AFTER-COOLER CLEANING – Jim Shates/Jeremy
AT-34, 5.9, 330/370 CUMMINS
These
instructions were originally written by Jim Shates, owner of our sister ship
(and beta-tester!) “Annie’s Song”. I updated them after I did the same
job.
They are
based on articles by Tony Athens, of South Bay Marine www.sbmar.com
The Aftercooler is the large (maybe 18” tall by 6” wide) white rectangular thing on the middle of the port side of the engine.
The picture
on the left below is the
aftercooler in Tardis with the top cap already removed.
Its function
of the aftercooler is to cool the intake air to produce more power at higher
RPMs.
If you were
not throwing spitballs at the girls during high school physics class, you’ll
remember that compressing a gas heats it, and it expands and takes more volume.
For some
strange reason, diesel people refer to these things as aftercoolers: car people
usually call them intercoolers.
Why
should I care ?
Its an
critical part of your engine, especially at higher RPM. Cummins have ‘missed
the boat’ on maintenance of these things.
My owners
manual specifies to backflush fresh water thru the zincs every 300hrs/12 months,
but that isn’t gonna cut it... Tony Athens recommends removing and cleaning it
every 1-2 years. After three years and 1200hrs my aftercooler was about 30%
blocked with salt/calcium deposits, and the lower O ring seal was showing signs
of leaking.
Essential
Homework
OK, before
you even think of anything else, read the first 2 articles on Tony’s website:
http://sbmar.com/Maintenance/Aftercooler.cfm
He had
outlined the problems and procedures far better than I can.
Disclaimer:
I’m not a paid professional shill for Seaboard Marine, just a customer!
They specialize in Cummins repowers for commercial fishermen, so they emphasize
simple, bulletproof engine setups that work hard for their money. They’re not
an ‘official dealer’ so they’re not afraid to deviate from the factory
gospel either…
American
Tug Specifics
OK, done your
homework?? Now, for a few things specific to our Tugs.
2. Close the engine seacock. Hang the ignition keys on it (Kurt’s tip) for the obvious reason….
5. Loosen hose clamps at top and bottom of after-cooler. (8mm bolts). It will be easier to remove the end caps if both clamps are loosened on the top hose and the bottom hose.
6.
Remove the three bolts from the top cap (10mm bolts), work the cap
loose and remove. This should reveal the tube nest and the upper “O” ring
seal. Leave the “O” Ring in place until you are ready to remove the tube
nest. Note the amount of the tube nest that protrudes above the cooler housing,
about 5/16 to 3/8”. This is where you want the tube nest when it is
re-installed.
7. Remove the lower three bolts (10mm) and work the lower cap off. After the cap is clear the tube nest can be removed from the bottom. Remove the upper “O” ring, support the bottom of the tube nest and it should drop down and carefully clear the housing. If you’re really unlucky, it’ll stick in there, and require persuasion with WD40 and maybe a rubber mallet…. Note the orientation of the tube nest as it comes out of the housing; it should go back the same way. Air flow is rear to front through the fins; air flow to the engine can be restricted if not installed properly. The ‘flat’ sides of the tube bundle face the air inlet and outlet.
8. Follow Tony’s instructions on cleaning the tube nest. Jim used a 3/16” wood dowel, tooth brush and simple green, and also used 400 grit wet/dry sand paper to polish the sealing surfaces where the “O” ring mounts on the tube nest and the caps. Jeremy found minimal corrosion, but lots of salt/calcium deposits on the tubes.
9.
Reassemble in the reverse order. We deviated here from Tony’s
instructions because we couldn’t find the anti-sieze goop he used. Jim used
“Permatex Copper Anti-Seize Lubricant” and Jeremy used Aqua Lube waterproof
grease. Basically, look for something that is heavy-duty, waterproof, O-ring
safe – that’ll do the job.
10. You will also need two new “O” ring seals. The Cummins part number for these is: 4019975 for our engine – yours might vary as Cummins used several different sizes. These “O” rings are the ‘fat’ .250 thousands in diameter. The reason we mention this is Cummins gave Jim the wrong seals originally and he had to have the correct seals air shipped in, he wasn’t very happy. Take your engine serial number with you – and double-check the parts guy, My experience is that Cummins Dealers are not very savvy on the marine-related stuff – most of their business is trucks/RVs. O yeah - be ready for ‘Sticker Shock’ – Jeremy paid $62.50 EACH for these…. However, Tony/Seaboard now sells kits (of 2) for around $40.
11. Coat the mating surfaces with the anti-seize lubricant then insert the tube nest from the bottom with the fins oriented in the correct direction (flat sides facing the air intake/outlet). Push the tube nest up so the sealing ring protrudes the proper amount. To hold in this position use a small “C” clamp and a block of wood on the edge of the sealing ring. This will secure the tube nest while the bottom “O” ring and cap are installed.
12. Stretch the lubed O ring around the tube bundle and install the bottom cap. You’ll have to attach the water hose first probably. After securing the bottom cap remove the clamp from the upper end. Install the “O” ring and upper cap. Torque both upper and lower cap bolts to specifications, 22ft-lbs (30Newton-Meters for you metric people). Install and tighten hose clamps.
14.
Open sea cock, start engine and check for leaks.
Jim Shates “Annies Song” AT34-#47 Jeremy Bell “Tardis” AT34-#48