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Topic: 722.6 Transmission Whine, will not move, no fluid pressure at cooler Reply to Thread
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  Topic Review (Newest First)
03-24-2019 06:42 PM
TheWitz I just went through something similar on a 2003 C240 4matic. No codes, no limp mode, when the car was cold from sitting overnight I could start the car and it would move in forward and reverse for a minute or two, then the whine of the pump would become apparent and the transmission would no longer engage any gear. I opened the cooling line at the radiator, while the engine was running and found no flow. Transmission fluid level was reading too high and the level didn't change after engine start which told me the pump wasn't pumping.

The whine of the pump was telling me the pump is running but starving for fluid. I had recently changed the transmission fluid because of anti-freeze contamination. I had also installed a new conductor plate and new transmission filter. I had then put about 500 miles on the car when this problem cropped up. Since the filter was new, I had discounted it as a problem.

Bottom line was I installed another new transmission filter and now the pump whine is gone and the car is back on the road. In my situation I should have flushed more transmission fluid through the system to remove as much crud as possible. I had dropped the pan several times and was not finding any sediment that would clue me in to a clogged filter.

It's an inexpensive thing to try before taking more drastic measures.
02-27-2019 02:09 AM
Johnhoedemakers Thanks for the reply and the manual Martin, highly appreciated.
02-24-2019 08:53 AM
MAVA
Quote:
Originally Posted by Johnhoedemakers View Post
I have the same issue with a 1998 SLK230 with approx. 120Kmiles.

Welcome to the forum, and sorry for your problems...

No flow problems are super rare on these transmissions, yet in the Thirteen-YEARS or so I have been here at Benzworld. Just these last two years i have seen four-cases of no-flow situations with the 722.6

The solution for starters is the main pump has quit because possibly the drive gear broke in it, or the gaps from the bell-housing is too large, or the pump gears themselves have too large of a gap.

I assume you are testing the flow from the left hand side of the transmission exit line, but it would not make any difference either line as it is one continuous path.

If you can DIY, it can be fixed as I have walked many here to rebuild their transmissions. If you are willing to take a crack at it, here some literature on the 722.6 with many photos. Some solutions... to figure out the 722.6.

https://www.benzworld.org/forums/w14...ce-manual.html

Let us know what you decide to do..

Martin
02-23-2019 05:00 AM
Johnhoedemakers
Same issue

Quote:
Originally Posted by Johnhoedemakers View Post
Hi, did you find the solution eventually?
I have the same issue with a 1998 SLK230 with approx. 120Kmiles.
02-13-2019 08:44 AM
Paaw7541
Quote:
Originally Posted by 79Mercy View Post
Hey guys really need some advice if anyone has any to lend. The car in discussion is a 2000 E430, vehicle was purchased with what we were told was a failed transmission. Vehicle would drive normally for approximately 5 min, loud whine noise would appear and transmission would fall out of gear. Checked fluid level, found fluid level actually a bit high, now knowing it’s because the pump is not functioning

Some of the first checks were for oil in the harness, none found and control unit is dry.

No major metal particles were found in the pan and no abnormal amount of clutch material found.

Known good valve body installed with good conductor plate and good solenoids, problem still present. Same exact problem.

Removed transmission from vehicle and dismantled transmission. Inspected everything and checked clearances as per wis documents, nothing abnormal found. Front pump was found to be fine, bushing was ok. And no discoloration from heat was found. Trans was put back together with new Teflon seals and new alum hardware as stated in wis.

After replacing the Teflon seals and re assembling trans, vehicle drove for approx 250 miles normally, then without warning symptoms appears. Same exact symptoms. Whine noise, trans lost movement.

At this point i i stalled a known good 722.6 from another v8 car, same Trans and same torque rating. Vehicle drove fine for about 5 months, then same exact symptoms occurred on the replacement transmission.

Removed the pan and found coolant contamination in the atf fluid. Replaced the radiator, drained torque converter, removed valve body and cleaned. Put all back together. Vehicle drove for about 100 miles and then all of a sudden the same symptoms occurred again.

I removed the replacement Trans and inspected, only to find nothing out of the ordinary. Everything appears to be visually ok. This time i put in a new front pump assembly, because i was out of options at this point. After installing the new pump the transmission only operated for about 10 min before the same thing happened.

I can crack the cooler hoses at radiator and find NO flow with engine running.

If anyone has delt with this and found a cure please let me know. I’m out of options at this point. I believe it’s a mechanical pressure problem, as even with no control unit installed the vehicle should be stuck in 2nd gear, limp mode.

Any advice is helpful. Thank you.


Experiencing same problem with S500 and 93k. Have you found solution to that problem?
01-13-2019 10:53 AM
Johnhoedemakers Hi, did you find the solution eventually?
12-14-2017 09:33 AM
mrboca What are the codes ? are they obtained from the transmission module ? Codes 110, 111 from the TCU ?

It is unusual for two transmissions having the same problem. When the transmission is replaced, the computer needs to adapt
12-13-2017 06:31 PM
79Mercy
Quote:
Originally Posted by MAVA View Post
Funny as this may sound, but do you have the shifter bushing, and the bushing at the transmission arm?

Did you forget to install the six torque(TC) converter bolts. The oil pump is a mechanical device, and all it takes is for the TC to be bolted to the flywheel. The oil pump gear has a direction, but do not know if the gear is backwards. I need to look at the fluid flow diagram in park.

You did not replace any frictions?

When you opened the clutch packs did you get larger spring clips to bring the gap to specifications?

How many miles on the old tranny?

You checked fluid running in park?

Now you are in limp.. Have you checked the Transmission Computer(TCM) for fluid?

Checked your codes at the 38 pin connector...

Martin
Yes the shift linkage bushings are installed on both the Trans and linkage at shifter module.

Yes the torque converter bolts are installed correctly. The Trans works for a few min and then whines and looses pressure

No friction discs were replaced, all were virtually like new and measured well within spec. Different snap rings werenít needed.

Both original and used transmissions have approximately 150k on them.

Fluid level was set and checked in park each and every time with the Mercedes tool.

The Trans will not go into limp mode, i lose everything. Limp mode should be reverse and 2nd gear only. I have nothing at all, which is why Iím lead to believe this is not an electrical problem. If the transmission module were to be unplugged with the engine running, i should still have 2nd and reverse, for emergency operation with electrical failure.

Yes the module is dry of fluid as well as wiring harness.

I donít have the code written down on me right now but basically says the speed comparison of n3 speed sensor is not plausible compared to n2. This is set because i have no fluid pressure.
12-13-2017 05:48 PM
MAVA Funny as this may sound, but do you have the shifter bushing, and the bushing at the transmission arm?

Did you forget to install the six torque(TC) converter bolts. The oil pump is a mechanical device, and all it takes is for the TC to be bolted to the flywheel. The oil pump gear has a direction, but do not know if the gear is backwards. I need to look at the fluid flow diagram in park.

You did not replace any frictions?

When you opened the clutch packs did you get larger spring clips to bring the gap to specifications?

How many miles on the old tranny?

You checked fluid running in park?

Now you are in limp.. Have you checked the Transmission Computer(TCM) for fluid?

Checked your codes at the 38 pin connector...

Martin
12-13-2017 05:25 PM
79Mercy
722.6 Transmission Whine, will not move, no fluid pressure at cooler

Hey guys really need some advice if anyone has any to lend. The car in discussion is a 2000 E430, vehicle was purchased with what we were told was a failed transmission. Vehicle would drive normally for approximately 5 min, loud whine noise would appear and transmission would fall out of gear. Checked fluid level, found fluid level actually a bit high, now knowing itís because the pump is not functioning

Some of the first checks were for oil in the harness, none found and control unit is dry.

No major metal particles were found in the pan and no abnormal amount of clutch material found.

Known good valve body installed with good conductor plate and good solenoids, problem still present. Same exact problem.

Removed transmission from vehicle and dismantled transmission. Inspected everything and checked clearances as per wis documents, nothing abnormal found. Front pump was found to be fine, bushing was ok. And no discoloration from heat was found. Trans was put back together with new Teflon seals and new alum hardware as stated in wis.

After replacing the Teflon seals and re assembling trans, vehicle drove for approx 250 miles normally, then without warning symptoms appears. Same exact symptoms. Whine noise, trans lost movement.

At this point i i stalled a known good 722.6 from another v8 car, same Trans and same torque rating. Vehicle drove fine for about 5 months, then same exact symptoms occurred on the replacement transmission.

Removed the pan and found coolant contamination in the atf fluid. Replaced the radiator, drained torque converter, removed valve body and cleaned. Put all back together. Vehicle drove for about 100 miles and then all of a sudden the same symptoms occurred again.

I removed the replacement Trans and inspected, only to find nothing out of the ordinary. Everything appears to be visually ok. This time i put in a new front pump assembly, because i was out of options at this point. After installing the new pump the transmission only operated for about 10 min before the same thing happened.

I can crack the cooler hoses at radiator and find NO flow with engine running.

If anyone has delt with this and found a cure please let me know. Iím out of options at this point. I believe itís a mechanical pressure problem, as even with no control unit installed the vehicle should be stuck in 2nd gear, limp mode.

Any advice is helpful. Thank you.

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