Fluid Leak From The Vent Tube On 4L80E/4L85E Transmission - keywords pump repeat

This PI is being superseded to update recommendations. Please discard PIP3243.

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Transmission fluid coming out of the transmission vent hose on either the 4L80E or 4L85E transmissions. This can occur when there are no abnormally high transmission temperatures occurring and the transmission has the correct fluid level.

Note: Abnormally high transmission temperatures or overfilling of the transmission will also cause fluid to come out of the vent due to overheating of the transmission fluid. Check transmission fluid temperature, if above normal compared to a like vehicle this PI would not apply.

Pump porosity issues which may cause cross channel leaks within the pump which may exhibit themselves as fluid out of the transmission vent hose. Additionally, there can be machining flatness issues which also produce the same effect. This condition may possibly occur on a remanufactured unit and would occur at very low mileage in any case.

Replacement of the transmission pump body and cover will correct this concern. Correct any clutch or band damage that may have occurred as necessary.

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.