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+--- Thread: 722.4 and OM606 (/showthread.php?tid=7134)
722.4 and OM606 - kashi123 - 04-03-2016
Hi guys,
I have a fresh 722.4 behind my OM606 with dieselmeken pump set at 90cc.
I know this is not a good idea but the 722.3 I had earmarked for this project turned out to be dead and until I Have saved up enough to rebuild/strengthen it, I am stuck with the 722.4 which I got off a friend for very little money.
It performed very well without any vacuum supplied to it, quite hard shifts at partial throttle but nice smooth shifts at half and full throttle with no flaring. So I got carried away and invested in an external trannycooler and new filter and oil.
Also hooked up the vacuum control valve and adjusted it so that there is a nice linear decrease of vacuum as throttle increases, couldn't get it quite down to zero at full throttle but pretty close.
So feeling pretty pleased with myself I took in for a drive, beautifull silk like shifting at partial throttle but alas a lot a flaring in all gears when the OM 606 gets going.
So the question is: will it hurt the tranny to shift without vacuum all the time with quite hard shifts or should I put up with the flaring which can't be good!
This tranny doesn't have the T handle to crank up the pressure, just 2 settings which I don't really understand so left well alone.
This is all fitted to a 2.5 metric ton G Wagen so quite heavy!
So really the options are:
1. Remove vacuum and live with the hard shifts, will this break it?
2. Keep vacuum and wait for it to die, but shifting nicely
3. Somehow supply less vacuum?
4. Wait for the certain death of this tranny and rebuild the 722.3
Any and all ideas are very welcome
Thank you
Richard
RE: 722.4 and OM606 - kashi123 - 04-03-2016
This was bugging me so after some energetic googling I Went out and measured the quantity of vacuum supplied to the VCV. It was 30 inch plus, from what I Have read this should be around 10...
So I hooked up a spare VCV between vacuum supply and the VCV on the pump and set it to supply a steady 10 inch to the pump VCV.
Too late for a testdrive but first thing tomorrow!
RE: 722.4 and OM606 - kashi123 - 04-04-2016
Well, that made noooooo difference whatsoever. Still lots of flaring, I Turned down the turbo boost to 12 psi which by the way make a huge difference if performance from 17psi, but it still flared.
Disconnected vacuum and at all but the lightest throttle it is acceptable- ish. Full Throttle it shifts nicely.
BUT, tried it in low range and then it really clunks.
Sooooo:
1. Leave as is and live with the clunks?
2. Hook up vacuum only in low range?
3. Decrease vacuum supply even further?
Thanks
Richard
RE: 722.4 and OM606 - Tito - 04-04-2016
I would disconnect the vacuum. I drove a 722.3 like this. Shifts where hard though. Shift flares just kill transmissions quite fast. You get a lot of energy loss which heat up the friction material and burn them. if you're a math guy, run some calculations and you'll see its gone soon! And indeed there is extra heat buildup when shifting hard but this is for a shorter period.
So I would try to get along with a clunky harsh gearbox.
RE: 722.4 and OM606 - kashi123 - 04-05-2016
Thanks! I will try that
RE: 722.4 and OM606 - Petar - 04-06-2016
Do you have the restrictor before the VCV ??
If I were you i'd try hooking up a swichover valve to vent the vacuum at more than 1/2 throttle or so.
RE: 722.4 and OM606 - kashi123 - 04-06-2016
Hi,
Yes i have a second vcv before the pump vcv lowering vacuum from 30 inches to ten.
But i can't get 0 vacuum at full throttle, only a 5 inch drop. (At the tranny side)
Also I am think I am not getting full throttle as has been described before on this forum.
So I think I will take off the vcv at the pump and if the gearchanges get to much on my nerves rig up another stand alone vacuum system.
Just been out in at and as long as I drive sportily it is ok.
In low range it is however terrible, we'll see how it goes.
I hope the tranny holds up but I am not counting on it...big offroad trip in two weeks time so baptism by fire!
Thanks for the advice, much appreciated
RE: 722.4 and OM606 - Eric78 - 04-08-2016
Is a 722.4 behind a 606 in any state of tune wise? t\They are notoriously the most fragile of Merc automatics.
RE: 722.4 and OM606 - kashi123 - 04-08-2016
Yes, lightly tuned, 90cc 7,5 mm dieselmekenpump.
Oh you meant the 722.4, apart from fresh oil/filter and an extra oilcooler, in a word: no.
Will run it without vacuum and see how long it lasts...
RE: 722.4 and OM606 - kashi123 - 04-25-2016
So, just back from a weekend hard offroading and the 722.4 is still intact!
In then end i fitted a VCV and the vacuum amplifier thing ( flying blue saucer) and set the vacuum so that it doesn't flare at all and the changes don't bang and it worked!!
Let's see how long it holds up.....
RE: 722.4 and OM606 - klogz123 - 01-08-2018
hi kashi123 how long did the 722.4 last with the om606 the reason I ask is I have a w124 with a om606 and the 722.4 with low miles and basically would like some pointers please