4L30E Overhaul Kit 1990, new and ready to install. Fits the 4L30E. Ships fast from the USA.
If your BMW 525i, early 3 Series six-cylinder automatic, Isuzu Trooper or Rodeo, or Honda Passport has a 4L30E that leaks from every joint, is slow to pick up Reverse when cold, or slips once the fluid is hot, the rubber and paper inside the unit has given up. This 4L30E overhaul kit is the sealing set for a teardown of 1990-and-later units. It includes the paper gaskets, rubber parts, O-rings, lip seals, metal-clad seals and the sealing ring kit. It is a soft-parts kit only: there are no friction plates, steels, band or filter in the box.
The 4L30E is a light-duty four-speed that GM built in Strasbourg, France. It is unusual in being built in two sections: an adapter case at the front with the pump, overdrive roller clutch and overrun clutch, and a main case behind it with the reverse, second, third and fourth clutches, a band, and a second valve body. That layout means more sealing joints than most four-speeds, and more pistons and rotating seals for the oil to escape past. The overhaul kit replaces all of them: the gaskets between the cases and under both valve bodies, the piston lip seals, the metal-clad front and rear seals, and the rings that carry oil into the spinning clutch drums. When those parts harden with age, line pressure leaks away inside the case and the clutches cannot hold, even if the frictions still have life left.
Reverse complaints are the most common 4L30E problem according to Transmission Digest, but they are not always seals. The same article documents a leaking converter clutch solenoid causing a cold no-reverse that goes away when warm, so test the 1990-1999 4L30E TCC solenoid before you pull the transmission. Check the fluid level hot and inspect what is on the pan magnet. Our transmission slipping diagnosis guide shows the pressure and stall checks that separate a leak from worn clutches. If the frictions are burnt, you need more than this kit; weigh the cost with our rebuild vs replace vs reman guide.
This kit is listed as a 4L30E overhaul kit for 1990-up units; the listing also references the A4S-310R designation. The earliest applications are 1990, in the BMW 525i (E34) and the Isuzu Trooper; later uses include the BMW 318i, 325i and 328i, the Isuzu Rodeo, the Honda Passport and the 1997-2001 Cadillac Catera. The kit covers the rubber and paper parts shared across those years, but two things vary. The adapter case, center support and spacer plate differ between BMW, Isuzu and the other makers and do not interchange, so lay each new gasket over its mating surface before you install it. Transmission Digest also notes that 2000-up Trooper and BMW units moved to a pulse-width-modulated converter clutch with a different pump. Read the identification tag on the case and send us your year and VIN if you want us to confirm. Other 4L30E kits, including later years, are listed under rebuild kits.
Soak the lip seals in Dexron III before assembly and lube the sealing rings with assembly gel so they seat in their grooves without rolling. If Reverse was weak, check the reverse piston bore for scoring before you fit its new seal; a damaged seal surface will leak again no matter how good the seal is. Air-check every clutch circuit and the band servo before the valve bodies go on. Because frictions are not included, measure the clutch packs; if they are worn or burnt, the 4L30E banner rebuild kit for 1990-1997 adds a full friction set. Inspect the 4L30E pump bushing, since a worn bushing will damage a new front seal. On BMW units, finish with the 4L30E filter and pan gasket kit. GM lists a dry fill of about 7 quarts of Dexron III with the 245 mm converter; set the final level hot.
| Fits | 4L30E 1990 |
| Part type | Overhaul Kit |
| Condition | New |
| Brand | OEM |
| Ships | From the USA |
| Warranty | 1-year |
No. It is the overhaul sealing kit: paper gaskets, rubber parts, O-rings, lip seals, metal-clad seals and sealing rings. Frictions, steels, the band and the filter are sold separately.
The seals and rings are common, but the adapter case, center support and spacer plate differ between makers. Match each gasket to the surface it seals before you install it, and send us your VIN if you want fitment confirmed.
Sometimes. Worn reverse piston seals are a common cause, but a leaking TCC solenoid can produce the same cold no-reverse. Test the solenoid and check the fluid level before tearing the unit down.
GM specified Dexron III for the 4L30E, with a dry fill of about 7 quarts with the 245 mm converter. Check the final level hot.
Inspect the pump bushing, the reverse piston bore and the clutch packs. Replace worn frictions, add a new filter and pan gasket, and test the solenoids while the valve body is accessible.
