ZF4HP22 ERRATIC OR NO UPSHIFTS

COMPLAINT: Harsh shifts into "D" and "R" and chattering of driveshaft when taking shift lever out of "D" or "R".Find car diagnostic tool for more?

CAUSE:
a. Coolant in transmission fluid.
b. Friction coefficient of friction disc LB3 and/or brake band B2 too high.
a. (See note) If coolant is detected in the transmission fluid, replace radiator and all friction linings in the automatic transmission.
b. For vehicles with transmission 722.4 already equipped with a brass radiator, or if no coolant can be detected in the transmission, install nitrated outer steel plates LB3 to resolve the complaint.

CORRECTION:
A leak in the transmission fluid cooler allows coolant to enter the automatic transmission.
This will change the friction coefficient of the friction linings in the transmission.

Therefore, the cooler was changed from aluminum to brass in the period between 2/86 and 6/86. These radiators are marked with a yellow paint dot next to the Behr name plate on top of the radiator. In addition, these radiators can be recognized by the brass-colored threaded connections for the transmission fluid hoses. These brass coolers are in order. The following tests to determine if coolant entered the transmission have to be performed only on vehicles with aluminum coolers.

Coolant in the transmission can be recognized by the following signs:
a. Transmission fluid has milky discoloration,
b. Transmission fluid foams heavily when drained,
c. The gasket on the large intermediate plate shows severe swelling or a green slimy coating (upper right arrow in Figure 1).
d. The intermediate plate shows signs of corrosion under the gasket (lower left arrow in Figure 1).
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