722.9 Pump Failure - Transmission Digest

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Automatic Transmission

722.9 Pump Failure

A common and well-known failure with the 722.9 transmission is the way the pump bushing seizes to the converter neck (Figure 1).

Wayne Colonna
By Wayne Colonna
Published:
722.9 Pump Failure Technically Speaking Subject: Pump bushing seizes to converter neck Unit: Mercedes 722.9 Essential Reading: Rebuilder, Diagnostician Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor

Technically Speaking

  • Subject: Pump bushing seizes to converter neck
  • Unit: Mercedes 722.9
  • Essential Reading: Rebuilder, Diagnostician
  • Author: Wayne Colonna, ATSG, Transmission Digest Technical Editor

A common and well-known failure with the 722.9 transmission is the way the pump bushing seizes to the converter neck (Figure 1).

Related Articles

This can allow the pump drive gear to move off center, catching the corner of the crescent and piling up (Figure 2) and taking out the converter housing with it (figures 3 and 4).

This makes for a nice job in the shop if there is no chance of seeing it come back the same way it arrived. There has been much speculation as to the root cause of this problem. However, a new-style pump available from Mercedes has a needle bearing in the pump in place of the original pump’s bushing (Figure 5).

According to Jaggi from Jaggi Imports the problem was a bad combination of materials. The material in the pump bushing was not compatible with that of the converter neck. The part number for this new-style pump is 722 270 0197. Word has it that the redesigned pump has resolved this recurring problem.

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