First time preventative maintenance

No one mentioned it, but you've got to do quite a bit of disassembly (windshield cowl/tray under the wipers) before you can even get to the sparkplugs.

SM-G781V ?

 

You seemed to have missed the free and easier to use owners manual I pointed out.

No one has a factory repair manual other than pieces captured as pdfs from Toyota's TIS site.

 

see video 13 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

^ one quibble: he slathers plug threads with ant-sieze and advocates 20 ft lbs torque. Toyota Repair Manual says 15, and no mention of lube, so presumably clean/dry threads.

yeah, an astounding amount of disassemble required, just because the coils bump the wiper cowl underside an inch or two before they can be extracted. Not Toyotas finest engineering.

attached repair manual excerpt has spark plug info. Last page, with plug torque, is a thousand pages or so away from the rest.

Plug spec is shown in owners manual, except that spec has been superseded by Toyota, to a slightly hotter plug (“20” designation revised to “16”). I posted that updated Denso plug spec up the page, plus it’s Toyota part no (in post 14).

you’ll need a 14 mm (or 9/16”) socket. If it’s got rubber inset to grip plug, I’d recommend to tape socket to extension securely, to avoid it pulling off after new plug install.

 

I won't invest on anything but oil change first on the first 1 year/5k miles and check if everything is fine, the car does not burn oil, and everything works. After that:
1. Clean the EGR and intake manifolds, don't waste time too muchon trying to shining up the EGR cooler
2. Change the engine coolant with genuine Toyota SLLC if it has not been replaced before
3. Change the transmission fluid at the same time
4. Change the spark plugs at 240k miles
That's all, hopefully no problem before reaching no. 4.

 

One thing, the colloquial name "cooler" is not for naught: if it's purpose was solely to flow exhaust gasses, it wouldn't have the internal raidator. If that radiator has a patina of carbon, it may still have "sufficient" flow, but it's cooling ability is hampered. Several hour-long soaks with a concentrated solution of oxi-clean (or lye solution if oxi is inusufficent) can get it like-new clean, and restore it's cooling efficacy.

For expeidience when doing EGR cleaning, get the EGR cooler soaking started first, then go onto cleaning of the EGR valve, the pipe twixt EGR valve and intake manifold, the intake manifold (pay special attention to the EGR passages at each port), and the intake ports on the head. Maybe set an hour timer for rinse-and-repeat of the EGR cooler.

 

I soaked the EGR cooler in a brake cleaner solution by plugging both side holes. I have a used cooler for spare and reduced down time. I also have used intake manifolds and EGR valves. It costs less than $100 but can reduce the down time by hours.

 

I tried about 12 hours of brake cleaner soak, then gave up on that. A water-based, caustic cleaner (Oxi or lye solution) is much better.

 

That's true,I don't see much difference after soaking it with brake cleaner. It remove sludge and oily things well. I think hard carbon deposit best cleaner is always hot steam water+dish soap.

 

Removing the wiper assembly is the easy part and certainly changes an impossible egr cooler removal job to simply ridiculous.

You have to know how to remove it to get to the spark plugs as well. Might want to simply pull the plugs and inspect while you are bloody and greasy anyway.

I have been trying to get our egr fanatic and parts illustrator for a living guy Mendel to whip up some decent exploded views with tools.

 

You are not going to get to the cooler with the wiper assembly still in place.
Just duck-duck-go search for spark plug removal on the Prius and they will show you
how to remove it. Fairely simple and quick. A lot of bolts, that's all.
Getting the wire harness plastic holders out is the biggest pain.
Mark with painters tape where the wiper blades are before removing them so you know
where to reinstall them.
That bolt is NOT that hard to do if you have a small 1/4 inch ratchet.
oxi will take forever to work and multiple water changes to get it clean.
Pressure washer and oven clean is the best way to clean it.

 

@Raytheeagle said he did one EGR cleaning without wiper/cowl removal, resolved to not go that route again.

@rjparker im not sure a blow-by-blow narrative would be helpful. It’s somewhat akin to reading a completely typed out speech word-for-word, versus just referring to cue cards. The latter is better I think.

 

Some challenges aren't required to repeat.

Wiper Cowling removal is easy enough.

Clean the cooler.