T-78 Mechanical Seal (T-78)

Type 78 trash pump mechanical seal designed for Honda, Bluemaxx, and other portable pumps handling dirty or debris-filled water.

The Type 78 mechanical seal is a widely used design for portable “trash pumps,” commonly found in Honda, Bluemaxx, Koshin, and similar pump brands. These seals are specifically built for handling dirty water, sludge, and light debris, making them ideal for construction, agriculture, and dewatering applications.

At Seal House, we standardize this seal with premium Silicon Carbide faces, Buna (Nitrile) elastomers, and 304 stainless steel metal components for improved durability and longer service life in abrasive environments.  Please note we offer 17mm in in Carbon/Ceramic for clean water applications.

Available shaft sizes (choose from drop down menu above):

• 17mm CAR/CER (carbon/ceramic–for clean water applications)

• 17mm SIC/SIC (silicon carbide/silicon carbide)

• 25mm SIC/SIC (silicon carbide/silicon carbide)

• 30mm SIC/SIC (silicon carbide/silicon carbide)

OEM & Cross Reference

Koshin KTH-80X
OEM Part Number: 3220115678 (25mm)
Commonly used in Honda WT, WB, HL, MP and similar trash pump models.

Key Features

Designed for trash pumps & portable pump applications • Silicon Carbide vs Silicon Carbide faces for abrasion resistance • Buna (Nitrile) elastomers for reliable sealing • 304 Stainless Steel metal parts • Direct replacement for many OEM configurations • Built for dirty water and light solids handling

Applications

Trash pumps (dirty water / solids handling) • Construction site dewatering • Agricultural irrigation pumps • Rental pump fleets • Portable gasoline/diesel pumps

Important Installation & Design Note (READ BEFORE INSTALLING)

Unlike standard mechanical seals, the Type 78 operates in a reversed configuration:

The rotating face is installed in a sleeve (impeller side)
The spring portion is stationary in the housing

Because of this, the terminology is different from standard seals:

What is normally called the seat = spring portion (stationary)
What is normally called the rotary = rubber cup + face assembly

Dimensional Reference Guide

For this seal type, dimensions are defined as follows:

D2 = Rotary face OD (rubber cup fit size)
L2 = Thickness of rotary ring + rubber cup
D1 = Stationary (spring portion) rubber cup OD fit size
L1 = Height of rubber cup on stationary portion
L = Overall working length when installed

Always verify dimensions against your pump, as installation differs from standard mechanical seals.

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