722.5 Auto box misery
06-21-2009, 10:15 AM
#1
Member
Thread Starter
722.5 Auto box misery
Hello All,
My current problem applies to a 1991 300CE-24 with 104 engine and 722.5 5-speed auto box.
Auto box is misbehaving.
1. Starts fine, up changes quite smoothly and at correct speeds.
2. At the 3 to 4 up-change point, it engages 4th for about half a second then changes to 5th.
3. Switching from D to 4th with the lever has no effect, it remains in 5th.
4. Down-changes are very slow and only happen when very low road speed is reached.
5. Manual selection of 3rd results in 3rd being selected after around 2 seconds (very slowly). If
left in 3rd, it behaves musch as it should short of being reluctant to select 2nd except at very
low road speeds.
6. Kick down (foot flat to the floor) results in 2 or 3 seconds of 'thought' and then off we go!
So, basically, everything seems to work but in some cases completely at the wrong time.
My feeling is that this is a vacuum related thing. It's as if the gearbox is entirely unaware of
the position of the accelerator and thus when I am hoping for a down-change.
If anyone can shed any light on this, I should be forever endebted.
My thanks in advance and regards to all.
RayH
My current problem applies to a 1991 300CE-24 with 104 engine and 722.5 5-speed auto box.
Auto box is misbehaving.
1. Starts fine, up changes quite smoothly and at correct speeds.
2. At the 3 to 4 up-change point, it engages 4th for about half a second then changes to 5th.
3. Switching from D to 4th with the lever has no effect, it remains in 5th.
4. Down-changes are very slow and only happen when very low road speed is reached.
5. Manual selection of 3rd results in 3rd being selected after around 2 seconds (very slowly). If
left in 3rd, it behaves musch as it should short of being reluctant to select 2nd except at very
low road speeds.
6. Kick down (foot flat to the floor) results in 2 or 3 seconds of 'thought' and then off we go!
So, basically, everything seems to work but in some cases completely at the wrong time.
My feeling is that this is a vacuum related thing. It's as if the gearbox is entirely unaware of
the position of the accelerator and thus when I am hoping for a down-change.
If anyone can shed any light on this, I should be forever endebted.
My thanks in advance and regards to all.
RayH
06-21-2009, 11:33 AM
#2
MBWorld Fanatic!
Hey, I don't have any thing to help you with right now, but do you think you could help me out?
Where are the little yellow tab marks on your spedometer (that show when the transmission should upshift)?
Also, what RPM does it tach at in 5th on the highway?
Thanks!
Where are the little yellow tab marks on your spedometer (that show when the transmission should upshift)?
Also, what RPM does it tach at in 5th on the highway?
Thanks!
06-21-2009, 12:18 PM
#3
Member
Thread Starter
60, 100, 160 & 220 kph.
RayH
06-21-2009, 12:46 PM
#4
MBWorld Fanatic!
Ah, thanks 
I have the 722.3 right now and I would ideally like to switch to the 722.5 if I change the rear diff to a higher ratio so I don't tach at like, 5k at highway speeds (128kph or so)
I have the 722.3 right now and I would ideally like to switch to the 722.5 if I change the rear diff to a higher ratio so I don't tach at like, 5k at highway speeds (128kph or so)
