theories
David,
You have convinced me that you do not understand the mechanics of what goes on inside these aftercoolers..
Let’s talk about your current statement—Fresh water flushing would not help
Look at picture 1—Here is an aftercooler that had a total of 9.5 engine hours but the boat was then parked for 6 yrs with saltwater in it.. This aftercooler destroyed itself from the seawater side, not from the air side with condensation or saltwater laden air... We see this all the time but to a lesser degree. The seawater slowly eats the aluminum between the bronze cap and the housing that then breaches the o-ring. With lots of grease between the bronze cap & aluminum and fresh water, this never happens, and I mean NEVER.
Picture 2 is an after with under 500 total hours and 8 years in service.. Picture #3 in a new factory after that we took apart for servicing.. Actually, we the see first signs of this on at least 50% of the new aftercooler we service before shipment.
Now I want to address your thoughts on zincs as to they’re working or not working in fresh water………this is really simple--------THEY do not need to work or do much of anything if the boat is parked in a lake or with fresh water in the system. These components were designed for salt water use have really have no need for zinc when in fresh water, and FYI they cause zero harm if left in place.. When you go on a trip into salt water, they do what they were designed to do.. So, in so many words, all that crap about zinc vs aluminum anodes in fresh water is just that—CRAP—25+ yrs of dealing with this has proved that beyond any doubt, and no book or couch engineer with change that —That reminds me of the people that believe if you put a pipe dope or Teflon tape on a zinc plug, it does not work as you lose electrical connection—NOT TRUE AT ALL—a 100% old wives tale.. Now, if it was a 100% fresh water boat and it never saw salt water, I’d be using Mg anodes (ala water heaters) IF I really thought I needed anode protection in fresh water, which I do not. At least they would do something as to anode protection if needed.
Now let’s touch on the air side of the aftercooler which really is where most of the issues we see start. It all comes down to moisture getting in-between the brass alloy ring at each end of the aftercooler and the aluminum housing.. The gap or clearance here is measured in 1000’s of an inch ( about .010”~.015”) and any moisture at all has no issue bridging that gap, and electrically connecting the brass alloy to the aluminum.. Viola, you have a small electrical cell that does its thing 24-7-365.. When assembled dry at the factory, it usually only takes about a year to do some decent damage and with 2-4 yrs, the damage can be so extensive that the housing & the core may not come apart.. But also what is going on, that the o-ring now gets breached and saltwater will start misting the air intake. The entire process of what is going on is a mess but luckily some pro-active maintenance starting early on in the aftercoolers life keeps this under control for decades.. PROPER SERVICING per my protocol.
You mentioned a composite housing -- Way easier and more practical to just bore the aftercooler about a inch deep at both ends ( maybe 2mm), shave off 1 mmm at both ends and drop in a flanged engineering plastic sleeve with a 1mm thickness.. Problem is now 90+++ % solved.. Way too simple for an engineer to “see”
Acid washing—Not sure where you are going with this but I do have an issue --- 30% HCL and water is way too strong. 10% is just fine—30 mintes to an hour does it all, (except maybe in some problem circumstances) . As to what you are accomplishing, basically you are dissolving calcium, lime, and old zinc deposits.. Done every 5-10 yrs is all that is needed, and before I’d do it, I’d be sure my aftercooler was recently serviced per my protocol—The last thing I’d want of for any HCL especially at 30%) to migrate past one on my aftercooler o-rings.. Plus, you have to remove all your zincs. RYDLYME has a pretty good web site video on acid flushing.
Just an FYI—We always soak the seawater side of the aftercoolers in 10:1 before we pressure test.. The reason is simple—calcium/lime inside the tubes and in soldered joints can “mask” a small leak.
So here we are………………. As to “Theoretical”……………… Talk about something that does not apply.. If 25+ years and a 1000+ aftercoolers does not put that to bed in your mind, then I won’t be able to help.. This aftercooler design, along with many others out there, were designed with “theories” along with the DRY Manifold on the QSM.. Just look at where these “theories” got us to today...You don’t need theories, just COMMON SENSE……………Tony
-- and generally doesn't help people keep their ears open.
