exhaust brake issue

[bukzin]

Hi everyone,

Any of you have experience with this...


02 Holiday Rambler Endeavor exhaust break stays energized when throttle is applied.

Throttle positioning sensor, relay, solenoid and actuator checks OK

[YC_1]

Another form of engine braking

This is what is on my engine. It is NOT a compression brake nor is it an exhaust brake as we know it.

[bukzin]

YC 1 wrote:
Your sig shows an 06 model. You comments say 2002?

A 2006 probably is just as described and may use a variable ratio turbo for the braking.

A 2002 may have a mechanical one and need lubing.

Yc1, Good eye. Its a friends coach.

Thx

[ncrowley]

If it is an exhaust brake, a PacBrake probably. When was the last time you lubed it? The recommendation is once per year using a special lube.

[wolfe10]

Another easy electrical check:

Most coaches have a "pre-select" gear when exhaust brake or engine compression brake are activated (not just in "stand by). So, your Allison shift pad will go from "6" to some lower gear-0 with 2 and 4 being common choices.

So, when you are driving, what does the left/only Allison shift pad indicate?

BTW, engine compression brakes are VERY common on the ISL in RV applications. Have exactly that engine in our 2003 Alpine (Cummins ISL, 400 HP, 1,200 lb-ft torque at 1,300 RPM and two stage engine compression brake). A very good power to weight ratio in 38' two slide coach.

[WayneLee]

IMO, we are stuck on two points:

(1) Exactly what type of engine braking are you talking about? We are discussing two different types of slowing down, exhaust braking or engine braking.

The main difference between the two is in how they operate. A Jake brake (or engine brake) creates braking force by releasing the compressed air inside the cylinders. In contrast, an exhaust brake blocks the path of the exhaust, causing an increased pressure in the exhaust manifold. Jake breaks cost $2,000+ and, therefore, are usually not found on RV's. Jake brakes are normally found on the 18 wheelers.

(2) Now, if we assume that that you have an exhaust brake, how to use it? IMO, many RV manufacturers put the exhaust brake system into "armed" mode when the engine starts up. Then, the braking system becomes active when you depress the brake pedal. Then, the system goes back to "armed" mode when you press the accelerator. Usually, the coach has a switch to choose between on and off for an exhaust system.

So, to the OP, IMO you have an exhaust brake with the "automatic on/off" system with a switch somewhere to turn it on. That switch is currently in the "on" position. As long as you are not experiencing any engine performance issues, it would appear to be working correctly.

[wolfe10]

Exhaust brake stuck fully closed-- no power (perhaps 30 HP from 400 HP engine). Instead of the exhaust being virtually no back pressure, back pressure would be 50+ PSI (exact maximum PSI speced by the engine manufacturer).

And exhaust manifold temperatures could go extreme.

If engine compression brake stuck on, the engine would not run, as the exhaust valves would remain open after the compression stroke. Yes, if engine compression brake on LOW, three cylinders might still function???

[tropical36]

bukzin wrote:
Hi everyone,

Any of you have experience with this...


02 Holiday Rambler Endeavor exhaust break stays energized when throttle is applied.

Throttle positioning sensor, relay, solenoid and actuator checks OK

What might be the symptoms of this brake being on?
Does it make the tell tale sound?
Does it have any power to speak of?
If it is indeed on, then I'd say it's stuck and needs special lube, that's designed for it.
I assume you're asking about another coach and not your own.

[oldmattb]

I had a problem with a mis-wired trailer that caused the brake lights to remain on. This caused the exhaust brake flap to remain closed, and limited travel to about 10 MPH.

Matt B

[wolfe10]

And, with the Cummins ISL, it could have EITHER an exhaust brake or engine compression brake. Only engine I am aware of that was offered both ways, with the exhaust brake being the less expensive.

The exhaust brake would be a separate device downstream of the turbo on the exhaust side. The engine compression brake would be in/on top of the head.

[crasster]

WayneLee wrote:
If by energized, you mean the switch is lighted and the engine break is ready to work whenever you lift your foot off the accelerator, then YES, that's how its suppose to work.

My '07 Holiday Rambler Diesel with a 400HP Cummins worked that way. I drove with the engine break turned on all the time.

Yes, OP, I was wondering if you meant this by "energized" because that can mean a plethora of things.

[YC_1]

Your sig shows an 06 model. You comments say 2002?

A 2006 probably is just as described and may use a variable ratio turbo for the braking.

A 2002 may have a mechanical one and need lubing.

[dons2346]

If your exhaust brake was indeed "energized" where it was always closed, you probably wouldn't be able to move the coach at road speeds. If the switch stays lit, that is the way it is supposed to work.

[WayneLee]

If by energized, you mean the switch is lighted and the engine break is ready to work whenever you lift your foot off the accelerator, then YES, that's how its suppose to work.

My '07 Holiday Rambler Diesel with a 400HP Cummins worked that way. I drove with the engine break turned on all the time.

[Mandalay_Parr]

How about the brake switch?