M8 Twin Cooled Coolant Pump Operation
Thread Starter
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Road Warrior
Joined: Feb 2016
Posts: 1,354
Likes: 399
From: Vancouver, BC
M8 Twin Cooled Coolant Pump Operation
I'm trying to verify if the coolant pump on the M8 twin cooled motor operates continuously or is temperature controlled. I know on my '15 Ltd. TC motor the old style pump operated the whole time the motor is running. I've been told the new (to the TC motor) style pump is based on the one used on the M8 and only operates when required. Can anyone confirm?
Perhaps someone with a Touring service manual could look it up for me? My manual had an appendix on the cooling system with a section called "Cooling System Operation" that clearly stated, "The pump will not run until the engine is started, then runs continually while the engine is running."
I'd really appreciate it if someone could help answer this one for me as it's driving me crazy.
Thanks
Perhaps someone with a Touring service manual could look it up for me? My manual had an appendix on the cooling system with a section called "Cooling System Operation" that clearly stated, "The pump will not run until the engine is started, then runs continually while the engine is running."
I'd really appreciate it if someone could help answer this one for me as it's driving me crazy.
Thanks
Seasoned HDF Member
Joined: Jan 2006
Posts: 11,467
Likes: 2,996
From: Charleston, SC
An electric pump (4) mounted near the voltage regulator
circulates the coolant through the system.
Coolant flows from the pump (4) up through the left downtube
to a manifold (8) between the cylinder heads. Coolant flows
through passages around the exhaust valve seats in each
cylinder head. Coolant then exits both cylinder heads to a
collection manifold (9) which combines the flow and returns
coolant to the left radiator (6). Coolant then flows to the right
radiator (2) before returning to the pump through hose (3).
A fan (7) is mounted behind each radiator to boost air flow at
low road speeds and at engine idle. The fans are controlled
by the ECM based on coolant temperature and vehicle speed.
Temperature switch (5) mounted in the left radiator reports
coolant temperature to the ECM.
The coolant bottle (1) stores extra coolant to control coolant
expansion and contraction during operation.
The pump will not run until the engine is started, then runs
continually while the engine is running. The fans will cycle on
and off while the engine is running, depending on vehicle speed
and coolant temperature. If the fans are running when the
engine is stopped, the fans and pump will continue to run until
coolant is at a certain temperature or for a predetermined length
of time, whichever occurs first. If the fans are not running when
the engine is stopped, they will not start again with the ignition
OFF.
circulates the coolant through the system.
Coolant flows from the pump (4) up through the left downtube
to a manifold (8) between the cylinder heads. Coolant flows
through passages around the exhaust valve seats in each
cylinder head. Coolant then exits both cylinder heads to a
collection manifold (9) which combines the flow and returns
coolant to the left radiator (6). Coolant then flows to the right
radiator (2) before returning to the pump through hose (3).
A fan (7) is mounted behind each radiator to boost air flow at
low road speeds and at engine idle. The fans are controlled
by the ECM based on coolant temperature and vehicle speed.
Temperature switch (5) mounted in the left radiator reports
coolant temperature to the ECM.
The coolant bottle (1) stores extra coolant to control coolant
expansion and contraction during operation.
The pump will not run until the engine is started, then runs
continually while the engine is running. The fans will cycle on
and off while the engine is running, depending on vehicle speed
and coolant temperature. If the fans are running when the
engine is stopped, the fans and pump will continue to run until
coolant is at a certain temperature or for a predetermined length
of time, whichever occurs first. If the fans are not running when
the engine is stopped, they will not start again with the ignition
OFF.
Thread Starter
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Road Warrior
Joined: Feb 2016
Posts: 1,354
Likes: 399
From: Vancouver, BC
So the new M8 pump operates constantly (which is the same as the way the old TC pump ran).
I guess I had heard incorrectly and have been passing on bad info.
Hopefully the new pump is more robust than the one it replaced (it sure appears that it is anyway).
Thanks for clearing that up!
I guess I had heard incorrectly and have been passing on bad info.
Hopefully the new pump is more robust than the one it replaced (it sure appears that it is anyway).
Thanks for clearing that up!
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