Using the previous photo of the 3.5 engine removed to assist with locating the engine block coolant petcock on the driver's side, I attempted to locate it again. Did not locate it from the engine bay, so went beneath the vehicle (while on ramps), to try and locate. I removed the 10mm screws that fastened the under-engine cover to chassis (12 total?), to have belter access to where I believed the engine block coolant petcock to be. After searching with flashlight, it was located just above the driver side steering rack boot, in a constricted space. There was a wire harness bracket just below where the petcock was , blocking direct access. I slid the bracket off the treaded bolt used to hold the bracket in place. It allowed for just some additional room since the harness is also connected to the alternator and a somewhere else (unable to determine the third was)..Removing the harness clip from the alternator also allowed just some additional slack ( Photo 1 below with 2 yellow arrows referencing the 2 harness locations that were disconnected, and the black arrow referencing the draincock location).
Was able to maneuver my hand in the limited space and place a 5/16" ID hose over the valve. Then maneuvered a 10mm socket onto the10mm bolt to open however, unable to get a a good turn using a ratchet due the very limited space. Experimented with different extension lengths but still could not generate enough force to loosen the bolt. I assume it is to be turned left / counter-clockwise to loosen. Perhaps Mike can confirm what he may have used to loosen the driver side engine block coolant petcock. The passenger side engine block coolant petcock location appears to haveadditional space to to access with ratchet and loosen hopefully without any issue! (Photo 2). Decided to tray again in a few days after some additional research (may try a Tite-Reach tool or a cheaper alternative like Pittsburg Pro. at Harbor Freight). Tite-Reach video below. If unable to loosen the driver side coolant petcock, will just drain the radiator and overflow reservoir.

PHOTO 1


PHOTO 2



Tite-Reach tool video;

 

When i replaced my bank 1 catalytic converter. I was able to get to all 6 nuts to remove. I just had to remove the oil dip stick, and airbox. From the front leaning forward I was able to get all.

I assume for bank 2 you could remove a few stuff out of the way to reach down as well. If you could get a stubby wrench, or ratchet. You should be able to reach down standing next to the fender. Maybe get a small step stool to help you reach in. This is one of the hard to reach places. Where you need some creative thinking to get it loosened up.

 

Understood, thank you Mike. Will follow up should I figure out access to the passenger side engine block coolant petcock.

 

After another try successfully accessed the Driver side engine coolant drain petcock.
I began by removing the radiator cap then the front under engine cover (approximately 16 10mm screws hold it to frame, but easily removed. All screws appear the same in length however, keep track of what was removed from where to confirm).
Then drained radiator (placed 5/16" ID hose over spout, which can be purchased at HD or LOWES, and placed the other end in a container to collect used coolant. Turned petcock left / counter-clock wise to loosen and coolant began to flow. When fluid stopped, tightened the petcock and removed the hose. Moved to the Driver side engine block coolant petcock while under vehicle on ramps.. Accessed it by using a 1/4" ratchet with 3" extension and shallow 10mm socket. May have to experiment with what may work the best however, I believe the use of a ratchet may be the best solution. Placed 5/16" ID hose over spout, routed the other end away from work area and placed in container to collect the used coolant. Placed the 10mm socket with extension over the 10mm petcock bolt .first then lined up the ratchet with the extension and began to loosen. Waited until coolant stopped draining (not much) and tightened the petcock bolt and removed the hose. Moved to the Passenger side engine coolant petcock, and place 5/16" hose over spout and routed it away to container again. The driver side petcock is much easier to access and has more room. I used the same 1/4 ratchet set however, can use larger ratchet if needed due the the additional space. Loosed the petcock (even less coolant drained from the passenger side). Tightened the petcock bolt when coolant stopped and removed the hose. Then used a Mityvac MVA6851 Fluid Extractor Syringe, to extract the existing coolant from the coolant overflow reservoir. I then used the Lisle Spill Free funnel (believe it to be 24680, see video tutorial below), to add new coolant (Toyota 00272-SLLC2 50/50 Pre-Diluted Super Long Life Coolant) to the radiator. When coolant began to collect in the funnel and no longer entered the radiator, stopped adding coolant and started the engine, turned on the heater. Waited until no bubbles were seen in the funnel then turned engine off. Installed the stopper into the funnel and placed the funnel over the coolant overflow reservoir. Removed the stopper and transferred remaining coolant into the coolant reservoir to the FULL line. Snapped reservoir cap into place and replaced the radiator cap onto the radiator. So fare appears to be running with no issues / leaks but will continue to monitor. Hope the above write up proves helpful to any individual contemplating performing the process themselves as well.

Lisle Spill Free funnel video tutorial;

 

Is it best to fully flush the coolant using the 3 plugs or is it okay you just drain and refill using the radiator plug. Thank you everyone!

 

I'd assume if unable to access the 10mm driver / passenger side block coolant plugs, draining the existing coolant via the radiator plug and coolant overflow reservoir whould be fine.

 

I'd highly recommend a good effort is made. Also, head back towards the transmission, there are coolant lines at the heat exchanger. Pop the lower one off and that should help significantly. Coolant line is right by the cat. Remove it!

New engine w new fluid was good for 10 plus years. Not getting 1/2 the fluid out scales the next service to 5 years or so. Keep that in mind.

 

Would removing the coolant line going to the trans cooler / exchanger be done instead of removing the engine plugs to drain coolant (if unable to reach), or should be included with the coolant drain / fill procedure;