I plan on doing an EGR clean out. Why manifold too?

It's easy to pull the manifold..... Why risk getting water in the engine?

 

You want to clean the intake manifold because it's the last leg of the EGR circuit. If you clean everything else, leave the intake manifold, and it's got enough carbon in it's EGR passages, your EGR flow will continue to be compromised.

I would caution against using water based cleaners on the intake, cus they tend to be caustic, and there are metal embeds in the intake that'll react, corrode, develop crusties. The intake is relatively easy to clean; brake cleaner, brushes and rags are all you need. A very skinny brush is good for the EGR passages, one per port.

Info regarding tools, torque values (in the two attachments), links, etcetera, in first link in my signature.

 

Most importantly, the manifold is the only leg where the EGR path separates into four.

The car has a built-in monitor test for EGR flow, but it relies on only one sensor and can only tell you overall flow. That's enough to keep tabs on every other leg of the system, but not enough to tell if those 4 manifold passages are getting clogged differently. You have to check that with your own personal eyeballs.

If they get clogged differently, what happens when the EGR is used (which is normally moderate loads, not at idle and not at heavy load) is that some cylinders get too much and some get too little. The ones with too much may misfire, which is (relatively) benign, and the ones with too little may be at risk of detonation, a more serious mechanical risk.

You may be able to catch such a situation in the bud if you notice the engine beginning to run roughly, but only at moderate loads, not at idle or at high load.

But the manifold is such an easy job, compared to all the rest of the EGR stuff, that simply taking it out and cleaning it is very cheap insurance.

 

Right, and when the manifold's EGR passages to one or two individual cylinders are plugged worse than the others, that's likely more damaging than moderate clogging of the cooler---even if overall EGR gas flow is the same.

 

EGR passages in the intake manifold tend to become fully clogged “in order”, commencing with cylinder one, at passenger end of the engine (aka the “front”). Third gen head head gasket failures commonly occur at that end as well.

 

You can change the PCV valve with ease once you remove the intake manifold, it'll be sitting right in front of you. No real work getting to it.

 

Considering I did ours at 70K kms, I just cleaned with carb cleaner, cleaned the threads as best I could and applied Loctite 243 Threadlocker Blue (the more benign stuff). Torque value in attached (didn't need the "ball joint ratchet wrench" mentioned).

 

Just do it! you'll be surprised how much carbon and gunk will come out of the manifold lol

 

I'm currently in the midst of cleaning out my intake manifold, pipe, valve and cooler...
I just bought a 2010 with 225k miles on it and its thrown a P0401 code.
Engine runs fine, no coolant loss, unknown the level of oil loss yet as I don't drive it much.
quite possibly this thing has never ever been cleaned out given the level of gunk.
That, and it probably needs an oil catch can... that will be next.



To your manifold question though yeah its easy to take out, definitely may as well clean it.



However... one thing that has me stumped... maybe just because I'm still a Prius newbie...
Has anyone ever cleaned the pipe coming off of the exhaust manifold going to the cooler?
That thing has to be just as badly gummed up does it not?
Every search I've done on it seems to just stop at the cooler...
Anyone have some insight?

 

Occluded epitomized.

 

Imagine how much worst the EGR cooler is???
You MUST clean that also. 99.999999% chance it's clogged.
If you don't clean it, you're wasting your time.
Don't forget the egr passages in the intake....

 

We don't clean that pipe. I haven't taken one off, but the intake of the cooler where it connects to the pipe doesn't show much soot till you get to the little channels in the cooler. And looking into the end of the pipe from the exhaust manifold didn't show much soot the couple times I took a casual look.

 

(Ignore the yellow highlighted cooler below. I took this off another post and added blue to the exhaust manifold)

I'll try and get a picture of any buildup in there once I have the cooler out.

If there is significant deposits and gunk like there was in EGR pipe (between the EGR valve and intake manifold) -
I wonder what the best way to clean it would be rather than having to pull the entire exhaust manifold out.
According to the Techdoc it seems like a whole other day project including lifting the car to get it out

If it does need cleaned while its still installed,
the problem would be fighting gravity if you're using any fluids.
and just pushing that gunk IN to the main exhaust pipe doesn't seem like a good idea either.



Brief rundown from the techdoc about the EM removal: