Heads-Up …Cummins After-Cooler Maintenance

Great post @fwebster (as always). I don’t have Cummins anymore, but regardless of engine manufacturer, always a good reminder to look beyond basic oil and filter routines.

 

“Go broke trying to save money”

 

$120K check makes my $22K bill every four years for HE and Charge air cooler cleaning look cheap. thanks Frank.

 

That is the first thing I did on both boats with Cummins engines because of the education Mr. Webster gave me. Thanks Frank!

Bennett

 

I think you mean “Dr.” Webster!!

 

Doctor, Dentist, Chiropractor...he fills them all!

 

Something that can really help with the longevity of the aftercoolers is installing (and using!) a freshwater flush system. Flush after every outing to prevent salty seawater from eating the system while the boat sits at the dock.

It can be flushing caps on the strainer tops, or a fully plumbed system where you attach a hose from the cockpit. Whatever will let you flush regularly. I did this on my QSC and generator; it really seems to help.

 

Thanks Frank
After purchasing my boat two year's ago the first thing I did was complete cooling system. That was after reading one of your posts about after coolers and proper maintenance.

 

I hear of folks doing the freshwater flush, but I slept better at night after installing my Salt Neutralizer injection system. I would think it would be more popular a mod as I have not ever heard that the neutralizers are ineffective. Having done the work myself and assisting on a few others, regularly servicing the aftercooler and heat exchangers does not really take too much technical prowess. Youthful dexterity does help but most of the marine mechanics I know don't necessarily posses that trait.
CD

 

Like everyone else, Cummins seems to have long wait periods for a lot of their components in Canada as well. Especially the older cta goodies. Seems to be the way it is these days.
Have a qsl and cta (non marine) in the shop atm. It was 8 weeks for the qsl @ 40k and having problems even getting a date for some of the cta components. Was lucky enough to have a core in the back to rob a block and crank out of for the cta.

 

When I bought my boat I had both aftercoolers replaced. I read up a fair amount on having the mating surfaces where dissimilar metals of the aftercooler meet coated with alco-metalube and made sure the new units had that.

Has anyone else done this? What about when you service the aftercoolers? Do you coat them prior to re-assembly?

 

QSB and QSC

There are two factors on the corrosion issue. One is the raw water side of the QSB and QSC aftercoolers as this video shows how to properly avoid. The second issue is condensation on the air side. If you boat in a saltwater environment the intake air is laden with moisture and salt. That moisture is captured as condensate on the cold aftercooler coil then drips down onto the aluminum housing and corrosion proceeds where the water collects. For boats that idle around extensively this is a problem. Conversely, boats that are working the engines and up on boost the air is hot heats up the aftercooler housing preventing accumulation of the moisture and avoids corrosion.
The QSM engines do not have any aluminum exposed to raw water so corrosion on the raw water side is rare; there would have to be a leaking O-ring seal. However, the aftercooler housing on the QSM's are subject to corrosion on the air side; probably more significantly than the QSB or QSC engines. Fortunately, there is a plug that can be removed at the bottom of the QSM aftercoolers to see if there is any moisture collecting and it's easy to get to.
The bottom line is to run these engines up on boost and keep the aftercooler housing hot.
Tom

 

The video Tom posted shows perfectly how to grease the aftercooler when reassembling. Do this any time the aftercoolers are re-assembled. I've done this with mine.

Apparently Cummins used to assemble the aftercoolers dry, but are now using Alco Metal-lube during factory assembly. I confirmed this was the case with my 2019 QSC engine. My 2018 QSB was dry when I disassembled for service.

 

Agreed @b_arrington
the new aftercoolers were shipped with the metalube

 

That is an excellent video that Tom posted from SeaBoard. It shows the placement of the o-rings well and it's easy to see how it is supposed to work. If your engines are Cummins B's and C's and you are a little unsure of what is going on with these aftercoolers, watch it a few times and pay particular attention to a few items.
Sea water does not come in contact with the aluminum of the aftercoolers by design.
at 1:35 in the video, note the o-ring and where it rides. Tight around the core and against the case. At 6:45, note the machining of the cap. There is a beveled edge around the inside. When the cap is tightened down during assembly, that beveled edge is what compresses against the o-ring, creating a seal against the core and a seal against the case. The seal against the core and case prevents any seawater from touching the case and any charge air from leaking out of the air side of the aftercooler. It is those seals that make us happy boaters or not. Study the video so you know where to look for corrosion or surface irregularity issues that could hinder a good seal.
Corrosion an inch inside the case doesn't matter, it's where you see the o-ring that does.
As he said, the problems start when there is condensate that gets between the core and the case on the charge air side of the o-rings. As said above without the protection of the grease, corrosion starts from the mere contact of the core with the aluminum case. Add the condensate and it gets worse, add a saltwater environment, and it gets worse yet. The corrosion will work its way toward the o-ring, eating the aluminum case until it chews up the sealing surface of the case where the o-ring rides. The support for the o-ring is now gone at the spot where that occurs and there is no longer any compression on that tiny section of the o-ring and a leak starts. Raw cooling water now comes in contact with the case, enters the air side of the aftercooler and things get worse from there, sea water is ingested into the combustion chambers.
Reassembly to help ward off corrosion of these is really all about the grease as stated above and you can see in the video. Don't skimp on it. It should be oozing out when you're done, just like the video. That will help keep the end surfaces of the case corrosion free from just being in a damp salty marine environment or if a little leak develops from an anode plug until you can get it stopped.

 

Did mine after haul out…..Just need spring to come.

 

This will be the first season with this boat so I will be changing them over the winter
Just got done painting them will be installing them in a couple weeks

 

I replaced mine last winter and I bought them from Seaboard Marine. They were greased the proper way.

 

When I did mine I had some corrosion in the area where the square silicone seals contacted the aluminum case. I ground out the corrosion and used some metal epoxy patch to fill the area. I had slight pitting in the seal area but it cleaned up with some light sanding. Per SB MArines's advice I left out the square silicone seals and reassembled with a liberal amount of metal lube. I am sure mine had never been done since new. A 2006 boat with 350 hours and I did them spring of 2020.
CD