BD Exhaust Brake - I'm puzzled about sticking relay.

[Prairie Dog]

Yea, it sure sounds like you've put your finger on it it and it's just the relay acting up. I wonder why you've had so much bad luck with them...?
My problem is the dump valve sticking when I first start it in cold weather. I've had to hit it with a heat gun to free it. I just try to avoid using it in the cold anymore.

 

[Killgore]

I tend to blame the relay failures on the temps that we endure down here because the problem didn't show up until the heat of the Summer. Of course, Jelag installed relays in close proximity to the manifold without experiencing any issues. I was hoping that someone in the Deep South who had an EB had seen the same problem. That being said, I don't imagine there are too many EB's being used around here because the pressing need for one, mountains and steep grades, don't exist. I pull an 11,000 lb. fiver and North Georgia and East Tennessee are my picks for getting away from it all, and that's when the EB is in it's glory. Of course, I use it all the time when I'm grinding back and forth to town as well as stop and go traffic. I'd hate to drive without it as it has become part of my muscle memory. It is an excellent tool that enhances safety as well as cuts maintenance costs relative to the brakes.
- Ed

 

[Killgore]

Scott, you must live in a pretty humid area and the moisture in the dump valve is turning to ice when the pressure is released.
- Ed

 

[Prairie Dog]

Scott, you must live in a pretty humid area and the moisture in the dump valve is turning to ice when the pressure is released.
- Ed

Yes, it sure can be. It may also be because I don't run a tank so there's no place for the moisture to go. Or it may just be worn.

I was thinking about the idea of running a bigger relay..
That may not work well because a bigger relay will have a stronger coil and that will demand more current. The neg voltage for the relay comes from the trucks ECM and is really just a "Lo" signal generated by digital drivers. Those devices are severely limited in regards to how much current they can flow. If you try to pull too much current from them then their output just gets weak and the negative voltage will drift upwards (referred to as tri-state). This wont hurt the driver but it won't power the EB's relay either. This would probably show up as a weak relay..
So installing a wimpier relay may actually be better if the big ones seem to fail or get weak.

Scott

 

[K5IP]

I am not familiar with this particular situation, but from an engineering perspective, pitted or welded relay contacts often occur from large transient voltage spike that result from the relay driving an inductive load (I.e. coil, clutch etc.) Protection to prevent this is usually a diode placed across the offending load. The diode should be installed with the cathode at the positive side (supply) and the anode at ground.
The diode effectively shunts the prevailing voltage spike to ground protecting the contacts.
You might check to see if a protection diode is included. If not, consider a 1N5005. Very cheap to try.
Rog

 

[p-Bar]

Brother and I discussed this too he is an EE . He suggested a cap and a carbon resistor in series across the contact . Values are written down at my shop usually a diode goes across the coil but that allows for a slower release which may not be good. Your thoughts K5IP

 

[Killgore]

Hah! I'm lost in the woods. Most of the time if a hammer won't fix it, I reach for a bigger hammer. However, this makes sense.
- Ed

 

[Killgore]

Well, as a follow-up I need to report on the sticking relay situation. This is both an admission of my stupidity and any apology that I may owe to Hector/BD. The 60 amp relay begin to stick several days ago and I upgraded again to a heavier 80 amp relay off a Ford. When the brake was engaged I could now hear the relay switching and it sounded like a metronome. Yeow, this sounds like an airline leak, and it was. One of the quick disconnects into the cylinder was loose refusing to allow pressure to stabilize and hence the compressor was continually coming on and off, probably 100+ times a minute, and in the process simply burning the points on the relays as they cycled. Problem solved! My suggestion to anyone having a similar problem is to look on a relay failure as emblematic of a possible air leak, and not just a failure of the relay.

- Ed

 

[Prairie Dog]

Good info Ed, I would never had thought of that.

 

[gaylejoe]

I have the exact problem with my BD Exhaust Brake. My started sticking and would not turn off. Now, it doesn't come on at all. I did try changing the relay
today but it would not come on. We are traveling with an RV in Crossville, TN and have tried to find someone here with knowledge of the BD Exhaust Brake without success. I would like to get it working. If someone knows of anyone in this area we would appreciate the information. I can be reached at
210.860.6006. Cell service iffy but text msg's do get through.