Allison 3000 Transmission Filter Kit, 6 in with Gaskets

This is the internal filter service kit for the Allison 3000 and 4000 series automatic -- the medium-duty box, the transit bus, the fire apparatus and the diesel pusher, not the 1000/2000 series behind a Duramax pickup. It replaces both cartridge filters that live in the sump: the main filter and the lube filter. Kit contents are two 6-inch filters plus the gasket and O-ring set that seals the filter covers back to the pan.

Length matters more than anything else here. The 3000/4000 was built with two sump depths, and the filters are not interchangeable between them. The 6-inch filters in this kit are the deep-sump length and replace Allison 29548988, 29558118, 29558329, 29540494, 29545779, 29526898 and 29506337. If the unit takes the shallow sump, it uses the 4-inch filter (29548987) instead and this kit will not seat. Measure the old filter before you order. Cross references are Donaldson P560971, Fleetguard HF28943 and Baldwin PT9415-MPG KIT.

On the job: drop the pan, pull both filter cartridges straight down out of their bores, and get the old O-rings out of the bore -- they hang up in there and a doubled O-ring is the usual reason a fresh filter service comes back leaking or with low main pressure. Lube the new O-rings with clean transmission fluid, push each filter squarely into its bore by hand until it seats, then set the pan and torque the bolts evenly rather than in one pass. Refill, run the unit up to operating temperature, and check level on the dipstick or through the shift selector display with the engine idling in neutral.

A skipped filter change is what starts most of the expensive failures on these units. Clutch material and case debris that the filter should be catching goes straight into the control main circuit instead, where it hangs solenoid valves and scores the valve body bores. Fresh filters and clean fluid on schedule is the cheapest thing you will ever do to a 3000 series.