So I thought I’d post some notes from the recent Prevost Webinar I attended on Nov. 4th. This Webinar covered Winter Preparation – Heating System Maintenance.
The following items were covered in this webinar:
* Battery systems
* Booster cables to jump start
* Engine cranking
* Pneumatic system issues
The first comment was SAFETY – more critical in winter conditions.
Battery systems – Group 31 (4) (most common) or 8 D
– Ignition & battery switch are one in the same
– Volvo 9700 – separate battery switch to left of ignition switch
Main difference is physical size and they are cabled differently
Proper cabling is crucial
– 8D – cabled in series – reserve capacity and cold cranking amps need to be the same
– Group 31 – more connections – engine and transmission wires are smaller wires
Booster cables to jump start
– use booster stud – do not jump directly to battery (on ’94 & up)
– (-) negative on post (located on frame), (+) stud sticks up from battery
– * do not make a connection w/ donor vehicle running – connect 1st, then start donor vehicle
Engine Cranking – do not crank starter for more than 15 seconds
– starter motor needs fixed voltage
– volts x amps = watts
– as voltage drops, amps through cranking motor increases
– so, lower voltage = higher amps through starting motor and cabling system
Volvo D 13 Engine – No Ether! Can cause engine damage on air intake heater. Auto at 54 degrees F coolant or lower
Preheaters – Concentration: Webasto / Spheros (separate company)
– when preheaters are run year round, less problems
– Webasto: DBW 2010, DBW 2020
– rare that air shutter needs to be adjusted
– Spheros Thermo 300 – approximately 102,000 BTUs & has computer interface
Info on these preheaters can be found on the Prevost website under Parts & Service →Tech. Manuals→Manufacturer Publications.
Preheater not working? Is it a Prevost issue or a preheater issue?
There is a difference between “Switch On” & “Start Up”
If the preheater does not “switch on”, then it could be a Prevost wiring problem.
Check wire 127 A (there were several diagrams and schematics shown throughout the webinar presentation)
* Run preheater every month
– Fuel nozzle replacement
– Flame detector (can get dirty) – there are 2 types
Understand operation – see shop manual on website
– filter screen on fuel pump
Information on correct coolant can be found in the operation manual, the maintenance manual, and on a decal by surge tank.
– Volvo is different from Detroit Diesel
– D13 – extended life coolant only
Coolant filter – strainer on supply line to heater control valve on evaporator to heater core
Pneumatic System Issues
Tech under coach – use safety glasses
The following needs to be done in the proper order
Run engine on fast idle 1st.
1) wet tank – drain completely
check brake tanks for proper psi*
2) primary brake tank
3) secondary brake tank
4) accessory tank
5) needle recovery tank
* 120-130 psi = check valves o.k.
note any moisture – air dryer may need to be serviced
Check schematic for particular vehicle tank locations.