Section 10 --- Chassis Information
Cayman 2005
330
EXHAUST BRAKE
The Pac Brake exhaust retard system is an auxiliary braking device that is
attached directly to the engine turbocharger. The exhaust brake operates by using
a dash switch. The dash mounted switch will operate the exhaust brake when dash
switch is ON and throttle is RELEASED.
When the exhaust brake is activated, a flapper inside the exhaust brake moves
and restricts the flow of exhaust gases. This causes an increase of exhaust pres-
sure within the engine. Increased exhaust back pressure quickly slows the engine
speed resulting in powerful engine braking action. When the exhaust brake is acti-
vated, the amount of engine braking power developed is related to engine RPM.
When an exhaust brake application is made, the engine braking affect increases
with higher engine RPM.
The exhaust brake is wired to the electronically controlled transmission. When the
exhaust brake is activated going down a hill, it will help control road speed or suf-
ficiently slow the road speed until the Allison Transmission can automatically
shift to the next lower gear. Downshifting automatically occurs from high gear
down to second gear. Certain road conditions and engine speeds may require the
transmission be manually shifted down in order to generate adequate engine RPM
and increase the engine brake effect.
NOTE:
The brake lights will illuminate while the Exhaust Brake is applied.
NOTE:
Activating the Exhaust Brake switch will cancel the cruise control.
CAUTION:
Use of the exhaust brake on wet and slippery surfaces can result in over-braking
and loss of traction.
Maintenance
Moisture, dirt, carbon, and improper use all contribute to exhaust brake failure.
Starting the engine and idling for short periods of time is not recommended. Moisture is created
within the engine and the exhaust system during cold startups. When normal operating temperatures
are not obtained, moisture may get trapped in the valve housing resulting in rust and leading to insuffi-
cient operation of the exhaust brake.
To help prevent exhaust brake freeze-up caused by periods of non-use, it is recommended to use sil-
icone spray at the points shown. Apply liberal amounts of silicone spray to the moving joints whenever
the motorhome is parked for storage. Use a pair of pliers to manually operate the valve several times and
work the lubricant into moving parts.
NOTE:
Do not use petroleum-based lubricants as these will burn off and possibly create a
fire hazard.
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