Water pump not flowing well at idle?

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May 28, 2010 | 03:24 PM

#11

xhevi

Three Wheeling

Joined: Apr 2010

Posts: 74

Likes: 2

From: Westchester, NY

ok, here is what i found on RAVE workshop manual... there is a table on RAVE page 04-10
hope it might help...

Cooling system - V8
Type:
Pressurised, spill return, thermostatically controlled water and antifreeze mixture. Vertical flow radiator with remote header tank and pump assisted

Cooling fans:
9 blade axial flow on viscous coupling and 11 blade axial flow electric Electric cooling fan switching points:

For A/C system:

On When vehicle speed is 50 mph (80 km/h) or less and ambient temperature is 28 °C (82 °F) or more

Off When vehicle speed increases to (62.5 mph (100 km/h) or ambient temperature decreases to 25 °C (77 °F)

For engine cooling during normal running:

On 100 °C (212 °F)

Off 94.5 °C (202 °F)

For engine cooling at ignition off (to counteract heat soak):

On If, within 10 seconds of ignition off, intake air temperature is 60 °C (140°F) or more and engine coolant temperature is 110 °C (230 °F) or more

Off After 10 minutes or if engine coolant temperature decreases to 100 °C (212 °F)

Coolant pump Centrifugal impeller, belt driven from crankshaft

Coolant pump drive ratio 1.293 : 1

Coolant pump output at 1000 rev/min 10 litres/min (2.64 US galls/min) at 0.7 bar (10 lbf.in2)

Thermostat

Waxstat with pressure relief valve

Thermostat operating temperature:

Initial opening 82 °C (179 °F)

Fully open 96 °C (204 °F)

Expansion tank cap relief valve - system operating pressure

1.4 bar (20 lbf.in2)

Last edited by xhevi; May 28, 2010 at 03:27 PM.

May 28, 2010 | 08:59 PM

#12

jycsalas

Super Moderator

Joined: Aug 2008

Posts: 1,174

Likes: 106

From: Middle of Caribbean

So what does this all mean?

Plain and simple... the design of the DII cooling system is that of which the idle speed of the water pump isn't sufficient enough to allow full flow of coolant through the radiator.

That is why when you guys rev the motor, or are driving, the temp drops.

BUT if you have bad cooling system components (clogged radiator, air in the system, bad water pump etc..) it will just over heat faster during idle.

May 28, 2010 | 09:17 PM

#13

Mark G

Recovery Vehicle

Joined: Sep 2007

Posts: 823

Likes: 75

Have you checked your fan clutch? When the rig gets warm/hot it should feel stiff. Very likely to be bad. A lot of guys here have had to replace theirs. I did too on mine.