With the talk about blown head gasket in the Gen4 forum...

The Prime is basically a Gen 4 Prius albeit with a larger traction battery.

 

Didn't think the exact cause was pinned down. If the expansion and contraction from shut down and restart of a warmed up engine was all it took, there'd be more car models suffering for it.

 

Are head gaskets even an issue with the Prius (any flavor)?

 

a huge issue

 

i have 86,000 on my pip, 30k only on the engine, and i'm aready having problems.

but we don't know the exact cause on gen 3, and we know nothing about gen 4 except the leaky heat exchanger

 

people question that being the cause because gen 2 didn't have a problem

 

A proper hybrid will keep the engine running after start up until the engine reaches operating temperatures. That mass of metal doesn't loss its heat in an instant when the car shuts it off. The loss is slow enough that any contraction and expansion isn't enough to cause stress leading to failure in the engine off spans the hybrid operates in. The car will cut those periods short when it is colder out.

I'd be more concerned with the coolant level in a gen4.

Plus nearly every new car now has an auto stop system, and those started showing up in Europe decades ago.

 

The design of the Gen3 engine is the cause of premature headgasket failure... Gen1, Gen2, Gen4 Prius have never had this issue. Also the theory of frequent thermal expansion / contraction is false, that's not how big chunks of metal work, they hold their heat quite well... Specific to the title of your post, there's no evidence that Gen4 has head gasket problems after 7 years. This is only an issue on Gen3 engines.

 

Because of the history with the gen3, people were concerned. The possible causes were addressed for the gen4, but it might have a leaky exhaust heat recovery unit. Unnoticed coolant loss from that can lead to overheating and gasket failure.

 

Yes. My hunch is the 3rd gen EGR is the very frequent culprit. Fourth gen's are ok, unless you ignore a leaking Exhaust Heat Recovery system long enough. (donning my flame-proof suit now...)

 

I do my own oil changes, so I check then.

 

Most of us glance over at it when we're checking oil level, same with how often to check brake and inverter coolant level.

As for watching your phone app too much, there's nothing wrong with leaving your OBD2 in to monitor data for a long drive, or multiple drives if you need to diagnose something. But folks who always have their OBD2 plugged in will likely end up having it cause an electronic glitch to the car at some point. I suspect its because OBD2 readers tend to heat up and they are not designed for constant use whenever you're driving so all that heat will eventually create problems. So use it sparingly.

Also from a security perspective, bluetooth signals are easy to hack and a hacker driving down the highway next to you could try to experiment on you. And odds of that happening are much higher if your OBD2 is always plugged in:

"A year ago, online-security researchers Charlie Miller and Chris Valasek attached themselves remotely to a Jeep Cherokee. They were able to disable the transmission and brakes and -- only with the car in reverse, at low speed -- take over the Jeep's steering. The hack worked because the car's steering can be controlled when the car thought it was automatically parallel parking. Scary, but fortunately there's not a lot of damage you can do at 5 mph. Jeep has since patched that vulnerability." https://www.extremetech.com/cars/232947-jeep-cherokee-hack-gets-worse-at-least-if-hackers-can-get-physical-access-to-the-car-first

They make an OBD2 cable with a switch in it that I bought for $5... On my list of things to do is mount everything behind the dash with switch mounted in the spare switch spot, so you don't have to worry about digging around in your glove box for it.

 

That's fine for up to 100K miles... But as the engine gets more worn out it will burn more oil and you need to check more often. I'd recommend every other time you fill the tank on high mileage cars.

 

you have a 2017. if the heat exchanger hasn't already let go and be repaired, you're probably fine.

if you're concerned, pop the hood at whatever interval makes you comfortable.

i don't understand, why would the engine overheat before the coolant?