Gen 4 Engine into Gen 3 Prius Partial Guide

Mmm, they may have preceded The Hybrid Pit Stop, if that’s who you’re alluding to.

editorial: it’s “due”

 

Only if it's also 'preceded'.

 

Dang, got me.

 

It was September of 2018 @Ragingfit ’s video compilation was posted here, and this was likely a month or more after the deed:

Swapping in a Gen 4 Prius' 2ZR Engine into the Prius v | PriusChat

And @cnc97 ’s swap a couple of months previous:

Engine swap question | PriusChat

 

Nope it wasn't Hybrid Pit

 

That’s the route I took. Cams and valves (some of mine were bent) from the G4 head in to the G3 casting.

 

CAUTION: People need to understand the RISK of swapping in a (Gen3) JDM engine. I personally examined a number of JDM import engines at a JDM Import Swap Shop in Dallas. The following is detailed elsewhere from when I did it...

KEY ISSUE: it's crucial what model year the engine is, particularly the block (ie pistons/rings)!

* JDM's don't have a VIN and therefore no obvious provenance of model year.
* A JDM with a good 2015 is theoretically possible but not likely. And impossible to know! If you could find a guaranteed 2015, you would get a good block (ie no oil burning, no HG blowing issues over time.) But nobody knows, because nobody does tear-downs to discover what model year parts are inside.
* And based on experience, examining other P/N's (EGR etc) showed me that all of the engines I examined were earlier models! (Typically 2010 or 2011.)

If you go forward with a JDM, understand that you're reasonably likely to start burning oil when the engine hits somewhere around 100k miles, and the HG may go sometime after that. (Literally your mileage may vary :-D )

 

2015 head gaskets still go a lot..but usually no oil burning. "If it has an electric water pump with over 125k miles on it, it will kill even a Fel Pro"...

 

All this is very true but when you're getting this done and doing it all for about $1,600 I mean it's all you can do is to get it done I paid like 12 for the engine $1,100 and something to my door and then paid $435 or something like that for my buddy to put it in I didn't have time or space to work and it was winter It was just to get me back in the car and well get me out of it by the time the interior falls apart or what have you any minute now

 

Kudos to everyone on here trying to share their knowledge, to make everyone's driving experience a better one. I am from the UK and modifications like this are very uncommon. I would like to try this, however it seems the engines we've got here are slightly different. Please correct me if I'm wrong. Attached are some of the photos. Beside the water pump area, is a hose that goes all the way back and I'm presuming it's meant to be plugged into somewhere. Where do I connect this? All the gen 4 engine that have been used so far for this mod, never had this part.

 

Yes I believe this water hose has been discussed it goes to the back of the engine down low somewhere there was just a post about this a month or two ago or something maybe three. Looks like my pictures there thank you for those good pictures Nice clear. It looks like they've really beefed up that torque plate a generation 3 looks much cheaper and sloppier design this one here looks like they've fitted something around it and added beefier springs it looks like and so on other than that I think things look pretty similar have you looked at a US domestic market pictures of the same engine?.

 

What’s the situation with your current engine, head gasket failing, oil consumption getting out of control, both? What’s the miles? How long have symptoms been going on?

4th Gen engine swaps “work”, but there have been a lot of post-swap overheating reports. Too, it’s more difficult than swapping a 3rd Gen engine.

doing a head gasket replacement may suffice.

Or, with the complication of oil consumption: piston/ring replacement (with revised components). This can also be achieved with a new purchase short block: more expensive, but convenient.

 

I dropped a JDM 4th gen into my 2011 yesterday. Running well so far, aside from a hesti

It did not have that pipe. I saw one mention of that outlet above the water pump & crank pulley needing plugged… but I don’t recall where I saw that.

I used 4th gen EGR and engine, 3rd gen for everything else.

 

Yes. Definitely regret that I couldn’t use the flywheel and torque plate. It’s got much stiffer springs and is generally more robust. Sadly they enlarged the shaft/spline size in the transmission and plate.

 

Did you modify the 4th gen egr to conform to the 3rd gen water connections?

 

My engine has done 186000 miles and it consumes oil. Been consuming since 135K. During the winter for the past 2 years, it would judder when the weather is sub-zero but I had never seen any mayonnaise cream in the engine oil, until Dec 2023. This time, I knew something was different and I checked the engine oil after like 160miles, only to find the mayonnaise. I cleaned the engine oil cap with brake fluid abs covered it back. After another 20 miles journey, there was a repeat.

Now I don't want to go through the blown head gasket again, neither do I want to deal with the oil consumption.

Majority that do the mod experience success apart from the few. Even the few at the end of the nightmare, figure out a way around it and the car starts working as normal.

I definitely look forward to this mod. Plus its a learning curve. If it works, it's something I'd encourage Prius drivers in the UK to do. I know, it's a big risk but I see this, just like every other person here, as an engineering breakthrough.

I saw someone on YouTube who got same engine as mine installed. He claimed it was JDM and he had to block off the hose with a clamped bolt and applied JB Weld at the beginning of the rubber hose, just to make sure coolant did not find a way through the hose and everything worked without any qualms. I'll probably do this.

I've ordered my engine today, I'll prep it with a cleaned Gen 3 EGR valve but I won't start the work until the weather starts getting better - at the moment, the weather is freezing and cold, so may be work would start mid March.

Wish me luck everyone.

 

So it seems then ideally you would get the Gen 4 engine and transmission usually those plugs and things come cut for the high tension wires going to the transmission so you always get the plug part that's bolted to the transmission that the wires should be in but they'll be cut in case there's any matching problems in the generation 3 maybe the generation 4 gets more compact better designed connections on its transmission generally they come on the transmission when you buy it they don't unbolt them I don't think they just cut them off so that seems like it might be a thing because I'm thinking that's one of the things that was needed to be upgraded was the torque plate it's design and it's damper springs needed to be more robust or two-stage type of springs something and it looks like they might have got to it with the Gen 4 unfortunately it's just still connected to a 2ZZ engine with some different rings and sleeves and sheet metal plates to I don't know what goes on really but at the core it's still a problem for me anyway.

 

That's great using a tractor forklift whatever to put the engine in I worked in a salvage yard and used to pick up station wagons and stuff down in the bottom of the yard they'd be 20 ft over my head and I'd be running up a hill with ruts and all kinds of good stuff in it and the tractor would be swaying side to side I've dropped humongous station wagons from 20 ft up in the air straight down on the ground on their roofs good stuff matter of fact that's probably how I'll test my battery mounting in my Prius is out cut my brackets and trim everything and mount it in a junk car like I have it in my car put it up on the forklift and drive down through the yard let it go flying off the forklift fall on its roof then flip it over and see if my battery came undone I bet it doesn't.

 

No man I thought somebody here just recently put the four in a three blah blah blah and that hose was dealt with The water hose didn't need to be blocked off and all of that but I think it can be if you really want it to be I don't think it completes or has to complete a circuit because there's other things completing all the circuits too so that may be true so then maybe that's not what's contributing to the overheat problems that some people have had which I can't imagine a 2ZZ overheating generally speaking not at all but to each their own I've had two of these blown head gaskets and all that and water pump running when it wanted to I think I've seen the overheat light come on for a 10th of a second once maybe twice in the life of the two cars and generally time you get home and park it and raise the hood and pour a drink and get ready to work You can touch the coolant coming out of the hoses no problem name it to a pan put your fingers in it it's like little warmer than bath water and I'm in North Carolina where it gets 100° so.

 

You should replace the egr valve. Clean the cooler and intake manifold