Laguna Auto box problems - anyone encountered similar?

Delinquent · Unread post by **Delinquent** » 09 Jul 2008, 10:58

Hi all,

trying to find out what could be wrong with my Dad's car, an '03 laguna Auto.

It's happened three times now, with varying symptoms.

The first and third time it has happened the box decided to down-change without need, the first time dropping 2 gears and the third time just 1 gear. (and wouldn't then change out of newly selected gear)

The second time the fault occurred, the box did not change down, it stayed in the same gear but the autobox fault light came on.

Stopping the car, switching the ignition off and then on clears the fault. No fault code is therefore logged in the memory which has been checked with diagnosis equipment. On all three occasions the fault occurred within one mile of the same location on the commute to work, which was within five minutes of starting from cold.

Any ideas?!?!

AndersDK · Unread post by **AndersDK** » 09 Jul 2008, 21:07

First rule on suspect autoboxes : check fluid level.
Second rule : check fluid quality (the infamous burnt smell)

Delinquent · Unread post by **Delinquent** » 10 Jul 2008, 11:47

OK, will do - got to change the waterpump and cambelt tomorrow anyway so while we're under there...!

If it does smell burnt, other than changing it, what would that indicate I should do?

AndersDK · Unread post by **AndersDK** » 10 Jul 2008, 18:55

Delinquent wrote:If it does smell burnt, other than changing it, what would that indicate I should do?

Sadly - every workshop manual I've come across on autoboxes - clearly tells the operator to REPLACE the autobox when a burnt smell is undoubtedly diagnosed

This is because the (or just one of the) wet clutch plates has burnt out, requiring a very delicate dismantling and rebuilding. Certainly a specialists job.
Autoboxes still are the most complicated devices found in cars. It really does not compare to anything else - but a huge pile of precisely machined parts.

Delinquent · Unread post by **Delinquent** » 11 Jul 2008, 10:08

LOL won't be following that route - It's not worth it.

I have actually rebuilt an autobox before, however it was on an old sharknose BMW - so probably a tad simpler in construction!!! Never looked inside a modern one... could be a learning curve I suppose

Oh well, will see how the oil smells this evening - still kind of hoping it'll be an electronic fault somewhere but you can guarantee with this car it'll be whatever is the most expensive / annoying / troublesome!