Prevost Webinar on Winter Prep – Heating System Maintenance

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
* Preheaters
* Coolant
* 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

Proper clamping

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

Webasto: disc
Spheros: rod

Understand operation – see shop manual on website
- filter screen on fuel pump

Coolant
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.