Exhaust Brake.

[Drurban]

Hi everyone,

I have a 1997 Isuzu Mu 3.1TD and it has an exhaust brake on it and I dont know how this works, I see the there a two rubber tubes that connect to it Iam guessing Vacuum lines.

If anyone can explain how this works would be much appreciated.

Cheers
Ruben

[pig75]

It's not a break. It is part of the Quick Warm up System. It basically restricts the air in and out of the motor so it warms up quick

[sanramonrover]

Contrary to other posts, MAYBE it is an exhaust brake! I have one on my 4JB-1 fitted into a 1991 KB pickup. Works a treat! Two vacuum lines - one in from the vacuum pump on the back of the alternator, other is a exhaust (vacuum) line to the open air. A switch on the dash activates a solenoid to let vacuum into the chamber on the exhaust brake. Also in series with that wiring are two switches - one on the clutch pedal, one on the accelerator. Letting foot off the gas activates the brake, touching the clutch,or accelerator activates it.

If you need photos, let me know.

[geeves]

This came up in another thread also from Costa Rica. Was it your thread? I think the final answer was that the exhaust brake in question was either aftermarket or special for that market.
The only thing Ive seen on NZ and Aus trucks might be able to be modded to a partial brake but it is not restrictive enough to do a complete job. There is a switch on the dash that when activated and the coolant temperature is below a certain point (different on 3.1 and 2.8) it restricts exhaust flow warming the engine quicker

[sanramonrover]

Yep, that was me. I do have a 4JB-1 engine out of a larger cargo truck fitted into this KB. I have also seen them on other large diesels here. So guess yours isn't an engine brake..
Cheers Fred

[Drurban]

Thanks everyone for the info, I will be replacing my exhaust system so I will be getting rid of it anyway.
Yes I would like some photo's sanramonrover if you can.

Cheers

Ruben

[sanramonrover]

The only decent photo is on this page http://www.griffco.ca/isuzu/isuzu.htm
Not too clear, but might help.

I think I just discovered a weakness in this system: I was cruising downhill, the exhaust brake was working fine when I needed to slow suddenly to avoid a sudden stop in front of me.

It seemed that I had to really stand on the brake pedal to get the needed braking effect - something I had never felt before. My theory is that the exhaust brake was using all the vacuum (from the pump on the alternator), leaving insufficient for the brake booster. The exhaust brake is just "TEE'd" off the hose to the brake booster chamber. Kinda scared me!

[geeves]

There is a non return valve in the line to the booster Your exhaust brake should come off between the alternator and the valve and probably have its own non return valve.

[sanramonrover]

Ahah! Good point. Thanks Geeves. I'll look for it.

[edalcor27]

It's not a break. It is part of the Quick Warm up System. It basically restricts the air in and out of the motor so it warms up quick

good day sir if this is part of qws it is possible to re wire it and use as exhaust break?

[pig75]

No it wont work. It will not hold shut at high RPM

[geeves]

without substantial modifications.
Not worth the effort

[edalcor27]

ok sir thanks for the reply