BD Exhaust Break additional to Retarder?

Topic: BD Exhaust Break additional to Retarder? (Read 956 times) previous topic - next topic

BD Exhaust Break additional to Retarder?

October 31, 2017, 02:41:12 am

Ok peeps, I am a newbie, real new, two weeks to be exact and this is my first ever forum post. I would like to have asked the previous (2nd) owner of the coach, but after finding out he was unaware of the two modes on the Trans I decided to gain my knowledge from other sources..... The owners manual is chock full of all sorts of treasures and invoices, extras, tires receipts and maint. to include the installation of an after market exhaust Brake....
Here is my question; I my quest to try and understand the multitude of systems switches etc... I discovered my coach has a Banks System, naturally the Allison Trans Retarder.... But also a BD Exhaust Break. I guess similar/almost redundant systems are safer, but I have no idea where the controls for the BD system are to even assure it functions. Any guidance would be appreciated.

Re: BD Exhaust Break additional to Retarder?

Reply #1 – October 31, 2017, 09:05:59 am

CD,

Welcome to the ForeForum.

Please tell us what coach you have-- a good idea to put it in your signature.

And, if fit from the factory with an "R" transmission (retarder) the exhaust brake will have been added after it left the factory. So, unlikely we will know how they wired it.

Have you physically verified that you DO have an exhaust brake? Looked for switch near driver's area?

Re: BD Exhaust Break additional to Retarder?

Reply #2 – October 31, 2017, 10:17:06 am

CD,

Welcome to the group! You have a '99 U270, so you will have the Cummins 8.3L turbo diesel. Although we don't have a retarder, your engine compartment should look similar to ours. Photos below show the exhaust brake fitted to our coach. Lift up your bed, and see if you see anything like that installed somewhere in the exhaust pipe between the turbo and the muffler. If you do, then you do have a exhaust brake. Whether it works or not is another question...

The control for my exhaust brake is pretty obvious. It is mounted on the wall next to the driver seat. Your switch may be more "stealthy".

Re: BD Exhaust Break additional to Retarder?

Reply #3 – October 31, 2017, 10:31:13 am

Link below to the BD Performance exhaust brake page. On that page there is a link to the installation instructions. Apparently the only "control" for the brake that you would be likely to notice in the driver area would be a "ON-OFF" switch of some kind. Might be a toggle switch, push-pull switch, or a rocker switch - no telling. Could be located anywhere. If you can take and post some photos of the dash area of your coach showing all the switch panels, we can tell you if we see any non-stock additions.

1027124 - Exhaust Brake - Motorhome 8.3L Air/Remote 4in Exh. 65psi

Re: BD Exhaust Break additional to Retarder?

Reply #4 – October 31, 2017, 01:59:56 pm

If you find the control switch, then it's easy to test the brake.

You'll need to have the air system pressure up - showing at least 100psi on both dash gauges. With the bed raised up, have one person stand in the bedroom and watch the brake, while another sits in the driver seat. Turn ignition switch to "RUN" position - it's not necessary to have the engine running. Next, turn the brake control switch to "ON". The person watching the brake should see the air cylinder rod extend and the restrictor plate lever move to the closed position. If it's like mine, there will also be a loud "CLANK" noise when it moves. Next, have the "driver" step on the gas pedal. When you do that, the air cylinder rod on the brake should retract, probably with another loud "CLANK", and the brake opens. When driver lets off the gas pedal...the brake closes. Turn off the control switch (or the ignition switch) and the brake should go to the open (with cylinder rod retracted) position.

If the brake does not work, then you'll need to trouble shoot.

1. Check for good 12 volt at the control switch. If not present, look for a fuse holder on the power feed.
2. Turn the switch on up front, then check for power at the solenoid valve located adjacent to the brake assembly.
3. Check for sufficient air pressure at the air cylinder. Should be about 60psi - adjust supply line regulator if too low.
4. Check to make sure the brake is not "frozen" by rust or corrosion. The lever that is moved by the air cylinder rod should move freely.
5. Check for air leaks in any of the air lines, the regulator, and at the air cylinder rod seal.

Re: BD Exhaust Break additional to Retarder?

Reply #5 – October 31, 2017, 02:04:52 pm

Chuck,

If the exhaust brake is wired properly, you can not test the brake except when driving.

Proper wiring is from exhaust brake switch to Allison ECM to brake solenoid. Allison will only trigger exhaust brake in 2nd and higher gears, as it would stall the engine if engaged at idle.

I completely understand that since with as added aftermarket, we have no idea how it was wired.

Re: BD Exhaust Break additional to Retarder?

Reply #6 – October 31, 2017, 02:18:54 pm

Brett,

I realize some exhaust brakes are connected through the Allison ECU, and that the transmission has some input/control over the operation. In fact, this is the way my exhaust brake is supposed to operate. However, others are designed to operate independent of the transmission, such as when the vehicle has a manual transmission. In reading through the installation manual for the BD brake (found on the page linked above), I see no reference to any sort of interface between the brake and the transmission. Perhaps this particular brake was chosen for this coach because it also has a retarder. By keeping the exhaust brake operation completely divorced from the transmission, it would be possible to simultaneously operate both the exhaust brake and the retarder without any conflict. That, of course, is just supposition on my part.

IF the OP still has a BD brake (i.e. it wasn't removed), and IF it was installed strictly in accordance with the manual linked on their product page, then the simple operational test I described above should work. IF it is wired through the Allison ECU, then your statement is correct, and Step #2 in my operational test would fail (until the coach is being driven in 2nd gear or above).

Re: BD Exhaust Break additional to Retarder?

Reply #7 – October 31, 2017, 02:27:17 pm

Chuck,

Ya since not OE, all we can do is speculate. Just would hate to see him condemn the exhaust brake only to find out it is wired through the transmission and is operating as it should.

Bottom line, he needs to determine what he has and how it is wired. That would start by physically verifying that there is an exhaust brake (will be bolted to the turbo on the exhaust side).

Re: BD Exhaust Break additional to Retarder?

Reply #8 – October 31, 2017, 08:19:23 pm

While I was working for Foretravel We had a customer with I believe a 97 u270 that did not like the retarder so had it removed and had an exhaust brake installed. This was done in Tampa FL.

Re: BD Exhaust Break additional to Retarder?

Reply #9 – November 01, 2017, 12:23:02 am

Ok, first and foremost (no pun intended) I really appreciate the helpful responses. I will try and clarify all above...
Yes Mr. Wolfe, I stumbled across the BD pamphlet in some misc. paperwork stuffed in the owners manual. Being rather an odd thing, I ran our to the coach and indeed the Exh, Break is physically present. I took your fyi and updated signature quickly, thank you.
The OE Retarder is still in place and works like a charm, love it!

Tonight, I dug further into the tote containing the owners manual, 3 other ringed note books and loose paperwork to find the original invoice to install the BD system back in '07. No wiring diagram but several notes relating to a 12v toggle switch on the dash...of which I have 2 or 3 that are not labeled..... Mr. Chuck, I will heed your suggestion and take a picture of the dash tomorrow... The switch should be one of the 2 or 3 unmarked.

I will check tomorrow based on your replies, and update tomorrow pm.

Any hypothesis as to why one would spend the time and funds to create a redundant system unless paranoid mountain driving?
Insight invited...Update tomorrow & thank you all, this has been very positive and I appreciate it!

Re: BD Exhaust Break additional to Retarder?

Reply #10 – November 01, 2017, 11:18:12 am

Exhaust brake could supplement retarder at higher RPM to keep transmission fluid temps lower. Exhaust brake isn't very effective at low rpms.

Re: BD Exhaust Break additional to Retarder?

Reply #11 – November 01, 2017, 11:29:52 am

Quote from: Old phart phred – November 01, 2017, 11:18:12 am

Exhaust brake could supplement retarder at higher RPM to keep transmission fluid temps lower. Exhaust brake isn't very effective at low rpms.

Agree, for heavy rigs with heavy toads [because toad brakes are not being used, if using lever for retard], use of retarder can cause high transmission temps, An exhaust brake will take some load off retarder. I would have no problems using both.

Re: BD Exhaust Break additional to Retarder?

Reply #12 – November 01, 2017, 12:35:31 pm

Ya, I have absolutely nothing against both transmission retarder and exhaust brake.

BTW, the new generation PacBrake PRXB does work quite a bit better at low RPM than any previous exhaust brake. With a second valve, it is able to generate full back pressure and therefore braking HP at lower RPM. I was one of the first guinea pigs/testers when the PRXB came out.

Re: BD Exhaust Break additional to Retarder?

Reply #13 – November 01, 2017, 01:23:13 pm

Quote from: wolfe10 – November 01, 2017, 12:35:31 pm

BTW, the new generation PacBrake PRXB does work quite a bit better at low RPM than any previous exhaust brake. With a second valve, it is able to generate full back pressure and therefore braking HP at lower RPM. I was one of the first guinea pigs/testers when the PRXB came out.

The BD tech doc I linked up above implies that the BD brake also incorporates some sort of variable back pressure control. They refer to it as "BD's exclusive Variable Orifice Technology" but don't go into any detail on how it works. Probably a good thing it has it, because the BD brake is rated at 65psi (maximum) back pressure, and the "strong" Cummins exhaust valve springs in the OP's 8.3L are designed to hold "up to" 60psi. I doubt you would ever see more than 60psi back pressure in normal operation, but I suppose it is possible.

Re: BD Exhaust Break additional to Retarder?

Reply #14 – November 01, 2017, 01:36:28 pm

Ya, VERY important that max back pressure not exceed the engine manufacturer's specs for that engine. And I now with some engines, including the Caterpillar 3116 in our 1993 U240, even a few engine serial numbers different can really change permissible back pressure.

Re: BD Exhaust Break additional to Retarder?

Reply #15 – November 01, 2017, 02:01:45 pm

We had a nice discussion about exhaust springs here about a year ago (see link below). Dave Head stated, speaking from his experience with his PRXB, that around 1993-94 Cummins went to the heavy exhaust springs on the 8.3L. My '93 model coach does not have the strong springs, but I am OK because my D-Celerator exhaust brake is fitted with the optional 35psi back pressure control spring.

I think the OP would be safe in all normal ops, but he might want to avoid engaging the BD brake at his engine's maximum (Governor Break) RPM (2450 for my C8.3).

D-Celerator Exhaust Brake.

Re: BD Exhaust Break additional to Retarder?

Reply #16 – November 01, 2017, 02:07:03 pm

I need to check with Cat on my allowable back pressure when I get a round tuit. I do have a dash mounted pressure gauge that I haven't quite figured out, its got a redline pointer at about 35 psi so maybe indicates the back pressure. Will have to take a look see this Saturday when its warmer. The mountain tamer exhaust brake has a morse cable "throttle" that's marked min & max that changes the stroke on the guillotine valve, so maybe I can stroke it further at lower rpms.

Re: BD Exhaust Break additional to Retarder?

Reply #17 – November 01, 2017, 04:16:14 pm

Quote from: Old phart phred – November 01, 2017, 02:07:03 pm

I do have a dash mounted pressure gauge that I haven't quite figured out, its got a redline pointer at about 35 psi so maybe indicates the back pressure.

The gauge could read exhaust back pressure, or intake manifold boost pressure. Shouldn't be hard to figure out. Does it vary up and down all the time you are driving, or only when you engage the exhaust brake?

Re: BD Exhaust Break additional to Retarder?

Reply #18 – November 01, 2017, 07:59:44 pm

Bingo, we have winner here. It's an exhaust back pressure gauge even though it's factory labeled oil pressure. It's got a red line at 29 PSI. It's a mechanical gauge and the pressure tube has broken off. That would explained some soot, the sound I heard when it was engaged, and the Very faint odor of exhaust that I smelled when the exhaust brake was working. I guess I'm kinda dense but the drive home, I was totally focused on driving. I will post some photos tommorow in a new thread.

Re: BD Exhaust Break additional to Retarder?

Reply #19 – November 05, 2017, 01:18:34 am

Sorry for the delay & follow up! Had a Granddaughter that needed her first puppy and I got hung up in the hunt...
I believe I located the switch, but at idle or low RPM there is no perceptible actuation of the valve. I believe Old phart phred reply #10 may have hit the nail on the head on the "Why". Thanks, that makes sense, to use possibly 4,5,6th gears and cuts out where trans break would start cutting into it effective range(s). Being a new coach to me, I plan on having the first service/wellness check performed by a local Cummins shop and I am sure they can confirm its specific set up and parameters.

I am grateful for all the very valid input, it was enlightening for a newbie, and I am thankful for the support.
Excited to read & learn more!

CD

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