How to clean clogged EGR cooler?

FYI I used oven cleaner and OxiClean and none were a single-treatment solutions. I also corked the ends.

Someone suggested using a utility locate flag. That's actually a great idea. Stiff enough not to bend, but small enough to get into the passages. That being said, there are some passages on the corners that will be difficult to get.

Honestly, if time is money, I'd just have a clean EGR ready to go. Since this isn't my only vehicle I persisted.

 

Yeah the sooner you deal with it the easier it is. Maybe 100K miles for first cleaning, then 50K for subsequent.

Of course: "the majority of vehicles will not...".

 

It'll be interesting to see how the EGR coolers look on OCC equipped vehicles after 50k.

I also think trying to limit the blow-by via thicker or better oil might prolong cleaning intervals.

 

Keep in mind too, no OCC is 100% effective. I think having two fairly good ones in series might help. By my (maybe flawed) math, if you have two that are 50% effective, in series, you'll be catching 75%. My current experiment:

 

I'll let you spend that. I'll be over here with my few hundred dollar car and $20 OCC setup. We'll compare in a few years.

 

What do you mean by "bypass"?

Touche. I bought the first one for myself, and the second was for another car (in the family), but they got cold feet about it, so hey, I was stuck with it, might as well use it.

There are cheaper higher end ones than the Moroso's, for sure. JEGS is a good site, lots of options.

 

Depends what you mean by "bypass". If you mean an uncooled tube connecting cat to EGR valve? High temps while driving.

EGR Block-off plate? Might be worthwhile, might be catastrophic. I know the 6.0L Ford guys do that all the time, but a Prius is a not a diesel. I also know that many companies are now making redesigned EGR Coolers for those problematic Ford diesels.

Some Ford will guys get "solid gaskets" or weld the EGR on both ends, so it looks stock, but nothing is flowing through it. Not sure the EGR system nor the MAF or any other sensors is look specifically for the dirty air coming through the EGR, although the curves are likely tuned for the warmer air. The EGR valve would still open, just nothing flowing through.

 

What I think: the the engineers designed that engine to run properly with as-new EGR, did not foresee the abysmal degree of carbon build-up, rushed it to market with insufficient testing.

They're counting on the EGR system to keep combustion chamber temps from going through the roof (reducing oxygen in the combustion chamber, under certain acceleration conditions). A bypass sounds tempting, but even that will make a difference (as you mention), suppling hotter exhaust gas.

I think the best tact is to periodically restore it to as-new condition, before it gets too far gone. Even if the clogging is not that severe, all the cooling fins having a soot coating reduces their effectiveness.

Of course Toyota won't acknnowledge this, put EGR cleaning in the maintenance schedule. This would acknowledge that "the vast majority of vehicles will not experience this problem" claim is bogus. So they say wait for death-throe symptoms and warning lights.

 

It would be fun to add a dash light to indicate when the EGR is open. Besides a OBDII Just for fun!!!

 

As I was putting mine all back together I did notice some changes that could be made to make the removal of the cooler easier. Slotting the EGR Valve to Cooler connection, removing some of the flange to make accessing the nut easier, drilling the EGR and replacing the stud with a bolt, slotting the cooler/exhaust flange and putting valves on the coolant lines.

If I was running a fleet of the 2010-2015 cars, I'd probably be doing that.

 

I had my pipe from EGR heat exchanger to intake manifold checked today, no gunk, $100 at dealer 125,000 miles, almost exclusively at 60 MPH

 

How many miles on your V?

 

Yikes that's about $10 per bolt!

I don't trust them. Did you see for yourself?

 

when I did mine the pipe looked good but the cooler was almost plugged.

 

125,000 almost exclusively at 60 MPH

 

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There is no "gen 2's internal egr." There is a persistent canard about that popping up in PriusChat from time to time. All Prius generations do a valve-timing trick to achieve an Atkinson-like combustion cycle, but the way that works is by having the intake valves close slightly later, across the end of the intake stroke and the start of the compression stroke.

At that time, what is in the cylinder is fresh burnable fuel charge, not exhaust, and that fresh charge is what gets partially pushed back into the intake manifold.

As unquantified statements go, those must be true enough; the peak combustion temperature is lowered by having some unburnable stuff included in the charge, and recovering some heat from the unburnable stuff certainly makes it cooler going in. It's just the actual size of either effect, in degrees, that nobody ever goes into in threads like this, and which I certainly don't know myself, not even the ballpark or the number of digits left of the decimal point, and same for the temperature rating of the head gasket materials. (Ok, I'm guessing three or four digits for that.)

I'm sure there are engineering documents where that information can be found and engineers who know where to find them, they just never seem to filter into PriusChat posts. We certainly have a lot of posts that sound very confident about just what is happening to what because the what is hotter than what, but I've never been sure if they're being posted by anybody who knows any more about the numbers involved than I do, and what I know about what I know is that I don't.