How to clean clogged EGR cooler?

Just wanted to update this thread with my own experience with removing and cleaning the EGR bits, intake manifold, and replacing the PCV valve.
If you don't like long stories and a lot of waffle, just skip to the pics

The videos posted by NutzAboutBolts were a Godsend so a big thank you to him, I wouldn't have attempted it otherwise.
I've never done this on any car so it was learning experience for sure. I wasn't in a rush so I just took my time and did a bit each day.
Also if anyone is planning on doing this, do what I did and put your bolts/nuts/clips etc in seperate ziplock bags with a bit of paper inside and write on it what they are and where they go. Trust me, this saves a lot of pain if your memory isn't great.
Also each hose and wiring plug I disconnected, I put some masking tape on it and the bit it connects to and numbered them, ie
1 to 1, 2 to 2 etc to match them up. So much easier.

I started with the pipe connecting the EGR to the intake manifold because it was the easiest thing to take off first.
This showed me the shape of things to come. It was a little bit dirty as you can see



It scrubbed up nicely though :


Then I moved on to the intake manifold and throttle body. I spaced it and forgot to take photos, except one, of the EGR side port.


When I took the throttle body off the intake, it looked just like the one in NAB's video, some oil sitting there in the bottom of the intake. I soaked it out with some shop towel before removing it

So here is the intake after cleaning. After reading other posts on PC, I made sure to pay particular attention to the small EGR ports just inside the main large ports as they
were totally clogged. I soaked it overnight in Purple Power but it didn't really do that much, so I used parts cleaner spray can and a garden hose on 'jet' mode to blast the crud out
of every orifice until water was flowing freely with no more gunk coming out. Basically spray, rinse and repeat several times until clean.


Next came the disassembly of the EGR parts. I clamped the coolant hoses and marked them all with numbered tape to avoid confusion for reconnection, a necessity for MY brain!
Access is tight getting those bolts/nuts and studs out at the back but perseverance wins in the end. A telescoping magnet stick comes in handy as I found out!
EGR valve and connecting elbow piece (Not sure what it's called) before cleaning:


After cleaning :



Then came the most cruddy part, the cooler. This was the most time consuming part to clean, it was totally blocked:


I scraped each end out and you can see what came out just from 20 seconds of scraping:


Then I gave it a good spray with parts cleaner, and you can see the thick black mess in the plastic tub. This pic shows how it is so blocked that liquid is just sitting there and not flowing at all.:

I've seen some people say they cannot get this part clean and just buy a new one, but if this one can be cleaned, I'd say any can.
I sprayed it through with lots of parts cleaner fluid, then dunked it in a bucket of hot soapy water to rinse it out. I got some wire and poked it down between the fins.
I also repeatedly poured kettlefulls of boiling water through it and that definitely helps to loosen all the crap.
Basically repeat all these steps several times. I then put the wire on my cordless drill and stuck it right down inside as far as I could.
I needed thicker wire so I got a wire coat hanger and snipped of a piece long enough to go right through the cooler.
It's so much quicker on the drill than just poking it manually. I also used the garden hose on jet again, blasting it through from both ends in turn, and kept repeating.
I also used EZ Off oven cleaner inside the cooler. I would spray as much as I could in there and let it sit for a little while then drill it and rinse it out. I was alternating between this and the parts cleaner (which is under higher pressure)
The cooler had an overnight soak in hot soapy water too and the water was brown in the morning.
I didn't damage any of the fins inside as far as I can tell, and I think I unblocked it 90%+. Here's what it looks like after:


Daylight !! :


While I had the intake out, I put in a new PCV valve. The opening was pretty clear, and the valve itself wasn't seized so I don't know if a new one was needed but I figured I should while I'm in there, and it only cost a few bucks anyway.

After reinstalling everything, again taking my time and double checking everything is hooked up and coolant topped up (only lost a tiny bit) I started it up and took it for a test drive.
The shuddering issue I had before has basically gone away, and it is more responsive on acceleration so I'd say it's been worth it.
And since I had also just put in a new water pump and thermostat, (touch wood) I'm getting no overheating issues. Hope I don't jinx it.
And while I had access to the top of the strut mounts, I changed those out too along with the stabilizer links because they were shot, same with the rear shocks.
So hopefully this helps others who might be considering this task !

 

Did you have any chance to jot down flow scores from before and after this job?

 

No sorry, I'm not knowledgeable enough to know that was a thing, and I don't have Techstream either which is another hindrance !

 

Looks like you did a great job!
If you do a search online for the cooler, you could probably find
one at a junk yard somewhere. I found one for $55, including shipping.

That will really speed up your job for next time!

For the intake manifold holes, you can get a pistol bore brush.
Put it in a drill and use Gunk to spray it down and clean with the
bore brush. Fast and easy.

Using a Pressure washer would make the job a lot faster.
Then oven clean on the Cooler. NOT on the EGR valve though.

 

@sidraT not sure if it’s been previously asked and answered, but anyways: how many miles were on it?

Also, a few thoughts for next time:

1. If you disconnected throttle body coolant lines, this is not necessary; they have enough play you can do all that’s needed, and it can be tied to inverter or hood latch, to keep out of the way if needed.

2. Did you notice when you clamped the cooler hoses, then pulled them off, a deluge of coolant promptly dumped from the cooler above? If you preemptively drain 2 quarts of coolant (at rad drain, into clean container), the coolant level in system drops below the Exhaust Gas Recirculation system, so no coolant spills.

3. I would reserve strongly basic cleaners (purple power, oxi-clean, oven cleaner etc) for the cooler only. Anything non-stainless, it can be problematic, react down the road, and brake cleaner is all you really need. But yeah for the cooler it’s very effective.

And I’d be remiss if I didn’t mention pressure washer for the cooler. I’ve not used it, but @Raytheeagle swears by it.

Some more info here:

Bad Flywheel | PriusChat

 

Thanks Yeah I guess I could have saved myself some time by getting a good used one but you know i actually got some satisfaction out of doing it because I learned something new while doing it. If I still have the car in a year or two I'll probably do it again now that I know what to do.

 

267k, it's getting up there.
And yeah I had actually read that someone mentioned about not having to disconnect the TB coolant lines, and I totally forgot about it when it came to doing it. Space cadet. And I had considered doing the coolant partial drain,(I think I had read post of yours before regarding that) but it is difficult for me to get underneath to get to it so i just decided to clamp instead. I lost some coolant but nothing that a few shop towels wouldn't soak up. As for pressure washer, would be nice but my budget didn't stretch that far, the hose gun on jet mode did pretty well considering !

 

Yeah the intake manifold at EGR pipe connection looked pretty knackered.

 

Cruddy rather than knackered. Cleaned up nice. Probably cleaner than it's been in years.

 

Toyota’s TSB for the Exhaust Gas Recirculation clogging uses the pat phrase “while the majority of of vehicles will not experience this condition” (may be paraphrasing, but words to that effect). I’m curious too: were there any warning lights and/or codes (P0401); that andr shaking/bucking at startup up are qualifying criteria listed in the TSB.

Toyota engineering fail:

 

Hey guys. I’m a diy guy and just did a head gasket job on my 3rd gen Prius 2. When I took off the egr cooler and pipe it was obviously completely clogged and wasn’t flowing at all. (219k miles) and never had any maintenance done. I see everyone struggling with cleaning them. I found an easy way (well easier way) to clean them. They make a metal rod that holds insulation in the walls of a home it’s similar to a coat hanger just 10 x’s stronger and similar diameter. I put it in my drill and went through the holes of my cooler like butter. I let it soak in hot water and dawn soap over night and then cleaned with the rod and drill and air hose. And then at the end I used brake cleaner to just clean off residual residue. Flowing perfect and really only took about 10 minutes of actual work other than the soaking process just to soften a little. May mot even need to soak. I did just because I didn’t figure out the trick with rod till after the fact. Hope that this helps at least one person. I found a lot of helpful info on here so figured I would contribute.

 

like this one here?

 

I used coax cable wire, the skinnier kind. Deburred the nipped-off tip too; otherwise it tended to snag.

 

I used a bicycle spoke attached to a drill to clean the cooler. The spoke has the perfect size and strength. After inserting the wire I inserted the tube of brake cleaner inside of each hole to blast the carbon out.


It was almost completely clogged after 173k.

 

I feel like I have joined a sacred crew of those who have gotten the cooler out and reinstalled it. This was a hell of a job!!!! I spent two hours just getting the back nut off and the bottom bolt out. I never want to do that job ever again. Took a total of six hours to complete everything, but the cooler is clean (used a power washer). Was surprised that the cooler wasn't more clogged. Maybe that is due to vast majority of driving on the freeway. No way to know. I did not put the bottom bolt back in as it is totally unnecessary, and I don't think it would have been possible for me to do anyway. Glad it is done!!!!

 

That's what makes it so important for people doing this job to begin by capturing the EGR flow test result before starting the work, and again after cleaning, and report those (on that thread linked above) with the car's mileage and some other information about the way it's been driven. It's not that there's "no way to know"—there is one, but it's slow, and works better the more people participate.