Lock up clutch

[Gareth1244]

Hi
I've noticed on a constant throttle my e320 cdi stutters slightly when starting to go uphill. Only really noticable on motorway. Suspected lock up clutch and drove it with scanner connected. At cruising speed there is still slip between the engine and transmission of about 80rpm. When it stutters the difference drops to about 15 and then goes back up. Sounds like the clutch is engaging at the stutter when it should already be engaged. No warning lights coming up or transmission fault codes. Having oil changed and flushed but wondering about lock up solenoid but surely sol must be ok or it wouldn't lock at all.

Thanks
Gareth

 

[Dodipops]

May be contaminated fluid due to antifreeze getting in through the radiator cooler, flushing the fluid should stop it or make it better for a while, if it does you may find you need a new radiator.

 

[Tuercas viejas]

May be contaminated fluid due to antifreeze getting in through the radiator cooler, flushing the fluid should stop it or make it better for a while, if it does you may find you need a new radiator.

Yes if you have coolant contamination then that can be a big issue if neglected as antifreeze attacks "the papers" in the clutch packs, and that can cause rapid deterioration of the friction plates .
That stated!
The MB transmission lock up clutch solenoids have been up dated several times and a loss of resistance 'Ohmage" is a big cause of T/C related problems..
If you drop the valve body, the T/C lock up solenoid is the front one (L/H side) opposite the electric socket boss molding on the (Rht side) .
The ohm reading should be 2,6 ohms with it removed from the board . If it drops below 2,3 Ohms then its not controlling properly.
We always replace these when doing T/C related repairs, and box rebuilds ,. On this side they are cheap at about $42 for the latest & greatest. .


Often we use a lecky paint stripper heat gun to heat these solenoid's up to about 90C and re-read the ohm rating since they live in hot environment.

While you are at it, you can check the shift solenoids at 4,5 Ohms and the "big one" aft of the socket being the gallery control pressure solenoid being 5.,5 to 5,9 ohms.
Caution as these are are spendy at about $350 a pop.
We do about 4 transmissions a week in my /our shop and we always fill with with MB fluid.

As a recommendation we always add a can of BG ATC Plus to the fill.
I won't go into chem' specifics trying to be a back streets boffin, but it strips petroleum distillates adhering to the T/C clutch and provides better controlled slip conditions when working.
Hope that helps & all the best
Tuercas viejas
(Council house "Mr Fix It " in the street & garden shed maestro of the transmission in the 1970's )

What is BG ATC Plus and what does it do?

With modern transmissions operating at ever higher temperatures, transmission fluids deteriorate much faster. Deposits form on crucial components causing slipping, erratic shifting and sometimes complete failure. BG ATC Plus enhances the properties of both new and used automatic transmission fluid.

bgprod.co.uk

We buy this stuff by the case weekly .
Jay, the BG Rep loves us with no quibble sales of Auto Chem products

 

[Gareth1244]

May be contaminated fluid due to antifreeze getting in through the radiator cooler, flushing the fluid should stop it or make it better for a while, if it does you may find you need a new radiator.

It's a 2005 car and has the update radiator but I suppose its possible
Ta

 

[m80]

As I remember we can get a sample of the ATF tested for glycol contamination.
I 'think' there are 3 clutch sets in the box, this may just be wear and tear.

 

[Bellow]

Hi
I've noticed on a constant throttle my e320 cdi stutters slightly when starting to go uphill. Only really noticable on motorway. Suspected lock up clutch and drove it with scanner connected. At cruising speed there is still slip between the engine and transmission of about 80rpm. When it stutters the difference drops to about 15 and then goes back up. Sounds like the clutch is engaging at the stutter when it should already be engaged. No warning lights coming up or transmission fault codes. Having oil changed and flushed but wondering about lock up solenoid but surely sol must be ok or it wouldn't lock at all.

Thanks
Gareth

If the clutch should be engaged and isn't then that suggests a transmission problem - but no fault codes.

If the engine output is momentarily faltering then the slip will drop as (open) torque convertor slip is a function of the torque it is transmitting. Could your problem be engine related?