Jake Brake

[becker]

I have tried posting this message 3 times. The administrator says he does not know why it will not post. He said to resend it. I am retyping everything to see if I included some unsupported characters.

I am on the road. I have a 2008 Monaco Dynasty 425hp Cummins with a Allison 3000 MH 6-Speed World Transmission and Electronic Shifter. Normally on steep downhill grades I can flip the Jake Brake on and it will hold the speed I want, normally 50mph. Now it will not only not hold the speed but the switch feels like it is not connected. I can flip it back and forth and nothing happens. There is a second Jake Brake, HiLo switch, and it works fine, next to the Jake Brake that I use for speed retention and to slow down when I approach a town speed post. I generally only use the second Jake Brake when I am below 40mph and it takes me down to 15mph and then turns me loose.
My question is has anyone else experienced this and is it something I can fix? I appreciate your input. Maybe all of a sudden I am not operating them correctly.

[Dutch_12078]

Both the "Jacobs Exhaust Brake®" and the "Jacobs Compression Release Brake®" are registered trademarks of Jacobs Vehicle Systems, LLC. Since "Jake" is just a shortened version of "Jacobs", I don't understand why one would be called a "Jake brake", but not the other. Confused minds want to know!!! 😉

[Bill_Satellite]

I clicked there and there. Despite the Jacobs name, an exhaust brake is not a Jake Brake. A Jake brake is an engine compression unit and an exhaust brake works by increasing back pressure on the exhaust system.

[Ivylog]

The OP and I have a true Jake Brake... engine compression brake with a hi/low selector switch.

[lwasouth]

Most problems with exhaust brakes are caused by lack of lubrication. If your coach sits for any length of time the Exhaust (Pac) brake should be lubricated with special high temperature lube at the end of use. Pac brake sells a special lube.

[Big_Katuna]

The mechanical Jake brake can be very noisey.

There also can be a retarder built into the transmission. Most Foretravels have those.

[tropical36]

lanerd wrote:
Actually Bill, Jacobs makes an exhaust brake also.... so it "could" be called a "Jake" brake too. I know, I know, everybody considers the engine brake as being the Jake brake. Just thought I'd throw that out there. For a newbie, it could be confusing.

And DG, I don't think I've ever heard of a MH that had both.

Ron

I've never heard of having both either, come to think of it and was just trying to make some sense out of the post.
I guess those with an engine brake, could add and exhaust brake, if they wanted, but wouldn't know why.
Engine brakes are probably the best and most sure you can add them as well, even though, intensive and expensive, especially if the work should be hired out.
Having said this, I have no complaints with my single stage Pac exhaust brake and as long as it continues to function, like it does.

Question: Which makes the most noise during application, engine or exhaust brake and notice signs here and there that forbids their use.

[tropical36]

Bill.Satellite wrote:
A Jake Brake is NOT, in any form, an exhaust brake. If the OP actually has a Jake Brake then it has nothing at all to do with his exhaust. A PAC brake is a completely different animal from the Jake. A Jake Brake uses the engines own compression cycle to slow the coach. No fuel is injected so the compression cycle works against the rotation rather than adding to it during ignition and slows the coach using the engines compression cycle.

Click here...
and here...

[DrewE]

I think the OP means that the on-off switch doesn't feel like it's switching (the lever or rocker is loose and doesn't snap into position, say), while the high-low switch clicks properly but has no apparent effect because the system as a whole is stuck off.

From the description, it sure sounds to me like the switch simply broke or wore out and needs to be replaced. It should be a pretty straightforward and inexpensive thing to fix. It would also be quite straightforward to check with an ohmmeter as ivylog mentioned.

[William_B]

I am confused with the OP's statement that the on/off switch doesn't seem to work, but the high/low does?? If you can't turn the Jake on then the high/low wouldn't work. The high/low is simply a choice of whether to use 3 cylinders, low, or all 6 cylinders, high. If the high/low switch works then obviously the on/off switch works. Remember your foot has to be completely off the accelerator for the Jake to work at all.

[Executive45]

Mine has three switches for the engine brake. One switch is simply an ON/OFF switch. This switch obviously activates the engine brake. The other switch, next to it is the high/low switch which regulates whether the brake controls all six cylinders or just three. The third switch is the floor pedal which also activates the engine brake. Normally, I leave the ON/OFF switch in the OFF position. This allows the engine to cruise when I let off the throttle. If necessary, I press the foot pedal which activates the brake. That said, it appears your ON/OFF switch may have failed. I would start with checking your fuse panel(s) first. One in the front compartment and another in the engine bay. Make sure all fuses and breakers are good. Use a meter. If they check ok, then remove the panel and check the wiring under the switches. Sometimes they simply come unhooked and other times they fail. Switches themselves will fail also. You should have Carling switches but they will have proprietary Monaco numbers on them. You'll have to call Monaco to get the corresponding Carling numbers if you want to replace them from someone other than Monaco. Northwest RV in Eugene carries them and they are pretty inexpensive thru them...Dennis

[Canadian_Rainbi]

And to add to the confusion our 2002 Itasca Horizon with the 5.9 Cummins ISB, the switch is labeled "Engine Brake" but is in fact an Exhaust brake.

[lanerd]

Actually Bill, Jacobs makes an exhaust brake also.... so it "could" be called a "Jake" brake too. I know, I know, everybody considers the engine brake as being the Jake brake. Just thought I'd throw that out there. For a newbie, it could be confusing.

And DG, I don't think I've ever heard of a MH that had both.

Ron

[Bill_Satellite]

A Jake Brake is NOT, in any form, an exhaust brake. If the OP actually has a Jake Brake then it has nothing at all to do with his exhaust. A PAC brake is a completely different animal from the Jake. A Jake Brake uses the engines own compression cycle to slow the coach. No fuel is injected so the compression cycle works against the rotation rather than adding to it during ignition and slows the coach using the engines compression cycle.

[Big_Katuna]

I have had posting issues with rv.net the past few days. Use Woodalls.net instead.

[tropical36]

becker wrote:
I have tried posting this message 3 times. The administrator says he does not know why it will not post. He said to resend it. I am retyping everything to see if I included some unsupported characters.

I am on the road. I have a 2008 Monaco Dynasty 425hp Cummins with a Allison 3000 MH 6-Speed World Transmission and Electronic Shifter. Normally on steep downhill grades I can flip the Jake Brake on and it will hold the speed I want, normally 50mph. Now it will not only not hold the speed but the switch feels like it is not connected. I can flip it back and forth and nothing happens. There is a second Jake Brake, HiLo switch, and it works fine, next to the Jake Brake that I use for speed retention and to slow down when I approach a town speed post. I generally only use the second Jake Brake when I am below 40mph and it takes me down to 15mph and then turns me loose.
My question is has anyone else experienced this and is it something I can fix? I appreciate your input. Maybe all of a sudden I am not operating them correctly.

You're being somewhat confusing in referring to a brand name for describing a retarding system of braking, but with what you're saying, it sounds like this Jacobs brand, you speak of is actually two different systems. One is an engine brake and the other is a two stage exhaust brake. Also sounds like the exhaust brake is working and the engine brake is not. Either that or it's only an engine brake and the one sw. works in conjunction with the other.
I only have a single stage exhaust brake, made by Pac and leave it on all the time. Not only does it serve me better by doing so, I'm hopeful that it won't freeze up with constant use and save my wheel brake linings, as well. I do smear some lube on the movable parts, once in a while and that should help it some, also.
As for your problem, someone should be able to chime in with some words of wit here, once it's figured out. I'd probably begin with said switch and to see if there was power available on one side and if the switch itself, was indeed working. Then go from there, back to the engine.