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Strange problem with exhaust brake in a 1995 Intrigue

Yahoo Message Number: 23908
We took our coach to a local Cummins Service Center in Greensboro, NC, to have the exhaust brake fixed. It turned out to be missing altogether, so a new one was installed. While driving it home on Friday, we had a very strange problem that happened twice. With the exhaust brake switched on, and then activated by slowing down, the coach was put into a state where it could not generate sufficient power to shift out of 1st gear, even when the brake was turned off.
There seems to be a funny interaction with headlights and/or radio, for both times this happened it turns out that I had to turn them of off to resolve the problem. And, when at least the headlights were off, the exhaust brake seemed to work properly.

In each case, I pulled over to the side of the road or into a big parking lot, turned off the radio (to be able to hear), and found that the engine wouldn't go above 1500 RPM. Switching off the brake and the headlights released the problem. (Had to turn the lights on because it was raining intermittantly!)
I intend to call Cummins on Monday and will take it back if necessary, but thought it would be worth while asking whether any of you have had a similar problem.

Bill Davis

1995 Intrigue #1096

Re: Strange problem with exhaust brake in a 1995 Intrigue

Reply #1 –
Yahoo Message Number: 23911
Hi Bill,

This issue is clearly pointing to the +12vdc distribution from the chassis battery and /or the grounding. Measuring voltage in the exhaust brake system while exercising the the radio and headlights should confirm this. Good electrical ssytem schematics are needed to solved your condition.
Fred Kovol

Re: Strange problem with exhaust brake in a 1995 Intrigue

Reply #2 –
Yahoo Message Number: 23916
What, exactly, do you mean by "it turned out to be missing altogether..."?

Mike

cwmdavis wrote:

Re: Strange problem with exhaust brake in a 1995 Intrigue

Reply #3 –
Yahoo Message Number: 23917
Quote from: Mike Cebula
What, exactly, do you mean by "it turned out to be missing altogether..."?

Mike
Missing, as in broken off. The mechanics were gone when I picked the coach up, so don't yet know much more than that.

Bill

Re: Strange problem with exhaust brake in a 1995 Intrigue

Reply #4 –
Yahoo Message Number: 23921
The exhaust brake I have on my '95 Magna is inserted in the exhaust ahead of the muffler.
It is about 4" long and has a butterfly valve that blocks the exhaust when activated. I assume that part was still on - otherwise you would have had a horribly loud exhaust.
The external part of the brake is an air cylinder (which I assume is the part that was not there) that activates the butterfly valve. It is connected to a quick release valve which in turn is connected to an air valve a few feet away via an air line. That air valve is mounted on a frame rail in the engine compartment and the 12V or 24V solenoid on it is the main activator for the exhaust brake. When it is picked, air goes to the air cylinder and closes the butterfly valve - completely. When the solenoid is dropped, the air quickly escapes and the air cylinder relaxes and a heavy spring re-opens the butterfly valve. It is when that butterfly doesn't open that you have power problems.
IF that air valve has a quick release feature of its own, the quick release valve on the air cylinder is deemed not necessary. However, if that air valve doesn't have the quick release port on it, then the air cylinder on the exhaust brake MUST have the quick release valve on it. Got to have at least one place where a quick release valve is installed and working. If only one, the air valve on the frame is the preferred location for releasing the air.

Since your setup wasn't working for a while, it's also possible that the air valve is defective - either the valve itself is gummed up or the solenoid is weak/defective.
Have someone else start the engine and you should be able to physically see the air cylinder on the exhaust brake cycle on then off immediately after starting the engine if the switch near the driver is turned on. (I think it may even do this with the switch off - not sure - never checked for that.) With a new exhaust brake that has clean not-yet-sooted up butterfly metal, this should also be very audible if you are near it.
As far as electrical, at various times on my '95 I traced intermittent problems to the middle fuse strip in the forward compartment. That strip is fed via a relay located above the first strip. The relay is activated by the ignition switch being turned 'on'. The connection to pick that relay right on the relay was loose at one time and was intermittently dropping the relay. That meant that everything on that middle strip was being blinked on/off. The most noticeable failure that clued me in was the dash gages completely turning off then back on. Other items were affected but not noticed because they weren't in use. I believe power to the air valve solenoid for the exhaust brake goes through that strip too. After finding that loose nut on the relay, I tightened every screw and nut in that compartment and found some more that were a little more loose than I liked. Just be careful to not short out anything - rather tight and awkward in there.
Age is the enemy in this case. I don't doubt I have a screw or two loose too.....

Mike

cwmdavis wrote:

Re: Strange problem with exhaust brake in a 1995 Intrigue

Reply #5 –
Yahoo Message Number: 23924
When you say the coach would not generate enough power to shift out of first, are you sure the exhaust brake is not sticking in the closed position? I had that problem on my coach, and the symptom is no power, and black smoke powering out of the exhaust. I would check that the exhaust brake moves smoothly, and I would lubricate it with Superlube synthetic lubiricant (made by Synco).

Al Colby

2000 Intrigue 10979

Quote from: cwmdavis
We took our coach to a local Cummins Service Center in Greensboro, NC, to have the exhaust brake fixed. It turned out to be missing altogether, so a new one was installed. While driving it home on Friday, we had a very strange problem that happened twice. With the exhaust brake switched on, and then activated by slowing down, the  coach was put into a state where it could not generate sufficient power to shift out of 1st gear, even when the brake was turned off.

There seems to be a funny interaction with headlights and/or radio,  for both times this happened it turns out that I had to turn them of off to resolve the problem. And, when at least the headlights were off, the exhaust brake seemed to work properly.

In each case, I pulled over to the side of the road or into a big parking lot, turned off the radio (to be able to hear), and found that the engine wouldn't go above 1500 RPM. Switching off the brake and the headlights released the problem. (Had to turn the lights on because it was raining intermittantly!) I intend to call Cummins on Monday and will take it back if necessary, but thought it would be worth while asking whether any of you have had

Re: Strange problem with exhaust brake in a 1995 Intrigue

Reply #6 –
Yahoo Message Number: 23925
When you say

1 intermittant rain

2 no problem until brake was actuated 3 brake stayed on until lights were turned off
Sounds like there is a partial short (due to rain?) between lights and brake ckt. There is not enought voltage to turn brake on but there is enough to hold it on. (Usually about 70 to 80% voltage will hold a solenoid. sometimes less) I would look in compartment under driver as that might be most susceptable although it could be anywhere in the length of the coach. Anyway, most likely where it can get wet. If you can wait, give it a few days to dry out and try it again.

Good luck

Dave Tuttle (aka billy byte, my trusty hound) 2000 Allure 30443

Re: Strange problem with exhaust brake in a 1995 Intrigue

Reply #7 –
Yahoo Message Number: 24122
Bill,

Have you had resolution on this yet?
I'm curious if the 'missing' parts were a result of a problem that was 'solved' by disabling the exhaust brake instead of fixing the problem.

Mike,

'95 Magna #5266

Quote from: Mike Cebula
The exhaust brake I have on my '95 Magna is inserted in the exhaust ahead of the muffler.

It is about 4" long and has a butterfly valve that blocks the exhaust when activated. I assume that part was still on - otherwise you would have had a horribly loud exhaust.

The external part of the brake is an air cylinder (which I assume is the part that was not there) that activates the butterfly valve. It is connected to a quick release valve which in turn is connected to an air valve a few feet away via an air line. That air valve is mounted on a frame rail in the engine compartment and the 12V or 24V solenoid on it is the main activator for the exhaust brake. When it is picked, air goes to the air cylinder and closes the butterfly valve - completely. When the solenoid is dropped, the air quickly escapes and the air cylinder relaxes and a heavy spring re-opens the butterfly valve. It is when that butterfly doesn't open that you have power problems.

IF that air valve has a quick release feature of its own, the quick release valve on the air cylinder is deemed not necessary. However, if that air valve doesn't have the quick release port on it, then the air cylinder on the exhaust brake MUST have the quick release valve on it. Got to have at least one place where a quick release valve is installed and working. If only one, the air valve on the frame is the preferred location for releasing the air.

Since your setup wasn't working for a while, it's also possible that the air valve is defective - either the valve itself is gummed up or the solenoid is weak/defective.
 
Have someone else start the engine and you should be able to physically see the air cylinder on the exhaust brake cycle on then off  immediately after starting the engine if the switch near the driver is turned on. (I think it may even do this with the switch off - not sure - never checked for that.) With a new exhaust brake that has clean not-yet-sooted up butterfly metal, this should also be very audible if you are near it.

As far as electrical, at various times on my '95 I traced intermittent problems to the middle fuse strip in the forward compartment. That strip is fed via a relay located above the first strip. The relay is activated by the ignition switch being turned 'on'. The connection to pick that relay right on the relay was loose at one time and was intermittently dropping the relay. That meant that everything on that middle strip was ]being blinked on/off. The most noticeable failure that clued me in was the dash gages completely turning off then back on. Other items were affected but not noticed because they weren't in use. I believe power to the air valve solenoid for the exhaust brake goes through that strip too. After finding that loose nut on the relay, I tightened every screw and nut in that compartment and found some more that were a little more loose than I liked. Just be careful to not short out anything - rather tight and awkward in there.

Age is the enemy in this case. I don't doubt I have a screw or two loose too.....

Mike