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An Isuzu exhaust brake on a Fuso

With the planned layout of fuel and water tanks it would be necessary to re-route the standard exhaust system. Given that I would need to replace the majority of the exhaust I decided that I may as well go all out and change the standard 21/4” system to a 3″ system. Doing this should have the added benefit of more power due to better gas flow.


When picking up my truck from ATW, John, ATW’s technical expert, had given me a lead to where I might get a 3 inch exhaust brake, one that had been ordered in for someone but was never picked up. This exhaust brake was being sold off at below cost, as it had been sitting on the shelf for over twelve months. That definitely worked for me, as these things are definitely not cheap.


For anyone that does not know, an exhaust brake is a pretty simple device. Basically, it’s made up of two main parts; a butterfly valve and an actuator (normally vacuum operated).

The exhaust brake I bought was for an Isuzu, not a Fuso. I knew this upfront but figured that with a bit of work it should not be that difficult to convert it to work on my truck.

Today I pulled the standard exhaust system off the truck so, with both exhaust brakes side by side, I was able to have a closer look at them. To my surprise, the two were very similar.

That’s a bit of an understatement actually; they were virtually identical when it came to mounting positions.


After dismantling them both I found that there were only two main differences.

1.      The Fuso butterfly opened counter-clockwise whereas the Isuzu one opened clockwise.

2.      The cam plate, which connects the butterfly axle to the actuator, was out of rotation by about 60 degrees.


The butterfly problem was solved by simply undoing the two securing bolts and flipping the butterfly around. To resolve the cam plate issue I welded up the existing hole and made a new slotted hole positioned correctly.

All in all, it only took about two hours to convert the Isuzu exhaust brake. I was expecting this job to be way more difficult than it was; but I am definitely not complaining.