4th gen head gaskets are starting to show up in large numbers...

Read the thread. Thanks!

So what would you recommend?
Letting a dealership do it for $4800?

Also, there are many Gasket Master locations, or so they say.... Maybe they all don't cuss at dissatisfied customers..

I like that they use the Felpro, the dealer probably doesn't. I wonder if I asked for that particular HG gasket they would use it?
Probably not....
What I don't understand with these quickie HG replacements is,, Why are they not resurfacing the head? Why not disassemble the valves, clean every thing, at least lap the valves and install fresh valve stem seals?

Same with a dealership repair. My friend said they could have it done in a 2 days. I suspect they are not doing anything to the head other than wipe down the gasket surface???

 

Just found this YT short from Gasket Masters on Gen4's.
You can see that dealio in the block to 'even out the thermal blah,blah of the cylinder walls'.
But that doesn't help the HG, apparently.
https://youtube.com/shorts/JL3hIUro7SM?si=SU2laAbmR-eEOwv6

 

If this comment sounds like an excuse, maybe someone should ask GMs what they think and what they are seeing. As stated at the end of the video posted by the OP, well just take a look see here and now

What's the newest Gen 4 they've gotten with a leaky gasket issue? And was it a daily driver, uber, taxi or something else like a courier service ?

Knowin they're providing their content keeps my eyes open.

 

I’m not convinced gen 4 has a head gasket issue yet.
I am convinced early years have had some exhaust heat exchanger leaks

 

Why does the 'type' of miles matter?
What is the difference between a long distance vacation taker and a long distance courier driver?
Why would the engine, in particular the head gasket care one way or the other? High miles are high miles.
I'm aware that short trips to the corner where the engine never gets completely warm is a different thing.

I'm convinced at least one has the head gasket issue at 205k miles on a '17, all maintenance performed at the dealership,,, at great expense, I'm sure.

Do you think there was a change in the Block - Head - Head Gasket between Gen3 and 4?

I rode in this car a week earlier. I found it slightly quieter and it had a wacky multi-color display.
Then earlier this week the owner claims "This morning it started shaking with a check engine light".
The dealer said they could see the seeping in Cyl #2 with a borescope.

A coolant hose leak would overheat the engine, true. Does the Prius keep running the engine up to 'meltdown temps'? Does it shut down the engine before that?
Anyways, this is word of mouth from the owner. That's all I know.

 

some gen4 exhaust heat exchangers are defective. if they leak, the engine keeps running. when the coolant level drops enough, the engine overheats and the light comes on. by then, it's too late.
do the head gaskets blow for other reasons? maybe, but i can't recall any.

 

What good is a warning light if "it's too late"? Why would toyota even bother to give you a light like that?

Some other manufacturers have a low level sensor in the coolant reservoir. That is a very useful warning light to have.
It gives you a warning that something bad is about to happen!!

I have it on good authority that the red coolant temp light comes on at X temp. (~220°F , these temps are approx of how I remember what I was told by a friend with a scangauge, and a failure happening to his car.)
If you "press on regardless" the engine shuts off at X temp ~240°F, keeping you from doing major damage. Thanks toyota!!

(these numbers are guesses on my part. Someone with knowledge can help here).

You're claiming the only reason Gen3 and Gen4 HG's fail is due to overheating?
I think many will claim otherwise. I'm one of them that has gone through the beginning of a Gen3 HG failure. Never got a warning light.

 

Ah, democracy.

 

Exactly!
We're all just dumb ill-informed voters.

The only ones that know for sure are top engineers at toyota.
And thus,,,, we have a new engine in the Gen5!
And only time will tell if it can do 200k miles without a major failure,,, routinely.

 

i said gen 4, and i said there may be other reasons, but i didn't recall reading about them.
i never said gen 3, and there are a dozen theories on that, including toyota's tsb.

 

In every car I've ever owned with an engine-oil light (including every Prius I've owned), it has been an engine-oil pressure light, which is enough to tell you "your engine is eating itself right now".

Some newer-generation Prii that I haven't owned have actual oil level sensors, and there were some luxury brands (that I also haven't owned) that had that feature earlier. But in the lion's share of cars, the oil light is an "it's too late" warning.

The experiment here (on a gen 3) saw the water temperature light come on at 248 ℉ (120 ℃). (There are two engine temperature sensors in the gen 3, one in the cylinder head and one in the EHRS return hose. The one spoofed in that experiment was the latter. I haven't done one where I spoofed the former.)



The gen 3 ECM behaves differently depending on whether there are any trouble codes involving the water pump. If there are, it will abruptly stop the engine at 105 ℃ (221 ℉), which is before you would even see a red warning light. But it doesn't do that if it isn't aware of a water pump problem.

In the absence of a water pump problem, I am not aware of any temperature where the engine is automatically stopped. There might be one, but the repair manual doesn't say so, and I've never done an experiment that could confirm it.

 

Thanks for the detailed explanation!
My pal that told be about the engine shutting down may have said something about the water pump only running at low speed, still, that's an engine saving system!


Technically,, if you shut off the engine immediately when the oil pressure light comes on you could avoid disaster.

I agree that level sensors for coolant and oil would be ideal, but those systems could go forever and never be needed, but when they are needed, it could be an engine saver, or at least give you time to get off the road and check things out, before the Drop Dead lights come on.