EGR/Intake Manifold Cleaning

If you haven't begun yet, this is the best time to take a 'before' reading of the EGR flow test result and save it for later:

EGR flow data

Many people forget that step before they start the job, and then get to the end with no comparison they can make to see what their work actually accomplished.

Edit: by the way, while that post shows Techstream, any scan tool that can show "mode 6" monitor test results can show that.

 

Everything but the cooler can be cleaned with brake cleaner, brushes and rags. Caustic cleaners are only safe for stainless steel, namely the EGR pipe and cooler, but only the cooler warrants caustic use.

Not having spare components, my strategy is to get the cooler off, corked*, filled with a caustic solution, and stood up in a corner of laundry sink as early as possible in the process. Let it sit about an hour, rinse, inspect**, and repeat till clean, or as close as you can get it. I’d cap the sessions at 5 max, any more won’t help much I think.

My caustic has been powdered Oxi-Clean so far (twice). If and when there’s a next time I’ll try KOH (Potassium Hydroxide) solution, probably 30% by weight. It’s a common component of soap making, still obtainable. NaOH (Sodium Hydroxide, aka lye) sales are restricted due to its use in making methamphetamine. Oven cleaner contains lye, albeit relatively dilute, and its a somewhat awkward/expensive way to obtain caustic. A generous sized bottle of KOH is inexpensive. You’ve got to be careful with though, follow safety protocols.

* ID of smaller end is roughly 21 mm; I believe suitable for #4 stopper

** Be fastidious when inspecting for degree of clean, any residual carbon may be trivial for flow, but still is detrimental to cooling. A point light source inside the entrance, not glaring on the end flange, is good.


if you haven’t already, have a look through the relevant links in my signature (on a phone turn it landscape to see signatures)

 

Just checked, sodium hydroxide (lye) is again available on Amazon.ca, not sure about the States though.

comparison:

Google AI summary, KOH vs NaOH efficacy

 

I'd never really researched how Oxi-Clean works, or even what it's active ingredient was. Google AI info, an interesting read:

https://share.google/aimode/IgvkPvSDSMaZpl86j

That said, I'm going to try KOH (30% by weight) solution if-and-when.

 

Wary of unseen water or other liquids getting trapped in those manifold EGR passages, I used only mechanical methods of clearing them, then shook the manifold in various orientations and vacuumed from both ends to remove any loose particles. That may not clean it perfectly, but apparently was good enough. I should unclog the manifold again soonish (having already added >50k miles since I did it).

I'm still getting good flow test results, so haven't bothered with the cooler (heat exchanger). It will clog a lot quicker if you're burning much oil.