice puzzled me a bit, as I’d imagine a worn synchromesh would be accompanied by grinding/crunching and there are no noises whatsoever. Also, surely it wouldn’t work perfectly until the day it decided to play up?

I wonder whether it is a linkage issue, but when I had a similar problem on my Corsa C, it only affected first and second gear and was consistently happening until I sorted it. I’ve looked on the internet, but I haven’t got anywhere, so I’m hoping your experience might throw something up before we go down the replacement ’box route! Darren Meaney When I first read your letter, I suspected that the fault may not lie with the gearbox, but with the clutch. There was a technical service bulletin (field remedy 2130) issued for this problem, which was due to the input shaft not being greased, causing the clutch plate to stick and not slide on the splines. But as you say that the gear still cannot be selected even with the engine turned off, this makes the clutch less likely to be the cause.

There was also a bulletin (field remedy 2305) with reference to gearchange problems, but this affected third gear and was caused by failure of the third/fourth shift fork, which was prone to bending. The cure required the removal of the transmission and an upgraded fork fitted.

If, as you say, the gear cannot be selected even with the engine stopped, this is also unlikely to be a synchromesh problem. The job of the synchromesh unit is to slow the shafts to an equal speed, thus if the gearbox is stationary this is unnecessary.

This takes us back to a gear selection problem and it’s possible the excessive heat caused by the longer journeys is the reason behind it.

To start with, I would check the external mechanism. You do not mention which gearbox is fitted to your girlfriend’s Astra, but according to my data it should be a cable-change unit, which will not be the same as your Corsa. If this is the case, I would check the cables, as these are likely to be affected by the heat from a longer journey. There is an adjustment method for the cable gear change, but as the problem only occurs after a long journey, it is unlikely to be adjustment-related, but more of an internal friction problem.

If, after checking and dismissing all of the likely external possibilities, it may require the gearbox to be removed for repair, but this would not be my first step.