722.3 Transmission spinning not engaging
 

Well the 603a turbo motor running perfect when all of sudden yesterday the transmission failed to engage. The engine would rev but no forward movement. I checked my fluid and discovered it was too high. I drained it to the proper level but still nothing. The fluid was the nice red color not brown and did not smell burned.
I checked my vacuum and linkage connections. All were as they should be.

I can put it in gear and without touching the gas pedal it will move forward and in reverse on its own. If I apply the gas the engine spins and it does not engage.

Luckily I was able to get it into my garage before it refused to go any further.

Any help is appreciated.
Mark

Take a look at the trans output flange, there have been a few reports of the nut working loose and flange splines stripping out. Elevate the rear wheels, parking brake off, put trans in park then try to rotate the drive shaft. You might have to use a bar to gain leverage.

Swapping the flange is easy.

To check the rear diff flange, leave trans in neutral, block the rear wheels or apply parking brake then rotate the drive shaft.

The next things to check would be trans line pressure, if the pressure regulator spring failed, line pressure would drop and not burn the fluid.

Past that, the input splines in the trans gear train may have stripped out.

Since this is an old g-wagen the tranny has a short drive shaft that goes to the transfer case. All looks good there. Through a little research this morning I am leaning toward the pressure modulator valve on the side of the transmission. Since it is slipping in all gears it makes sense that it would be the problem.
Thoughts?
M

Why was the fluid too high?

Does your G wagon share a radiator with a transmission oil cooler?

Are you sure the fluid is now correct?

Have you checked the Bowden cable / accelerator linkage?

Have you checked the gear selector rod and bushings? (Probably not this if the car moves but I like to go down the whole list!)

Have you checked the working pressure? (you need a gauge for this)

(All simple stuff - I reckon you are better off looking for the simple if you haven't done so already before you start thinking about more complicated stuff)

Perhaps I should start with a drain and renew of the tranny fluid. Draining the torque converter as well.

M

If the fluid looks red a fluid change won't help but, if the filter collapsed changing the filter will help.

Don't move the car by driving, if the trans isn't damaged, moving it will cause problems.

Here is a tech file for the 722.3 / 722.4 showing test points and other info. The test points are 10 mm x 1.0 pitch ( some brake lines use this thread for a quick EDIT > thread pitch < EDIT test )

You can use a banjo bolt or weld a hydraulic or pipe fitting to a bolt to make an adapter.

You could have a pump failure. The fluid could have drained back to the oil pan
thats way the level was too high.

pump
 

Did not realize that that was one of the characteristics of a pump failure.

Mark

It is just one thing there are other possibility's too.
Incorrect modulating pressure. Modulating pressure control
valve or pressure relief valve is dirty or sticking. Vacuum line to
transmission vacuum capsule clogged or leaking. Working pressure
control valve dirty or sticking. Low working pressure. Defective
primary pump. Pump failure I guess sometime you will hear a whining noise before total failure. Pump failure must be rare also.

Pump gear failure assuming no gears at all. Remove cooler line from radiator, start engine...if nothing comes out you know its the pump gear. Have a helper start the car while you hold a bucket under it. It will fill extremely quick so be ready to shut it down immediately.

Modulator would not cause no gear, only a lack of shifting, same with governor.

Here's a link for the front pump reseal

http://www.peachparts.com/shopforum/general-information/319957-722-315-pump-re-seal-pictures.html

But measure that working pressure first!

Great thanks thanks for the advise. To start, I will run with ps2cho's test today and go from there.

Mark

Also I see that there is a secondary pump. What is this additional pumps function and could it be suspect as well?

M

Secondary pump is required only for towing and tow-starting
vehicle. It is designed as an external gear pump and is positioned in
rear section of the transmission.
If needed, secondary pump is driven
by centrifugal governor shaft. Secondary pump operates only if engine
is not running and vehicle is rolling (tow-starting procedure), while
brake band B-2 slowly engages. Pump stops operating when vehicle comes
to a stop or if transmission has shifted into 4th or 5th gear (engine
running).

primary pump
 

Reviewing the various documents to replace the primary pump.

My understanding is I must remove the front cover #8 to access the bolts #11 that hold the pump to the front cover correct?
So when I do this I should purchase and replace the #1 and #2 seals.

Is this as deep as I need to go with the tranny on the bench?

Will I need anything else here?

Never mind I reread the excellent post by WHunter and understand the procedure.

Thanks

Could the torque converter be at fault?

Actually, instead of pulling the cooler lines first, just start the car get under and see if the torque converter is even spinning....

The torque converter is attached to the flywheel. It will be moving at the speed of the engine.

Diving in and randomly changing parts is a bad idea. You need to do a pressure test.

Agreed.

I did remove the top trans cooler line, started the engine, moved the shift selector through the gate. No fluid, not a drop came out of the cooler line hose.

Mark

X2

Pressure test if you have the technology

Ya...I was just wondering if the flywheel bent somehow and got the TC stuck or the bolts sheered off however very unlikely...just was a quick and easy look.

Pump failure confirmed. It should fire out of there like no other regardless of shift selection.

Plan the removal! :)

Removal scheduled for tomorrow morning.

Mark

OK Got the G back and sure enough the primary pump was kaput. They pulled the tranny replaced the pump, all related seals and the pressure modulator (per my request). It now runs amazingly well!

Thanks for all the help.

Mark

Glad to hear :)

when the engine is shutoff half of the torque converter drains back to the pan due to gravity, if the pump is not working or the flexplate has broken or the bolts holding the torque converter have sheared off (they are mandatory to renew every time they are disturbed) the transmission will not work as the main pump doesnt work.

You will also see a high level on the dipstick. To test follow was ps2cho said, undo a cooler line and see if you get any fluid pumping from it as soon as the engine starts.

Thank you
 

I just wanted to post a big thank you to the contributors of this forum. I had this exact problem on my 94 e 320. I ordered a new flange from the dealer and am keeping my fingers crossed that the output shaft is ok. Thanks again:) for saving me an expensive trip to the transmission shop!

I have no grasp of the transmission systems but from expereince know that when overfilled the trans loses forward traction and will work in reverse. (95 E320) and lowering the fluid does not correct the overfill. It will still keep slipping..One must drain the fluid and then add back to the full level slowly with it running and parked. Then you are good again.. Very curious why if anyone cares to explain..