Self proclaimed expert explains why Prius Headgasket Failures are normal, early, and inevitable

I don't know, but that could be one of those questions where there's both a qualitative answer ("why, yes!") and a quantitative one ("by about 0.073 degrees") if somebody sits down and figures it out.

 

I think as long as there is a thermostat involved it would not run cooler...but at the same temp. I once had a street rod with a lowered oil pan that held 8 quarts instead if 5. It didn't mean the engine was oiled better, but it did extend the life of the oil changes.

 

The other calculation is the cost / benefit ratio.
Different numbers for different driving conditions , parts availability, labor and warranty.

Two of the static numbers to plug into the problem are how much extra coolant and air flow does the bigger radiator provide.
Nice examples in #101

 

Well, I am there right now.. the point of figuring it out, just hoping some of the brilliant minds here can guide me properly so tests can begin.

I just think, if avg engine temps are X for one week of driving and after installing the average drops by Y then good progress is happening.

hmm, I guess my thought was, if having 2.5qts was OE amount and an additional 1qt of capacity was increased, wouldn't more coolant help keep the engine cooler? like more layers of clothing helps keep you warmer?

are we talking about increasing the fluid capacity? if so... I have one angle of lower cost most effective figured out plus another higher cost in the works. I will 3D scan a block and then redesign it to have more/larger cooling jackets which should keep things at a lower overall temperature. plus increasing the bore with stronger walls where not possible on OE block, will net more power and less need to be on the peddle. which should also help cool better my thinking. a few projects ahead of the waterjet slicing and 3D scanning like the resizing of the V cooling jacket(s) which can be installed on a nonV with little effort.
now as I learn about volumetric principles and how to measure. I need to figure out how much is ideal to add additional or if maybe there is a maximum amount of fluids for the system to not through a fault.




Separately, I figure to help with the whole testing of these theories, I'd need more vehicles with logged data pre X modification and after X modification so we can see what is truly making a difference. Recognizing the lack of an easy-to-use obd2 logger I am almost done with my concept device. What you are seeing is an obd mx into a passthrough obd2 port with a custom PCB board wired to the obd2 port pins. you know the chicken dance where you short two pins, this can do it once I program it by touch the screen to trigger obd2 port connection. wifi, Bluetooth and a web GUI to see system info from the CAN and all! When I get time word is, techstream for all cars someone was able to connect to it using some code and a PCB board similar to this design. now, I really want to get Bluetooth Techstream to my laptop with this but... if someone just stuck a sd card in it, connected it to their wifi ap... then they can enable so logging is enabled and we can figure out how to get your data file into my database where I'm hoping to have a lot of Prius stats from many vehicles for many miles of logging. for now, its giving me fast data speeds to read the CAN for the rear electric motor project

 

The thermostat is there to keep the engine running at a specific temperature. It only opens to allow more cooler coolant into the engine when that temp is reached. I don't think it matters how much is "in the queue" waiting to come into the engine. I think your theory would be correct if the thermostat were removed and the coolant circulated freely and constantly.

 

To verify, are you postulating the Prius v has greater engine coolant capacity than the regular 3rd gen Prius? The Owner's Manual say otherwise:

Prius Owner's Manual:



Prius v Owner's Manual:

 

Get rid of gen 3............ problems over

 

Is the purpose of getting the engine cooler related to better thermal efficiency, reducing a possible fault code or some other reason(s)?
The V or v in the post above is referring to a v8's water jacket and inline referring to a 4s internals??
What are the blue (3D printed ?) parts ?

I"ve been following a few of the reverse engineering projects of hybrid battery control and safety features for some years and have a pretty extensive understanding of how much I don't really get about how the data is calculated in pulses, voltage and resistance as well as the way different protocols are bridged into any one system.

I'm nolt a big car person so I typically use available tools and try to get a common understanding of OEM tools and gauges and app tools and how they compare to each other, so I can better understand how others are seeing what they see when looking at similar tools and models of prii.

 

A Prius v (the wagon) and the regular gen 3 liftback use the same aluminum casting for the transaxle housing, but the liftback uses only the green (here) water passage to cool it, leaving the purple one uncovered and unused. In the v, there is a plate with hose nipples added over the purple passage, and enough extra coolant is in the system to also fill that passage and the added hoses.



However (I wasn't quick enough to catch this in post #101), all of that is part of the inverter/transaxle coolant loop, and nothing to do with the engine coolant.

Thanks to Mendel for comparing the engine coolant amounts, enough to jog the ol' memory and say "oh, right, the transaxle difference would show up in the other cooling system."

 

I guess my thought was, more fluid means more cooler fluid can flow through the system.

INTERESTING! Which year Prius was the clipping of the manual from? It reads like a 2017 Prime and the exhaust heat exchanger versus a 2013 without, unless I am wrong and all Gen 3 vehicles has the exhaust heat exchanger. If so, then the difference between the fluid levels is noticeably different and more in the V.

Oh no, do what I did, install the new 2.0L Hybrid motor.

Well yep, that purple part is the one I scanned in thinking two things, one extra capacity would mean lower engine temps but... you perfectly debunked that theory. The other was that lower MG temps in a non V would be observed by not only adding this part but also expanding the fluid capacity. It's looking as if only the latter can be gained in a non V with the addition to this part.


Damn!

I guess then reverse engineering the block with improved cooling jackets is the only option. hmmm

 

Better thermal efficiency by which we are trying to lower the highest temperature the engine gets to in efforts to avoid future head gasket issues. Its my understanding that the wide range of engine temperature fluctuations is the culprit for bad head gaskets. Its my beelif if we lower the range of which the temperatures can fluctuate, we can save more engines from future head gasket issues. I can be wrong about all of this but, trying to do what I can so that when my friends and relatives eventually needs their head gasket replaced, they can use a block I designed and know they wont experience a bad head gasket and neither will the next owner should they decide to sell.

The blue 3D scanned parts is that of the additional cooling cover on the Prius V that other Prius models do not have.

I didn't have time this weekend to play with my new OBD2 tool, I really want to get techstream working without the need to plug in a cable to a computer.

 

Those 3D prints look nice.

About GM video in the OP, the explanation given for the gasket in that one GM video is definitively one of the reasons for gasket failure in the Prius, but one GM video doesn't always present the whole story behind even the one video being shot. There are other reasons for gasket failure and the electric water pump failing is one. Some believe that the EGR system clogging is the main reason for gasket failure. They may be right.

There is a new mongoose with bluietooth. it's $200 more than the cable version.

 

He is an expert. What credentials do you have? Heat cycling, hg metallurgy, and EGR clogging are the key factors that caused hg failure

 

Yep, I saw the new mongoose and ended up having my own OBD2 board printed... come to find out the board I have has BLE, not classic Bluetooth so Ill have to have another one made so that Bluetooth serial is whats on the board! smdh....

and thanks, I have been 3D scanning sooo many things on these cars. This is the CVT I needed to scan to make the engine to cvt adapter so I can mount the 2.0L M20A-FXS to the Gen 3 CVT. plus a lot more! These days I am able to make anything for a Prius.... anything!
having the suspension components scanned allowed me to work with the coilover manufacturer to find a part he makes already for another Toyota vehicle that shares almost the exact same parts dimensions as the Prius! shhh don't tell anyone I know what it is, heh, they think Tacoma and aren't even close.



Plus having now all the scans allowed me to make many custom parts for my vehicle that I must say are splendid. If you are wondering why the hatch without the spoiler, lets just say I also scanned under and the spoiler as well...