Intake manifold cleaning and found this

^ Dealing with the instigator is always useful, but when the damage is done, that’s your primary task.

@oasmith : excellent pictures; if Toyota engineers are counting on the Exhaust Gas Recirculation system to keep the engine in a stable zone, that carbon-clogged morass speaks volumes.

 

Is the EGR valve stuck open?

You could do a piston soak which should help lower oil consumption by freeing up the oil control rings. But if the cylinders are scored you'll always have some oil burning.

 

You have a bad headgasket, possibly a warped head.
You already wasted time and money on a sealer that doesn't work. WHY would you try it again???
Time for a new head gasket, and have the head checked to see if it's warped. Hopefully, no bent rods.

 

You'll need a torque wrench. And other tools. And will need to take your time.
It depends on you skill level and if you're willing to do the work.
You may get a newer hopefully engine and just replace the whole thing....

 

I would think its far too late for a head gasket after 150,000 miles of hg leaking on a 400,000 mile engine. Lost power is a sign of a bent piston rod which will soon be a broken rod. If you want to keep the car, a replacement engine is the way to go. In some areas you can have a rebuilt engine installed for $3500. Just think, no more two quarts of oil a week, no more severe rattling on engine starts, increased mpg and much better reliability. For the price of a down payment on another used car.

 

That engine gave you almost 400,000 miles. I'd consider that pretty impressive and it owes you nothing. You've gone well beyond in mileage than most cars on the road. If you truly like the car, then you're on the right track with a replacement engine. Good luck!

 

Yes different pistons and rings. But when I suggested rebuilt, that means new parts, rings, bearings, gaskets, eg rebuilt, not simply used. Plus there is no easy way to tell what year the used engine came from since the jdm engines that are most available have no vins. Most of the US origin used engines have their vins removed. Plus the 2015s are scarce since they did not sell as many and the head gasket failures have been going on for years now.

 

Consider a 4th gen engine? The go-to thread, a video saga by @Ragingfit, is pinned at top of Prius v accessories and mod's forum. Odd location, technically sensible, but...

 

Well semi-compatible. The aforementioned video series seems the best approach, retains 3rd gen EGR components, intake/exhaust and throttle body. Some coolant hose rerouting is needed, and some other minor mods.

 

From reading on Prius Chat, my understanding is the block are interchangable.
Without modification. Or maybe something about he water pump? The 3rd Generation
head will fit on the 4th Generation block.
So If the head isn't damaged/warped, you can just swop the blocks. And the 4th Generation
block is updated along with the pistons and rings....

Right or wrong?

 

That’s pretty much what @cnc97 did, used the block of a 4th gen salvage engine, with 3rd gen head. The damper at junction with transaxle requires swapping over from 3rd gen IIRC. More info on the latter in @Ragingfit video series (pinned in Prius v mods forum).

 

That's right! I forgot about that part. I knew there was something. It's larger on the 4th I think.

 

This is due to stop-leak product? A 50/50 mix of water/white vinegar might dissolve it. If you can extract a bit of the goop do a test.

 

This is way better

 

For that long of head gasket leak, the catastrophic failure is comming, dying catalytic converter, heatercore, radiator, water pump and entire cooling system is full of gummy sealers.

I would sell it as parts instead of putting more money on it. Unless you live in FL or states that has no MOT and emission test.