Engine/Transmission (1998.5 - 2002) exhaust brake hisses

[pencilplug]

When my 2001HO is at idling with the brake on I hear a hiss normal or not

 

[phantomusa]

Turn your brake off when idling

 

[pencilplug]

When the brake is off it don't hiss

 

[phantomusa]

There you go you fixed it

 

[RustyJC]

Normal.

Rusty

 

[DenverPilot]

Normal. Can't completely block the exhaust or the engine would quit.

 

[MLee]

Also when its on, in cold weather, it will help your engine warm up quicker. Kind of slows down the air in and air out scenario. And yes it will hiss then to.

 

[B.G. Smith]

Mine is 06 and It does sound different when idling with the brake on but it doesn't hiss. I think it runs on three cylinders when cold and brake on. I would check the clamp before and after the brake. One of mine failed a few years back. * * bg*

 

[RustyJC]

The Mopar/Jacobs exhaust brake on my 2002 ETH/DEE dually was controlled by the ECM, was closed at idle and did have a pronounced "hiss". This is normal for this particular brake on the 2nd generation trucks. It was touted as a feature to speed warm-up of the truck after a cold start.

Rusty

 

[p-Bar]

Mine has a hissy fit when idling too, very normal

 

[DenverPilot]

The Mopar/Jacobs exhaust brake on my 2002 ETH/DEE dually was controlled by the ECM, was closed at idle and did have a pronounced "hiss". This is normal for this particular brake on the 2nd generation trucks. It was touted as a feature to speed warm-up of the truck after a cold start.

Rusty

Usually they were installed with an activation switch. Sounds like yours was on all the time?

The former owner of my truck spent the big bucks ($100) to get a correctly sized Jacobs pull knob switch to go right on the stick shift.

Wonderful for control in the mountains, or additional braking in town without the trailers, and then clicking it off at the stop light.

The original activation switch is still wired in parallel and down on the floor console but I just ignore it most of the time.

Nice setup for towing. Just click it on when needed while still running the gears if needed at the same time.

 

[RustyJC]

Usually they were installed with an activation switch. Sounds like yours was on all the time?

The former owner of my truck spent the big bucks ($100) to get a correctly sized Jacobs pull knob switch to go right on the stick shift.

Wonderful for control in the mountains, or additional braking in town without the trailers, and then clicking it off at the stop light.

The original activation switch is still wired in parallel and down on the floor console but I just ignore it most of the time.

Nice setup for towing. Just click it on when needed while still running the gears if needed at the same time.

Ummmm, no, it wasn't on all the time, but when it was, it hissed at idle.

Rusty

 

[DenverPilot]

Ummmm, no, it wasn't on all the time, but when it was, it hissed at idle.

Roger. Understood.

 

[pencilplug]

Thanks for the input it is a Mopar Jacobs the few time in the cold I did turn it on and the truck seemed to get warmed up a little better

 

[DenverPilot]

Thanks for the input it is a Mopar Jacobs the few time in the cold I did turn it on and the truck seemed to get warmed up a little better

If you dig through the back issues of TDR you'll find some old articles comparing available exhaust brake systems on the older trucks.

The Achilles heel of the Jacobs is that it requires a vacuum pump and line leaks or even failure of the pump is a pain.

Many carry a shorter fan belt that will fit WITHOUT going around the vaccuum pump for on-road/on-trip roadside repair. Deal with the dead vaccuum pump once you're back home.

Other systems available at the time did other things like electrically driven vaccuum pumps not attached to the belt drive system, etc.

 

[RustyJC]

We're discussing 2nd generation trucks. They do not use a belt driven add on vacuum pump.

Rusty

 

[DenverPilot]

We're discussing 2nd generation trucks. They do not use a belt driven add on vacuum pump.

Rusty

Are you thinking third gen? Second gen Jacobs that was the Cummins-approved setup (didn't void Cummins warranty - available at any Cummins shop as an add-on for the trucks in that 98-02 year range) was definitely engine belt vacuum pump driven.

BD and PacBrake made air compressor driven models also at that time which Cummins didn't approve of, that today are a cheaper replacement with the vaccuum pumps being over $1000 to replace in the Jacobs branded one. (Not exactly worried about Dodge/Cummins warranty now, 16 years later. Heh...)

I can take a photo of the Jacobs sticker and the pump on mine if you like. It was installed a week after the truck was purchased new by the original owner. Have the receipt for that around here somewhere too.

Good system. Controlled by the ECU natively. Shuts off at throttle input of any kind until TPS is at idle for a couple of seconds. But when that pump goes... probably not worth the money to fix it.

A quick Google will show posts (even here) on forums telling folks no to bother fixing them clear back in 2007 timeframes. All in second gen sub-forums.

 

[NIsaacs]

available at any Cummins shop as an add-on for the trucks in that 98-02 year range) was definitely engine belt vacuum pump driven.

I can take a photo of the Jacobs sticker and the pump on mine if you like. It was installed a week after the truck was purchased new by the original owner. Have the receipt for that around here somewhere too.

But when that pump goes... probably not worth the money to fix it.

If your belt drive add on vacuum pump goes south just remove it and use the oem that all 1st and 2nd gen trucks have. Not sure why yours has an add on.

Nick

 

[RustyJC]

If your belt drive add on vacuum pump goes south just remove it and use the oem that all 1st and 2nd gen trucks have. Not sure why yours has an add on.

Nick

Exactly. The Mopar/Jacobs e-brake on my 2002 tied into the factory vacuum system that was used for the HVAC controls. No belt driven add-on pump.

Rusty

 

[DenverPilot]

If your belt drive add on vacuum pump goes south just remove it and use the oem that all 1st and 2nd gen trucks have. Not sure why yours has an add on.

Nick

Maybe I'm misunderstanding the info out there. Numerous people say to simply bypass it if it fails.

But is that pump stock and used for other things on the truck? (I'll be honest, I've never looked, but is it plumbed to the brakes or something else? I can't see a use for a stock vacuum pump on a diesel, but if it's a stock pump I'm guessing brakes? I can't think of any other system that needs vaccuum.)

This all may be my misunderstanding of the info out there. I was under the impression it was added for the exhaust brake because I can't think of what else it's used for, and also because folks in all sorts of threads everywhere say to bypass it if it fails until you get to your destination. What else fails along with it, besides the exhaust brake?