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Old 02-07-2013, 07:10 AM   #1
Join Date: Nov 2012
Posts: 78
Exaust brake question

1) Does the Cat exaust Brake require any servicing?

2) Does the cruise control have to be switched off for the exaust brake to function?
3) The exaust brake is not working--where would I begin trouble shooting?

Wayne Cadieu
2008 Allegro Bus 43 QRP
Cummings ISL
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Old 02-07-2013, 07:24 AM   #2
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There is an actuating rod that should be lubricated with a high temp lube. There is a specific lube sold by PAC Brake but there are others. Whether the brake will work with the CC on depends on how the engine ECM is programmed. You can manually actuate the brake to check function but I don't know the drill. If yours is PAC Brake brand check their web site.

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Old 02-07-2013, 07:31 AM   #3
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I would start by getting pacbrake lube or an equivalent lubricant. Coat the actuator shaft thoroughly as well as any pivot points. To work the lubricant into the unit use a pair of pliers to work the actuator several times. It may have just stuck due to lack of TLC.
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Old 02-07-2013, 06:30 PM   #4
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Depends on your exact setup because there are different ways it can be done - ie variable geometry turbos, but if yours is the conventional butterfly valve in the exhaust pipe, yes, there are 4 points that need lubricating. I couldn't find the right lubricant so use graphite spray instead.
Inside the cylinder is a very strong spring and mine is very hard to override.

The cylinder is controlled by a 12v solenoid valve so you could find it and disconnect the feed and power it up with a lead to see if the air+mechanicals are working properly.

On my rig, the cruise control will cause the exhaust brake to function and the exhaust brake will then trip the cruise control off so I never use both at once.

What isn't working?

Does the transmission select second gear when you lift your foot. Yes or no.

Does it seem to not be working because you come over the top of a hill at 65 and nothing appears to happen when you lift the foot.

Can you or someone else watch the exhaust brake while you are driving to see what is actually happening

Give us some more idea of what the symptoms are.
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RVs. USA - Airstream Cutter; in Australia - MC8 40' DIY Coach conversion & OKA 4x4 MH; in Germany - Hobby Class C; in S America - F350 with 2500 10.6 Bigfoot camper
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Old 02-09-2013, 04:34 AM   #5
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I have a 3126e 330 hp in a 2002 Newmar 3852 and the exhaust brake works with the cruise control on and does not kick the cruise off when it engages. When I lift my foot off the accelerator it per selects second and begins downshifting. Seems to work very well. I will ask my mechanic about lubricating the mechanism. Good thread !
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Old 02-10-2013, 07:37 PM   #6
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Mystery, some years of Freightliner chassis , activate the brake lights when the exhaust brake engauges, and so the cruise has to be resumed after the exhaust brake is used.

cadiwa, there are , fuses, switches , relays , air solinoid and the air cyl involved, in the exhaust brake operation. As Tony Lee asks, if the trans gear indicator shows 2nd gear when the switch is on and the coach is coasting at over 30 MPH, then at least the trans control is seeing the switch and you can start looking around for possible other issues.
Could be as simple as a burnt through air line between the solinoid and the air cylinder. Others have had that problem.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.
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Old 02-11-2013, 07:34 PM   #7
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My Cat owners manual says if you use your exhause brake regularly you don't have do do maintenance on it. Otherwise, there are lube instructions to follow.

My exhause brake does work when the cruise is on, does turn on the brake lights, and the resume button needs to be re-activated to resume cruise.
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Old 02-12-2013, 09:15 AM   #8
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My '02 3126 does work with cruise. Problem is if TPS closes due to a slight downgrade the exhaust brake comes on. Therefore it isn't of value while using cruise. If I forget, and it activates the cruise does not need to be resumed.

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