Technical question -- Engine Swap

My intial thoughts on this question would be. Pull the battery disconnect on at the battery and there will not be any current from the HV battery going to the engine compartment or power invertor from the HV battery. The auxilary battery should also be disconnected, as in any auto engine change..
There is still one remaining potential HV danger and that would only occur if you were to tow or rolled the vehicle while the MG2 is engaged with the final drive. This could become a ReGen situation and HV AC might be present at the Invertor. However, if the Aux battery/12volt elect systems are dead, I can't imagine this happening.
Otherwise, the engine chance shouldn't be a big deal. If you are just pulling the engine and not the CV tranny, you must be considering pulling out the top, rather than out the bottom. I haven't considered this since normal procedures show dropping both together, out the bottom after removal of the sub frame/steering system. If your mechanic can figure a way to take it out the top and avoid the other problems, please let us know how it goes.

Good luck.

Steve

 

There are some impressive caps in the inverter but I don't know how long they keep a charge ... if any. The battery has no caps to speak of and when the car is powered down, the relays on each end and middle are supposed to be open. Test with a VOM to be sure but that is how the schematics show it working.

Bob Wilson

 

That is a problem I have been puzzling over since I can't install my lift until I pour a better concrete floor.
The car would have to be raised, inedpendent of the front wheels, since the lower control arms are attached to the sub-frame I mentione earlier.
You would need enough clearance under the car to slide the engine or engine and tranny out from under the front. I have been considering raising the front of the car on blocking and jack stands. In my case I want to remove the engine/tranny as a unit from one car and transplant it into another.

Seperating the engine from the tranny shouldn't be a big deal, only about 6 bolts, and lowing just the engine. The engine is smaller and easier to handle than the tranny. Being smaller, it might be possible to take it out from the top, since you don't have to remove the power inverter. I might even go out the bottom seperately once it is disconnected from the sub-frame. Something to explore. That is why I ask that you let us know how you do it and how it goes.

From my experience, with other makes of cars, I find it help full to remove the radiator/condensor out of the way at least for better access. The Prius has a removable upper radiator support that would improve access. Removing the radiator could be removed but the AC condensor compliated this because of the loss of refrigerant, etc..

Steve

 

You can remove it from the bottom as long as you can get the car high enough. I have done this on several occasions on other cars and I assume the Prius would be the same.

As long as you have clearance, you can do it. Just make sure you do it safely.

 

I just replaced the transaxle on a 2001 prius by dropping the engine/transaxle out the bottom. All I had to do was jack up the front and set the side frames on jack strands. There was enough room to drop the eng/trans using an engine hoist. I didn't even have to remove the hood like with most vehicles.
It's really just like any other FWD vehicle except for the inverter that needs to be pulled, and the extra cooling hoses for the transaxle.
Good luck!

 

You haven't said exactly what you're seeing the car do, but from the way you have written it up, I get the sense that you turn the key to START, hear the engine whirr for several seconds, then stop, the P3191 code tells you it failed to start, and the mechanic thinks the engine is starting and then cutting off.

Your mechanic might not realize that your engine is started by MG1 spinning it up to about 1200 RPM (enough to sound like "engine started" in any other car) and then after a few seconds of that, if everything works, the engine actually starts. If the engine never starts and produces its own power, after a while the ECU gives up and logs the P3191 code, and MG1 stops spinning the engine. It sounds as if your engine simply isn't ever starting (just as the code says) and you should be doing the usual checks on compression, fuel delivery, and spark in order to find out why.

Your traction battery is obviously good enough to spin the engine up to starting speed for several seconds at a time, so that's not a suspect right now. You are, however, using some charge from the traction battery every time you try to start, and nothing goes back in unless you get the engine to successfully start and produce power, so that's the problem you need to solve while you still have enough juice in the traction battery to keep trying.

Hope this helps,
-Chap

 

Yup just like ChapmanF says, you have to go back to basics;
1) Is it getting fuel
2) Is it getting spark
3) Do I have good compression

At this point it pays not to get too complicated. Put your 12V battery on a charger to keep it charged. Check all of your electrical connections and make sure all plugs got plugged back in.

 

Some of the P codes are generic and you have to read a sub-code to diagnose what is going on. I'll lover over P3191 tonight but if I remember correctly this one has a boat-load of sub-codes.

I'd love to bring my scanners and drop in but:

• 74 miles to Summit NC and Taylor Automotive
• 490 miles to Huntsville - bit long for a 'house call'

Did you get a ScanGauge II? We might be able to identify if there is an XGAUGE that might give the subcode you need.

Bob Wilson

 

Nothing wrong with keeping the 12V battery charged, but do remember that the juice to crank your engine comes from the traction battery, and there aren't chargers for that down at the neighborhood AutoZone. That means your mission, should you choose to accept it, is to figure out what's keeping your engine from starting, and how to fix that, while carefully rationing your starting attempts.

Note to self: if I ever do an engine swap, I'm gonna start with a force-charge to 100% SoC before I start unhooking things....

-Chap

 

I've done this too many times to count. No cherry picker or shop lift required. Rear of car on normal ramp stands, front on medium size jackstands. Remove wiper stuff, inverter, subframe with steering rack then lower engine/tranny down. No way to pull them up and out..must go down. I use a Harbor Freight motorcycle jack under the tranny and made a "lowering winch" out of some scrap wood and metal ties from home depot for controlling the decent of the engine. If removing engine too put engine onto movers dolly then slide both out the drivers side. (you may have to lift up the drivers side car body with floor jack to clear the wheel well).

I bought 2 of the official Toyota engine hooks part 12281-21010 (special order at dealer) and longer bolts 90080-11222 that bolt onto top of engine, helps keep the center of gravity right.

Photos show engine left in the car but you can easily pull engine and tranny together.
(You need to lower engine a few inches to get tranny out so the lowering winch is handy)

 

If you pull the orange plug on the rear of the HV battery and disconnect the 12V, wait 15 minutes you will not get hurt by electricity. I have never heard of a Prius Technician shutting off power and getting electrocuted...if anyone has, please chime in.

BTW, if you have a tired Gen1 gas engine, look for a Gen2 (04-09) low mileage donor, it's the same engine with minor external changes to make when you do the swap.

EDIT AUGUST 2013 if appears the engines have different cam timing etc internally so best to use 01-03 engine until swapability confirmed.

 

I have never pulled just the engine, it might be possible, but not a lot of room to separate if the tranny stays in it's normal location. (engine and tranny must come apart about 2 inches to clear the vibration dampener aka "flywheel") Radiator and condensor can stay put, but unbolt the AC compressor from the engine and tie it up so you don't have to evacuate the refrigerant.

If you are only pulling tranny, leave AC compressor bolted to engine and unbolt the clamps that hold the AC lines to frame etc so there is enough "give" in the AC lines to lower the engine down 6-8 inches then the tranny comes out drivers side.

 

We seemed to establish here that the block, head, pistons, connecting rods, and camshafts are all different part numbers; that wasn't the full extent of the differences, just the point where I stopped copy/pasting part numbers. The different block, crank, and rods called for different bearings too. I don't doubt the engine will fit and run; it's just that we don't really know what all the differences are. According to Patrick Wong, compression and valve timing were among the differences.

Also, in doing such a swap, I'd want to very prominently label the year of the new engine somewhere, so no mechanic later on will order parts off the Gen 1 list by mistake.

-Chap

 

Is it easy to describe where on the engine top these attach? I can't quite make it out in your photo.

Thanks,
-Chap