Is it the transmission ??

[Patrick-Irish]

Before I go to an auto gearbox specialist and incur what it likely to be a high cost, I'd like to bounce it off this forum first to see what you think.

I've got a 2001 X5 4.4i. 108k miles on the clock.

There is a sporadic hesitation in the car pretty much at all speeds. By hesitation I mean as you drive along you can feel half second dips in power. At slower speeds it can occasionally be quiet pronounced and happens not in any steady kind of pattern but definately every 10 seconds or less it can be felt, just for a half second. If I keep my eye on the rev counter it can be seen to fall back slightly as well. At steady motorway speeds it can be felt too, though not quiet as pronounced.

The gears can be slow to engage, when shifting from park to drive or into reverse. It can take maybe a second to engage the gear. Very occasionally the car jerks slightly when reverse is selected.

I am fairly sure the box has leaked some of the fluid out of it too. There are quiet a few drips on the drive.

Sounds like a transmission issue straight away. But the thing putting doubt in my mind is the rev counter dipping. Why would the revs dip if it was a transmission problem ? I would have thought this might indicate some sort of engine problem.

Another thing. The weather suddenly went really cold this morning, and I didn't really feel the issue in the car when going to work. So now I'm thinking air intake ........ it's well known performance can change with changing air temperature and density. Maybe the engine was getting more air this morning and was overcoming the problem. So again, that points away from the transmission and more towards the engine, air intake or air mass meter issue for example.

So what do you think ? Anyone have this issue before and found the solution ? Any comments and advice welcome.

Thanks.