engine rumble/vibration on startup, 155K

For just head gasket replacement engine doesn't need to be removed, nor refrigerant drained. Machining the head likely not needed either. Preferably shouldn't be. Specs for flatness of all the mating surfaces in the last link in my signature. if you're on a phone turn it landscape to see signatures.

 

Is it a NEW engine, remanufactured, or used? Replacing the short block if the head is okay?
Coolant, not oil would be leaking into the cylinders.
Depending on how long you've been driving it, and how hot it got, resurfacing the head is a "maybe"
at this point. If the valves are leaking, no reason to reseat them. But should replace the valve
guide seals.
If the head needs all that work, it would probably be more cost effective, and time, to install a
remanufactured engine from the Hybrid Pit would be the best route. With that many miles on the
engine, you're likely burning oil. So maybe that remanufactured engine would be best way to go.
It will cost less, and will be quicker to get the car back to you.

The ONLY thing to "disconnect" on the hybrid system is the safety plug behind the rear seat.
A VERY simple 1-2 minute effort.

NO reason to "replace" the ac coolant. You just remove the compressor from the engine, you won't
have to remove the refrigerant lines.

Yes, the gasket CAN be replaced without removing the engine. Myself and other have done it.
My head was not warped, but one valve had an extremely small leak. It took almost 5 minutes for the
wd40 to seap through. So I reseated all the valve.

You should have him remove the head and check if it's warped. You do that with a special straight edge.
If it is no warped, and the valve aren't leaking, the least expensive way is to just replace the head gasket.
Of course, no coolant, and probably a good idea to change the oil and filter, after running it to operating
temp to check for any leaks. And any crap that gets into the oil passages will get caught in the filter.

 

18 hours!!!???
For that much money, get a remanufactured engine...

 

This is a diy site primarily populated by guys who are willing to do it themselves for the lowest money regardless of no guarantees of reliability. Some of the loudest voices are "academic" only with no direct hg or egr or oil burning or brake booster fails symptoms ever heard or felt

Toyota and most pro mechanics agree on this. Your hg is confirmed.

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They are going by the book; exactly how the dealer would do it; EXCEPT Toyota dealerships won't do a hg job on these engines due to their need to provide you with a good warranty and reliability. Most pro shops are the same these days; the old gen3 engines with low tension rings, pistons and hg failures need rebuilds. Toyota does recommend rebuilds using revised pistons and rings and did so for free when these engines were young.

A 12-13 year old gen3 needs to be replaced with a pro built rebuild for long term reliability. Hybridpit in the LA metro would be my next phone call. You could drive back or have them ship for an Arizona shop swap. It may cost as much as your pro's engine out hg job but you will end up with a like new engine that will last another 150k miles.

We have had guys change their hg three times in a few months. Each time engine in but various timing and oil leak problems caused rework.

 

What tier gas have you used in the car? Cheapest you can buy or Tier 1?