June 1996

The Big Block Chrysler oiling systems with the filter in the stock location use the #21250 filter adapter. The gasket used for this filter plate should be the "green" gasket. If you still have a gray gasket, a new green gasket should replace it as soon as possible. It is available in the Oil System Gasket & O-ring package Milodon #21590.

Baring in mind that Milodon oil systems have been in use for over 40 years and many of those systems are still in use, there is a rare occurrence of failures with the early "gray" gasket. Any occurrence however is unacceptable.

The green gasket has been supplied in all kits since 1996. Milodon oil systems have been in production since 1965 so there were many gray gaskets supplied. These systems were used on everything from street cars to the Hemi Pro Stockers of the 70’s without incident. While the majority of applications worked fine, if the filter plate clamping force is not sufficient there is a possibility the gray gasket could be pushed out by oil pressure. The green gasket contains kevlar fibers and while oil can leak around it, the gasket itself has adequate internal strength not to fracture and be pushed out of place.

1. The two filter plate bolts must be tight enough initially. Being countersunk bolts that are torqued to 35 ft/lbs, they will then require a substantial effort to loosen them. Make sure the bolt threads are clean enough to go all the way down by hand. Then remove, coat with oil and torque down for final installation.
2. The bolt inside the filter cavity sits about 1/8" deeper that the outer bolt. If that threaded bolt hole inside the filter cavity picks up any chips etc, the bolt could bottom in the hole before it properly clamps the filter plate. While appearing tight it would allow a loose gasket and subsequent leak.
3. In rare cases, the hole may have too little sealing area around it due to pump cover thickness variations and hole placement. There should be a minimum of .130 sealing surface for the gasket to seat on.