Cleaning the EGR cooler. Or Not!

Mendel,
Were you able to remove the EGR Cooler lower nut and stud (“highlighted in yellow” identified in your post dated Oct 25, 2022) without removing any other item/component? If so, could you please explain in detail how you were able to remove the stud and nut? For example; did you use a mirror and flashlight? Did you use a magnetic 12 mm socket and magnetic E8 Torx socket? Did you use 1/4" or 3/8" drive socket set? Any additional information you can provide would be greatly appreciated. I plan on removing the nut and stud this coming week.
Note: On my 2014 Toyota Prius it’s extremely difficult to run your hand along the side of the EGR Cooler with all of the hoses, high voltage wires, piping, etc.

Thank You!

 

You need to use a real 1/4 drive, like snap on. Craftsman are too big.
A swivel socket, or joint with an extension is the easiest way to get the nut off.
Then the torx bit to remove the stud.
Most people do not reinstall them... But it's not really hard with the proper tools.

You'll have to loosed wire wraps to move them around to be able to reach everything.
It can be tricky to do, but if you take your time and look at it, you can figure it out.
And it gets easier each time. Unless you have a long time between each service.

 

Thank you very much for the information.

I plan on removing both the nut and stud permanently.

I also plan on removing the lower EGR Cooler bracket specific to the referenced nut and stud after I remove the Cooler; that way I will not have to deal with it when I install the EGR Cooler next month.

 

To remove the lower cooler nut, little or nothing else needs removal. I happened to have a 1/2” drive, Jet brand, ratchet wrench with swivel head. I had a 1/2” to 3/8” adapter on it, then I’m a little fuzzy: mighta just been a long 12 mm socket, or a 1.5” extension and short socket. You need a minor amount of extension, it’s really hard to snake the wrench in (swivel head helps), and to find a space to rotate wrench handle.

to get the associated stud out, I used a 1/4”, diminutive Jet wrench with E8 Torx socket, “maybe” with short extension. It was very difficult to break loose (dissimilar metals) and it took me at least 15 sweaty minutes. Could only rotate wrench handle one click at a time, and I was afraid of rounding off the stud’s Torx indentations. It resisted virtually all the way out.

no magnetic gizmos used IIRC; you can get finger tips on everything. Sometimes reaching a left hand around clockwise from left side is easiest to reach it, say when trying catch nut or stud as it becomes free.

my take: the Toyota engineers did not consider this component would be needing occasional removal, and it’s just dumb luck it’s possible.

 

Most parts are on the engine when the assembly line installs the engine. There are many jobs where they recommend pulling (actually dropping) the engine. One such job is the timing chain or gasket; originally the brake booster; any short block work, transaxle etc. A good mechanic on a lift can drop it and the subframe in a couple of hours or less.

 

Mendel; Thank you very much for the detailed response on removing the lower cooler nut and stud. I tried to remove the nut yesterday (25 Mar 24); but after I maneuvered the 1/4" drive socket 12 mm, extension (short and long) and racket wrench through the maze of hoses, wires, etc. I was concerned that the socket and/or extensions were going to separate and fall to no man's land (figure of speech). If they separate and fall to no man's land (figure of speech), I'm not sure if I could retrieve them.

 

Well sooner or later you'll need to remove at least the nut. Maybe stuff a towel in the drop zone. I found it not too hard to catch; you can get finger tips on it IIRC. Another trick: jam a small amount of tissue paper into the socket, just enough that the nut's kinda jammed into the socket. And hey, if it drops, no loss...

Another trick to consider: break the nut loose, then switch to E8 and start backing out the stud, with the nut on the end.

Note too:, when the nut comes completely off the thread studs, it's still in the zone at the end of stud with the torx "teeth", won't drop if you're careful.

 

Question on this - I thought one of the major concerns during the engine coolant change was getting out any air that may be trapped in the engine coolant tubing. By partially draining a section of the coolant plumbing and pouring it back into the reservoir during an EGR cooler cleaning, we are essentially leaving a massive section of air in the plumbing near the cooler that will be pushed through the system at startup, correct?

Are we safe to start the engine after pouring things back into the reservoir and go on with our lives or do we need to follow the same procedure as a coolant change and allow the plumbing to recirculate the coolant using the various air ports followed by 10min of maintenance mode?

 

If you pour in the coolant SLOWLY, and a LITTLE at a time, it gives the coolant a chance
to push the air out.

 

I have changed coolant dozens of times and never had problems with air. I simply run the engine with the cap off for a few minutes until it stops bubbling.

 

Well, that's pretty much what happens, and it's not that big a deal. The gen 3 cooling system is a "degas bottle" design, where the plastic reservoir is not just a stagnant backwater overflow tank; it's part of the active coolant circulation, and air that gets "pushed through the system" just ends up there. The system even includes the hoses (blue here) from some of the high points of the system right back to the degas bottle to carry the air.



Toyota even used to provide an extra air bleed valve you could fiddle with in the EHRS return hose in the earliest years of gen 3, and then did away with it in a later revision of the part. The system seems good enough at degassing itself anyway.

That's pretty much all there is to it. You make sure the right amount of coolant is present (initially above the FULL line on the bottle, because air in other places takes up some of the space), and run the engine up to temp and several minutes longer. When you stop it and after everything has cooled, you find the air has traded places with the extra coolant in the bottle and the level has dropped to FULL.

Yeah, the procedure isn't really complicated at all. Toyota's instruction is to do the warmup and several minutes of running with the cap on, not off, but even ignoring that instruction doesn't generally cause a problem. (With the cap on, the system is able to develop pressure, which squeezes any bubbles to half size and probably rounds 'em up faster. The degas bottle is designed with enough headspace to accommodate the air being displaced.)

 

Pretty much what I did. With our ‘10, I left the air vent* open while pouring fluid back into reservoir, and closed it only when coolant flowed out. Also squeezed hoses as I filled.

level in reservoir ended up a bit high, settled down to full mark with a few days of driving.

* Vent is on ‘10s, and maybe ‘11, then nixed by Toyota. Seems to me leaving a top EGR hose disconnected would achieve the same function.

 

... which, had the function been necessary, they would probably have added to the instructions, at the time they took out fiddling with the nixed vent.

 

As thunder follows lightning.

 

Makes sense. Mine is a 13' so I guess I have no choice but to leave the top hose of EGR disconnected.