EGR Cooler screws

They are the exact same studs as the ones used for the exhaust manifold. Not sure on the dimensions, but I would guess M8x1.00 or M8x1.25.

Stud = 90126-08052
Nut = 90179-08101 (not 100% sure, multiple options are listed)

 

I did the same thing, go to dealer parts they can order for you and they are dirt cheap. I got all new hardware for cooler, they were rusted anyways.

 

Should be able to find those items here:


EXHAUST GAS RECIRCULATION SYSTEM. For 2013 Toyota Prius Four HYBRID | Toyota


Still, I would try again to find the ones dropped; they're in there somewhere, lol. I assume you've got the engine cover off?

 

They are most likely stuck between the subframe and the steering rack. Don’t ask me how I know...

 

If you go that way, bring the cooler along. It seems to me you could connect the cooler to exhaust with a metric bolt, instead of the stock stud plus nut. You could get it slightly long, then put a washer or several behind the head of the nut to finetune the projection.

And for the short bolt holding the cooler to the cylinder head, just a metric bolt, again maybe slightly long and count on a washer or several behind the head. Or just omit that bolt, and the nut going on the stud at the underside of cooler, the hard one to reach. The thing is plenty secure anyway.

Still, if I was in your shoes, I would restore it to stock. I am a bit obsessive. The parts numbers (gleaned from my previous link):

1. Top bolt: 91671-80820
Pump Assembly Screw - Toyota (91671-80820) | Toyota Parts

2. Back of cooler stud: 90126-08052
Toyota Online Parts | Genuine Toyota parts | Toyota Parts Online product search | Toyota Parts

3. Back of cooler nut: 90179-08101
Manifold Nut - Toyota (90179-08101) | Toyota Parts

They're all about $1 apiece. You could order through any dealership, would take a few days. If you can't have the downtime, use the Home depot bolt in the interim, for the back connection.

Number 2 and 3 corroborate @The Critic's info, btw.

 

The screws are 8x1.25 with 12mm hex washer flanges. The stud is als8 8x1.25.

 

How do you know?

 

Experience is sometimes the best teacher.

Having done this job 8 times, I’ve grown my experience tool box some.

 

I cleaned the EGR tube last week at 91000 miles. Some deposits, but not too bad. I used a nylon brush I bought at Walmart, but no soaking in Oxiclean or use of a solvent. Pretty simple, but don't know if I want to attempt the EGR cooler.

 

It’s not that bad.

Get the pressure washer out and it’ll make short work of the deposits.

Good luck .

 

Nobody “wants” to do the cooler. It’s necessary if you want the vehicle to last.

 

Egr cleaning fluid and then pressure washer = like new

 

What is EGR cleaning fluid?

 

Air compressor or pressure washer will do the job.
I used a few cans of spray break cleaner because I had an air compressor, I felt that I needed to have some liquid cleaner to go with it.
If you have a pressure washer, I imagine, you could get it done with it alone.

 

A pressure washer works great on the cooler and valve , what I use on the EGR pipe is acetone , got it spic and span ! I just zipped tied the cooler and the other parts to a chain linked fence and blasted away

 

Exactly that.
It comes in a spray can

 

Maybe this:

Diesel EGR Extreme Cleaner | Wynn's Europe

And here's a comparison test:

Diesel EGR Extreme Cleaner | Wynn's Europe

Still, pressure washers aside, I swear by oxi-clean. From what I've read here it's less effective as clogging gets more extreme, but still, worked fine for my low mileage case, and very thorough, shiney-new clean.

I like too, that it's relatively benign, can be used indoors, water soluble. It takes time to work, but that's ok.

 

While the other components are easy to clean...I will just buy a new cooler when the time comes. TDIs taught me that lesson.