High-flow mesh filter and reusable pan gasket for the GM TH400 Turbo 400, 1966-1991 - flows more fluid than the stock paper screen on a service or rebuild.
A TH400 that whines at idle, takes a second to engage Drive or Reverse, or slips when it is hot is often a transmission starving for oil at the pump inlet, not one that needs a rebuild yet. The TCI 228500 kit is the routine fix: a replacement filter for the 1966-1991 GM Turbo 400 (TH400 / 3L80) and a TCI pan gasket, so one pan drop puts a fresh strainer under the pump and reseals the pan. TCI makes it for street and race units that see heat, load and high-stall converters, and it fits the stock pan.
The TH400 filter is a flat strainer bolted to the valve body, with an intake pipe that plugs into the case through an O-ring and feeds the front pump. Everything the transmission sheds, clutch lining, band material, bushing and steel wear, settles in the pan and gets pulled toward that strainer. GM warned its dealers in 1968 that the TH400 strainer is a full-flow part with no bypass valve: when it loads up, it simply restricts the pump intake, and the result is pump cavitation noise, slipping or intermittent loss of drive. Sonnax flow testing of a TH400 with a restricted pickup shows cooler flow dropping off sharply as engine speed falls, which is why the symptoms show worst at idle and on a coast to a stop. TCI describes this filter as having a larger surface area for flow while still catching particles, and the pan gasket as a thicker, coated design that seals better than a plain fiber gasket.
Check the fluid level hot in Park first; a low level gives the same pump noise and late engagement. If the level is right and the fluid is dark, drop the pan and look. Fine gray paste and a little friction dust are normal for the miles; chunks of lining, brass flakes or steel slivers mean the filter is a symptom of something bigger. Our TH400 filter and pan service guide covers what each type of debris means, and the TH400 pump failure guide helps you tell a starved pump from a worn one.
TCI lists this kit for the 1966-1991 GM TH400 three-speed automatic, the unit behind big-block Chevrolet, Buick, Oldsmobile and Pontiac cars, GM trucks and motorhomes, and countless swaps. It fits the stock-depth pan only. A deep aftermarket pan needs a longer pickup or a deep-pan filter to reach the bottom of the sump, so match the filter to the pan you run. The TH350 and 4L80E use different filters, so confirm your unit with our TH350 vs TH400 identification guide or send the year, vehicle and VIN. Browse everything else for this unit on our TH400 parts page.
This is a filter and gasket only, not a reseal kit. If you are tired of draining over the pan rail, pair it with our TH400 oil pan with drain plug. If the debris tells you the unit is coming apart, step up to the TH400 overhaul kit.
| Fits | GM TH400 / Turbo 400 / 3L80 three-speed automatic, 1966-1991 |
| Filter type | Fine steel mesh screen (high-flow, reusable-style race filter) |
| Includes | TH400 racing filter screen and reusable pan gasket |
| Best for | High-stall converters, towing, and performance builds where fluid flow matters more than fine filtration |
| Manufacturer part | TCI 228500 |
| Not | A full rebuild or reseal kit - pump seal, modulator and o-rings are separate |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
TCI lists it for the 1966-1991 GM TH400 (Turbo 400 / 3L80) used in GM cars, trucks and motorhomes, plus swaps using that transmission. It is for the stock-depth pan.
Not by itself. A deeper pan moves the bottom of the sump away from the pickup, so a deep pan needs its own filter or a pickup extension. This kit is for stock-depth pans.
The kit is listed as a filter and pan gasket. Check the bag when it arrives; if no O-ring is included, replace the old one anyway, because a hardened O-ring lets the pump suck air.
GM's 1976 truck literature calls for fluid and filter every 15,000 miles in severe service (towing, hills, heavy heat or city traffic) and every 60,000 miles otherwise. Most TH400s today fall under severe service.
Dexron-type ATF. A GM-licensed Dexron VI is back-serviceable where older Dexron II or III is specified.
Only if the slipping came from a restricted pickup or low fluid. If the old pan holds heavy lining or metal, the clutches or pump are already worn and need repair.
