15 ft of 8AN steel-reinforced braided hose with straight and 90-degree ends plus case and radiator adapters to re-plumb 4L60E and 4L65E cooler lines.
If you are adding a large stacked-plate cooler to a towing Silverado or Sierra, putting a built 4L60E or 4L65E behind an LS swap, or just tired of patching rusted factory lines, this kit re-plumbs the whole cooler circuit in one box. It includes 15 feet of 8AN braided hose, two straight and two 90-degree 8AN hose ends, two 1/4 in NPSM to -8 adapters for the transmission case, two 1/4 in NPT to -8 adapters for the radiator tank, sealing rings, metal gaskets, two hose separator clamps and thread tape. That is enough hose for both the feed and the return line on most trucks.
The 4L60E sends fluid out to the cooler after it has passed through the torque converter, which is where most of the heat is made, and the fluid coming back from the cooler is what lubricates the gear train and bushings. A restricted or leaking circuit means hotter fluid and less lube at the same time. That is a bad combination for a unit whose most common failure is a burnt 3-4 clutch pack, and it gets worse with a loose high-stall converter that makes more heat in town.
Most aftermarket kits for this transmission are 6AN. The -8 size has a larger bore, so it flows more fluid with less restriction. That pays off when the cooler is large or far from the case, when the converter stalls high, or when the truck spends hours pulling a trailer. The hose has a CPE rubber inner core, a layer of 304 stainless wire for reinforcement and a black nylon outer braid, and the hose ends and adapters are machined aluminum.
Low fluid from a cooler leak can make a healthy unit flare between gears, but slipping that stays after the level is corrected usually means internal damage. Codes such as P0741 for converter clutch slip or P0748 for the pressure control solenoid are valve body and solenoid problems that new lines will not fix. Our 4L60E common problems guide separates those, and the Camaro common problems guide covers the heat and power issues that hit performance builds. If the unit has already failed, the 4L60E master rebuild kit for 2004-up trucks covers the soft parts.
The kit is sold for GM 4L60E and 4L65E transmissions. The case adapters are 1/4 in NPSM, the straight-thread port GM uses on these cases, and the radiator adapters are 1/4 in NPT. Most factory radiators and many aftermarket radiators and coolers use a 1/4 in pipe-thread port, but not all of them do, so check your radiator tank and cooler ports before you cut hose. If your truck has been swapped or carries a non-factory radiator, send us your year, VIN and radiator brand and we will help you match it. Other parts for this unit are on the 4L60E parts page.
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Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No extra adapters should be needed on a stock 4L60E or 4L65E. The kit includes two 1/4 in NPSM to -8 adapters for the case and two 1/4 in NPT to -8 adapters for a radiator tank with pipe-thread ports.
Not if you tow or plan to add a larger cooler. A stock truck runs fine on 6AN, but 8AN has a larger bore and less restriction, which helps with long runs, big coolers and high-stall converters.
No. The case ports are a straight NPSM thread that seals on the gasket and ring. Use the included tape only on the tapered NPT threads at the radiator.
The kit has 15 feet, which covers the feed and return lines from the case to the radiator on most full-size trucks. Measure both routes first if you are adding an auxiliary cooler in series.
Dexron VI is the GM service fluid for the 4L60E and 4L65E. Check the level with the engine running and the fluid at full operating temperature.
