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01 Prius Electrical System Coolant Replacement

Recommended 2 year interval, I've extend to 3, due to the very high quality of our water, lacking nearly all mineral content, and being very nearly distilled. Changes too often will introduce excessive corrosive agents and other contaminants, which after a period of reactivity (and damage) will dissipate, leaving the coolant ideally chemically "dead".

The changing procedure is covered on pages HT-6 and -7 of volume 2 of the repair manual. I find the description deplorable, and to this day wonder what's intended. I believe it's an attempt at purging all the air from the system in one refilling operation. Let me say emphatically, that this is simply IMPOSSIBLE, and be prepared to top-up the coolant after each operation, much more at first and then lesser with time until the level becomes stable.

Other informed perceptions on this most welcome & thanks ! ...

Reply to
Steve Giannoni
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I believe that the coolant replacement interval is 3 years for the original factory fill and 2 years after the original factory fill has been replaced. The original factory fill is diluted with distilled water and the maintenance interval assumes that the replacement fill is diluted with tap water. If you use distilled water (as opposed to tap water or "nearly distilled) water, then you could stretch the replacement interval to 3 years.

I don't have an opinion on the procedure for replacing the coolant. To be honest, the only car I've actually read the coolant replacement procedure on is for the MR2, due to the front-mounted radiator and mid-engine location.

Reply to
Ray O

No, I think it's always 2 years, even for the first change, which I did at 2 years, both electrical and ICE coolants. This begs the question as to why any change is necessary assuming you use distilled (or nearly distilled) water. After the 3 years the exiting electrical coolant fluid looked completely clear and free of any sediment. The drain plug which is at the lowest point has a substantial hollow recess facing up which had nothing in it and the whole was bright and clean from the gasket on in. Haven't done the ICE coolant yet.

Interesting / important "self-note" from 3 years ago :

On page CO-2 of the 2001 Repair Manual Volume 2, the location of the engine coolant drain plug is referenced " ? engine drain plug on the engine coolant drain union ( on the right front of the cylinder block ), ?", and includes a sketch showing the engine and the "Engine Drain Plug" as a strange looking item floating somewhere sort of on the mid-right side of the engine, facing toward the rear of the car. I see now that Toyota's right and left side of the engine is as facing forward in the old conventional drive configuration, so in the Prius, the engine's right side faces toward the rear of the car. But now, they seem to get it reversed with the "front" of the engine being the drive end. Go figure! I'd be embarrassed to reveal how long I hunted for that @#*&*&% plug on the wrong side of the engine.

Reply to
Steve Giannoni

You can safely stretch coolant replacement to 3 years if you dilute with distilled water. Just keep an eye on the coolant, if it gets crudded up before 3 years, change it.

The repair manuals use SAE conventions when referring to the front, sides, and rear of the engine. These conventions are not the same as conventions for front, sides, and rear of the vehicle or engine bay.

Reply to
Ray O

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