Testing W124 Auto Gearbox (1994 3.0 Diesel)

[landspeed]

Hi!

I've done a search for a couple of questions regarding the W124 automatic gearbox, which I haven't been able to answer.

I'm going to be test driving one of these cars soon (a 1994 W124 3.0 Diesel Auto), and wonder what I should look for to make sure the gearbox isn't slipping?. How smooth should the changes be?

Does the car have torque convertor lock-up, where it locks up and eliminates slip at the torque convertor, usually in the higher gears? This is one of the important questions I can't find the answer for!

Thanks for your advice

 

[MercTech]

Roadtest Auto

The gearbox in this vehicle is a 722.4 and to my knowledge is to early to have convertor lockup. When checking the gearbox operation start by checking around the gearbox for oil leaks, then check the oil level (in park with the engine runing) and at operating temerature. Also smell the oil for burning if it is at will have a strong smell of burning and will no longer be red in colour. When driving check that all the gears are present (4 Gears) plus reverse. The upshifts at partial throttle should only be noticeable if close attention is paid. At full throttle or kickdown the gear changes should be clearly felt. Check gear change from reverse to D while stationary, there should be no noticeable clunk if there is it could be the gearbox at fault or it could be the propshaft coupling. Finally check that when it upshifts there is no flaring up of the engine revs and when selecting D stationary there are no odd whistling noises.

Good Luck

 

[landspeed]

I will keep that info when I do a test drive in the couple of days. It is a bit surprising that it doesn't have lockup - my old F reg Nissan Bluebird had a 4-speed auto box with lockup But I suppose different manufacturers change different components of cars at different rates. I know that the gearbox is very smooth on the Mercedes so hopefully all will be OK.

Thanks

 

[Parrot of Doom]

You'll know if its slipping when you press the accelerator to pull away quickly from a stop, and the revs rise and you go nowhere. I've driven a few autos, so long as the gear changes both up and down are silent and smooth, it should be ok.

Also, park the car in neutral, put the parking brake on, and flick to D or R, if it takes any more than a second to select either then thats cause for suspicion (although it will take longer to change when cold than when its warm).

You should also drive it using the manual gear selection to make sure its all working correctly.

If you want to check the ATF I did a thread on this just recently, the process should be quite similar for yours.

 

[Bolide]

E300 Diesel autoboxes

You may find the box a little lumpy when cold but, when warm, it should upshift almost imperceptibly when accelerating on 1/2 - 3/4 throttle. It should kickdown easily to third at about 45 in top but they won't kickdown above about 60 mph

I've found full-throttle upshifts on quite a few E300 Diesels give a pronounced flare between gears and think it may be a characteristic. Though I'm told a new external actuator valve on the box (£30) helps a lot

If the box bangs shifts or is always harsh or slow on one particular shift (say, 2 to 3) then the box is worn & needs rebuilding. It's possible to make the box bang into a higher gear if you lift off just as it's about to change up but they shouldn't bang shifts on a steady throttle

If there's lots of snatch when going between P and R, or if there's a bang from the rear as you pull away, then the prop doughnuts, diff mounts and/or diff are worn, possibly box too

On a 100k car the box should be nigh-on imperceptible at all times, fetching you new gears and engaging them for you just before you realise you'd like them - like a rather efficient butler might

Nick Froome
www.w124.co.uk

 

[television]

The transmission is a 722.5, I thought this model had lock up

Malcolm