722.6 Auto Transmission. When cold jolts into 2nd gear when exiting a slow corner or
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Junior Member
Joined: Mar 2012
Posts: 15
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c180
722.6 Auto Transmission. When cold jolts into 2nd gear when exiting a slow corner or
I hope someone may be able to help me with this annoying issue.
Each day whether it is the morning or afternoon, and whether it is a cold day or a normal spring/summer day, I have this same issue where the auto transmission jolts into gear. It doesn't happen after the auto transmission has heated up to its operating temperature, only when it is cold. I believe I may have now isolated it to mainly happening where there is a change in the road-wheel speed such as exiting from a roundabout, or slowing for a pedestrian crossing and then speeding up again. I have tried to explain common symptoms below.
Considerations
Car: C180K. 2006. 100k miles on the clock. Car is generally in very good condition
I had my local garage replace the transmission oil and filter for me. This made a slight improvement, but didn't eradicate the issue at all.
As mentioned earlier, this happens when i use the car for the first time in the day whether it is morning, afternoon or evening.
The issue of jolting into gear happens as the car decides to try and change into 2nd gear.
I've not tried to see if this issue exists when leaving a roundabout in 2nd/3rd gear
The jolt doesn't happen in a straight line
The jolt doesn't happen changing up to 3rd and fourth
The jolt doesn't happen when selecting drive from park
Once the car is good and warm the issue disappears
Scenario 1
When i leave my house and drive in a straight line the gears shift from 1st to 2nd to 3rd no problem. When I negotiate the mini roundabout about quarter of a mile away the issue happens. I am probably approaching in the mini roundabout in 3rd gear and slow to a road speed somewhere between 1st and 2nd (more likely to be a road speed of 2nd gear rather than 1st if i was driving a manual transmission). As i exit the roundabout (having gone 3/4 of the way around the roundabout) the car jolts into gear which is probably 2nd gear (I wouldn't say it is as harsh as a bang, but more of severe jolt). It then progresses up through the gears in a smooth way for the rest of the drive down a straight road. If i have to slow the car down for traffic lights of to negotiate parked cars, the box changes down the gears smoothly with no jolts.
Scenario 2
Another scenario where the jolt happens is when i go over some very small speed bumps. My daughter's school is about a mile from the house and when i go over the speed bumps at the school (these are the small rounded bumps approximately 4-6 inches in radius). As I approach the speed bumps I slow down to a slow walking speed to go over them. I wait until the rear wheels have gone over the bump before accelerating. However, as i accelerate away the transmission jolts into 2nd gear as mentioned above and sometimes also gives a lurching/jumping sensation as if the car is chugging along like a 'clowns' car. It chuggs maybe three times before settling down.
Could this issue be a speed sensor issue in the transmission? If it is, i don't see why it only happens when the box is cold
I am reluctant to take the car to a MB dealer because they want EURO 175 to diagnose the issue and i am afraid that they will just try replacing parts without fully understanding the issue first.
Any advice or solutions would be very welcome. If you truly believe the dealer can help me by attaching the box to their technology then i am happy to do that.
Thanks in advance of your support
Each day whether it is the morning or afternoon, and whether it is a cold day or a normal spring/summer day, I have this same issue where the auto transmission jolts into gear. It doesn't happen after the auto transmission has heated up to its operating temperature, only when it is cold. I believe I may have now isolated it to mainly happening where there is a change in the road-wheel speed such as exiting from a roundabout, or slowing for a pedestrian crossing and then speeding up again. I have tried to explain common symptoms below.
Considerations
Car: C180K. 2006. 100k miles on the clock. Car is generally in very good condition
I had my local garage replace the transmission oil and filter for me. This made a slight improvement, but didn't eradicate the issue at all.
As mentioned earlier, this happens when i use the car for the first time in the day whether it is morning, afternoon or evening.
The issue of jolting into gear happens as the car decides to try and change into 2nd gear.
I've not tried to see if this issue exists when leaving a roundabout in 2nd/3rd gear
The jolt doesn't happen in a straight line
The jolt doesn't happen changing up to 3rd and fourth
The jolt doesn't happen when selecting drive from park
Once the car is good and warm the issue disappears
Scenario 1
When i leave my house and drive in a straight line the gears shift from 1st to 2nd to 3rd no problem. When I negotiate the mini roundabout about quarter of a mile away the issue happens. I am probably approaching in the mini roundabout in 3rd gear and slow to a road speed somewhere between 1st and 2nd (more likely to be a road speed of 2nd gear rather than 1st if i was driving a manual transmission). As i exit the roundabout (having gone 3/4 of the way around the roundabout) the car jolts into gear which is probably 2nd gear (I wouldn't say it is as harsh as a bang, but more of severe jolt). It then progresses up through the gears in a smooth way for the rest of the drive down a straight road. If i have to slow the car down for traffic lights of to negotiate parked cars, the box changes down the gears smoothly with no jolts.
Scenario 2
Another scenario where the jolt happens is when i go over some very small speed bumps. My daughter's school is about a mile from the house and when i go over the speed bumps at the school (these are the small rounded bumps approximately 4-6 inches in radius). As I approach the speed bumps I slow down to a slow walking speed to go over them. I wait until the rear wheels have gone over the bump before accelerating. However, as i accelerate away the transmission jolts into 2nd gear as mentioned above and sometimes also gives a lurching/jumping sensation as if the car is chugging along like a 'clowns' car. It chuggs maybe three times before settling down.
Could this issue be a speed sensor issue in the transmission? If it is, i don't see why it only happens when the box is cold
I am reluctant to take the car to a MB dealer because they want EURO 175 to diagnose the issue and i am afraid that they will just try replacing parts without fully understanding the issue first.
Any advice or solutions would be very welcome. If you truly believe the dealer can help me by attaching the box to their technology then i am happy to do that.
Thanks in advance of your support
Senior Member
Joined: Apr 2019
Posts: 428
Likes: 96
From: Houston
001 s600, 94 sl600
The harsh first shift feeling may be coming from a limited slip rear axle clutch. Try driving in circles (in a parking lot) with different throttle openings to see if the limited slip clutches are smooth. There are special additives to use in axles making noise , chattering, jerking. Be sure and check in both directions. LUBEGARD makes two different additives---one to de-jerk auto transmission, the other for limited slip rear axles.
Sometimes just driving in circles in each direction will smooth out the clutch actions.
Sometimes just driving in circles in each direction will smooth out the clutch actions.
