Auto transmission dropping into a low gear

IronGiant

More Sedona woes   let the mockery recommence
The engine has been fine since I got that fixed, but on returning from holiday yesterday, towing a caravan (more mockery) doing 60 up a barely perceptible incline I noticed the transmission unexpectedly dropping to a lower gear whereas on the outward trip on the dual carriageways we stayed mostly in 5th. Later on it dropped into and seemed to stick in a really low gear such that we were doing nearly 4000 rpm at (now) 45-50mph.  As we were heading for the M1, I backed down to a crawl, changed route and crept along embarrassed like an archetypal caravanner at 40-45 mph until the gearbox started to respond properly, then joined the M40 where it was happy once more, although I stayed under 50mph.   Today I drove it solo and gave it a good work out and everything seems fine, parked up and checked the fluid. It's got one of those dipsticks that seem to smear and make taking a reading nearly impossible. If anything it looks a bit high but no sign of foaming.  Colour was still mostly pink.

Any ideas gearbox gurus?

car-man

From a fellow caravanner

It's possible you may have had a slight overheating that sorted itself out.

Hopefully it was just a glitch but I usually advise a gearbox oil and filter change whenever an auto box starts messing about...most of the time that solves most issues but auto boxes are a specialist subject.
The DSG type gearboxes are a different subject altogether as the internal bits are a lot different.

IronGiant

This is a good old fashioned auto box and I think your temporary "overheating" diagnosis is probably correct.
I might pop up to Kia and buy some "genuine" Kia fluid and give it a fluid change. The previous owner had it serviced at theiir local garage so I don't know when it was last changed nor what was used. Thanks.

mjn

As above, fluid and filter change firstly.

Secondly, sell it

IronGiant

Thanks

gibbsy

You could sell it to my mate Rob. He loves his Sedona and just like you he clogs up the roads towing his shed behind him.

I had the same problem when towing, not an auto though but a diesel. I was on the M50, revs just kept dropping away had to keep changing down barely crawling home towards Wales. Managed to get to the services at Ross so decided to give the engine a rest. It was then that I found out I was driving into one hell of a headwind. Must have been like towing a brick fitted with a sail.

IronGiant

I don't clog up the roads towing my shed, in fact it's normally some old man Sunday driver in a Golf GTD that holds me up

On the extremely rare occasions that it's actually me rather than the myopic pensioner in front of me holding up traffic I always pull over and let traffic pass so

car-man

I think the genuine oil would be best...costs a bit more but it was made for the job.
Looking up a gearbox oil change on your car tells me they don't have a filter that you can replace unless the box is being reconditioned.
The drain plug is close to the subframe by all accounts so watch the oil for splashing about. Filling is through the dipstick hole.
Don't put the full amount in at first...run the gearbox through all the gear selections a few times before the final fill.

gibbsy

Not yet. Still creating havoc in an Audi. I wish I could hold people up with a caravan. I really do miss it.

IronGiant

Just to add the icing to the cake, I had a nice letter from Lincolnshire Police this morning telling me I was caught on camera doing 40mph in a 30mph stretch just minutes after leaving the caravan site on our way home.   Stupid, stupid, stupid: guilty as charged, I forgot the 30mph sign was there. First ticket in 40 years