First off, I would like to make it clear that I am not in the mood to listen to purisits ranting to me about how my modifications to my engine MAY have hurt my transmission. If there is proof of that in what I find after fixing the problem I will have no issues admitting it but until that point...NO LECTURES PLEASE.

The history of my transmission:

When the car was accuired at 262,000miles on the clock I dropped the transmission pan and changed the filter/complete fluid change. The fluid was red, the tranny filter was clean, it had never been opened in its life. Has shifted fine up until this point, has NEVER flared between a shift and doesn't leak a drop of fluid. Dropping it into drive or reverse results is quick (about 1second or less) engagements of gears. Reverse will light the tires up (I am not joking). Fluid smells good however with 2 days driving of flaring between gears, it has a noticeable slight smell coming about it. Nothing horrible but I can tell its been disliking this problem.

That aside, the problem:

Out of the complete blue, the tranny in my 300SD (w126) starting flaring SOMETIMES. I say sometimes becuase occasionally it will shift perfectly...tight...firm...hammer a gear (a good sign). However more often than not, out of the blue, it decided to start flaring REAL bad on the 2-3 shift. The next day (massaged it as much as I could...transportation was a must) it started to do little quirks on the 1-2 shift and the 3-4 flare started to show up...not gradual like you would expect from a clutch/band wearing out...we are talking sudden.

What I have done/found:

First thing I did was disconnect the vac from the transmission (to hopefully firm up the shifts so I could make it to school and back today). No dice. It changed NOTHING. Checked the modulator with the mity-vac...tested good. Vac system works flawlessly...always has.

I checked the level of the ATF (it read a little high...but that wouldn't cause flaring RIGHT?) and I added just a touch more. Changed nothing (was worth a try...dipsticks never give me good readings). Also checked the coolant bottel...looked good...no ATF. I adjusted the modulator 1 turn clockwise and got no change. I pulled the modulator and all associated parts looked good. As I said before it holds vac and such and has never given me problems.

Next on the list, I drained the fluid. Looked good but was getting just the slightest of smell to it. Its been unhappy these past two trips to portland and back. Dropped the pan and had a good look. No flecks in the pan, no chunks, no metal, nothing. I dropped the filter (still looked new) and threw it in the pan for later.

Inspected as much as I could see...everything looked okay. I dropped the valve body off (both the plate and the body...and the pump pickup part that connects to the filter). I put these on some clean towels on the bench.

Kept inspecting inside the tranny...everything looked okay...still no metal or flecks of anything, just a lot of red ATF.

I went over to the bench and started tearing down the valve body. Couldn't find any problems (everything moved good...no broken springs....clean). and reassembled. The gaskets were still like new.

That leaves me right here...at my computer...typing this thread out heh.

Here is what I THINK is the problem...

For whatever reason, the tranny has lost the main line pressure. Now what I need to know/find out is if there is a pressure relief spring or something that I need to be looking at and see if it is broken. This tranny is virgin (other than the filter change I did) so it has no upgraded B2 piston or K1 spring. While I am all for upgrades, now is not the time to throw money at problems unless it is part of the solution...so unless you seriously think B2 piston or K1 spring is the problem, please refrain from suggesting their replacement. I doubt the B2 failure simply becuase the transmission has no problems with getting gears or holding them. Its between that is the problem. 1-2 is probably the best shift of them all.

So my question for you guys (and gals) is, do you think my hypothesis of the main pressure being low is an accurate one? If so...how would I go about repairing this problem? I came to this conclusion only becuase of the severe randomness of the problem starting and also the way in which it acts on all gears. I searched the forums (even the DIY pages) and all I could find was simple easy to fix stuff or old dead links to manuals no longer in existance.

Would the tranny still engage in drive/reverse so quickly if the main pressure was low? My car has the 2nd gear startout however I've never been able to just barely touch the throttle and ease off in 2nd gear...it automatically pops down into 1st as you are taking off...every...single...time (atleast from a standstill).

Any thoughts/help would be appreciated. As I mentioned at the top, please no "cute" comments regarding the tranny giving up the ghost because I am putting "more power than is recommended" through it...I would apperciate the professionalism.

Thanks guys...I gotta get some sleep...organic chemisty in the morning.

If nobody has any ideas what this problem may be, I guess I'll have to do my usual thing and persue the solution myself. Anyone have an online version of the tranny manual? That last picture is for those of you who think I am a jerk after reading this post....see I still have a heart!

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The pictures are scary I guess...but its all just paths for fluid...much like electronic circuitry

I got some documentation from a forum member here and I am going to see if it has anything I need regarding problems with the trans.

I may have found the problem...


...was doing some reading and noticed they mentioned that a valve, spring, and plastic part should all come out when you remove the vac modulator on the side of the tranny...

...all I got to come out was the plastic part...didn't see/feel a spring or any valve.

I'll have to eyeball it tomorrow and see if its buried/stuck down in there. It COULD be possible that it is sticking in the full vac position and thus keeping the modulating pressure rather low and thus resulting in WAY too soft of shifts...


...but severe flaring?

put it back together and test your pressures - working, modulating and governing. IMHO, this is the place to start.

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'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Yes, double-check the modulator. Mine went through this about a year ago. When I pulled the modulator, I found that part of the plastic portion had broken off in the transmission. Fortunately, I was able to retrieve it with needle nose pliers. I spoke to the technicians at the dealer about this and they admitted that they had never encountered this. Their only suggestion was that possibly the plastic had a small fracture in it when it was installed originally. (It does appear to be a little fragile.) We inspected the new part carefully and I have not had any problems since.

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Sam

84 300SD 350K+ miles ( Blue Belle )

The modulator is all good.

I think the differences in my manual (for g-wagon) and mine just shows a spring where there isn't one in my setup. Other than that, the modulator is fine.

I pulled the valve and am going to clean it. I cleaned out the valve body real good and I guess I am going to throw it back on.

If it continues to act weird, I am going to have to hook up a gauge to the modulator pressure boss on the tranny and put a gauge in the passenger compartment.

What else would determine the modulating pressure...I checked all associated valves (found one that "might" have been sticky) but mostly looked good. Gave everything a good clean anyway (light grey stuff from mileage comin off).

Thoughts?

well i am new to this forum and thank god i finally found it. this is what i have been searching for since i got my 300sd. anyway, on to your problem, assuming you have not already solved it.

i get from your posts that your ride is modified a good deal so you have adjusted timing and fuel pump. could the throttle linkage to the pump be the culprit?

Thanks for chiming in with ideas. I already ruled out the whole vac modualator setup (the thing on the back of the IP that runs down to the tranny via vac line) by disconnecting it and finding that I still had flares.

Unfortunately the problem does not seem to be surface simple...I've narrowed it down to something internal in the tranny...and its not clutch packs or bands...becuase each and every gear shift (1-2,2-3,3-4) is flaring and previous to this random occurance, I had no flaring.

I could bust into 20 paragraphs about transmission theory/operation that i learned last night at 2am reading the manual for this thing but I am sure none of you want to hear it

Re-assembled the whole thing...still flares.

I am going to have to hook up a gauge to the ports on the tranny and see what is going on. Having a wrenching feeling that either the modulating pressure has dropped too low (perhaps broken spring somewhere besides the valve body?) or the main system pressure is low which would mean the front pump is having problems.

If anyone has ideas, please let me know. If nothing comes up, the gauges are going on friday...its going for a test spin...if I see something is out of wack, the tranny is coming out of the car.

This is not a good week for this heh...

...and no I am not taking my car to a shop I firmly believe that I (and my dad if necessary) can repair the tranny as good if not better than shops around here haha. Dad is a good transmission guy but he has never been into a benz tranny before. Little different than a t-500

You've got the right idea. "main system pressure" and "working pressure" are the same thing and just as you said, related to what the front pump puts out, but also affected by a leak beyond the pump that constantly bleeds pressure off. If you know what the pressures are supposed to be under what conditions, I'd like to know myself.

I'd encourage you to try rebuilding it yourself. You can do it without any fancy tools. You have to have a special tool to install a new seal on the B3 piston, but I'll show you how to do it with a 3 liter soda bottle if you get that far.

__________________
'82 300SD - 361K mi - "Blue"

"Good judgement comes from experience. Experience comes from bad judgement."

listen, look, .........and duck.

Update:

I checked out the modulating pressures via the ports on the tranny and also the governed pressure.

NO modulating pressure

Perfect governed pressure.

I already had pulled the valve from the tranny that sits underneath the vac pod (and its associated plastic thingy) and all looked good in there...seemed to move smoothly.

Anyone know if there is supposed to be a spring in there somewhere? I didn't see any pieces...

I am correct to presume that since the gov. pressure is good that the working pressure is okay. I have the gauges and everything if I need to check that too but engaging gears and anything other than an actual shift between gears being too soft works great...

If anyone has any ideas, let me know. I am going to keep studying the parts manual.

BTW I had the gov. pressure up to about 48-50PSI when crusing along at 60 or so...(not totally sure on the speed) from what my manuals say this seems pretty close to the right value. It regulated from there down quite smoothly so that is how I came to the possible conclusion that the working pressure is okay.

Thanks!

Long story short...

...my initial valve body cleaning/inspection must have fixed whatever was wrong. I was testing the main pressure on the tranny (quite high mind you) and whenever I touched the brake while sitting in park, it would flucutate...

I was like "this is not right" and then looked at how I had connected the vac setup in "test mode"

Apparently instead of hooking it to the vent, I acidentally hooked it to the main vac through the restrictor.

So my 2-3 flare is fixed (from the valve body work) and the rest of the flares are now gone

Atleast now I am comfortable with all the trinkets inside the 722.3 tranny

Thanks for everyones help!!! If anyone has any questions or needs manuals, just let me know.

Hi sorry I didn't start a new thread but I am having very similar flaring problems with same 722.3 ttransmission with a highly modified motor.trust me i know the consequences of running a modified engine because I just blew the transmmsion and had to buy another transmission out of a running driving car however when I put the transmission in it was flairing between gears so I made sure vacumm pressure was good then I put a k1 spring kit in still flairing so I tried adjusting the pressure of the vacumm regulater still flairing any ideas on what could cause this problem thanks.

Problem is--The Engine is now producing More Power than the transmission was designed to handle.

You Cannot expect to 'Highly Modify' the Engine--yet leave everything else in drivetrain std and expect it to work faultlessly!

For a Given throttle position Trans set up for X amount of torque, but Now You are putting X times say 2 amount of torque through it--Of Course its gonna slip--Be summit Wrong if it Didnt!

Only suggestion--Alter Vac Modulator Pressure--See if its got enough range to compensate--In the meantime--Keep yer right boot off the floor.

You may need to build up a specific trans with more clutch-plates per pack to do it properly, Say a donor from a V8 powered car.

The old saying--

Speed costs money son, How fast you wanna go....?

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http://i190.photobucket.com/albums/z...0TDnoplate.jpg

Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

722.303 is what came in my 84 & 85 SDs. I'm curious. What highly modified engine are you talking about? 617?

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85SD 240K & stopped counting painted, putting bac together. 84SD 180,000. sold to a neighbor and member here but I forget his handle. The 84 is much improved from when I had it. 85TD beginning to repair to DD status. Lots of stuff to do.