2010 prius head gasket blown vs crack

Sell it to a soccer mom for a couple of hundred bucks.....

 

I did a head gasket on mine at 168,000 I now have 195,000. A cracked block is not impossible, but pretty rare. What DOES happen is if enough coolant is put into the leaking cylinder (the blow-by pressurizes the cooling system to maximum, then when you park it squirts backwards into the cylinder). If enough coolant gets into the cylinder, when it goes to start it hydrolocks and bends the connecting rod. If you have a bent rod it might be better to start from scratch, but if you can verify that all the pistons come up to exactly the same height, replacing the head gasket is not out of reach. A fast mechanic might be able to do it in a very long day, many people could do it in a weekend, but I am fat and slow and it took me two weekends. one for teardown (and then to go and mill the head flat) and another for assembly. Lanmeister just went down the same road, and his vehicle had a few other issues, but he finally got it running good with about a total investment of 3000 (including purchasing the car)

If you are trying to use the car at all as-is release the pressure on the cooling system by carefully venting it off each time you shut down. It is also possible to leave the radiator overflow tank cap loose to accomplish the same thing, this may save you from a bent connecting rod, if it is not already bent.

If the battery is good you can re-coup your few hundred bucks just by selling those modules if you find the engine repair a lost cause at any point.

 

If the head is still attached, you can remove the spark plugs, and use a screw driver or
some type of a rod to insert in the spark plug hole, rotate the engine and get the piston
at the highest spot, mark the stick, then do the same for the other 3.
They should all be the same, probably within a millimeter or so, max.

If the head is off, rotate until two pistons are at the top, then the same for the other two.
All 4 should be at the same height. It not, likely a rod is bent...

 

Tough call, but if I woke up with this car in MY driveway and it's as reported (above average condition, new ignition coils, new spark plugs, new [aux] battery, new egr) then I would verify that the bottom end is straight and repair the motor.

The difference between THIS post and the other 90-percent, where I would recommend a motorectomy, is that YOU would be doing the labor and since the car was already an inanimate object when you bought it, you're not thumbing rides until it gets fixed.
You only have a few hundred bucks in the car thus far, so your exposure on this project will be limited to some time and maybe a few hundred more bucks in parts and other expenses.

.....besides.
More lock-downs are coming.
you have to do SOMETHING with all that free time, right?

 

You're welcome. And you can do pistons 1 and 3, then 2 and 4.