Overview
Four-bolt flange gasket for the exhaust diverter valve on HydraMaster truckmounts. HydraMaster part number 000-057-146, listed variously as Gasket, Four Hole Exhaust Diverter, Gasket, Four Hole Exhaust and Gasket, four-bolt flange — for exhaust diverter.
The exhaust diverter is what sends engine exhaust either through the heat exchanger or out to atmosphere. Its flange joints run hot, cycle constantly, and are the joints most likely to leak on a truckmount.
What it fits and how many
Named in the parts lists of:
- Boxxer 421 — 3 fitted
- Boxxer 427 — 3 to 4 fitted depending on the assembly
- Boxxer 423S — 2 to 3 fitted
- Boxxer XL — 1 fitted
- Titan 425 — 2 to 3 fitted
- MAXX 450D / 470D / Diesel — 3 fitted
- CM402 — 1 fitted
Count the flanges on your machine before you order. The quantity varies between models and between assemblies within a model, and there is no worse moment to discover you are one gasket short than with the exhaust apart.
Related exhaust parts
- Gasket Exhaust Donut 1.5" (057-177) — the slip-joint gasket used elsewhere in the same exhaust system
- HydraMaster also list diverter kit 078-808 and diverter nut, bolt and gasket kit 078-331. Neither is currently a stocked CCW line — ask us if you need one.
Fitting advice
Replace every gasket you disturb, not just the one that was leaking. They are inexpensive, and a used exhaust gasket has already taken its set to the old joint.
Check the flange faces for distortion while you have them apart. A leaking diverter flange is very often a warped face rather than a failed gasket, and a new gasket will not fix a warped face.
Exhaust fasteners loosen with heat cycling. Check them again after the first few hours of running.
An exhaust leak inside a van is a safety matter, not just a performance one. Do not run the machine with a known leak.
Frequently asked questions
How many do I need?
Between one and four depending on the machine and which assembly you are working on. See the list above, and count the flanges before you order.
Is this the same as the donut gasket?
No. The donut (057-177) seals a slip joint. This one seals a four-bolt flange.
Can I re-use one that looks intact?
No. It has already conformed to the old joint under heat.
What material is it?
HydraMaster does not state the material in the parts lists we hold. We are not going to guess. Ask us if the specification matters.
Working on a diverter? Tell us the machine model and serial number and we will check the assembly drawing for the exact gasket count, fasteners and any other parts you should replace at the same time.
