Old spark plug still clean?!

Yeah leakdown test. It sounds like head gasket leaking between cylinders one and two, and you have coolant loss. But doesn't hurt to check. A mechanic with compressed air and leak down valve tester can do this:

You can watch @NutzAboutBolts EGR cleaning video linked here. Some boiler plate info:

The simplest way to see where you're at, is to check the degree of carbon build up in the EGR pipe, a stainless steel connecting pipe between the EGR valve and intake manifold. Watch @NutzAboutBolts video #16 here:

Nutz About Bolts Prius Maintenance Videos | PriusChat

Two or three other videos linked there too, for the full cleaning of the intake manifold, full EGR clean, and Oil Catch Can install.

Good thread:

EGR & Intake Manifold Clean Results | PriusChat

Another:

Oil Catch Can, Eliminate that knock! | PriusChat

Some tools worth having:

E8 Torx socket (mandatory)
E6 Torx socket (optional, but good to have, to remove the throttle body studs from intake manifold)
3/8" ratchet wrench, regular and long handle, flex head, you can never have enough (or 1/2 plus reducer)
1/4" ratchet wrench, or 3/8" to 1/4" reducer
Ratchet extensions: you can never have enough
Long needle nose piers, straight and bent tip
Ratcheting 12mm box wrench (optional, but makes disconnection of the EGR cooler from exhaust easier)
Torque wrench (3/8" and 1/4" both good to have)
Floor jack and safety stands (or ramps): basically some method to raise front, if you need to take underpanel off, which you may need to, both for access and to recover dropped items.

Comment regarding clamping of coolant hose, mentioned and or shown in videos:

1. When removing the intake manifold for cleaning, you do need to lift the throttle body off the intake manifold. Still, the coolant hoses connected to the throttle body have ample slack, enough that you can leave them connected, and just tie the throttle body to something adjacent, say the inverter wiring harness.

2. When removing the EGR cooler, removing coolant hoses is necessary, but if you drain 2 liters/quarts from the radiator drain spigot prior (into a clean container), the coolant level in the system will be dropped below the EGR componennts, and you won't spill anything. Just be sure to not tip the cooler when lifting it off (and catch the rear gasket): there are a few tablespoons of coolant trapped at the lower back corner.

Pour that into your previous drained coolant, and when done pour it back into the reservoir. If you've got the coolant bleed bolt (2010, 2011 model years), leave it open while pouring the coolant back in, till coolant starts coming out. For later model years, leave the topmost coolant hose on EGR disconnected till coolant starts coming out. Also, might help to burp the main radiator hose as you pour the coolant back in.

 

This is an easy one.....coolant is keeping it clean.

 

I roulette check on the head head gasket first because if that needs to be addressed all the egr stuff has to come off anyway.

 

No. Just forestalls the inevitable, and makes a royal mess* of the whole coolant circuit. Also, you are kinda playing Russian Roulette too, running a car with a failing head gasket: if you get enough (non-compressible) coolant in a cylinder you might bend a piston arm. If you're leaning towards engine swap maybe this doesn't matter so much though.

* One manufacture of stop leak advices a flush with 50/50 white vinegar and water to dissolve the product.

 

I think the main reason many are gravitating to fourth gen is lower miles and cost. Some coolant mods are needed. Watch @Ragingfit's video saga.

I can post a link in a bit. It's in Prius v mods forum, pinned at top I think.

I would consider head gasket replacement too, especially if current oil consumption isn't bad?

 

What's your oil consumption like?

 

4th gen engine swap:

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

@Ragingfit 's approach is likely the best. Other's have gone further, managed to use fourth gen EGR, bending the EGR inlet pipe on the 3rd gen exhaust manifold. But then there's been problems, the 4th gen EGR is different, and the 3rd gen ECM maybe can't work with it, is expecting 3rd gen EGR behaviour.

And here's head gasket replacement videos link:

New head gasket replacement video from Gasket Masters | PriusChat

 

No

 

If it's not dropping much, that speaks to an engine that's still viable. Debatable.

 

G2 motor takes 3.6 quarts with new oil filter. With oil filter filled before install.

When done let it sit for 15 mins then check the dipstick. Should be right at he Full line.

Next morning before starting the car check it again. Keep it at the full line.

 

Oops saw this in mypeople responded and thought it was a g2 forum.

Please disregard.