Coolant.

Prius VVT I Active 2017 ; 120K miles
Hi ! I'm new here but I have the same issue.
My coolant is disappearing from my side reservoir and I have been to a Toyota service , they've done a pressure test, no sign of leaks. How is this possible? During the last two weeks I have topped up 3 litres and they said there is no leak, keep monitoring and come back for another pressure test ,longer one, over night, to see what's happening...
One day after ,I still topped up...
Please give some advices!

 

Where is "Grays"?

Any knocking at start up? It's running ok?

Have you heard about Exhaust Gas Recirculation cleaning, Intake Manifold cleaning?

 

Is it warm this time of year wherever Grays is, or cold?

I ask, wondering if it would be practical to take both hoses off the heater core, and just couple the gozinta to the gozouta, drive around that way for a while, see if the rate of coolant loss changes?

 

It could well be a water pump problem, which has been mentioned before. I'm not sure that a pressure test will detect a
failure of the pump.

 

Isn't this a Gen-4 question?

That's a large coolant loss. If it's a leak, there'd be a puddle under the car after it sat overnight. If it's a head gasket, there'd be misfiring. A hole in the heater core would give an odor. Where else could the coolant go, unnoticed?

 

Thanks for your answers!
Grays , UK.
No problems with my Prius, it's running perfect, apart from the coolant issue.

Have you heard about Exhaust Gas Recirculation cleaning, Intake Manifold cleaning?
No, what is it?

 

Yeah, could be, but shouldn't I have a warning light, or leaks, or smoke, anything...

It's like 1 to 10 degrees Celsius, it's Ok.
I appreciate your help but I have no idea what are talking about, I don't have this kind of knowledge.

"would be practical to take both hoses off the heater core, and just couple the gozinta to the gozouta,"
Appreciate your help!

 

Some boilerplate text (and attachments):

The simplest way to see where you're at, is to check the degree of carbon build up in the EGR pipe, a stainless steel connecting pipe between the EGR valve and intake manifold. Watch @NutzAboutBolts video #16 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Two or three other videos linked there too, for the full cleaning of the intake manifold, full EGR clean, and Oil Catch Can install.

Good thread:

EGR & Intake Manifold Clean Results | PriusChat

Another:

Oil Catch Can, Eliminate that knock! | PriusChat

Some tools worth having:

E8 Torx socket (mandatory)
E6 Torx socket (optional, but good to have, to remove the throttle body studs from intake manifold)
3/8" ratchet wrench, regular and long handle, flex head, you can never have enough (or 1/2 plus reducer)
1/4" ratchet wrench, or 3/8" to 1/4" reducer
Ratchet extensions: you can never have enough
Long needle nose piers, straight and bent tip
Ratcheting 12mm box wrench (optional, but makes disconnection of the EGR cooler from exhaust easier)
Torque wrench (3/8" and 1/4" both good to have)
Floor jack and safety stands (or ramps): basically some method to raise front, if you need to take underpanel off, which you may need to, both for access and to recover dropped items.

 

Water pumps tend to leak when you are underway so it is hard to detect. They leak coolant around the shaft which of course drops to the ground. There should be traces of fluid sitting on top of the bottom paneling. No smoke and no warning lights.

 

Raise the front, remove the engine underpanel, check it and engine low points for " pink crusties".

 

I'm not following. What is a 2017 Active? Isn't that a Gen-4 Prius?

 

Some UK level?

 

I meant that we're talking about a Generation 4 Prius here. I'm sure hoping the EGR system never needs cleaning on my 2019. Looks like the inverter is in the way.

 

It will be more fiddly than a gen3 to do the same job.

But in 4 years, I'll be around 100k miles and ready to tackle it.

 

How about just the pipe, is that relatively easy to remove and inspect? Might be you never need to clean 4th gen EGR, they got it right this time.

 

Here in Uk ,we don't classify like you do, in US. That's the name Prius 1.8 Vvti Active 5Dr CVT, bought it from new in August 2017. It's Hybrid, petrol and electric. Sorry if I am not on the right topic. Thanks for your help!

 

The canary in the coal mine approach.

I could give that a shot.

But since the engine is running 1/3 as much as our Gen3 did, not sure if doing this at the same mileage will yield the same comparison.

But I'll collect that data as the miles pile up.