Roewe Plug-in Hybrid Cooling System Maintenance Guide

Fault Background

The cooling system of the Roewe plug-in hybrid (847 manual) is divided into three independent circuits: ①Engine circuit (engine, heater core, radiator, mechanical/heater auxiliary water pump); ②PEB circuit (low-temperature radiator → PEB → PEB expansion tank → water pump → EDU); ③ESS circuit (high-voltage battery pack expansion tank → water pump → Chiller → ESS). The bleeding and filling methods for the three circuits are completely different: The engine circuit relies on "running at 1500~2500rpm for self-bleeding + cooling for 30 minutes"; The PEB circuit relies on the diagnostic scan tool's ISC module to force the cooling pump to run for 20~30 minutes; The ESS circuit relies on pressurizing to 35KPa with tools TAC00003+T14001 and forcing the water pump output via BMS. Pressure cap test criteria: Engine cap 140~160KPa, PEB/ESS cap 35KPa. This article is organized as a maintenance guide following "bleeding and filling → pressure cap test → pipe and water pump removal/installation".

Bleeding and Filling (Three Circuits)

General warning: Do not open the expansion tank cap while the cooling system is hot—escaping steam or coolant can cause burns.

Engine circuit: Remove expansion tank cap → remove underbody deflector → collect with container → loosen drain valve to drain. Filling: Tighten drain valve → install underbody deflector → prepare coolant of specified concentration → fill to the neck of the expansion tank and let it sit → confirm A/C is off → start engine and run at 1500~2500rpm, add coolant as needed to keep level just below the neck → when level rises to the neck, install cap → continue running at 1500~2500rpm until the cooling fan runs, then idle until the fan stops → turn off engine and cool for 30 minutes → check for leaks → adjust level to MIN~MAX.

PEB circuit: Remove PEB expansion tank cap → remove front bumper → collect with container → loosen clamp and disconnect low-temperature radiator to PEB pipe to drain. Filling: Reconnect pipe and clamp → fill to MIN~MAX → connect diagnostic scan tool → enter ISC module, force output, click cooling pump control → observe coolant flow in PEB tank (flow = pump not cavitating) → keep flowing for 20~30 minutes (add if level is low) → when level stabilizes, disconnect scan tool → adjust to MIN~MAX → check for leaks → install front bumper.

ESS circuit: Open battery pack expansion tank cap → collect with container → raise vehicle on lift → loosen clamp and disconnect ESS to expansion tank pipe to drain. Filling: Reconnect pipe and clamp → fill to MIN~MAX → install TAC00003 on the high-voltage battery pack system expansion tank, connect T14001 pressure hose, slowly pressurize to 35KPa and hold → connect diagnostic scan tool → force output "motor cooling pump control" in BMS module to run the pump → check if coolant flows to the bottom pipe of the battery expansion tank → after flow is observed, remove pressurizing tools, remove expansion tank cap → run pump for 20~30 minutes → adjust to MIN~MAX → install cap → check for leaks.

Pressure Cap Test

Unified steps: Visually inspect for leak traces → check hoses for cracks, distortion, and secure connections → slowly pressurize → check criteria → release pressure via pressure relief valve → remove tools and reinstall cap.

Expansion Tank and Pipe Removal/Installation

Coolant expansion tank (engine & PEB): Remove manual service disconnect switch → drain (PEB + engine dual drain) → loosen 3 clamps (engine overflow pipe / PEB to expansion tank hose / expansion tank to heater core hose) → remove 1 bolt securing to PEB → remove PEB tray → pull expansion tank outward and loosen electronic water pump hose clamp. Installation: Clamps → PEB tray → tighten mounting bolt to 19~25N·m → 3 clamps → fill → install service disconnect switch.

Coolant expansion tank (battery): Open trunk → drain → remove trunk storage box → remove 2 bolts securing to body (8~10N·m) + loosen 2 clamps on inlet/outlet pipes → remove. Installation reverse order + fill.

Pipe family (unified pattern: remove service disconnect switch → drain → loosen clamps → replace pipe → fill → install service disconnect switch): Radiator to engine / engine to radiator / engine to heater core / heater core to water pump (3 clamps) / water pump to engine / engine overflow pipe / EDU to low-temperature radiator (requires front bumper removal) / low-temperature radiator to PEB (requires front bumper removal) / PEB to PEB expansion tank / PEB expansion tank to water pump (requires TM cooling pipe connector removal) / water pump to EDU (requires PEB expansion tank removal); ESS side: ESS expansion tank to water pump (requires trunk storage box + exhaust mid heat shield removal) / water pump to Chiller (exhaust mid heat shield) / Chiller to ESS / ESS to expansion tank.

Water Pump and Cooling Components

• Water pump - heater auxiliary: Remove service disconnect switch → drain → remove intercooler to throttle body pipe → loosen 2 clamps (heater core to water pump, water pump to engine) → lift vehicle → remove 2 clips securing to bracket → disconnect wiring connector → remove water pump. Installation reverse order + fill;
• Water pump - PEB: Remove service disconnect switch → remove PEB expansion tank to water pump pipe → loosen water pump to EDU pipe clamp → loosen 1 bolt securing water pump bracket to body → remove water pump. Installation: Bracket bolt 8~10N·m + clamps + expansion tank + service disconnect switch;
• Cooling fan assembly: Disconnect negative battery cable → remove service disconnect switch → drain → disconnect wiring connector → remove 2 cotter pins securing air filter intake pipe to radiator upper crossmember → carefully release 4 clips securing fan to radiator → lift vehicle and remove from bottom. Installation reverse order;
• Radiator: Disconnect negative battery cable → service disconnect switch → drain → remove cooling fan → loosen radiator to engine pipe clamp → release clips securing radiator to intercooler → lift vehicle and remove from bottom;
• Intercooler: Service disconnect switch → remove radiator upper crossmember (after removal, let it rest on low-temperature radiator) → release clips securing radiator to intercooler → remove 2 bolts securing condenser to intercooler and 4 bolts securing low-temperature radiator to intercooler.

Safety Warnings

• This article is for technical reference. Cooling system inspection involves high-temperature, high-pressure fluids and high-voltage components (PEB/ESS circuits). Must be performed by qualified professional technicians (with electrician certification + company training authorization) following OEM specifications.
• Never open caps when hot (burn risk); use appropriate containers to collect coolant during draining and dispose of properly.
• Remove manual service disconnect switch before draining/filling PEB/ESS circuits; pressurize slowly during pressure cap test, release via pressure relief valve before removing tools.
• After filling, run to bleed + cool for 30 minutes + check for leaks + recheck MIN/MAX—missing any step may leave air pockets.

Maintenance Insights

The core of Roewe's three-circuit cooling system is "one circuit, one bleeding method"—using the wrong method won't fully remove air pockets: The engine circuit has a mechanical water pump, relying on 1500~2500rpm high idle + fan start/stop cycle + 30-minute cooling for natural bleeding; PEB/ESS use electronic water pumps, requiring diagnostic scan tool forced output to run the pump for 20~30 minutes for forced bleeding—the ESS circuit is most particular: pressurize to 35KPa and hold, then start the pump, and only remove the pressurizing tool after seeing coolant flow to the bottom pipe of the battery expansion tank. This "pressurize + forced circulation" combination is to push air out of the battery cold plate. Memorize two criteria numbers: Pressure cap 140~160KPa (engine) / 35KPa (PEB/ESS)—if the cap's opening pressure is wrong, the boiling point protection for the entire circuit fails. Pipe family removal/installation is pure physical work but follows a unified pattern (service disconnect switch → drain → clamps → replace part → fill → service disconnect switch). Remembering the pattern is more efficient than memorizing each pipe. Finally, note: During PEB filling, "observing coolant flow in the tank" is the only way to confirm the pump is not cavitating—for forced pump output without flow display, this visual check is the only way to tell if it's running.

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【This article is for reference only】