722.6 TC lock-up disable!!

[Alex Crow]

Had an old CLK240 in the other day, with TC lockup issues.
This car had a Behr rad, with no reason to suspect glycol problems.
On roadtest it seems to be a valve body fault (you get a good idea, having driven so many with the TC problems).
Quoted for a new valve body, fluid/filter change etc, but customer hard up, and car not worth all that much.
So we turned off the TC to show the customer how we know what is playing up, and customer thinks it is perfect, happy with the drive of the car.

Thus we elected to go for a TC lock-up delete, as is popular on some Sprinters with the 722.6
Car now drives very well, with no fault codes and no gearchange issues. Obviously, we do see the revs climb a little more with throttle openings, and supposedly fuel consumption is affected slightly, but customer very happy.

Anyone else tried it?

 

[alexanderfoti]

Certainly an interesting way of resolving the issue per se.

The only downside I can see is that the tc will get hotter during hard driving as it's slipping more.

Why do the sprinters get this treatment more frequently? Do they fail more often?

Sent from a mobile device

 

[Alex Crow]

Certainly an interesting way of resolving the issue per se.

The only downside I can see is that the tc will get hotter during hard driving as it's slipping more.

Why do the sprinters get this treatment more frequently? Do they fail more often?

Sent from a mobile device

True enough about the heat thing, but this old fella is not going to be driving this old car very hard.
I have heard of this being done, with no ill effects, and was looking for the direct experience of others here - anyone?

Apparently, some models of Sprinter with the 722.6 are particularly prone to TC lock-up control issues, but vans are not my bag.

The disable mod used was very simple, and my fears of TC slip giving us fault codes were unfounded.

 

[WG M-B]

This can be done with a pop rivet

 

[WG M-B]

And the fuel consumption issues should only really become apparent pulling at top end in lock up.

 

[Alex Crow]

This can be done with a pop rivet

Please do elaborate!
I just drilled a 1.5mm hole, having first considered just blocking the solenoid valve.

Incidentally, with the TC lock up 'closed', there is reduced flow through the cooler - so the box might even run cooler with it open.
And I don't see any Sprinters going easy...

EDIT: Do you use the pop rivet to stop the TC lock-up control pressure plunger moving, maybe in an exhaust slot on the valve body?

 

[WG M-B]

Ground down pop rivet in the end of the tc lock up solenoid does the trick

 

[WG M-B]

This disables tc lock up and gives no fault codes etc
You think too hard !!!!!!!!!!!

 

[Alex Crow]

This disables tc lock up and gives no fault codes etc
You think too hard !!!!!!!!!!!

That was my first plan though!
I was going to tap to M2, screw in a bolt and saw off (pop rivet indeed!).
Either way they work the same, by robbing the TC lock-up control valve plunger from moving.

 

[WG M-B]

Yep and it works a treat

 

[Alex Crow]

Thanks for that.

Anyone else know anything?
Or links to web pages etc?

 

[Frontstep]

Not quite but interesting read http://dieselrepairblog.wordpress.com/2012/03/23/sprinter-transmission-rsn-repair/

 

[stumo]

The mod for the sprinter just involves enlarging the tc outlet port, so it never achieves full lock. Its a popular mod in the US since they only got the auto sprinter option.

The symptoms it cures are what's been called rumble strip noise (RSN). It only happens in lower gears on light throttle. It sounds and feels exactly like you are driving on a rumble strip on the edge of the motorway. The downside is higher revs and possibly heat on the motorway.

So its only really an issue for some types of usage. Like say an airport carpark shuttle van where its on light throttle and low gears all the time. I've experienced it in my sprinter (and rsn is an accurate description) but its never for long as i don't drive it on light throttle in low gears much at all lol.

I think its an issue on the sprinter because it locks up in all low gears. Interestingly its only the T1N sprinter affected. MB changed something in the later NCV3 sprinter from '06 so the same 722.6 in that model doesn't exhibit the rsn problem at all.

I'd be looking into one of those boxes to what the official solution is.

 

[Alex Crow]

The mod for the sprinter just involves enlarging the tc outlet port, so it never achieves full lock. Its a popular mod in the US since they only got the auto sprinter option.

The symptoms it cures are what's been called rumble strip noise (RSN). It only happens in lower gears on light throttle. It sounds and feels exactly like you are driving on a rumble strip on the edge of the motorway. The downside is higher revs and possibly heat on the motorway.

So its only really an issue for some types of usage. Like say an airport carpark shuttle van where its on light throttle and low gears all the time. I've experienced it in my sprinter (and rsn is an accurate description) but its never for long as i don't drive it on light throttle in low gears much at all lol.

I think its an issue on the sprinter because it locks up in all low gears. Interestingly its only the T1N sprinter affected. MB changed something in the later NCV3 sprinter from '06 so the same 722.6 in that model doesn't exhibit the rsn problem at all.

I'd be looking into one of those boxes to what the official solution is.

The sprinter mod actually involves drilling a hole that did not exist before, rather than enlarging one, and is the method I have employed.

Interesting you say it locks up in the lower gears, this came up on the forum recently re. passenger cars, and the answer was not clear.

The RSN is the same symptom we see with glycol contamination, and very familiar/diagnostic to those working with such cars.
Perfectly described as like running along the rumble strips, and just how I describe it when quizzing a customer on the same.
With the glycol issue, this typically starts between 45 and 55 mph, gently accelerating uphill, very throttle dependant.
Garages that do not know, end up changing drive shafts and prop center bearings and supports - all to no avail, obviously.
This points to a TC clutch issue, rather than a valve body issue. With valve body (sticking plunger/piston or solenoid) you might get the RSN, but also jerky engagement of the TC, and at all speeds from standstill up.

As I said above, yes the revs will be higher, but cooler flow is increased without TC lock-up, so should cope with it. Also, as I suggested, if the Sprinters can cope with it (think vanman), I am sure the cars can too.

I believe the change with the Sprinter was purely the software.

Thanks for the link Frontstep, that was the thread I was looking for in the first place - good call.

 

[alexanderfoti]

Come to think of it, my mums car has this exact issue.

Rumble strip type noise at all speeds above 25 mph, dissapears into tyre noise at 50mph

its been doing it for a couple of years now. If it can be disabled in STAR then that might be a cheap fix for her!

 

[AdamG]

There was a guy (palletman) on benzworld who did the DARF mod to his W211 E500:

http://www.benzworld.org/forums/w211-e-class/1565243-722-6-cdi-shudder-droning-rsn-2.html

His transmission ended up slipping after the mod but the thread ended inconclusively as he undid the mod and the problem remained.

I was thinking of doing this mod but got put off by this thread. I have now gone down the route of fitting the Sonnax TC release kit. I will update if it works.

Adam

 

[Alex Crow]

There was a guy (palletman) on benzworld who did the DARF mod to his W211 E500:

http://www.benzworld.org/forums/w211-e-class/1565243-722-6-cdi-shudder-droning-rsn-2.html

His transmission ended up slipping after the mod but the thread ended inconclusively as he undid the mod and the problem remained.

I was thinking of doing this mod but got put off by this thread. I have now gone down the route of fitting the Sonnax TC release kit. I will update if it works.

Adam

Yes, I read that, apparently the TCC issues went away, along with most of the gears - he said he was getting TCC slip fault codes.

Looking forward to the feedback on the Sonnax kit, probably going to buy into that at some point, but quite expensive for a complete kit with plenty of sleeves etc.
I think most issues come from the damper valve, rather than the control valve itself.

 

[Alex Crow]

...If it can be disabled in STAR then that might be a cheap fix for her!

If you find out how, do let us know, my German is not so good (it would have to be developer mode, the only disable in standard resets with ignition cycle).

 

[AdamG]

Yes, I read that, apparently the TCC issues went away, along with most of the gears - he said he was getting TCC slip fault codes.

Looking forward to the feedback on the Sonnax kit, probably going to buy into that at some point, but quite expensive for a complete kit with plenty of sleeves etc.
I think most issues come from the damper valve, rather than the control valve itself.

Yes looking at the jig, reaming kits and sleeves it is very expensive especially for DIYers.

I have already had the valve body checked and the damper valve rebored but it did not solve my judder.

I've now had the TC fitted with Sonnax's spring kit:

http://www.sonnax.com/product-lines/torque-converter/parts/3392

Interestingly JPat now sell complete valve bodies with full electrics for I think about £500 + VAT

Adam

 

[Alex Crow]

Yes looking at the jig, reaming kits and sleeves it is very expensive especially for DIYers.

I have already had the valve body checked and the damper valve rebored but it did not solve my judder.

I've now had the TC fitted with Sonnax's spring kit:

http://www.sonnax.com/product-lines/torque-converter/parts/3392

Interestingly JPat now sell complete valve bodies with full electrics for I think about £500 + VAT

Adam

I would say it is in no way cost effective for DIYers at all, unless they own a very great deal of cars with the 722.6 and problems.

Guess you covered the valve body then - does it drag the TCC, and stall or almost stall when cold?
Fitting that particular Sonnax fit is not a DIY either! Although I could contemplate cutting and welding a TC on my lathe, it is not likely to be very well balanced after, or leak tight for that matter. I do sometimes imagine though, what we could achieve in the workshop with ingenuity, A-Team style.
Probably stop short of cabbage cannons though, seem to remember that one.

The JPAT body is only £150 or so cheaper than MB, but should be just fine, and always worth saving the money.

EDIT: here you go... http://www.youtube.com/watch?v=HrFkCVyd4sQ