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Auto trans suddenly not shifting up.

Started by irvine, 15 July 2019, 05:14 AM

irvine

Hi guys, got a big problem, with my auto transmission ('74 280se 4 speed auto).

Today whilst driving the auto transmission wile pulling out of a junction didn't shift up.

I know the fluids were a bit low, around half way on the dipstick and had shifted up a little late the last few days.

I topped up with some fluid, cycled through p,n,r,d,s,l went for a drive getting up to temp and still it won't shift up...

Is there something I'm missing? I fear if I can't fix it easy I'm stuffed.

Thanks,
Neil. 

TJ 450

Half way up on the dipstick (between min/max marks) is probably the safe spot, was this checked with the trans at operating temp? If I was when cold it is probably over-full. Another thing to check is the control rod that links to the accelerator. This tells the trans when to shift. If it's fallen off or otherwise out of adjustment this could cause late shifting as it could be "thinking" you have your foot to the floor. Also check your shifter bushings too in case it's actually in S or L instead of D etc.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

irvine

Thanks for the reply,
when I recently checked the levels the fluid would of been warm, at least up to temp.
Everything is connected, I had a look under the car this evening and I had replaced the linkage bushings just last year.

I'm starting to think it's stuffed >:( >:( >:( >:( >:(
I let it totally cool off and went for a drive this evening and it still done it.

Other than the accelerator linkage is there anything else that may need adjustment???

Neil.

daantjie

I would drop the pan and change the filter. Mann brand only.  If you see lots of sludge and metal flakes in the pan then likely it's terminal  :'(
Daniel
1977 450 SEL 6.9 - Astralsilber

rumb

First step is to change filter and fluid.
'68 250S
'77 6.9 Euro
'91 300SE,
'98 SL500
'14 CLS550,
'16 AMG GTS
'21 E450 Cabrio

ptashek

What about the vacuum modulator? Wouldn't that affect shifts?
1993 "Pearl Blue" W124 280TE
1988 "Arctic White" W124 200T
1979 "Icon Gold" W116 450SE

TJ 450

The vac modulator only modulates the firmness of the shift, but it would be worth making sure it's connected correctly.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500

irvine

What's the vacuum regulator? Is it easily removed & refurbished?

I'll drop the oil/pan clean it out, new filter and check the movement of the linkages.

I don't have high hopes as it's a high mileage car.

Neil.

TJ 450

It screws into the side of the trans and has a vacuum line running to it. I reckon it's best to leave it alone though personally.

Pretty much the only thing that controls when the trans shifts up is that rod to the accelerator. You could try adjusting it back towards the firewall and see if it makes a difference. I can't remember exactly how it works on the M110 though.

There is also the kickdown solenoid, but I doubt that would malfunction.

I wouldn't jump to condemning it just yet as these transmissions are pretty reliable.

Alternatively, it might be worth getting an opinion from an independent MB mechanic that's familiar with these cars after confirming it all looks ok.

Tim
1976 450SEL 6.9 1432
1969 300SEL 6.3 1394
2003 ML500