Does Exhaust Brake Cut Fuel?

[bnold5000]

Hello Everyone,

I've been thinking about putting an exhaust brake on my truck (97 club cab 4x4 12v auto)....BUT.....
I'm trying to figure out whether the fuel is cut off or not when the exhaust brake is activated.
If the engine is still injecting fuel (at idle level) and combusting that fuel when the exhaust brake is activated (exhaust manifold severely restricted)......what are the long-term effects to "engine health" created by restricting the exhaust gases from leaving the engine. Is all that extra pressure pushing these waste products of combustion (that can not escape out the exhaust manifold of the engine as usual) past the piston rings and fouling the engine oil way faster than normal, etc? Does the engine oil lose its ability to lubricate without wear a lot sooner which results in wearing the engine out faster? I have Issues 14-53 of the TDR. I've read 14-23 looking for the answer to this question. So far, no cigar. Does anyone know?
Thanks for reading! See you out there in TDR land! B

 

[Chief USA]

I have a Cummins exhaust brake on my 2002. No fuel is cut off. A vaccum actuated valve plate is turned 90 degrees in the exhaust stream just after the turbo charger which significantly restricts exhaust gas flow and thus acts as a brake on the engine to help brake/slow the vehicle down. The exhaust brake can also be used to aid in warming up the engine on cold morning starts. I would say go for it. You will be kicking yourself for not getting one sooner. Had my service brake calipers not ceased up due to corrosion, I would still be on my original 17 year old brakes which still had about 75 % of the pad remaining when I replaced all of the calipers and rotors recently. Not only does an exhaust brake significant increase the life of the vehicle service brakes, it makes towing and hauling heavy loads so much more pleasant.

 

[GAmes]

I've put 1.3 million miles on mine since installing an EB. I use it a lot. The original engine only lasted 800,000 miles. You decide.

 

[JMcCoy]

The lion's share of the fuel is cut off whan you take your foot off the gas.

 

[Woodenhead]

No, it doesn't push all the exhaust pressure past the rings and wear the engine out faster. Even when the brake is on it's still letting the exhaust gas get past the brake, just takes some pressure to get around. The increased pressure in your cylinder with the foot off the pedal and the brake on pales in comparison to the pressure it sees from combustion when accelerating hard with lots of boost. There's countless exhaust brakes out there for who knows how many miles on these trucks, I have yet to hear that one contributed to premature failure. For reference, the pressure I see in my exhaust manifold is 40-55psi (depending on RPM) with the exhaust brake on, I also see drive pressure in that range when I'm running wide open.

Aside from being safer and saving service brakes, there are other benefits to the exhaust brake. When you decelerate or lift of the pedal normally you have some significant temperature drops in your engines exhaust path (head, valves, turbo), especially when descending long grades, then accelerate again and heat them back up. Using the exhaust brake holds the heat in, minimizing the thermal cycles, this is all quite evident by watching the pyrometer. It's also a useful tool when warming up an engine in cold climates, let it idle with the brake on.