Spark plugs replacement - maybe a stupid question...

Mat, if there is a way to remove the coil packs and plugs without removing the cowl, you can do that. But from my experience, this can't be done without removing the cowl.

 

Is it for UK / RHD cars? Can you share a screenshot or PDF or what the European manual looks like?
It looks like it is possible for RHD Gen 3 Prius to change spark plugs without removing the entire cowl:

 

Try it. If you can pull the coils and spark plugs out of the holes it works. If not, you're really not going to be wasting that much time.

As usual, with spark plugs, hand tighten them for a few threads to make sure they're not cross-threaded.

 

Right-hand drive I think there's just enough room. But other'n that, if you disconnect the coils and try to pull them out, they bump into the cowl or related, an inch or so too soon to be able to fish them out. It's a sand pounder for sure.

 

By the time you do all the fighting you could have had the 10 bolts that hold the cowl in and the five bolts that hold the wiper in or whatever it is they blast out as fast as I'm talking so you'd be finished with that and America another way you could do it is put a hole in the wiper tray or put four holes in the wiper tray right above the coils it'd be about an inch and a quarter with your hole saw so you can just undo the coil 10 mm pull them through the holes you made in the wiper tray etc etc but since you're only doing this every hundred thousand miles which for some of you people is a very many years I don't even know why you would bother It's the same in my sienna van and you can whip that tray out quite quickly it just looks like a lot of mess it's really not even in the generation 2 where you don't have to remove the tray to do the plugs You have to remove it to get it to break actuator I can pull that tray out and about 7 minutes so as time goes it's just not worth making up a workaround it doesn't seem like.

 

Yeah, for those of us with the double-jointed passenger wiper, "remove the wipers and cowl" is just the first step of so many procedures in the repair manual, it's like the "chop ½ onion" at the start of just about any recipe. You start not even noticing you're doing it.

One difference: removing the wipers and cowl doesn't make me cry. Advantage Prius.

 

It takes me 10 minutes (I've timed it) to get the wiper and cowl assembly out of there with an impact driver. But I've done it dozens of times. It'll take a first timer longer, especially if you don't have an impact driver or a battery powered ratchet. Be careful that you don't crack the windshield when removing the fasteners for the bottom of the cowl. Your extension if using an impact driver is close to the unprotected bottom of the glass.

 

The repair manual also warns you to be careful not to crack the windshield when lifting the plastic cowl grille out. Clips in its top edge fit onto the bottom edge of the glass. Be sure to slide it down away from the glass before lifting it.

 

Taking

if you’re only doing EGR, I’d just drain 2 liters, from radiator into clean container. This will leave EGR components above the coolant level, more or less dry. Throttle body coolant lines don’t need to be disconnected if it’s lifted off for intake manifold removal/cleaning; they have sufficient slack.

see my signature for more details, top two links (on phone turn it landscape to see signature).

 

Mike has been said you don't drain the coolant You just let a little out unless you've got a lot of oil in your coolant or something The windshield cowl taking out is pretty self-explanatory You take off the 14 mm wiper hold down bolts there's three of them one's under a plastic cover I do believe on the wiper arms and they lift straight off drop them in the trunk or on the ground lift up the plastics expose the tray put the plastics on the ground or in the trunk Don't lose the little corner pieces sometimes they fly off You lose them you'll never replace them and you got an air noise on the right side. Take out the 10 mm wiper transmission hold down bolts zip zip zip notice their special length they don't look like the rest of the bolt so you don't need the bag and tag them separately put them next to the wiper transmission on the ground or in the trunk. Now you feel the floor of the metal tray that is your wiper tray and you'll find 2 4 6 or 8 bolts you blast those out with your little gun leave them in the tray pick up the tray disconnect the wiring harness clips that are being held by the tray for the wipers and what not set the tray off to the side that should have been no more than about 12 minutes and now you have complete access to your spark plugs coils brake actuators other things on the firewall many times when I'm working on the brake actuators on generation 2's I'll leave the wiper tray out for a week That's why the windshield is very well coated with Rain-X. Matter of fact the generation 2 I'm driving now hasn't had the wiper tray in it for about 68 days no problem driving in the rain with Rain-X that's the way we've always done it and good luck with your project try to get real spark plugs The fakes will fall apart leave pieces in your engine not a good thing Best to round up a real supplier that you can trust and that is important back in the old days I was able to call nipppodenso direct in cali. And get sample pieces and what not sent directly to my shop without any problem now I'm sure that's probably not possible as everything has been ruined in that genre this was like in the '87 through 90 when denso opened up shop somewhere in California not far from TRD when TRD was a small hole in the wall and didn't have any stickers yet and there were no trucks to work on this is for real racing development for the 4T GTE in the gruppe B rallying days.

 

I worked with a Romanian engineer, asked him one time how he decided what to do, some renovation we were looking at. He licked a finger, held it up, to illustrate testing wind direction. That’s about how I came up with the 2 liters.

Just pouring it back into reservoir, nothing much extra, worked out ok for me. It was a little higher, but settled back down. I did open the coolant vent spigot while filling (have 2010, other years may not have this), poured slowly, and gave coolant hoses a few squeezes.

 

I saw a video once of igniters being removed from some other make of car, and I backed up and frame-stepped through the video, and sure enough, that car used igniters where the long stem part was flexible! The mechanic just lifted and bent them out from under the cowl on that car.

If our igniters were like that, you probably would be able to sneak them out and back in without cowl removal, even on the cars with the double-jointed windshield wiper.

Maybe somebody sells a floppy-igniter compatible replacement for Prius. Then you could replace the original igniters with those (to save taking the cowl out, you could take a hacksaw to the original igniters). Then you'd never need to take the cowl out after that. (Except for all the other procedures that need the cowl out.)

Another approach could be to go under the car and disconnect the amidships engine mount, the one that links the bell housing aft to the transverse member to restrain engine roll. Then with a jack under the rear of the engine, you might be able to roll the engine forward just enough to get the igniters out despite the cowl.