722.4 no reverse engagement

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On my 1991 300SEL (W140, 722.4 transmission) the reverse gear first went very slow (10-20 seconds) to engage. When engaged, it worked without slipping. Now (a week later) it does not engage at all.
From other postings I can read, that the problem probably related to the engagement mechanism for the B3 clutch, and that it may be fixed without removing and disassembling the transmission.
I could however not find further information on what exactly to do and where to locate the relevant parts.
Can anyone help?
If I have to disassemle the transmission, is there any hints of what to look for, and eventually a recommandation of what else to do, when it is taken apart anyway?
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http://www.transtec.com/tech_insert/94642.pdf
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Thanks Tiger, you're always there.
I always try to understand the problem before doing something, and the link supplements the ATSG manual (which I do have) quite well).
From this I understand, that the B3 piston clearance should be checked. But it does not provide information of how to adjust it. I guess it is adjusted by selecting the thickness of steel and friction plates.
From an old posting I read:
"Check the reverse (B3) band adjusting stud- it's on the lower front right corner of the case, behind the kickdown solenoid. if it is loose and has backed out, screw it back in and tighten the locknut, leaving three threads showing above the locknut. Next in order of probability is a broken B3 apply piston, on the opposite side of the case. Pretty easy to do in the car."
So, I was hoping something could be done without taken transmission apart. But I don't see how that information fits with my transmission (which in fact is 722.368 - not 722.4 as I first thought). Do you (or anyone else) happen to know about this?
Furhermore, the ATSG guide for reverse problems are: 1.Check lining plates and lip sealing rings on piston LB3. 2.Check one-way clutch.
This suggest that problem could also be en "F" clutch ("Freewheel Unit"), although I cannot figure out how this engages in 1 and R speeds.
I also read at various places, that problem could be clogged filter. I did replace filter not too long time ago.
From all this and the symptoms described, what is the experience around?
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722.4 transmission is used in 190E cars.
For W140, the only 722.3 transmission were used for diesel models and early V12 engine. All the other W140 uses 5 speed transmission... which is 722.5.
Are you positive you identified the right transmission for your car? I have tried searching your car... eurospec W140 to check if it has 4 speed auto transmission.
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If you actually does have 722.3 or 4 tranny and no reverse...
http://www.europeantransmissions.com/Bulletin/DTC.merc/97-20.pdf
You just have to replace a part on valve body.
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Hey Tiger, interesting site. Do you have any actual experience with this company or know of anyone who has used them? Just curious to find out more information on them.
Thanks!
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Yes, that must definately be tried before anything else in the next few days, when I get access to a garage. Are these parts easily avalible?
Next thing will be replacing B3 piston seals and friction plates. It seem like it can be done without too much trouble and cost. When it is open anyway, is there some other recommended things to do?
My diagnose says in any case, that the problem must be associated with B3 not engaging properly, either because of lack of supply pressure or because of leaking seals.
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The parts is available anywhere you can get your hand on tranny parts. I think you are in Denmark.
I would do the valve body before I do anything with B3. Valve body is not too bad... easily dropped with the pan off.. change required parts, renew gasket and bolt it back up.
To change B3 friction plates, you have to disassemble the tranny entirely. It is buried in the middle of the tranny. I have tried to rebuild my tranny 722.3 and It is really buried inside... that if you want to just get to that part... you might as well rebuild the whole tranny.
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Finally I got the time to investigate further. I took apart the valve body as suggested with particular attention to the valves/springs described at the fine link, you provided. Pistons/springs seem OK and move freely.
Unfortunatlely, I don't have a hydraulic diagram of it, so I can determine which parts are engaged in reverse and verify their operation.
After reassembly the transmission still works perfectly in forward, but no engagement at all in reverse.
I have thought of several options:
The cheapest one is just to concentrate on B3 and associated clutch. As you say, I might as well overhaul the entire transmission, but that would also drive up the cost (bands in particular). In both cases I may come in a situation, where it has all been taken apart and I then miss a part, which takes days to get (not a good situation, when I hire space in a workshop).
Then comes the simplest option by getting a used transmission from a scrap yard. I have found one identical tranmission, but price is much too high, leading to the most expensive but also most reliable option of getting a new by Mercedes (at an exhange price with the old transmission bringing it to a reasonable price... but still much more expensive).
I am leaning towards the last option.
Any recommendations?
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Hi Jens,
Bands don't break in transmission and alot of time, they are simply reused during the rebuild process. The seals are the most importnat thing in the rebuild process and they tell me that sometime they have to drill out the rivets in the clutchpack to replace a permanent seal. However, this is easily checked with sir gun on the clutchpack before you reassemble the entire tranny.
Don't you have any reasonable wholesale tranny rebuild shop in your country? It is not much money to rebuild the tranny costwise so some rebuild shop rather just rebuild and sell many tranny to other shops than to wait for one customer at a time. For example, I can get 722.3 tranny for $1250.
So these shop are thinking... okay it cost about $400 to rebuild, part and laborwise... so if they can make $800 per tranny and sell many fast, it is big money compared to actual tranny shop who sit a wait for those special $2000 profit to come in the door. Nowdays in USA, they are asking $2500 to rebuild 722.3 with only one year warranty.
http://www.autotransparts.com/cart.php?m=product_detail&p 9
I still think your tranny 722.3... this is easily checked by the side metal stamping right above your tranny oil pan.
Last resort is you buy a junk tranny and rebuild it yourself and then stick it in your car... but not everyone has the luxury of space and time... especially space in some countries.
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Well, at the time being, the USD exhange rate is low, so on top of price level in US for these things is already low, the European prices will appear horrible in comparison.
There is not the same tradition of rebuilding trannys in Europe as in US (most drive manual transmission). I can have the tranny rebuild, but I have not been able to find an exhange service anywhere.
Yes, I have seen the US companies selling rebuild trannys at eBay at 1.250 USD. Shipping to Denmark is not feasible though.
A rebuild job in Denmark is around 3.000 USD plus removal/ installation. Compared to have a new tranny at Mercedes at 4.000 USD (with the old in return), this option is not attractive.
A rebuild kit is around 400 USD. I am very tempted to go this way, except for the risk of missing parts during the operation and the risk that it does not cure the problem after all.
I have found one (and just one) junk tranny with exactly the same type (yes, it is for sure the original 722.368, which was normal for Europe). It has been driven 200.000 miles, and is priced at some 2.000 USD. Not attractive at all in comparison with the price of a new.
I have then found a 722.362 (for W140 600SE) in Germany also priced at 2.000. It is almost brand new (apparently installed in 2009 and has only 5.000 miles), and this sounds like a good option, if it will fit.
Do you know, if it is possible to do such exchange (maybe using some adaption parts from the old tranny)?
I have been looking for rebuild
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All 722.3xx is the same transmission. The only difference is the modulator valve may be different color and can be swapped to the correct one. The other difference is the version number... so later version number will have slightly better response. 722.368 and 722.362 is already the same... version 2 versus version 8... but the 362 is rebuilt so it is already 368 version... all rebuild will bring up to the latest version assuming the valve body is rebuilt to spec.
The gearing the same for practical matter. To adapt to different engine and body style is different rear end differential gear ratio. Do a spec search on your car and that donor car... you will see the tranmission gear ratio is all the same.
I have installed a newer 1988 190E tranny into older 1984 190E and it ran perfect. It actually drove like a 1988 190E. If you look at the tranny part number... it is also different but they are both 722.4xx tranny. The only thing I had to change is the output shaft... 1988 had a thicker bigger shaft (the thing that connects to the flex disc to the drive shaft. You probably have to do the same but super easily done. Just put a socket on it and loosen it up (that dimple lock will simply flex back and allows the nut to loosen up).
I'd go for that low mileage 600SE tranny in your case.
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Thanks a lot. I already bought it, and I am looking very much forward to receive it.
So with this and the old tranny, I can in any case adapt it to the vehicle. As you say, the modulator may be an issue, and another issue - if the differential gear ratio is different - the speedometer may give wrong readings. As well as I can read, the 300SEL has a final gear ratio of 3,46, whereas the 600SE has 2,65 - a considerable difference of 23,5%. Any suggestions to this issue other than use the old parts at the rear of the tranny?
Anyway, I am happy to have taken this decision, since the old tranny had 500k miles (engine still running perfectly well, all suspension parts and CV joints replaced etc.). I would have liked to to do the rebuild - but not the frustration of missing parts in the middle of the operation.
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You will not have any speedometer problem.
500,000 miles?!
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Yes :o)
To my knowledge at least. I know it served its first years as limousine service. Tax rules are so that they buy it without tax, and can sell it at market price after 300.000 km in 2 years or 200.000 km in 3 years. Tax in Denmark is some 180 % in total ("buy one car, pay for three"), so this is very much where they make their business. And I know from the dealer, that odometer showed 475.000 km at a service i 1999. The W220 facelift was done in 2000, and I believe that odometer was reset then. At least it showed 150.000 km when I bought it in 2005, and now it shows 225.000 km. That brings it to at least 700.000 km (438.000 miles).
Anyway, no real problems so far. Tranny problem is probably more due to age than to mileage, and engine runs smoothly (head was rebuild in 2005). Steering and suspension was a bit sluggish due to worn bushings and balls, but that has all been replaced.
At the end of the day, I have a car, I really enjoy driving (only forward though at the moment).
This is how it looks: http://www.benzworld.org/gallery/showgallery.php/cat/all/ppuser/36145
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Wow! A W220 facelift?! Fascinating.
My gosh on your tax system... that's insane.
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It leads to relatively low pre-tax prices, accessible to non-residents.
Some years ago, when car prices the UK were relatively high, there was a lively trade in personal imports from other European countries and even I brought a Merc in from Germany (in 2001).
I was quite close to doing so from Denmark, but the hassle-factor was much greater for me, so (probably) paid a little more and bought in Germany.
DAS
To reply directly replace 'nospam' with 'schmetterling' --

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Yeah, but the car manufacturers agreed to stop that lower-pre-tax- price-policy some years ago, so now we pay even more. Politicians are discussing to lower the tax, but that will give problems for people, who invested in new cars (drop in market value), so they cannot decide (how convenient).
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I am very sorry to hear that.
Many years ago we had a sudden price drop when a special car tax (about 10%) was abolished. I don't know to what extent some people suffered, but the overall effect for us was an improvement.
Now we 'just' have the standard 17.5% VAT on cars, so any price differences with our near neighbours are probably not so great. More connected with short-term swings in the EUR: GBP exchange rate.
DAS
To reply directly replace 'nospam' with 'schmetterling' --
[...]
Yeah, but the car manufacturers agreed to stop that lower-pre-tax- price-policy some years ago, so now we pay even more. Politicians are discussing to lower the tax, but that will give problems for people, who invested in new cars (drop in market value), so they cannot decide (how convenient).
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Got the new transmission. It is actually brand new (not just a rebuild) exept for the one year and 8.000 km.
But...... there is a significant difference between 722.368 and 722.362. The mounting face to the engine i way different - no adaption possible. Of course I didn't notice until I had them side by side. And the converter of the new one is much larger (makes sense since it is also for a larger engine).
I'm really in doubt what to do. I could get the overhaul parts, rebuild the old transmission and try to sell the "new" again. But still the gears and bearings of the old has 500k miles, and maybe I will not be able to sell the other.
So, I am getting closer and closer to the conclusion, that I will transfer the whole inside assembly to the old case, thereby still having a new one "inside". Unless someone strongly recommends me not to (I have already been mistaken about the feasibility).
Any suggestions?
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