Transmission Flare in 2-3 Shift - PeachParts Mercedes-Benz Forum

jdh122 · #1 12-02-2009, 11:37 AM

In the past couple of weeks my transmission has started flaring quite a bit during the 2-3 shift. The tach will increase as much as 500 rpm during the flare. The transmission fluid is at the correct level and is bright red (I changed the fluid, filter and gasket about 17,000 miles ago).

I've searched and it looks like the flare is most likely caused by either a vacuum leak or a bad K1 spring. Am I correct that these are the two most likely culprits?

If it is a vacuum issue, wouldn't it also affect shifts other than 2-3?

On a related note, about seven months ago I removed and blocked off the EGR. I plugged the vacuum line leading from the black box on the valve cover to the EGR, but otherwise left the black box untouched. Since this box only controls the EGR, can I remove it entirely and plug off the lines leading into it?

leathermang · #2 12-02-2009, 12:47 PM

Cheapest best trick is to try Trans-X first... no harm no foul if it does not work..
most trans shifting problems have the potential for being due to varnish buildup in the small holes in the trans valve body....some work using gravity with bb sized balls...
(so do not try to shift your car when it is upside down)....clutches and stuff inside your auto trans work through hydraulic pressure... for the record...
a little varnish can stop or slow the movement of that ball ( by gravity).. which is a back flow stopper... and give all sorts of symptoms in the operation of the car...
also check the archives for Trans-x... lots of good stuff...

Read and follow the directions on the can... on my wagon when I did the math it took two cans initially... then one can put in with the new fluid and filter installed...

tangofox007 · #3 12-02-2009, 01:09 PM

Quote:

Originally Posted by jdh122

I've searched and it looks like the flare is most likely caused by either a vacuum leak or a bad K1 spring. Am I correct that these are the two most likely culprits?

A vacuum leak would cause a hard shift, not a flare.

Quote:

Originally Posted by jdh122

If it is a vacuum issue, wouldn't it also affect shifts other than 2-3?

Yes.

Quote:

Originally Posted by jdh122

In
Since this box only controls the EGR, can I remove it entirely and plug off the lines leading into it?

You definitely want to plug the line upstream from the 3/2 valves.

tangofox007 · #4 12-02-2009, 01:13 PM

Quote:

Originally Posted by leathermang

Cheapest best trick is to try Trans-X first... no harm no foul if it does not work..

I am going to strongly disagree with the "no harm, no foul" claim. My information indicates that Trans-X is bad news for friction material adhesive. Personal experience would tend to confirm that theory.

A new K-1 accumulator spring would have a much higher probability of success with almost no downside risk.

leathermang · #5 12-02-2009, 01:37 PM

Quote:

Originally Posted by tangofox007

My information indicates

How about just a LITTLE reference to support that...?
since I have about 40 years of experience using it...
even on cars with no problems I change out the old fluid/filter after using it.... and install when putting the new in..

Just two days ago.... on our ' new' 2001 Lincoln towncar ( bought from my uncle whose motto is ' don't sweat the small stuff' .... and thus does little or no maintenance on his vehicles.... I used my devilbiss suction machine to pull a couple of quarts of old dirty trans fluid out and install two cans of the Trans-x..
Within 50 miles it was not ' jumping hard' when at a stop and moving the shift lever from reverse to drive... I also sat and ran it through the gears like the can says to do...

and I have never had any trans troubles with the cars I have installed it in... including about four which had problems that it cured immediately...( 20-100 miles of usage plus the at rest procedure )...

So this ' making problems with friction material' needs at least SOME statistical support to offset the long first hand no problem history I have with it.. ( have probably put it into 50 cars total over that period ).
and I have no stock in the company either...

tangofox007 · #6 12-02-2009, 01:52 PM

Quote:

Originally Posted by leathermang

So this ' making problems with friction material' needs at least SOME statistical support to offset the long first hand no problem history I have with it.. ( have probably put it into 50 cars total over that period ).
and I have no stock in the company either...

Just one question. In how many of those 50 cars did you cut open the transmission filter and inspect for friction material at the next service interval?

Do you have any statistical evidence that the Trans-X that you installed had no detrimental affect on the transmissions so treated?

jdh122 · #7 12-02-2009, 01:56 PM

Setting aside for a moment the use of Trans-X and the K-1 spring replacement, are there any simple adjustments (Bowden cable, etc.) that might fix this problem?

tangofox007 · #8 12-02-2009, 01:59 PM

Quote:

Originally Posted by jdh122

Setting aside for a moment the use of Trans-X and the K-1 spring replacement, are there any simple adjustments (Bowden cable, etc.) that might fix this problem?

If your other shifts are okay, probably not. The K-1 spring is inexpensive and really easy to install. The 2-3 flare is a common problem with the 722.3 transmission and is frequently cured with the spring kit.

Phil · #9 12-02-2009, 02:08 PM

Quote:

Originally Posted by jdh122

Setting aside for a moment the use of Trans-X and the K-1 spring replacement, are there any simple adjustments (Bowden cable, etc.) that might fix this problem?

Look up transmission adjustment, there is a good write up about setting up your trans. That said the K-1 is for the 2-3 shift and is cheap easy to do and if you do it change the filter and fluid at the same time.
This is the write up
It's CRITICAL... how you set your transmission's vacuum system on your diesel MBZ...

whunter · #10 12-02-2009, 02:42 PM

I agree:
The K1 spring kit is extremely easy and CHEAP to do.
* Remove the transmission pan.
* Remove four screws, (front of valve body, toward the driver side.
* Remove the cover plate.
* Remove the piston containing the old K1.
* Remove the old K1.
* Assemble/compress (with fingers) the new K1.
* Install the NEW K1 into the piston.
* Install the piston containing the NEW K1.
* Install the cover plate.
* Install four screws.
* I suggest a NEW filter and transmission pan gasket.
* Refill the transmission, typically between 3.5 and 4 quarts on the 722.xxx transmission.
* Start the engine and check/top off the transmission fluid level..

Average time (even on jack stands) = one hour or less..

Here is a link to the part, and it contains more links to the procedure.

1262704477 722.xx Transmission K1 spring kit

Have a great day.

leathermang · #11 12-02-2009, 02:46 PM

Quote:

Originally Posted by tangofox007

Just one question. In how many of those 50 cars did you cut open the transmission filter and inspect for friction material at the next service interval?

And , Pray Tell, why would I cut open a trans filter if the car was (NOW) working just fine ? If they go until the engine gives out then what would cause you do suspect trans friction material problems ?

If on the other hand.... you cut open the first trans filter after installing it...( the one you are going to change out with the old trans fluid ) and find clutch material .... you could reasonably assume that the hydraulic clutches were not engaging fast enough to avoid SLIPPING... which does cause erosion of the clutch material...

Have you seen ANY reports anywhere of this stuff causing any problems ?

whunter · #12 12-02-2009, 03:15 PM

IMO, Trans-X (and similar products) should not even be considered on the flare issue UNTIL after the K1 has been replaced.

Trans-X.
I have used it for years, always as a FINAL step before rebuild or replacement of the transmission.

* No vehicle manufacturer recommends it for new units.
* It cleans varnish, swells seals, and can in very rare cases plug the filter.
* Without a total flush or rebuild, you can not know what chemical concoctions previous owners may have put in, and some of them react badly together.

With all of that said.
If it allows a customer unable to afford a rebuild/replacement to get six months - two more years from the transmission = IMO it is a functional product for band-aid repair on a budget.

Phil · #13 12-02-2009, 04:05 PM

Quote:

Originally Posted by whunter

IMO, Trans-X (and similar products) should not even be considered on the flare issue UNTIL after the K1 has been replaced.

Trans-X.
I have used it for years, always as a FINAL step before rebuild or replacement of the transmission.

* No vehicle manufacturer recommends it for new units.
* It cleans varnish, swells seals, and can in very rare cases plug the filter.
* Without a total flush or rebuild, you can not know what chemical concoctions previous owners may have put in, and some of them react badly together.

With all of that said.
If it allows a customer unable to afford a rebuild/replacement to get six months - two more years from the transmission = IMO it is a functional product for band-aid repair on a budget.

I agree with this, Trans-X would be a consideration only after you have exhausted all the other possibilities short of a rebuild OR its the only way you are going to get home and then I would get it out of the trans as soon as possible.

snookwhaler · #14 12-02-2009, 05:53 PM

Quote:

Originally Posted by jdh122

Setting aside for a moment the use of Trans-X and the K-1 spring replacement, are there any simple adjustments (Bowden cable, etc.) that might fix this problem?

Back on track here.....

What year and model are we talking about?

I had a bad 2/3 flare as you describe and was able to adjust the vacuum down to a lower level as a temporary fix until I installed my K1 kit.

All the bowden cable does is control the shift points. BUT, there is a balance (sweet spot) in all of this.

The K1 kit is really simple and adds only about 5 minutes to a trans. pan drop and fluid/filter change.

jdh122 · #15 12-02-2009, 06:46 PM

It is a 1983 300D. I've decided to go with the K1 replacement. It's easy, cheap and likely to fix the problem. It's been 18,000 miles since I last changed my transmission fluid and filter, so I'll just do it all a little ahead of schedule.