W124 - 300TE Autobox .......erratic mode?

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punjabi

Active Member
Joined
Apr 22, 2005
Messages
110
Location
Surrey, UK
Car
V230, 300TE
The auto box has been fine until a recent 500 mile motorway day-trip after which it has become somewhat erratic when sometimes it shifts from 1st to 2nd with a delayed and a slight high rev motion :confused:.
This only happens when it has been driven a while and at random - not all the time! The tranny oil is clean and at the correct level, although I was thinking of changing the oil & filter to see if it cures the problem but the weather has been rather wet and cold!
The car has done 190K and is otherwise in excellent mech/elec condition. Any ideas what could be causing the problematic behaviour of the tranny?
 
The auto box has been fine until a recent 500 mile motorway day-trip after which it has become somewhat erratic when sometimes it shifts from 1st to 2nd with a delayed and a slight high rev motion :confused:.
This only happens when it has been driven a while and at random - not all the time! The tranny oil is clean and at the correct level, although I was thinking of changing the oil & filter to see if it cures the problem but the weather has been rather wet and cold!
The car has done 190K and is otherwise in excellent mech/elec condition. Any ideas what could be causing the problematic behaviour of the tranny?

sounds like a vacuum leak. Check all the vacuum pipes for leaks.
 
A vacuum leak will give a hard shift, this sounds like low fluid, sticking valve or slipping clutch.

If the ATF hasn't been changed for a while it's worth a go.

The Vac modulator might not be adjusted correctly, try disconnecting the vac line and see what happens. It should bang into the next gear firmly.
 
A vacuum leak will give a hard shift, this sounds like low fluid, sticking valve or slipping clutch.

If the ATF hasn't been changed for a while it's worth a go.

The Vac modulator might not be adjusted correctly, try disconnecting the vac line and see what happens. It should bang into the next gear firmly.

DM,
Fluid level appears OK - where/what is the Vac Modulator? Which is the 'vac line' - the 10mm clear pipe leading from the servo to under the air cleaner housing or inlet manifold?
Any difference in ATF & Dextron II/III?
 
The modulator is on the side of the gearbox and has a line running from the inlet manifold down to the modulator. Unplug the line and plug it so air doesn't leak into the manifold.
 
The modulator is on the side of the gearbox and has a line running from the inlet manifold down to the modulator. Unplug the line and plug it so air doesn't leak into the manifold.

I adusted my modulator and now have good changes, where it was flaring before. However the OP states that it suddenly started to happen indicating something may of come adrift/adjusted.....
 
I adusted my modulator and now have good changes, where it was flaring before. However the OP states that it suddenly started to happen indicating something may of come adrift/adjusted.....

But it won't be a vac leak. If the vac leaks a hard shift ensues, not a slurred one.
Pulling off the vac line is a test of the rest of the box.
 

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