Radiator coolant

Bob,

That seems a lot of coolant to vanish in the, presumably, no more than two years since your last coolant change. Any suspicions as to where the leak is?

-Chap

 

If the ICE is running, the belt-driven water pump should be creating the heater core flow; the electric pump only takes over when the ICE is off.

Can you really tell when the electric elements come on? I've never been able to (have been tempted to add LEDs just to convince myself it really happens).

-Chap

 

Hi Bob,

I suggest that you use the Lisle yellow funnel to hold radiator coolant. The advantage of that funnel is that you can have the coolant level 2-3 inches above the radiator, thus providing more pressure to get the coolant into the system.

Make the Prius READY and rev up the engine full throttle (which will probably only be 3K RPM when the gear selector is in P). Have the cabin heater turned on, MAX HEAT, fan speed on full. Rev up the engine for around 10 minutes or until the fluid level doesn't drop any more and the cabin heat is good.

If you continue to find the fluid level dropping then you probably have a cylinder head gasket leak or perhaps a leak in the radiator itself or a hose. Or maybe the engine coolant pump bearing is leaking. Look for pinkish stains on the radiator, engine water pump pulley interior, and the hoses (if you are using Toyota LLC or SLLC coolant.)

Check cylinder compression using Mini VCI to spin the engine at the proper speed, and a cylinder compression pressure gauge screwed into the spark plug holes, one at a time. All spark plugs should be removed during this test.