Double check that the radiator transmission cooler does not have a leak. Detach cooler lines, plug one side of cooler, pressurize with a few tens of psi shop air. Check for bubbling coolant. Or go the other way, remove cooler lines, pressurize cooling system with a cooling system test pump, look for coolant weeping out the transmission fitting at the radiator.

This is one of the worst ways for a transmission to go, getting soaked in hot glycol.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

On the subject of WOT I have the problem that under moderate to heavy braking the engine goes to MAX revs instantly. Hitting the kill button brings it back down to normal operation. I have a cable throttle arrangement and have tried heavier throttle return springs to no benefit. It strikes me that the governor/rack is advancing due to inertial force. Is that a correct assumption, or not, and is there a fix please?

Turbo 606 engine with non-turbo 606 IP + 6mm elements. Not "another" diesel 107!!

Thanks.

It was extremely frothy and light colored. One of my guys used to own several Lee Myles and Meineke shops, and he was convinced beyond any doubt the moment he saw it come out.

The previous guy (who did all the questionable or bad stuff) had left the tranny out in a semi-covered shed area for a couple of months while he worked on other stuff. I'm guessing it got condensation built up during that time outdoors (this is the Seattle area, after all). That is the only time the tranny has ever spent outdoors without being fully installed/sealed up.

The tranny worked fine prior to pulling the old motor and the tranny.

I have a rebuilt 722.618 on the way from Sun Valley Transmissions, along with a PCS TCU and remote TPS kit from whipplem104 (conveniently he is only about 20 or so miles down the road). Still need to get a 722.6 shifter (and pigtail). Had figured I would upgrade to the 722.6 if any of my current trannies failed at some point. Just wasn't planning on going for it from the get go on the project car. There goes some more savings into the project, but hopefully for the better in the long run. :/

__________________
1976 240D [W115.117/616.916] (acq 11Jun76)
1990 MB 300D 2.5 Turbo [W124.128/602.962] (acq 4Sep15)
1991 SL250D (ex-300SL-24) [R129.061/OM602.962/722.6, was M104.981] (acq 25May12, converted to diesel)
1993 Jeep Cherokee [XJ] (acq 12Apr14)
2008 E320 CDI [W211.022/642.920] (acq 27Jan24)

-- Deceased...
1993 300D 2.5 Turbo [W124.128/602.962] (totaled by Dominos driver 28Mar12)
2007 E320 CDI [W211.022/642.920] (totaled 18Dec23)

Your theory doesn't sound possible to me. I've got both an '87 wagon with OM603 turbo and a '95 sedan with OM606 non-turbo, and under full braking (as in ABS engages to prevent wheel lock-up) there is no hint of the engine speed increasing.

Either your modified injection pump has some problem (talk with the shop that modified it) or perhaps your throttle cable arrangement has some defect that increases throttle due to engine movement under braking. Could you share pictures of the throttle cable arrangement?

I haven't read your entire thread - did you include the third engine mount (really a transmission mount) at the tail end of the transmission?

__________________
Respectfully,
/s/
M. Dillon
'87 124.193 (300TD) "White Whale", ~392k miles, 3.5l IP fitted
'95 124.131 (E300) "Sapphire", 380k miles
'73 Balboa 20 "Sanctification"
Charleston SC

You are not going to get that much condensation in the trans from it sitting. And besides, you could fill the trans with water and it would still "work" for a period of time.

With zero cooler flow, you have zero pump pressure, oil water mix won't cause this type of failure.

The tranny also only had saran wrap lightly stuffed (by me) into openings, since it hadn't been intended to be outside, only to keep crap out. This is just north of Seattle, so rained a lot directly onto it, too. Was not better covered or protected when put outside than when I had just put the saran wrap in for indoor storage.

Also, the pump was attached to the motor when it had the WOT runaway issues, so presumably churned the froth through the system at 5000++++ rpm under no load. After the runaway, there was strawberry froth dripping out of the tranny cooler hose at the radiator (I have clamped hoses instead of the recently-soared-in-price crimped ones). We definitely have zero pump pressure, but with the strawberry milkshake, we didn't bother opening it up. Just pushed it out into the parking lot.

__________________
1976 240D [W115.117/616.916] (acq 11Jun76)
1990 MB 300D 2.5 Turbo [W124.128/602.962] (acq 4Sep15)
1991 SL250D (ex-300SL-24) [R129.061/OM602.962/722.6, was M104.981] (acq 25May12, converted to diesel)
1993 Jeep Cherokee [XJ] (acq 12Apr14)
2008 E320 CDI [W211.022/642.920] (acq 27Jan24)

-- Deceased...
1993 300D 2.5 Turbo [W124.128/602.962] (totaled by Dominos driver 28Mar12)
2007 E320 CDI [W211.022/642.920] (totaled 18Dec23)

Got the rebuilt 722.618 delivered today from Sun Valley. Also went down to Bellevue to whipplem104's shop and picked up the TCU, harness, and speed sensor, plus went through a bunch of how to use the tuning software. Russell was extremely helpful.

Remote TPS sensor should arrive in a few more days. (It will be hooked up to the Bowdoin cable and linkage that controlled the 722.500 tranny. Simple and clean solution, rather than trying to mess with the pedal movement and such.)

Now I just need to find the time at my shop to swap the trannies. First I need to put the rebuilt turbo from the project car onto my daily driver (1990 300D) so I can send *its* rebuilt turbo back to be fixed under warranty (pretty sure the turbo bearing is spewing oil - it is dripping out all over the place).

The other thing keeping me from doing it is that we have gotten a slew of engine replacement and Subaru headgasket jobs lately which will fill up our longer-term bays (we try to keep at least the 4-post and one 2-post lift available for one-day-or-less turnaround jobs to keep people coming and happy). Not a bad problem to have for my shop! But frustrating from the personal perspective of getting the new tranny in and fitted, build the new crossmember support, get the driveshaft lengthened, and start tuning the tranny enough to drive it down the block to my exhaust guy's house so he can bend pipe to fit a new exhaust to it.

I do still need to get the shifter, and ideally build a better RPM sensor to send 3 pulses per revolution to the TCU and tach, rather than the 122 per revolution from the om602 ring gear sensor. Am probably just going to do something with the harmonic balancer pulley or similar to get the three pulses, since it just has to be close to accurate, not precise enough for ignition timing and such.

__________________
1976 240D [W115.117/616.916] (acq 11Jun76)
1990 MB 300D 2.5 Turbo [W124.128/602.962] (acq 4Sep15)
1991 SL250D (ex-300SL-24) [R129.061/OM602.962/722.6, was M104.981] (acq 25May12, converted to diesel)
1993 Jeep Cherokee [XJ] (acq 12Apr14)
2008 E320 CDI [W211.022/642.920] (acq 27Jan24)

-- Deceased...
1993 300D 2.5 Turbo [W124.128/602.962] (totaled by Dominos driver 28Mar12)
2007 E320 CDI [W211.022/642.920] (totaled 18Dec23)

The R129 came with a 722.6 from ~ 96 + , also look at 97 + W202 ( C class ) Get the shift rod also.


The R129 came with a 722.6, get the factory cross member, you will be much farther ahead, it might bolt right to your car. You will also need the rubber mount and aluminum bracket that bolts to the trans. ( I think the al bracket and rubber are the same on all regardless of body )

Making the drive shaft longer is difficult, the ends are friction welded rather than arc welded. They don't have a ledge like a conventional USA style drive shaft. You could get something off the shelf, look for a R129 / 722.6 that uses the same differential as yours.



If the TCU will accept 122 PPR, use that, no need to change. If you want the tack to work, a pulse converter could be used. ( Though I don't know what type of signal yours is expecting. )

Gas tach = 3 pulses/rev from the spark
Diesel = 144 pulses/rev (not 122) from the ring gear teeth passing a magnetic pickup

That is a 48:1 difference. Need a fast TTL or CMOS divider circuit since 5000 rev/min * 144 pulses/rev * 1 min/60 s = 12000 pulses/s or 12 kHz.

Also you have to verify the signal voltage levels are the same between the gas and diesel system and account for that in the circuit design.

Or just find a diesel tach mechanism and swap it into the cluster.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Most Mercedes from around 97-03 used the 722.6, from C to ML, I think. The TCU can use both the D4321 and the tip-tronic shifters. The shift rod will have to be modified, regardless, given how far forward the tranny will be. Although perhaps the modification we already made for where the 722.500 ended up will work. Anyway, the shifter rod is a minor, easily dealt with issue.


I am sure there will be a cross member that fits the r129 for the 722.6. However, it likely won't fit where the tranny goes now, as the om602 is further forward in the engine bay. That's why the driveline has that crappy spacer setup right now. The 722.618 is much shorter than the 722.500 which means the tail of the 722.6 will be even further forward than the 722.5 already is (haven't gotten the car back on a lift to measure just how much yet, although will have it up tomorrow to pull the turbo to use as a loaner on my w124 while its turbo goes in for warranty repair).


Maybe a manual transmission shaft might fit (since I assume the manual trannies are shorter than the auto)?

However, what I currently have is the shaft from the w124.128 donor, and the shaft from the r129.061. The w124 shaft is far too long (even accounting for the 722.6 being shorter than the 722.5), and the r129 shaft is far too short.

Not sure how to find out lengths of alternate 6-bolt drive shafts? Does the EPC give that data?

Rear diff is the 3.07 ratio 6-bolt one. I believe only the early m104 r129s used that, to compensate for the lack of low end torque. (The diff allegedly is interchangeable with the more common 2.65 versions most [all?] other r129s had. Might want LSD later on.)

The TCU will function with the 144 rate (thanks, jay_bob, I thought the 122 didn't quite sound right, but hadn't gone back and counted). However, it will get "blurry" as it approaches 4000rpm and the TCU has to be configured to just guess on shifts at that point. Plus, it would be nice (although certainly not necessary) to have a working tach.

Can I just take the sensor from the m104 and use it? (With a three-pulse source, of course, like maybe the crank pulley.) That should output the signal both the TCU and tach are expecting, while keeping the om602 ring gear one for its ECU.

The instrument cluster in my r129 is the updated digital cluster (previous owner spent the $1000 to get it from the dealership, matched to VIN and mileage, when the old one went bad in the typical manner). I don't think I can swap out the tach on that cluster? (Haven't seriously looked into it as yet.) Seems like getting a 3-pulse signal going would be simpler/easier and kill both birds with one stone...

__________________
1976 240D [W115.117/616.916] (acq 11Jun76)
1990 MB 300D 2.5 Turbo [W124.128/602.962] (acq 4Sep15)
1991 SL250D (ex-300SL-24) [R129.061/OM602.962/722.6, was M104.981] (acq 25May12, converted to diesel)
1993 Jeep Cherokee [XJ] (acq 12Apr14)
2008 E320 CDI [W211.022/642.920] (acq 27Jan24)

-- Deceased...
1993 300D 2.5 Turbo [W124.128/602.962] (totaled by Dominos driver 28Mar12)
2007 E320 CDI [W211.022/642.920] (totaled 18Dec23)

If you keep the trans in current F / R location, all you would have to do is cut ears off the 722.6 / R129 c member and move them rather than making something from scratch. From what I recall, the body has a few sets of holes to accommodate the manual / 4 and 5 sp auto so something is bound to be close.


Why is the engine forward, can you push it back and do you know by how much? Was it the thickness of the spacer?

You really need to reference where the stock 722.6 R129 trans sits and compare to your car. I for see lots of extra work trying to make your current stuff fit for no gain.

If you are stuck with the current F / R position, you might be able to split the spacer difference between the front / rear discs, stretch out the spline , move the center bearing mount and maintain some pilot engagement. ( RE if you move everything a bit it might fit )



Go here W124 Performance and look up the differential chart, it shows what diff is in some R129, this way you will be closer to getting something off the shelf.


Manual R129 is too difficult to find.

EPC won't give dimensional data.

Check the W124 site above and ID your diff.

It won't get " blurry " if the TCU was built with any sort of real parts. Gas motors deal with this high pulse rate to 7,000 R +. Don't make extra work for no gain.

Everything is on one board on these cars ( at least 97 is ) I'd use a pulse converter to give the tach what it is expecting to see. Also, the HVAC might be looking for a tach signal, some AC compressors have a speed sensor to detect belt / clutch slippage.

The engine is forward because that is where the mount arms put it, plus having its weight over the front axle at least somewhat, being the shorter engine than the m104.


Really, the driveshaft is the only big deal, and only because I have to find somewhere that can modify/replace it to be the right length.

The shifter can be wherever, really (planning to have it offset towards the driver, so can put cup holders on the passenger side, like many modern cars).

The shift rod was already easily extended, may even still work with the 722.618, since the bellhousing will be in a similar location (just the tail end will be significantly different than the 722.500).

Easy enough to build a rear crossmember for the tranny mount.

That actually sounds like a lot more work and modifications than I was already planning...?

1991 r129.061 is not listed. But it should be the 3.07 ratio (I think I visually confirmed that on the housing a long time ago, but haven't looked recently). Besides, more important to get it all up an running first. LSD/ASR/whatever would be down the line. Trying not to get ahead of myself, or I'll never actually get to drive the thing.

No doubt. Just was throwing that idea out there in case anyone knew something about it that might be applicable.


That's a shame. But then, why would they need it? :/

Whipplem104's theory is that it is that the sensor itself does not have a high enough resolution to give proper readings at that high revs. Not a TCU issue. (Also, 144 x 4000rpm = 576,000 pulses, whereas 3 x 4000rpm = 12,000 pulses, so the gas motors don't have to have anywhere near the resolution.)

A converter or something to provide 3 pulses/rev on the crank pulley is definitely where I was leaning. The instrument cluster is pretty much a 2001MY one, so not separate components like the old w124 ones.

The compressor is the w124/om602 one, so it doesn't seem to require any tach input. It has its own engine overload sensors that trigger it to turn off.

__________________
1976 240D [W115.117/616.916] (acq 11Jun76)
1990 MB 300D 2.5 Turbo [W124.128/602.962] (acq 4Sep15)
1991 SL250D (ex-300SL-24) [R129.061/OM602.962/722.6, was M104.981] (acq 25May12, converted to diesel)
1993 Jeep Cherokee [XJ] (acq 12Apr14)
2008 E320 CDI [W211.022/642.920] (acq 27Jan24)

-- Deceased...
1993 300D 2.5 Turbo [W124.128/602.962] (totaled by Dominos driver 28Mar12)
2007 E320 CDI [W211.022/642.920] (totaled 18Dec23)

I know it isn't relevant in this context, but FYI engaging ABS is not considered "full braking". ABS lengthens your stopping distance. It gives you steering control in exchange for reduced braking. I.e. not the best way to stop the car in shortest possible straight line.

__________________
1998 E300 turbodiesel

America's Rights and Freedoms Are Not The Enemy!

I thought your engine was based on the M103 / M104. Was your car a 6 cyl originally? The R129 6 cyl arms may be a better bet. The M104 had 2 sets of block drillings for arms depending on what chassis it was installed in, not sure if your engine has the same.

A thought if the above won't work, it might be possible to use 94 - 00 C class W202 inline 4 or inline 6 arms. I'm pretty sure they are shorter, this would allow for a plate to be bolted to the block then mount positioned where needed.

Finding a shop is the big deal. This driveshaft has friction welded on ends not a pilot / arc weld like many other driveshafts. This means the shop will need to make internal sleeves to shorten or extend the drive shaft. Others have tried this and many shops won't touch them. If a shop is willing to so this, send a donor portion of a shaft so they are able to do this in one weld.

The real goal would be to find an off the shelf drive shaft that has the proper end to end length regardless of where the center bearing ends up as the location on the car can be changed.

Lots of extra work.

Yes, by modifying a stock one. You might even be able to use a non R129 cross member as a core. At minimum you will need the aluminum bracket between trans and rubber mount.

If you can't find a shop to stretch the drive shaft, that might be your only alternative. You are splitting the difference between 3 places not just one.

A quick check on car-part.com shows the 90 - 91 300E 4 matic to have the same rear diff, this might lead to the exact type of diff you have.

ASR won't be functioning since the throttle input is missing. I'm guessing it will fault out and not let the ABS side slow a spinning wheel. ( ASR first pulls throttle back then ABS applies braking to the spinning wheel )


Do you have any pics of the flywheel and sensor / counted the teeth? The old diesels read from the flywheel / flex plate ring gear teeth ( the 122 / 144 mentioned ) . Gas engines first read from a 3 tab on the flywheel / flex plate and later from a multi slotted ( 60 some? ) ring on the FW / flex.



I was under the impression that early R129 had 2 round multi pin instrument cluster connectors. I know for sure 97 + had 2 rectangular ones. I'd doubt your car has the later dash unless there was some sort of conversion harness. Does it have chrome rings around the gauges? ( 99 ish + cars got these )

The compressor won't require this input, the HVAC control panel might. The system knows that the clutch is slipping by comparing engine RPM to compressor RPM so you will need both. If someone has a wiring diagram / trouble code list please have a look.

The 602 has some similarity to the m104 family, but it only has one place where mounts can be attached. The 603 in the '87 I had could attach the arms in two places on each side, not just one. Comparing against the m104 still sitting in my garage, the arms *may* be able to be attached, but don't come close to working. The 602/w124 arms actually came really close to fitting, using the 602/w124 arms and the m104/r129 hamburger mounts. One side would fit and the other was about 1/4 inch off. Not certain this put it on a proper centerline, since I wasn't able to get it to drop into place. Then I handed it over to the supposedly skilled custom car shop, which did the highly questionable modifications (which I will likely be tearing out as I have the chance).

I will definitely check into the shorter arms from the w202 series. Thanks for that tip.


Here is a pic of the om602 on an engine stand, you can see the existing 602 left arm with r129 hamburger mount facing you (with m104, 722.500, and 722.418 in back). Click for larger image.



It would be great if I could find an existing front prop shaft segment which could just be balanced and installed. Maybe a C-class? The w124 shaft is far too long (even if I moved the motor even further forward), and the r129 shaft is far too short (by about 2 inches with the 722.500, presumably by much more with the 722.618).

The rear segment, as I recall (I haven't measured recently) is the same length as the donor w124. It is the front portion which is super short, like 2/3 the length.

The two front prop shafts side by side:


w124/om602 front prop shaft on left (with diesel vibration damper), r129/m104 on right:



Such as? I was figuring on modifying the hole location in the tunnel (nothing in the way) and either rigging the shift link slightly diagonally (it doesn't require much force) or else have it move a parallel linkage. Doesn't seem very complex. What am I missing? Yes, the center console panel will have to be modified, but I was expecting to need a custom one regardless, due to all the overall plans (and that I am not particularly fond of the r129 center console/armrest design).

Currently figuring on finding a 722.6 compatible crossmember and then adding rails along the tunnel to substitute for the current mounting bolt holes, so I can just place it wherever it needs to go. Just insert a metal plate to shim the mount itself if need be. Should still sit high enough to not alter ground clearance.


I recall reading some post quite a while back that said getting a diff with LSD would still give a significant benefit, even though the electronic locking trigger wouldn't be active (although also could always rig up a button, I expect).

EPC lists it as 1:3.69


Not as yet, but I will try to get some shots when we remove the dead 722.500 tranny. (Probably won't be until mid-September, now, though, since the shop got busy during the past several weeks, so couldn't tie up a rack. Good for business/money, bad for getting anything done on the project car. And now I will be out of town for the next four weeks.)

If I am going to modify something, I would rather finagle things on something accessible from outside, rather than something semi-internal (i.e. hard to get at to adjust). Finding some sort of front crank pulley method still seems simplest and least likely to cause other problems. Plus, I think there are various existing kits for other cars which attempt to use such a system for ignition timing (fortunately, I don't need ignition-timing precision, just "close enough" for rpm use).


I did not realize the later ones changed that much. Mine does have the two round plugs (identical to the single ones in the w124). It is, however, an electronic dash, installed by the dealership around 2010-2011. I guess they had new-style clusters for the older models, perhaps due to the common problem with the old analog clusters?


Ah, hadn't thought about that yet. AC was a distant "final step" in getting it all running. From the diagrams I have, it looks like the pusbutton unit (N22) does have an rpm input (A9L1) from the engine control unit (N16). Given that the N16 is removed, hopefully a regular m104-equivalent (3/rev) rpm reading will work for it, once I have such a thing...

Thanks for all the advice!

__________________
1976 240D [W115.117/616.916] (acq 11Jun76)
1990 MB 300D 2.5 Turbo [W124.128/602.962] (acq 4Sep15)
1991 SL250D (ex-300SL-24) [R129.061/OM602.962/722.6, was M104.981] (acq 25May12, converted to diesel)
1993 Jeep Cherokee [XJ] (acq 12Apr14)
2008 E320 CDI [W211.022/642.920] (acq 27Jan24)

-- Deceased...
1993 300D 2.5 Turbo [W124.128/602.962] (totaled by Dominos driver 28Mar12)
2007 E320 CDI [W211.022/642.920] (totaled 18Dec23)