- Subject: Leak caused by reusing pan gasket
- Unit: 6R140W
- Vehicle Application: Ford truck
- Essential Reading: Rebuilder, Diagnostician
- Author: Pete Luban, ATSG
A late-model Ford truck with a 6R140W transmission came into the shop with a complaint of a leak from the front. When the truck was raised on the lift, it appeared that it was leaking out the front, so the transmission was pulled to reseal it.
The front pump was resealed and the transmission was reinstalled. The technician reused the pan gasket because Ford Motor Co. says the gasket is reusable.
Once the transmission was filled, it became apparent that fluid was still leaking out the front; in reality, it was leaking out the front, but not from the pump.
The so-called reusable pan gasket (Figure 1) is actually the cause of the problem.
A closer look at the bolt-hole area in Figure 2 shows that part of the rubber sealing material has eroded away and is allowing transmission fluid to leak from the pan gasket. If the gasket were allowed to leak anywhere other than from the front, it would immediately be recognized as a pan-gasket leak or perhaps be mistaken for a case-connector leak because of oil running along the pan rail.
But in this situation it was leaking from the areas of the front two pan-bolt holes. In Figure 3 you can see that the two front pan-bolt holes are drilled through into the inside of the bellhousing area.
Because the fluid level is above this area when the transmission is full, fluid was leaking from these bolt holes, creating the illusion that the transmission was leaking from the front. Since this incident occurred, I have seen this happen again. Needless to say, the technicians in these shops will never reuse one of these pan gaskets again; you may wish to do the same.
- The part number for a new pan gasket is 6L2Z-7A191-BA.
Many thanks to Don from Loreng’s Transmissions for the “heads up” on this potential problem maker.