RV & Luxury Bus Repair Service

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.

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