Gen2 Prius Engine Removal Guide - Out the top of the engine bay

Hi all,

When I went to replace the engine in my 2008 Prius I found that there was no guides to removing the engine on its own through the top of the bay, only on how to remove both the engine and transaxle at the same time by dropping them out the bottom (which I didn't really see as a good idea given I lack access to a hoist, and I would prefer to wrangle an 80kg engine on its own rather than trying to wrangle both that and a 130kg transaxle), or on how to only remove the transaxle on its own. Straight up engine failures in NHW20s seem to be reasonably uncommon which is probably why this is the case. In my case, the engine had seized up totally, likely from overheating, as when I got the car it had no serpentine belt, the oil was about 50% coolant, and when I drained the engine cooling loop, I got maybe 100mL out of it, and most of that was from the reservoir bottle. I apologise for the lack of pictures, I didn't think to take many during the removal but I hope these written instructions will suffice. For reference, my car is RHD, and I will be referring to sides of the car as you would see them from the driver's seat, so when I say "right hand side of the car", I'm referring to the same side that I would be sitting on when driving.

Tools/Supplies Required:

• Yourself
• A friend who can follow directions and use their eyes and brain competently
• An engine that is not deader than a dodo
• An engine crane, preferably with a load leveller
• A jack, the lower profile the better as you will have to slide the jack well under the car to reach the front lifting point on the K-frame
• Jackstands (for the love of all that is good do NOT get under or work on a car supported only by a jack, and you will need the jack anyway to support the transaxle later on so it can't be holding up the car)
• A full set of metric sockets (in particular 10mm, 12mm, 14mm, 17mm, 19mm and 21mm)
• A breaker bar, preferably two, a shorter one and a longer one. I only had a 750mm long one, which proved to be a pain in the nice person when removing transaxle-engine bolts as it was too long to properly fit while under the car for many bolts which made removing them harder than it needed to be)
• An impact gun (optional, but VERY useful especially when reattaching the engine to the transaxle and removing the pulleys)
• Screwdrivers, both Phillips and flathead, of varying sizes
• A prybar, or alternatively a really big flathead screwdriver
• A multimeter capable of reading at least 450V DC, so when you go to remove the inverter you can see if it's about to turn you into human BBQ or not.
• Something to catch drained fluids, and some bottles to put them into dispose of them correctly.
• Mechanic's gloves, or if you don't have these, band-aids as you will likely skin your knuckles more than a few times.
• Eye protection, when you are working under a dirty car, dirt and other crud WILL fall down as you shake it loose while unbolting things so unless you enjoy getting that in your eyes I would recommend wearing at least some basic safety glasses.
• A service's worth of oil and coolant, and an oil filter. For everywhere in the world except the US and Canada, you will need approx. 7.5L of pink Toyota Super Long Life Coolant to completely refill both the engine and inverter cooling loops. For the US and Canada you will need approx 10L as you have the coolant heat recovery tank to contend with.
• A tube of molybdenum grease (optional but recommended). I used this to lubricate the splines on the transaxle input shaft and the engine's mass damper, it will help them slide back together. Don't use too much else it will stop you from sliding the transaxle on all the way, you only want and need a thin smear of it on both surfaces. It will also prevent the splines from sticking to one another which will make separating the two easier if you ever have to do it again.
• A new serpentine belt (optional). You'll be removing it to do this so it's a good time to fit a fresh one anyway.

Step 0: Now to begin with, you will want to follow the instructions from Lam's excellent Gen II transaxle removal guide, up until step 35, where he details on how to remove the axles. We will obviously not need to do this as the transaxle will be staying where it is. You will also not need to drain the transmission fluid, but now is a good time to change it if it needs to be changed. The wiring harness you've disconnected can be draped over the passenger's side (LHD driver's side) guard to keep it out of your way while working. You will also need to remove the intake as we will obviously using a crane to lift the engine.

Step 1: You will need to drain the engine you are removing of as much of its fluids as you can, particularly coolant, unless you enjoy the engine dripping on you while you're grunting underneath the car and wiggling the engine around. Remember to use the drain fitting on the back of the block and on the left hand side radiator tank to drain as much of the coolant out. Once the coolant has drained you can disconnect the two radiator hoses from the engine (beware of the spring clamps used, they are a gigantic pain to remove and I want to find the person who thought these particular ones with clips were a great idea and poop in their breakfast cereal), as well as the heater core hoses. While you are under the car, now is a great time to unbolt the exhaust manifold from the rest of the exhaust, I used the impact with an extension on the 14mm bolts and that took them off no problem. Set the bolts aside, and do not lose the springs from those bolts. Now is a good time to remove the fuel feed line as well, just remove the black plastic support clips (they just pop off), and then squeeze the yellow button on one of the fittings and pull it off. There may be 40psi of fuel pressure behind it if you've gone to IG-ON recently so eye protection is probably a good idea for this step unless you enjoy potentially getting petrol in your eyes. Disconnect the other end as well and place the hose aside for now.

Step 2: You'll need to clear some space on the right hand side of the engine bay so the engine can come up without hitting too many things. Because of how Toyota has laid out components in the bay you will need to first remove the washer bottle as it's covering a few crucial bolts. Disconnect the two washer pumps at the front of the bottle, there is an electrical connector on both as well as a simple rubber hose for each. If your washer bottle has fluid in it, once you remove the hoses it will start draining so I would suggest emptying the bottle beforehand, or leaving the hoses until you have the bottle freed from its perches. It is being held in place by one 10mm bolt at the back of the bottle and two clips, one upper one at the front holding it to the frame behind the headlight, and one lower one holding it to the wheel well. I wasn't able to get to the top clip with the headlight still in place, so I ended up breaking it off, the bottle is still held in place by the other clip and the bolt quite fine. The lower clip should just pop out with a little bit of prying. Once you have these removed you can remove the washer bottle with a bit of jiggling and set it aside. Now that you have the washer bottle out of the way you can remove the 3 10mm bolts holding the brake fluid reservoir bracket in place. You can then tilt the reservoir upwards, and use one of the 10mm bolts through the lower bracket hole into the threaded hole where one of the upper bracket bolts went to hold the reservoir up and out of the way. You can also remove the reservoir entirely, but that will mean you will have to completely flush the brake system afterwards with fresh fluid as you will have exposed the brake system to open air and contaminants.

At this point your engine bay should look something like this (note brake fluid reservoir suspended in the corner to keep it out of the way):


Step 3: Now that you've cleared some room for the engine to depart its home, you can start unbolting the engine from the transaxle. There are 6 14mm bolts and 2 19mm bolts holding the two together, start with the two 14mm bolts at the front side of the engine holding a cover plate on where a starter would normally be on a 1NZ-FE, these are shorter than the rest of the bolts so don't mix them up. Then, remove the upper two 14mm bolts on the rear side of the engine. The uppermost bolt is the most difficult to get to out of any of them as the axle is in your way and makes it hard to get a good swing on a breaker bar or spanner. What I did was use the impact gun with several extensions squeezed up between the engine and firewall and let it loose on that bolt to get it out, just pass the extensions through the exhaust manifold brace and it works. The other 14mm bolts you will need use use a breaker bar or long spanner on as there is not enough clearance to the block to use a rattle gun. Once you have those two bolts undone, you will need to unbolt the lower torsion mount as it is stopping you from accessing the last two bolts holding the engine and transaxle together. You will need a 19mm socket for this on the breaker bar or impact gun, there is a nut on the other side with a protrusion on it to stop it from spinning when tightening or loosening the bolts. You will also need to remove the 19mm bolt and nut holding the torsion mount arm to the K-frame. Once these bolts have been removed, the mount can be removed and set aside. Before proceeding any further, you will need to support the engine with an engine crane, as well as the transmission with a jack, as once you remove the last two bolts they will want to start coming apart. I looped one of the chains from the load leveller on the engine crane around the intake manifold, and the other chain I bolted the end of to an unused 14mm bolt hole on the back right side (looking at it from the front) of the engine. Once both are supported, the remaining two 14mm bolts can be removed.

Step 4: Now that there is nothing holding the engine and transaxle together, you are almost ready to separate the two. You will need to remove the remaining engine mount now, for this you need to first remove the two 14mm nuts on the underside of the mounting bracket on the engine, then you can remove the two 14mm nuts on the top of the engine bracket. Then, you will need to remove the two 14mm nuts holding the engine mount to its bracket on the body. You should then be able to slide the mount off the studs and remove it, you may have to give the A/C hard line a bit of a tweak to clear it (but be gentle, you don't want to kink or puncture it). Then, the 14mm bolts holding the bracket to the body can be removed as well.

Step 5: Before you can lift the engine out, you will need to remove the crank pulley and water pump pulley, as they will prevent you from sliding the engine over enough to get it off the input shaft and clear the transaxle bellhousing. I used the impact for this as it meant the pulleys didn't have to be pinned in place, but if you aren't using one, I would suggest cracking the water pump pulley bolts while the serpentine belt is still on as it will give you some extra resistance to stop the pump from spinning. You will need to remove the serpentine belt, to do this, crack the 14mm nut on the front of the tensioner loose but do not remove it(you may need the breaker bar for this, I did as mine had been done up ridiculously tight), and start turning the 12mm bolt on the top of the tensioner bracket anti-clockwise to release the tension on the belt. If the tensioner does not move and instead the bolt starts coming up, try undoing the pinch nut on the tensioner a little more, if that doesn't move the tensioner you may need to give the 12mm bolt a tap from a dead-blow hammer to free it, you don't need to wail on it but just a firm tap should free it.

Step 6: We are ready to lift the engine out at this point. Before you do so, take a moment to look everything over and make sure you have disconnected all of the hoses and wiring anchoring the engine into the bay, unless you feel like testing the tensile strength of said hoses and wiring with the engine crane. Once you are sure everything is disconnected and moved out of the way, start moving the engine to the left to get it off the transaxle. This will take a fair amount of wriggling and jiggling of the engine, along with some assistance from Mr Pry Bar, but once you have the engine almost touching the right hand side frame rail you should be clear of the input shaft and bellhousing and you can start moving upwards. As you bring the engine up you will also want to bring it forwards a bit to clear the A/C, brake and fuel hard lines behind the engine. Take it slow, one person should be watching the engine carefully as the other person jacks it up, watching for things it is about to get hung up or caught on. Done correctly, you should now have a scene looking something like this:


Step 7: You will now need to prep the new engine to take the place of the old one. The engine I had was complete, so the only things I had to do were remove the wiring harness from the new engine, take the pulleys off, apply some moly grease to the transaxle input shaft and mass damper splines, and get it hooked onto the crane, but depending on where you got your engine you may need to transfer other components over at this time. Now is also a good time to replace the oil filter on the new engine while it's on the crane and easier to access.

Step 8: Now you get to shoehorn that sucker back in there. Installation is the reverse of removal, and remember to be careful not to snag anything on the way down, lest gravity test the strength of an important engine bay component. Use the jack and engine crane to get the transaxle and engine reasonably well aligned before you shove the two back together, and then you can tighten the bolts down to stop them from trying to run away on you. Reinstall the engine mount and lower torsion mount, bolt the exhaust back on, connect the engine coolant hoses, put the brake reservoir and washer bottle back in place, reconnect the wiring, reinstall the inverter, reconnect the inverter coolant hoses, refit the bonnet and splash guards and you're pretty much done. Don't forget to fill the engine with oil and both loops with coolant before the first start.

When refilling the engine coolant, there is a bleed valve on the left hand side of the radiator core support, you'll see a large hole and a warning sticker above it, stick a hex key in it (I believe it is a 6mm hex key) and loosen it before starting to fill the radiator, that will make your life much easier when it comes to filling as you won't have to stop every few seconds to let air bubble out of the radiator neck. Keep filling until coolant starts coming out of the bleed valve and then retighten the plug with the hex key. Top up the radiator to the top of the fill neck and leave the cap off, and then top up the overflow bottle to the full mark, you will need to stop and check several times as you cannot easily see the full mark and fluid level unless you look at the back of the bottle. While you let more air bubble out of the engine cooling loop, you can start filling the inverter coolant loop. First things first, you'll want to grab a 10mm socket or spanner and open the bleeder on the front of the inverter. Again, this will make your life much easier. Open the cap on the inverter coolant reservoir and start filling. You may have to stop several times and let the coolant flow into the loop depending on how fast you can pour. Keep filling until coolant starts coming out of the bleeder valve, and then retighten the valve, and resume filling the reservoir until you reach the full mark. Check the radiator again, the coolant level will likely have dropped again so top it up again.

Now you are ready for the first start. You will want to start the Prius in Inspection Mode so the engine runs continuously (there are plenty of guides on how to do this if you search, it involves a bit of a dance with the pedals), and then set the climate control to max heat. Now go back to the front of the car, and as the coolant level in both the inverter and engine loops drop you will want to top each of them up. Once they stop dropping, put the caps back on each system and switch the car off to cancel Inspection Mode. Now you are ready to take the car for a test drive. I would suggest connecting an OBD-II dongle at this point and running an app like Torque Pro to monitor the engine temp as well as inverter temp, these should both remain at reasonable levels during the test drive if you have filled the cooling loops correctly. I do not have any advice for North American market cars and filling the engine cooling loop, since you have the coolant heat recovery tank that other markets do not have, but there are lots of guides out there on how to do a coolant change with that system so I won't (and can't) go over it here. If your test drive is successful, congratulations, you have successfully executed an engine R&R on your Gen II Prius. Don't forget to re-check and top up the coolant as-needed once the car cools down and over the next few days of driving it as air works its way out of the loops completely.