Coolant Low- Topped Off 3x in a Week

did they go into detail as to what they cleaned, and how well? Any before-and-after pictures? Did they clean the intake manifold in the process? How much did they charge for that?

what’s the miles now, and any further EGR cleanings done?

odds are good it’s the head gasket. Water pump may be failing too.

 

When you have it 'Pressure Checked' also have it borescoped in the #1 and 2 cylinders looking at the head gasket while the pressure is on.
This may be a very slow seepage into the cylinder (s). It takes time.... So you have to find a shop capable of this testing.

Head Gasket Failures seem to be common and chronic on Gen3's. Do you know about 'Gasket Masters'?

You could replace the water pump just to make you feel better.
There is a TSB that has new SW which states as part of its function is a change of Water Pump duty cycles.
I had that performed for free. You should get the latest and greatest SW in your car.
The European version of this TSB talks about 'Head Gasket Life' !

"Cleaning the EGR" is not much help if the small EGR ports in the plastic intake manifold are not throughly cleaned out.
Some think it's the uneven flow of those clogged ports that take out the HG in the #1 and 2 cylinders.
Good Luck

 

I would have monitored the coolant temp to know how far from normal your car was running. It is the missing datapoint and is the only way to know the water pump is failing before it gets to 248f. About $24 for a bluetooth obd2 interface and an app.

Better yet watch it fulltime and place a lower audible alarm on the temp.

P10 Hardwired Scanner

 

Ahh, those guys know their stuff. Every 50K's about the max interval I would go, for cleaning.

 

Disagree all you want... There's a known problem with Gen3 Prius blowing headgaskets between cylinder 1 and 2 and the symptom of that failure is loss of coolant.

As for the electric ICE water pump, sometimes it spins too fast and throws error codes, which is another known problem. But amount of people I see with ICE pump problems is trivial compared to amount of people I see with blown heagasket problems, which is why I tell people to never ever buy a Gen3 Prius unless you're planning to put a custom modified engine or Gen 4 engine in it.

That and high MPG piston rings that burn oil at 200K miles are the primary reasons there's almost no Gen3 owners who are in the 300K mile club, let alone the 500K mile club.

 

I agree with you 100% with your statement.

When the head gasket fails on these engines, the loss of coolant goes into the cylinder and cause misfires. Normally, the coolant is not pushed out the overflow of the reservoir.

When the engine water pump goes bad on this engine (not enough coolant flow through the engine), the engine overheats, and pressure builds up in the coolant system. When that occurs, the cap on top of the reservoir releases the pressure just like it is designed to do, and coolant is pushed out the overflow, like shown in the pictures in post # 8.

 

Don't worry about he leaking head gasget....

My Prius passed the compression test however there was a problem with my #2 and #3 spark plugs being badly rusted out- I changed my plugs only 15k miles ago. So that’s concerning. Sorry that I didn’t have the #1 and #2 cylinders borescoped but thought this information might be relevant.

The mechanic said it indicates possible issues with gaskets #2 and #3, but there are no visible evidence of those issues. The new water pump will get me home but if I still have issues with the coolant spitting out through the reservoir, then I’ll definitely have head gaskets problems.

So far, I’m replacing the water pump, thermostat, spark plugs and I’ll have to wait and see what happens. I’ll get the used water pump back when the car is ready.

It looks like this thread will continue as I get additional feedback from my car.[/QUOTE]

 

"Rusted Spark Plugs" YIKES.
That's a new one. But for there to be rust,, there must be water.
Are they saying rust on the business end of the plugs (combustion chamber) or rust on the threads where they screw into the head?

The Coolant system will easily pass this 'compression test' (Pressure Test) with a seeping head gasket.
There is compressed air in the reservoir which will expand as the coolant is slowly seeping and the pressure gauge will not drop a perceptible amount even if a 'teaspoon' of coolant has leaked away into the cylinder(s).
That test only shows that the hoses and seals are doing their job.
Not that drops of coolant are getting in the cylinders.

There is a test that measures Combustion byproducts in the coolant. That will show if there is a head gasket failure slowly happening.
You might have to search for a shop that does that testing.

When one of my many Gen3's started having a head gasket failure it showed up while using high power climbing in the Rockies.
I got the 'High Temp' light and pulled over. The coolant res had pressurized and was releasing steam and coolant out of that cap port.
But the car was fine the rest of the time. Only high power for extended time created the overheat condition.
I believe hot combustion gases were seeping past the head gasket into the coolant, but mainly during high power times.
(I don't want to talk about what product I used and how quickly I sold that car when I got home from that trip)

Also, you should go to the dealer and get the SW update that relates to the water pump.
Ask for any TSB's you are due. Why not have new SW to go with your new Water Pump?

If you still have coolant usage,,,,,, get ready for a big bill.
Look into gasket masters to see if they service your area. They are pros at doing that one job.

 

Buddy, you're messing up the "quote" functions. and other things....

 

Take a look at this recent thread about coolant loss:
https://priuschat.com/index.php?posts/3496635

 

In the USA the dealer won't know about the European tsb that specifically mentions head gasket failures under long idles (camping, waiting), excessive stop and go traffic (both causing lower than normal engine temps - often 30-40f lower) or very high loads including towing that "might" cause overheating (rare to never for most).

Normal road and freeway driving were excluded. The European tsb mentions revised water pump logic. Their ecm software is different than USA ecm software before or after.

All we can do is to ask for the latest USA "calibration id" ecm software that applies to our year and model (hatchback, v wagon or plugin). Most dealers will charge an hour's labor. Hacked Techstreams will no longer write ecm software.

None of the US tsbs that require the latest ecm software mention head gaskets or water pump logic. There is an assumption on Priuschat that revised water pump logic may exist in the latest ecm software.

One of those USA changed ecm software tsbs covers the revised egr valve TSB-0027-16. So I changed the egr valve and had them update the ecm software (calibration id). Others just look up the tsb ecm calibration id chart (not the European) and ask the dealer to update accordingly.

Finally no one who has changed the ecm software reports any obvious water pump logic modifications. I continue to see coolant temps drop quickly on idles and waits, the water pump shuts off immediately on any engine off state many times a drive and I never see high temps even at 85 mph tollways. I don't tow or get ridiculous when climbing mountains in Colorado or New Mexico.

Revised EGR Part from TSB-0027-16
Revised ECM Calibration ID for USA


Quite frankly, Toyoa tried fixes for the gen3 engines early on continued through 2016. Revised pistons, rings, intakes, egr valves and ecm software. All prior to the. gen3 2017 Prius v and the 2017-2021 Prius+ and alpha overseas. Odds are good nothing really fixed it until everything was done by 2016; and maybe not even then until the gen4 significantly changed the engine.


European HG Calibration ID

 

But it's @ASRDogman, he does things differently than most.

 

Is there any update on your car after the water pump and thermostat were replaced?

Did you take a look at the old water pump? How does the rotor rotate when you try to spin it?