Exhaust brake trouble

[HCanales]

My exhaust brake responds very slow, When I pull the knob the time laps is about 3-4 seconds to engauge and when I disengauge it takes the same. Could it be my vacuum pump? It also blows a ton of black smoke when it gets stuck and I accelerate. This problem could potentialy cause a run away engine I'm afraid. I thought when you push the accelerater it pushes the exhaust brake baffle out out the way, but not so here. I haven't used this unit in weeks and I'm not going to use it until I resolve this issue, I can't see this being healthy. I'm not sure what system I have or how it works. It does have a vacuum pump and the control knob says "Cummins" if that helps. Thanks HCanales

 

[ScottLewis]

This is from the Jacobs manual about troubleshooting the vacuum system.



"Brake is slow to shut off

The filter on solenoid may be clogged. Remove the

filter and clean with solvent and compressed air from

the back side. If this does not fix the problem, go to

the Brake Troubleshooting section. "



"Vacuum troubleshooting:

1. Check all vacuum hoses for kinks, leaks or damage.

2. With the engine running, disconnect the vacuum hose

from both sides of the vacuum solenoid and hold the

hoses together. The brake should come on and move

to the closed position. If it does, reconnect the hoses

and go to the Electrical Troubleshooting section. If

testing the vacuum with a vacuum gage, your reading

should be between 15 and 29 inches of mercury.

3. Check to see that the vacuum pump belt is in position

and the vacuum pump pulley and shaft are rotating,

spinning with the belt.

4. With the engine shut off, disconnect the vacuum hose

from the vacuum pump. With the engine running, test

for suction at the vacuum pump with your finger. If

there is no suction, replace the vacuum pump. "



Because it works but with a delay, I'd clean and inspect the solenoid valve first to be sure it isn't just gummed up.



Dan

 

[DE Jeeper]

You may have to clean and lube the valve. When I pulled mine for the twins install I noticed the action on the valve was tight. I had it on for around 100k and it was acting as you have described.



Aaron

 

[Blu-meanie]

It's supposed to have a 3 second delay before it engages (time to shift).

My brake was sticking, so I put a few drops of air tool oil in the solenoid.

 

[BHolm]

When you guys say "solenoid", which part are you referring to? Do you mean the vaccum canister that actuates the valve?



I don't think I would squirt oil in there as is probably uses a rubber bellows that could be damaged by oil. Making sure the actuator moves is a good idea. I think the most likely problem, as already mentioned, is to clean the valve itself. A little oil on the pivots if exposed, or remove it and clean the whole thing would solve the sticking. It is a pretty simple device.

 

[ScottLewis]

Not the actuator, it's the small electrically operated vacuum valve,sometimes referred to as a "spool valve". It's the device that uses the electric current from the switch to provide vacuum to the brake cylinder. This is the example shown in the Jacobs install manual. It's to the right of the arrow.

 

[BHolm]

Not the actuator, it's the small electrically operated vacuum valve,sometimes referred to as a "spool valve". It's the device that uses the electric current from the switch to provide vacuum to the brake cylinder. This is the example shown in the Jacobs install manual. It's to the right of the arrow.

Gotcha



They mention a filter on the solenoid... never noticed that. I thought the air was taken in right at the pump? Mine isn't slow, but I've been in some dusty conditions. I will have to take a look at that little bugger. Thanks for the clarification.

 

[HCanales]

Thanks guys I surly will try cleaning the filter first and see what happens. Does the system get soot in it? I did notice that one of the clamps on the elbow after the turbo has thick soot accumulated. My guess is from accelerating with it hung up and I'm wondering if the soot could accumulate inside causing it to stick.

 

[ScottLewis]

Simple answer is yes. This can especially be a problem when the turbo, and brake, never get hot enough to burn off the carbon. Less of a problem for those of us who tow fairly heavy. You surely want to investigate all those things before buying a pump.



Dan

 

[AABEN]

IF you will lub it about 2 times a year you will not any trouble with it . I lube mine 2times a year. Have not had any trouble.