1991 190E 2.6 Auto Trans Governor Gear

[mikedl]

1991 190E 2.6 Auto Trans Governor Gear

Transmission failed at 190K miles; no governor pressure; diagnosis: governor drive gear cracked; no other problems noted on tear-down of transmission; pumps inspected and no anomalies noted.

Governor drive gear replaced along with worn rear transmission mount, seals, filter, and oil.

Transmission operated correctly for approximately 200 miles, then failed again. Tranmission will operate in reverse and first gear; will not shift; no governor pressure.

Note: both failures occured on days with ambient air temperatures over 95 degrees F. Car had been operated at moderate speeds for about 10 minutes, then stopped with engine off for five minutes, then restarted when failure noted.

Any ideas or similar experiences??????

Thanks.

[C32AMG]

There are two know causes for a broken plastic governor gear in the 722.4 transmissions, a broken governor check valve in the VB and or a sized secondary oil pump. Did you find and fix the cause of failure in your transmission. Did you clean the governor filters in the secondary valve body? Are you using a pressure gauge that can read low pressures. Did the gear fail again?




A stuck “ON” kick down switch will cause the Trans to shift at red line, giving you the feeling of a no shift. I would disconnect the kick down switch / under the gas pedal first.

If that doesn’t work and if the governor gear is good, the problem is in the valve body, a stuck governor pressure valve or boost valve.

[mbdoc]

The Secondary pump will lock-up & cause that problem. JUST remove that pump & leave the 2 gears out of that pump! IT is there only for TOW starting.

[mikedl]

On transmission disassembly and inspection, the spring from the secondary pump check valve had migrated to the governor.


Before replacing this valve and doing the whole thing over again, I am thinking of following M.B. Doc's advice and disabling the secondary pump. Even in the wilds of New Hampshire, there is little call for tow/push starting.

Anybody think of a downside to this?