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. A green Kevlar material gasket is used to seal the pump
cover to the filter adapter plate. Replacements are available in the Oil System
Gasket & O-ring package Milodon #21590. During each engine
rebuild, the oil pump assembly should come apart for inspection and
be reassembled with new gaskets and O-rings.
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 early 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 gasket could be pushed out by oil pressure. The
green gasket contains Kevlar fibers and has increased internal strength to
and being pushed out of place. Adequate clamping force is a
Clamping force of the filter plate may be
diminished by several factors.
- The two filter plate bolts must be tight enough initially.
countersunk bolts that are torqued to 35 ft/lbs, they will then
require a substantial effort to loosen them. When assembling the
cover - Make sure the bolt
threads are clean and go all the way down by hand. Then remove
the bolts, coat with oil and torque down for final installation.
- The bolt inside the filter cavity sits about 1/8" deeper
that the outer bolt. If bolts are replaced over the years then the
length must be checked or 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 failure.
- Check that there is enough flat sealing are around the oil ports
in the cover. There should be a minimum of .130 sealing surface for the gasket
to seat on.