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1992 500SL, 1999 CLK 320 conv, 2015 ML350, (2011 ML550 gone, C320 wagon gone, 2005 C240 gone)
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595 Posts
Discussion Starter #1
Hi folks,
I am experiencing a transmission problems that started last Saturday when I was taking up on a ramp on the highway. I pressed down the throttle to the floor to accelerate quickly. The car kicked down to 2nd gear as expected but decided to stay on 2nd gear after that. I took the next exit and stopped when I could and turned the car off. When I started to drive back again the car stayed in 2nd gear until I came back home. The next day I test drove the car and it shifted nice and smooth until reaching 3rd gear this time but never went to 4th gear. I have been driven a couple of times since and the car shifts smoothly but does not go to 4th gear anymore. I replaced the transmission fluid yesterday but still no 4th gear. The last time I changed the tranny fluid and filter was 4 years and 40k miles ago so the transmission fluid that came out was still nice clear red but I changed it anyway but still no 4th gear after that. My car has 140k miles and I have been driving it several times a week, winter or summer, for the last several years. I have had my share of issues as you can expect with a car of that age and so far have been able to fix each of them but I never had any problem with the transmission until now. Not sure what my next move should be with that transmission problem now. Is the transmission gone for good or is there anything I should try? Any suggestion?
Thanks
 

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Outstanding Contributor
2003 SL500, 2003 SL55, and four R129s
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4,387 Posts
Martin (a.k.a. "MAVA") is an expert on the electronically-controlled 722.6 transmission. He probably knows quite a bit about your 722.3 transmission as well, so I'd send him a PM.
 

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Registered
1992 500SL, 1999 CLK 320 conv, 2015 ML350, (2011 ML550 gone, C320 wagon gone, 2005 C240 gone)
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595 Posts
Discussion Starter #3
Martin (a.k.a. "MAVA") is an expert on the electronically-controlled 722.6 transmission. He probably knows quite a bit about your 722.3 transmission as well, so I'd send him a PM.
Thanks, will do
 

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Registered
1992 500SL, 1999 CLK 320 conv, 2015 ML350, (2011 ML550 gone, C320 wagon gone, 2005 C240 gone)
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595 Posts
Discussion Starter #4
I drove the car to get it inspected today and it drove and shifted perfectly. Strange
 

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1992 500SL, 1999 CLK 320 conv, 2015 ML350, (2011 ML550 gone, C320 wagon gone, 2005 C240 gone)
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595 Posts
Discussion Starter #5
Did some additional test driving since my last message and the issue is still very much there. This time it got stuck in 2nd gear. It sounds like the transmission is giving up
 

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1992 500SL, 1999 CLK 320 conv, 2015 ML350, (2011 ML550 gone, C320 wagon gone, 2005 C240 gone)
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595 Posts
Discussion Starter #7
When last was the fluid and filter changed?
I just replaced the fluid few days ago to see if it would fix the problem but it did not. The last time I changed the ATF and filter was 4 years and 40k miles ago.
 

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2001 SL500
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337 Posts
I just replaced the fluid few days ago to see if it would fix the problem but it did not. The last time I changed the ATF and filter was 4 years and 40k miles ago.
Well assuming you used the correct quantity and spec for the fluid and changed the filter, yet no fix, you’re gonna have to pm MAVA the transmission expert.

was the fluid super dark or burnt ?
 

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Registered
1992 500SL, 1999 CLK 320 conv, 2015 ML350, (2011 ML550 gone, C320 wagon gone, 2005 C240 gone)
Joined
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595 Posts
Discussion Starter #9
Well assuming you used the correct quantity and spec for the fluid and changed the filter, yet no fix, you’re gonna have to pm MAVA the transmission expert.

was the fluid super dark or burnt ?
No the atf was pretty clear red. I PMed mava
 

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1992 500SL, 1999 CLK 320 conv, 2015 ML350, (2011 ML550 gone, C320 wagon gone, 2005 C240 gone)
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595 Posts
Discussion Starter #10
so I drove the car a couple of times since my last post. This time it went though all the gears but I did not drive hard at all. I noticed that sometime it would not up shift at the RPM's it is supposed to unless I slightly and briefly release the throttle pedal and then it up shifts to the next gear.
 

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93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
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8,105 Posts
Okay, finally back...

So you understand, fourth gear is achieved and locking K1 and B2 clutch packs. The way this is achieved is the band k1 and B2 is squeezed, so it does not rotate thus transferring the engine RPM straight through, and does NOT GO through the planetary gears in the transmission. Similar to overdrive, but here it is 1 to 1, and on a 722.6 it is like 0.7 to 1

Since you drive from a dead stop it is not B2 circuit of valves and band, but K1 which is right behind the oil pump which the oil pump is behind the torque converter. My findings with all 722.3-722.5's is the brake band K1 is always burned and worn-out way more than B2 brake band. K1 brake band can only be replaced by removing the transmission.

The things of last resort are to k1/k2 springs, and some guys have had partial success of changing all the teflon seals, the other solution may be to get a junk valve body from another 722.3 as Mercedes has discontinued ALL 722.3 valve bodies for sale, yet one can still buy a rebuilt transmission with a new or rebuilt valve body that comes with it, so go figure why they will not sell a valve body?

Try the spring(s) and I think you can buy a B1 valve... here is the thread on it:


Hope it helps, let us know what you end up doing..

Martin
 

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1992 500SL, 1999 CLK 320 conv, 2015 ML350, (2011 ML550 gone, C320 wagon gone, 2005 C240 gone)
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595 Posts
Discussion Starter #12
Thanks Martin for this detailed and clear explanation. I am going to see if can get a rebuilt transmission.
 

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93 SL500, 95 SL320, 96 S320, 98 S500, 2002 E320 4Matic Wagon & A little 91 5.0 FORD Mustang
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8,105 Posts
Try the spring!! No transmission work is a sure shot the first-go-around. The fix is around five to six tries. It is not like changing a hose. That is why mechanics thrown-in the towel, and replace the whole thing.

Martin
 
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