Car won't stay in 6th gear

[andibell]

Hi All,

As the title suggests, my car has decided it doesn't want to stay in 6th gear when driving...  With the engine off or the clutch dipped you can engage the gear and the change feels positive, but as soon as you apply foot to gas pedal it jumps out of gear and in to neutral.  

I'm guessing it's going to come down to stripping the 'box and investigating but wondered if anyone had come across anything similar in the past?

Thanks
Andrew

[Anonymous]

There is a chance it could be a bearing problem under load,input shaft bearings are a known weak spot of the gearbox.I would get it checked out sooner rather than later as if it is then you don't want metal bits flying around your gearbox screwing it up completely.

[frogger]

I doubt it is the input shaft bearing (unless you're not disclosing all symptoms!) as there would be a very noticeable nasty noise if the Input Shaft Bearing had gone to the extent that it was affecting gear selection!

The noise would be present with foot off the clutch pedal in neutral, and silent with foot down to the floor on the clutch in neutral.
Easy one to rule out by testing the above.

It is likely to be down to the selection mechanism, so rule out the things you can access without rebuilding the box first.
i.e. all connections at and around the gear stick, all connections and bushings at and around the cables at the box end.
      any obstructions to the movement of the selector arms in the engine bay (most likely culprit), or things putting strain on the cables.

Done any work in that area of the bay recently or is this a completely random effect that has suddenly occured?

[Anonymous]

Sounds like good logical advice,I'm no mechanic so go with what Frogger said.  s:) s:)

[andibell]

I doubt it is the input shaft bearing (unless you're not disclosing all symptoms!) as there would be a very noticeable nasty noise if the Input Shaft Bearing had gone to the extent that it was affecting gear selection!

The noise would be present with foot off the clutch pedal in neutral, and silent with foot down to the floor on the clutch in neutral.
Easy one to rule out by testing the above.

It is likely to be down to the selection mechanism, so rule out the things you can access without rebuilding the box first.
i.e. all connections at and around the gear stick, all connections and bushings at and around the cables at the box end.
      any obstructions to the movement of the selector arms in the engine bay (most likely culprit), or things putting strain on the cables.

Done any work in that area of the bay recently or is this a completely random effect that has suddenly occured?

Thanks for the advice.  

There's no difficulty in selecting any gear, even 6th.  With the engine off or the clutch dipped it feels as if the gear is engaged, certainly the lever moves comfortably into position and with the engine cover open you can hear the selector moving.  Just as soon as you apply the gas, it jumps straight out of gear in to neutral.
Matt had a quick look for me last night and couldn't see anything obstructing the connections.  The only work that's been done anywhere near there recently was to change a coolant hose and it was over a week later that this problem started.

Andrew