1298034 Valve As Fits Caterpillar Models

One New Aftermarket Replacement Bypass Valve Assembly for Caterpillar (Cat) Excavators

This aftermarket replacement bypass valve assembly (part number 129-8034 / 1298034) is a hydraulic oil filter bypass valve used across a wide range of Caterpillar (Cat) excavators, front shovels, knuckleboom loaders, loggers, mobile hydraulic power units, and wheeled excavators. It protects the hydraulic system by allowing oil to bypass the filter when pressure differential exceeds the designed threshold, preventing filter collapse and maintaining flow.

Compatible Models

Caterpillar Excavators: 311B, 312B, 312B L, 315B L, 317B LN, 318B, 320B, 320B L, 320C, 320C FM, 320C L, 320D, 320D FM, 320D GC, 320D L, 320D LN, 320D2, 320D2 GC, 320D2 L, 321B, 322B L, 322B LN, 322C, 322C FM, 323D L, 323D LN, 323D SA, 323D2 L, 324D, 324D FM, 324D FM LL, 324D L, 324D LN, 325B, 325B L, 325C, 325C FM, 325D, 325D FM, 325D FM LL, 325D L, 325D MH, 326D L, 329D, 329D L, 329D LN, 330B L, 330C, 330C FM, 330C L, 330C MH, 330D, 330D FM, 330D L, 330D LN, 330D MH, 336D, 336D L, 336D LN, 336D2, 336D2 L, 340D L, 340D2 L, 345B, 345B II, 345B II MH, 345B L, 365B, 365B II, 365B L, 365C, 365C L, 365C L MH, 374D L, 385B, 385C, 385C FS, 385C L, 385C L MH, 390D, 390D L

Caterpillar Front Shovels: 385C, 5090B

Caterpillar Knuckleboom Loaders: 2384C, 2484C, 539, 559C, 579C

Caterpillar Loggers: 322C

Caterpillar Mobile Hydraulic Power Units: 323D L, 323D LN, 324D LN, 325C, 325D, 329D L, 330C, 330D, 330D L, 336D L, 365C L, 385C, 385C L

Caterpillar Wheeled Excavators: M325B, M325C MH, M325D L MH, M325D MH, M330D, W330B, W345B II

Replaces Part Number(s):

1298034, 129-8034

New aftermarket replacement part - not remanufactured, not used.