Slipping Autobox

[SilasStingy]

My autobox slips when accelerating hard! Doesn't matter if I'm overtaking or just need some speed in a road crossing. Seems to happen in any gear but mostly when the car is cold. (Happens when it's warm also but seems to be more rare).
The ATF oil looks OK, it's red and doesn't smell burnt but it seems like the previous owner have filled it up a bit too much when checking the dipstick when the box is warm after going trough the gears.
Can this be the problem or should I check into something else?

 

[macabethiel]

My autobox slips when accelerating hard! Doesn't matter if I'm overtaking or just need some speed in a road crossing. Seems to happen in any gear but mostly when the car is cold. (Happens when it's warm also but seems to be more rare).
The ATF oil looks OK, it's red and doesn't smell burnt but it seems like the previous owner have filled it up a bit too much when checking the dipstick when the box is warm after going trough the gears.
Can this be the problem or should I check into something else?

If you have too much oil in the autobox then you will feel something I would describe as "flairing" a gear shift where it sounds as though it is slipping or the new gear feels wooly! As little as 300 ml too much ATF can cause this on many of the older design gearboxes.

The most reliable test of the ATF level is when the engine is hot after a run. Put shift in Park and whilst engine is running check the level. If you have a small amount too much I usually use some clean screenwash tubing and syphon the excess out.

If the oil level is okay then you can have problems with the top gear - (overdrive if fitted) solenoid. Others may advise about this.
Problems with Torque Convertors are outside my personal knowledge.Sadly autobxes are complex units and though I have never experience gearbox issues in 40 years some have -they are often terminal!

 

[Banshee]

If you have too much oil in the autobox then you will feel something I would describe as "flairing" a gear shift where it sounds as though it is slipping or the new gear feels wooly! As little as 300 ml too much ATF can cause this on many of the older design gearboxes.

The most reliable test of the ATF level is when the engine is hot after a run. Put shift in Park and whilst engine is running check the level. If you have a small amount too much I usually use some clean screenwash tubing and syphon the excess out.

If the oil level is okay then you can have problems with the top gear - (overdrive if fitted) solenoid. Others may advise about this.
Problems with Torque Convertors are outside my personal knowledge.Sadly autobxes are complex units and though I have never experience gearbox issues in 40 years some have -they are often terminal!

:thumb2 That's worth a tenner a year surely!!!

 

[Lazy-Ferret]

Great advice there from Macabethiel.

An Auto box can't really slip, as it selects the gears by using brakebands to stop various parts of the gearbox from moving. If the brakebands fail, then it tends to either loose all drive, some gears, or more often becomes very clunky.

The only place that slip can be found is in the Torque Converter, which is in very very basic terms two fans, in an oil bath. One fan is on the engine, and stirs the oil, the second fan is on the gearbox, and gets turned by the oil the first fan is stirring around. If the Turbines (fans) are damaged, then you loose drive, but that tends to be a very noisy affair, and you would know if that had happened.

The last thing, and most likely, as Macabethiel says, is the "Lock up" solenoid, which effectively locks the two fans together above certain revs, to make the engine connected directly to the gearbox.

That could be anything from a dodgy switch, right through to the solenoid is knackered though.

I would start with getting the oil level right to start with, using the technique Macabethiel has already mentioned.

 

[russell.huffer]

Autos do slip I had gearbox reconditioned on my Transit van and the brakebands on that kept slipping the problem is when they slip they polish and then they always slip.

Had many conversations about slipping gears on autos as they reconditioned this gearbox 4 times and it always started to slip again within a few thousand miles.

Ended up px it with no top gear in the end just to get shot of the bloody thing.


Kind regards

Russell.

 

[SilasStingy]

That's some good info there Macabethiel, thanks! I will sort out the level and see what happens. It does really feel like it's slipping, it can't get the gear in so it starts to jump and then I simply need to release the accelerator and the gear will slip in.
If I can't sort the problem out I will live with it, just hope that it won't wreck the whole box!