Omega Owners Forum

Chat Area => General Car Chat => Topic started by: 350sb on 26 June 2016, 15:53:05

Title: 2.5 TD Automatic Gearbox Slipped
Post by: 350sb on 26 June 2016, 15:53:05

Hi Guys,


I drove over a pot hole in a rush earlier on and noticed my Omega didn't want to pick up speed, as if it was stuck in neutral, when joining the A13 . I had to pull over and select Park and was nervous about what to do, as I never had a problem like that with my manual Omega. Then selected Drive and it drove off again. As I'm inexperienced with auto boxes, is there any way that a bump from a small pot hole which my left wheels drove over can cause my box to slip? The car is generally reliable except for the recent serpentine belt and water pump which wore away at the same time after 154000 miles.
Mark is there anything that I need to check?

Title: Re: 2.5 TD Automatic Gearbox Slipped
Post by: tunnie on 26 June 2016, 15:58:40

Box is on it's last legs, the AR25 fitted to 2.5TD was always borderline on power it could handle. The 2.5 TD was detuned from BMW for Vauxhall, if back to full BMW spec the box would barely last a few miles!

I'd check the fluid level is correct, perhaps change it. But time is not on side with the box itself  :y

Having said that it could be the selector switch loose, worth checking/cleaning this.

Title: Re: 2.5 TD Automatic Gearbox Slipped
Post by: 350sb on 26 June 2016, 16:16:34

Thanks Tunnie.


I'll check the switch. I did try to locate the drain nut on the gearbox last year while I had the steering arm replaced and found one on the side of the large sump , but not the small one. If it is the box, how reliable is the AR35?

Title: Re: 2.5 TD Automatic Gearbox Slipped
Post by: Nick W on 26 June 2016, 19:24:20

Quote from: 350sb on 26 June 2016, 16:16:34

Thanks Tunnie.


I'll check the switch. I did try to locate the drain nut on the gearbox last year while I had the steering arm replaced and found one on the side of the large sump , but not the small one. If it is the box, how reliable is the AR35?

These gearboxes don't have drain plugs, the fluid is changed by removing both sumps and making a hell of a mess. It's a common thing on modern gearboxes. Yes, it's a stupid idea.


AR35 gearboxes have proved to be robust and reliable. But these cars are getting old, so we have to accept that previously reliable parts are more likely to fail due to wear than they used to.

Title: Re: 2.5 TD Automatic Gearbox Slipped
Post by: STEMO on 26 June 2016, 19:30:02

I'm no mechanic, but if this jolt from a pothole threw the gearbox out of kilter for a while, and it's now back to normal, I wouldn't go changing anything just yet. See how it goes.

Title: Re: 2.5 TD Automatic Gearbox Slipped
Post by: Kevin Wood on 27 June 2016, 11:15:09

Quote from: STEMO on 26 June 2016, 19:30:02

I'm no mechanic, but if this jolt from a pothole threw the gearbox out of kilter for a while, and it's now back to normal, I wouldn't go changing anything just yet. See how it goes.

Yes, my money would be on low fluid level. It might have caused it to pick up a little air.

Title: Re: 2.5 TD Automatic Gearbox Slipped
Post by: TheBoy on 27 June 2016, 17:24:40

I'd also go with low fluid at this stage.

On the 2nd or 3rd autobox I shagged on my TD, it would intermittently slip badly. For me, the (temporary) solution was to put it in neutral for a few seconds, then back into D, and then it usually had drive.

Upon stripping the box (once I'd got an AR35 on there), every clutch plate was utterly worn out.