2005 journey exhaust brake

Deucenut · 08-10-2013, 07:06 PM

Recently we went up and over two mountain passes. With my exhaust brake switch on I take my foot off the gas pedal and the Mh gears down and starts to slow. I was curious as to how much the exhaust brake was was actually working as opposed to the transmission downshifting and the engine decelerating to slow the Mh. So while going down a moderate hill, with the transmission in 4th gear I was going too fast for the transmission to gear down. So I flipped the exhaust brake switch on and the transmission stayed in 4th gear due to rpm's. I was able to only very very slightly feel any deceleration when I flipped the exhaust brake on and off.

So my question is this: does the exhaust brake actually slow the Mh down or is it just a mechanism for the computer to tell the transmission to downshift, thereby slowing the motorhome.

jlfbatonrg · 08-10-2013, 07:21 PM

The transmission downshift is part of the exhaust brake function. The exhaust brake causes back pressure in the engine exhaust system that retards the speed of the coach. It works best when the engine rpms are high. Therefore, the transmission downshifts to increase the engine rpms and increase the effectiveness of the exhaust brake.

Deucenut · 08-10-2013, 07:25 PM

I understand it is supposed to create back pressure and higher engine rpm's cause this. But when I flipped the switch in the above situation, the rpm's were already about 2200..and I couldn't really feel any deceleration.

grtharris · 08-10-2013, 07:58 PM

You might should check your exhaust brake to verify that the cylinder and linkage are working correctly. If I remember right it made a big different is slowing down with the exhaust brake on.

1ciderdog · 08-11-2013, 11:27 AM

Were you towing your car trailer and was the grade kind of steep? I travel the southern Oregon mountains and often the exhaust brake is not sufficient to slow us down, especially in upper gears.

Deucenut · 08-11-2013, 11:59 AM

Quote:

Originally Posted by 1ciderdog

Were you towing your car trailer and was the grade kind of steep? I travel the southern Oregon mountains and often the exhaust brake is not sufficient to slow us down, especially in upper gears.

This time we weren't towing anything. Grade at the time was probably 2-3% downhill.

1ciderdog · 08-11-2013, 03:44 PM

The faster you are going the less the brake seems to work. I can tell the exhaust brake is working on mine but it doesn't seem like it helps much at 60 mph but down at 40 it grabs pretty well and is noticeable. As a wild guess it could be the butterfly is not closing as it should and may need to be lubricated.

Deucenut · 08-11-2013, 05:06 PM

Quote:

Originally Posted by 1ciderdog

The faster you are going the less the brake seems to work. I can tell the exhaust brake is working on mine but it doesn't seem like it helps much at 60 mph but down at 40 it grabs pretty well and is noticeable. As a wild guess it could be the butterfly is not closing as it should and may need to be lubricated.

So how do I get to that?? Is it under the bed or through the closet? What would you suggest to lubricate it with?

skigramp · 08-11-2013, 06:59 PM

I can't remember for sure ... but I think you remove the "top step" and the inspection cover below it ... (it might be the closet but I don't think so)

I bought some high temp spray lubricant and sprayed on mine when I thought it was not working correctly ... I think I bought it at NAPA ... small can lasts a lifetime

FIRE UP · 08-11-2013, 07:01 PM

Quote:

Originally Posted by Deucenut

So how do I get to that?? Is it under the bed or through the closet? What would you suggest to lubricate it with?

Hey Duecenut,
Like Ciderdog says, it many times depends on the grade, the speed your traveling at when the E/B is engaged. It will definitely have different effects at different speeds and different gears, depending on the exact gear you're in when engaged. If I'm cruising along at about 65 and start down a grade of say, about 5-7%, she'll automatically hit 5th when the E/B is asked for and hold it, or, start to creep down in speed 'till it hits around 61 or 62, then it will self program down to 4th and, the RPMs jump to about 2500.

Like he says too, many times the E/B is not sufficient enough for desired braking or speed so, I tap the service brakes a time or two to give it some assistance in slowing down. A diesel in and of itself does not normally do much in engine braking due to inherent design. Gas engines will actually do better as basic engines. That's why exhaust brakes and "Jake" brakes (Compression brakes) are such an enhancement on diesel engines.

As far as gaining access to the exhaust brake on your engine, you'll have to do what you have to do on your particular setup. Many of these coaches have different procedures to gain access to the engine and upper components. But, once you do, you'll see that exhaust brake, right next to the turbo. It's a horizontal cylinder with a plunger emerging from it that attaches to a lever, that's right in the middle of the exhaust pipe, very close to the turbo. You can't see the butterfly valve 'cause it's inside the exhaust pipe.

Although I've never actually done it, a couple of tests can be done to watch the exhaust brake activate the lever. You'll have to have access to some compressed air, (home air compressor etc.) and you'll have to remove the air line to the cylinder. Then, apply air pressure via a nozzle you attach to the air line from your compressor. If done correctly, you should see quite a swing in that lever as the plunger emerges from the cylinder. If the lever appears to have a full 90 degree swing, your exhaust brake is activating fully. If it only moves a slight amount, your exhaust brake is not and needs attention of some sort and or, some maintenance.

As far as what to use as a lube. If you do a search on ebay for "Exhaust Brake Lube" you'll find a company that sells a small bottle for around $10-$13.00, plus or minus a bit. I've recently heard that someone purchased some from a Freightliner dealer. I've yet to see what that product is. So, good luck and please post what you find out.
Scott

Jupiter · 08-11-2013, 11:14 PM

Quote:

Originally Posted by Deucenut

So how do I get to that?? Is it under the bed or through the closet? What would you suggest to lubricate it with?

FWIW - I can access mine (05' 39K) under the bed, but I must say that I never considered lubrication

cheers,
Joopy

grtharris · 08-12-2013, 06:53 AM

Should be lubed at every oil change. Here is a link to the Maintenance Tips.
http://www.pacbrake.com/PDF/L5300.PDF
I used SUPER LUBE Synthetic Lubricant.

1ciderdog · 08-12-2013, 10:26 AM

Quote:

Originally Posted by Jupiter

FWIW - I can access mine (05' 39K) under the bed, but I must say that I never considered lubrication

cheers,
Joopy

On my 39K the access the is under the bed as mentioned here. It is covered by a metal plate about a foot square (if I remember correctly) and held down by four bolts. Located towards the foot of the bed to the rear of the coach.

cbeierl · 08-12-2013, 11:25 AM

Here's the Pacbrake lube on ebay: PACBRAKE SUPERLUBE EXHAUST BRAKE LUBRICANT LUBE OIL