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

That’s a commendable hit list; @Ragingfit will maybe notice and have a look-over.

If the 4th gen had the spin-on style filter I’d stick with that, just less problematic at oil changes.

 

Read through all 55 pages, and forgive me for forgetting. Which throttle body is recommended or could you use either?

 

Yes, That looks right to me. You hit almost every point.
Leave the fuel rail and fuel injectors on the new engine.
And do not disturb the oil pump if you can help it. If it loses its prime it will not pump oil.

- Fix That Prius !!!

 

2z oil pump won't prime? Weird isn't it on timing cover? Mechanical pump ? If so like many Toyoda oil pumps .

 

Driven by the timing chain, inside the timing cover.
It seems to hold a pool of oil inside the pump. Great design unless you dump the oil out.

 

This is the standard oil pumps the Toyota has used since th S JZ and alot of other engines . I've personally replaced them in very many of these front timing cover applications usually you pack them with a lightweight grease and that allows them to prime I've never had one that didn't prime so I didn't even know this was a thing never heard of such I guess if you would have slap it together out of the package bone dry you could possibly make it take a long time to prime or something of the sort I guess I won't even try and figure that out. And the old style in the pan pumps you could just pull the distributor out and crank with an electric drill battery or plug in but those days are long gone and those type of pumps are gone. trochoid type or such

 

For future swappers:

If One were to pull a junkyard engine out without any idea as to how long it was sitting, do you recommend priming it and if so, how would one do so? If I remember correctly from the videos; crank the engine with no coils on?

 

Should we not be priming with the fuel injectors disconnected as well? This may help avoid flooding the engine with fuel while priming.

Also, anyone know if there is an option to prime the engine using Techstream?

Regarding overheating, anyone try disconnecting the coolant lines going to and back from the throttle body? Since this is the only difference in the routing of coolant compared to the original gen 3 - it may help to rule this throttle body coolant circuit out as being the cause of the overheating. The line going from the EGR cooler to the throttle body is the same as gen 3 but the routing of the coolant line going from the PEX tee to the throttle body is not the same as gen 3.

 

I would think as long as you're coolant is making a loop and doing its thing no matter where you take things out of the loop as long as the loop is continuous If you jumper the throttle body out you can't just stop the coolant the coolant has to go from where it enters the throttle body you disconnect there and where it exits the throttle body you push those two connections together so the loop is maintained even though you jumper the throttle body out you could essentially jumper the whole engine block out but of course that would be not productive

 

That would be a weird 'cause' of overheating anyway. The coolant lines to the throttle body do not pick up heat there. The throttle body temperature is close to that of the intake air being sucked in (and can be colder, in conditions like fog, where the vacuum developed at the throttle leads to cooling by evaporating the fog droplets). The coolant lines go there to deliver heat, to avoid throttle icing problems in those kinds of conditions.

 

Thanks for the replies. Here is why I asked the question and thinking the overheating issue may be related to the PEX tee connection.

- There has been some discussion around ensuring the coolant line going from the gooseneck water outlet (on the side of the gen 4 head) to the reservoir must be routed in an upward direction to allow for trapped air bubbles to travel up and escape out of the reservoir.
- Therefore, I wonder how does the PEX tee connection affect the ability for trapped air in the throttle body coolant lines to travel and find a way out the system?
- Anyone ever tried disconnecting the throttle body coolant lines and plugging the ports to which they connect on the system (one at EGR cooler and the other at the middle of the PEX tee) to rule out trapped air bubbles in the throttle body coolant circuit as being the cause of the overheating?

 

Im about to this dance again on another car. Looks like the gen 4 engines jumped about 100% in price from when I did my swap. Im being told by the wrecking yard theres two styles of the gen 4 engine. One with aluminum valve cover and one with a plastic valve cover. Hes saying they are not interchangeable. Any truth to this?

Replying to the post above. I have rerouted the hoses from heat exchanger to keep out of coolant loop. That solved my overheating problem.

 

Can you post a diagram and/or pics?

 

TELL ME ABOUT IT. I am looking into this as I appear to have a HG issue, but prices are still only a little more than parts to do it right. As I UNDERSTAND it (def double check), a gen 4 (blacktop engine) has a plastic valve cover and the aluminum valve cover is a gen 3. Don’t quote me on this yet. I have not found a black top (gen 4) engine that has a metal valve cover, but there could be one out there I am unaware of.

 

Thanks for the reply. Could you please elaborate on which specific hoses you rerouted? Which heat exchanger - radiator or heater core or other?

 

I wish I had pictures. Took me some time to figure out which way to reroute the hoses. I sold the car which is still going strong by the way. I found out the gen 3 motors have aluminum valve covers and gen 4 motors have plastic valve covers the black ones.

You'll see the 3 aluminum lines coming from exhaust near the firewall. Its like a freeway in Los Angeles so many off-ramps. You have the hoses from heat exchange, EGR cooler and heater core all right there.

 

This is the kind of question, especially in a thread like this one where lots of people are improvising, where you probably want to ask a bunch more questions. Like, not just "can you give more details on what you did?", but also "how did you decide that was the right thing to do?", and "what information did you rely on?", and "how did you check yourself to make sure your interpretation was right?".

To see why I say that, we've got another good example from just 45 pages earlier in this very thread. Way back in August 2019 was the birthday of the bogus notion that Gen 3 and Gen 4 EGR valves have different pinouts and need wires swapped in the plug. And six days later it got repeated by someone else in another thread who added the details of which wires to swap and called it "amazing" that the earlier poster had "figured it out."

Only nothing had been figured out. The two valves don't have different pinouts, and the proposed wire swap only ends up leaving the EGR nonfunctional, and the thread went on eight more pages and nearly a year before the combined efforts of multiple people managed to set that all straight.

And even continuing on to this month, more than two years after it was set straight, people continue to follow that old bogus advice and end up making their EGR nonfunctional without knowing it, and having to be set straight.

So, what's that old example good for? Well, think about, if you had just seen some early post saying two EGR wires should be swapped, what questions you would need to ask before following that?

If you just ask "h᠎i, can you say which wires you mean" and get the answer "the red and the purple", that's not enough info for you to decide if this advice is worth following.

If you ask "ok, how did you end up deciding those two wires needed switched?", that's a little more like it, but still wouldn't have been enough, 'cause there was a whole reasonable-looking story in that first post:

Pretty persuasive, right? I mean, even borrowed a new Prius and "tested the wires with a multimeter."

Only that story was a bogosity layer cake. Not just the kind of thing where somebody says "I drew the conclusion Z" and turns out to be mistaken, but a whole chain of reasoning "because V, W, X, and Y, I draw conclusion Z" where not one of V, W, X, or Y was even right to start with.

In slow motion:

• New EGR and old EGR obviously are different. The wiring in the plug was different. (V)
  Electrically, the valves work the same. The pinout never changed, as any quick look at the wiring diagrams (even the simplified ones in the repair manual) would have shown. Toyota may have changed the colors of some wires, but the electrons don't care about the colors, only where the wires go.
• The new egr plugged into the old plug was causing it to hang open (W)
  No it wasn't. The valves operate the same way.
• which was giving me the misfire codes (X)
  No, the misfires were simply because a Gen 4 EGR is oversized for a Gen 3 exhaust, and flows too much gas when it's open. That's the basic problem.
• tested the wires with a multimeter (Y)
  And found out what? The valve is driven by simultaneous pulse trains on four different wires, with the timing shifted. If you want to figure out which wires are which, I could show you how to do it with a four-channel oscilloscope, or with a two-channel scope, the wiring diagram, and some extra cleverness.
  
  A multimeter by itself won't show you enough.
• And finally, based on those four mistaken premises, the person switched two wires, without realizing that did nothing but make EGR nonfunctional, and preferred how the engine ran that way, because at least with no EGR it didn't have symptoms of too much EGR anymore, and thought "eureka, I have found the fix."

So really, if you were going to ask some questions to decide if that advice was worth following, they would have to be quite a bit more pointed. Like:

• Where are you getting your info that the wiring is different (besides color, which electrons don't care about)? Did you look in the wiring diagrams? Take the valves apart? What exactly did you find?
• Why do you think the wiring left the valve hanging open? Can you explain it on the wiring diagram? Did you think of a way to miswire a stepper motor so it would be able to open, but not be able to close?
• Why do you think that hanging open is what caused your misfires? What possible alternative causes did you think of? What tests did you think of to rule those out? What results did you get?
• When you "tested the wires with a multimeter", what did you test exactly? Can you explain your method for identifying the four drive wires of a stepper motor using a single multimeter?
• After you made your wire swap, it sounds like you no longer have symptoms of too much EGR, which feels like success, but what have you done to rule out that you haven't done something else, like disabled EGR completely?

Maybe it would have seemed not-very-nice to ask so many pointed questions of the person who first put up that advice. But it might also have saved three years (so far) of other people putting their engines at risk by following bogus advice.

Bringing it back around to the present topic ....

I think Joele3 is talking about the Exhaust Heat Recovery System (EHRS) exchanger, the one on the front exhaust pipe, down under the car. From post #1092, it sounds like Joele3 was having an overheating problem, and that just routing the EHRS completely out of the loop made those symptoms go away. That sounds pretty good as a diagnostic step: I did this, here's what changed, what does that tell us about what's going on? It doesn't sound very close to a whole story or a fix yet.

To get closer to a whole story, there would have to be some of those pointed questions asked. Like:

• What's your guess for why having the EHRS in the loop gives you overheating symptoms with your Gen 4-in-Gen 3 swap, when it doesn't cause overheating in a stock Gen 3 or a stock Gen 4?
• Have you compared the hose routing diagrams for Gen 3 and Gen 4? Have you drawn a similar diagram of how you actually routed the hoses in your swap? Do you see something in that diagram that you think would make the EHRS produce overheating, when it normally doesn't? Can you think of a way to test that explanation?
• Can you post your full diagram of how you routed your hoses, for other folks to look at? Sometimes another pair of eyeballs can spot things one pair misses.
• Have you checked that the thermostat down at the EHRS exchanger is doing what it's supposed to?

I know it seems like a lot of pesky questions, but that's the way to have threads eventually lead to advice we can be confident about.

It seems like sometimes we run on a shortcut version of scientific method that is more like "I've thought of something that could be right, and done this thing that seems to fit with that, and haven't tried anything that would show me if it isn't right, so I'll go ahead and say it is", but that's a little bit too much of a shortcut.

 

Always impressed with your feedback @ChapmanF


iPhone ?

 

I told my uncle to skip trying to look for gen 4 motor not many available locally around here. Way over priced. He went with a rebuilt from Hybrid pit. He drove down and picked it up.

 

Thanks again for the purchase - took about 10 hours to build her