Moving up to newer Prius, questions

Are you loosing engine coolant? Kinda sounds like the head gasket has failed.
It's extremely unlikely the transmission is bad.

The Gen 4 has less issues.... So I've heard anyways. Depends on who you chat/talk with.
And what you believe.

 

The latest thing is using the detuned Camry engine an MA or AM . Timing chain engine from Camry detuned for Prius duty . Once they regularly start pegging over 200,000 I'll be looking at until not so much . The power plant has to prove itself for me to buy it and then the interior and chassis are welp cheap not to. Keep type stuff.

 

What are you talking about when you say "engine from Camry detuned for Prius duty"?

The latest dual injection 2.5L used in Camry and Rav4 hybrids? Into a Prius?

 

It doesn't take much. Using a bore scope in cylinders 1 and 2 with pressure on the
cooling system might show coolant leaking into the cylinders.

387,000 plus miles on my 2010. I replaced the head gasket at 301,000 miles....

 

We have two Gen 4's, 2017 and 2021 and both have been boring for this DIYer! (I have to rely on our 2008's to get to do any of the fun stuff.)

Seriously, though, don't limit your search to the Prius....the Corolla and Camry Hybrids are, also, excellent! And even a late-model Avalon Hybrid. (My co-worker has one....rides as smooth as a Lexus!)

 

I'm not exactly sure, but a search may reveal when toyota started installing the redesigned exhaust pipe coolant heat exchanger. might have been around 2020.
up until then, there's a potential for a leak and blown head gasket:
MC-10166037-9999.pdf
tsb-coolant-leakage-at-front-exhaust-pipe-prius-prius-prime.211059
gen-4-prius-care-maintenance-and-troubleshooting.155

 

It's a common issue. Without doing a coolant system pressure test and a bore scope
in each cylinder, where you can see coolant leaking, you won't know for certain.

Check the coolant level when the engine is cold, like sitting overnight.
Then try to park it in the same place over night again. Or when you get fuel.
If you see that the coolant is slightly lower each time, or close, then likely, it's a failed head gasket.

It's no harder than on a non hybrid car. It will depend on what tools you have and your skill level.
The trickiest part is getting the timing chain cover back on. It's not hard, you can force it. You just kinda
"place" it on. Then get all the bolts in and tightened. It's easy to get the timing chain on because there
are 3 colored links to set the chain in place. Ease in the timing chain tensioner in place, rotate the engine
backward a little bit, and slowly to release it. Rotate the engine close wise two complete turn and check the
timing marks.

 

Then you can certainly do the head gasket!
Do it BEFORE it gets bad, and possibly warp the head.
But, always check it with a straight edge.
And replace the valve guide seals.
You will need a smaller valve spring compressor. Mine was too big, but I had a washer I placed over
the retainer washer, but it slipped and one retainer went shooting off! I eventually found it!

Lay the head on a level bench and spray some WD40(or other light oil) on the valve so it covers the
whole seat. Wait 15 minutes or so then carefully lift the head and check to make sure all the valves
are seating correctly and there are no leaks. If any are leaking, seat them all in.

I have 86,000 plus miles on my replacement head gasket.

Get the FULL head gasket kit from Toyota, and head bolts. If you're a veteran, they usually give you a
10% discount.

 

No, take the valve out, put some valve grinding compound on the valve and seat.
Then either use a suction cut on the valve and spin it back and forth with your hands and bounce it on the seat.
Do that several times, take the valve out, use carb cleaner or brake cleaner, and clean off the valve and the seat
and see if you have a nice even pattern.
Unless they are really bad, then you may need a machine shop. But the car would be running bad if they
were leaking a lot.

Are you burning oil? Depending how much it's burning, and how much you drive, you might want to
consider a short block.

 

The gen3 egr only causes startup stumbles and continuing low rpm roughness if it is stuck open. A revised egr valve and ecm software is available. A simple block flow test can rule that out.

A gen3 head gasket leak begins by showing symptoms very occasionally, often weeks between severe rattles that quickly clear for the rest of the day.

He is correct about that since a complete reengineering of the engine was done for the gen4s. It has no unusual amount of head gasket or oil burning issues.

Most mechanics, dealers and pro shops recommend a head inspection, rebuild and valve seals by a machine shop when repairing a gen3 head gasket.

Oil burning is common on gen3s and is an important factor if dealing with a hg problem. Toyota acknowledged that pistons and rings through a mid 2014 production change were poorly designed and replaced thousands with revised parts under warranty early on. Many with high miles and a hg problem choose a replacement engine if faced with a hg and oil burning. Or trade the car.

Videos
Shudder video when a hg is advanced.
“Hey Walt… they want to wait and see if it gets worse…”

Car Care Nut HG Borescope at 7:40

Start with no cost egr block flow test

 

gen 4 is smaller. I don't recall it getting smaller after a certain year. don't go by cubic feet, that can be misleading.
find width at several places, depth and height measurements

 

Gen 4 is 2016 through 2022 model years; not sure there's any significant about 2020. Maybe some misundertanding?

There are some cutbacks in storage, interior room, with 4th gen. The 3rd gen's upper glove box was nixed (hey, I didn't know it existed for a year or three), hatch slope more severe, hatch floor rises and lowers with the tide of spare versus no spare (another thing missing, on some levels). I think head room and seat heights are a bit lowered as well. Best would be to find one on the lot, have a good look, test drive.

Another thing, with 2016 model year you can't switch the speedo from mph to kmh, or vice versa, a slight oversight by Toyota...

Attached is Toyota USA's Gen 4 brochure. From the brochure, can you imagine this "look" for your living room: