420/44 DB Owners Club

Heat exchangers don't disassemble like the aftercoolers. Just take off the two end caps. That's all that's removable. Only reason to remove them from the boat is to pressure test them and/or paint them. Otherwise you can remove the end caps, rod out the tubes and put end caps back on with new gaskets, while still mounted in place on the engine.
Looks like i would have to disassemble some of the exhaust elbow to get in there to rod them out. Doesn't seem like a lot of room on either end?
 
Heat exchangers don't disassemble like the aftercoolers. Just take off the two end caps. That's all that's removable. Only reason to remove them from the boat is to pressure test them and/or paint them. Otherwise you can remove the end caps, rod out the tubes and put end caps back on with new gaskets, while still mounted in place on the engine.

Yep, that is on my list too. I got the SBMar end cap kit. Rookie question, but if i'm not removing the whole HX unit, does draining/changing coolant need to happen? The end caps only contain the tubed cooling passages that move seawater, right?
 
No coolant as its the raw water side, you'll get a little remaining antifreeze from your winterization, but not much.
Actually now that i'm thinking about what ZZ13 mentioned above i'm going to order the 1/8 inch plastic rods from Amazon to see if it gives me some flexibility in cleaning out the tubes without remove the whole unit.
 
Yep, that is on my list too. I got the SBMar end cap kit. Rookie question, but if i'm not removing the whole HX unit, does draining/changing coolant need to happen? The end caps only contain the tubed cooling passages that move seawater, right?
That is correct. If you use your boat enough you will find the tubes pretty clear, even in salt. Biggest thing I run into is pieces of broken off zinc clogging a few of the tubes on the bottom of the forward end. I pop off my end caps once a year.
 
What are these 1/8" rods you speak of? Link please if you have it handy.
Anything you can find that's narrower than the tube and long. I've used wooden dowels, stiff wire used to prop up plants, even a skinny screwdriver to clean up the ends of the tubes (generally any blockage is just a few inches into the tube).
 
This is what I found on the aft end of my port heat exchanger when I opened it up last week. I tried to rod them out with a brass 1/8” rod but there is no room to really work due to the bulk head in one side and the exhaust elbow in the other. Would like to run the rod about the length of the exchanger which is over 2 feet in length. Going to see if a plastic rod that is flexible will work.

2CCD58B1-10CC-4B7F-8AB0-6E05C123A5A4.jpeg
 
This is what I found on the aft end of my port heat exchanger when I opened it up last week. I tried to rod them out with a brass 1/8” rod but there is no room to really work due to the bulk head in one side and the exhaust elbow in the other. Would like to run the rod about the length of the exchanger which is over 2 feet in length. Going to see if a plastic rod that is flexible will work.

View attachment 80115
Can you get your hand in there with something short to poke out the ends? My guess is it's all right there at the end of the tube.
 
Can you get your hand in there with something short to poke out the ends? My guess is it's all right there at the end of the tube.
Probably could but i'm concerned about forcing it in further.
 
This is what I found on the aft end of my port heat exchanger when I opened it up last week. I tried to rod them out with a brass 1/8” rod but there is no room to really work due to the bulk head in one side and the exhaust elbow in the other. Would like to run the rod about the length of the exchanger which is over 2 feet in length. Going to see if a plastic rod that is flexible will work.

View attachment 80115
Nasty stuff. I found similar obstructions in the lower end of my port aftercooler along with a bunch of impeller pieces. It looks like you need to find a long flexible dowel to push through from up top. Perhaps a quick shot with a dremel carving bit would break up the pieces to where they would then fall out.
 
So i was able to rod out the HE this weekend though it wasn't easy it is doable in place. I picked up a couple 1/8" brass rods from the HD and order a pack of plastic rods from amazon. The brass rod was necessary for the ports that were truly blocked. My next plan of attach is to run a descaler through to ensure everything is nice and clean.
 
One more head scratcher that i can't seem to understand is why the difference in size of the port side exhaust tube? The Starboard side is much smaller in comparison. I can't seem to see a logical reason for the difference other than making it near impossible to change the waste tank filter.
 
One more head scratcher that i can't seem to understand is why the difference in size of the port side exhaust tube? The Starboard side is much smaller in comparison. I can't seem to see a logical reason for the difference other than making it near impossible to change the waste tank filter.

I think you answered your own question.....they love to give you a challenge....

:D

Bennett
 
I just talked to a broker representing a nice 2005 420 with the 480CE's. I asked the question about WOT, props, etc. He is pulling a survey from 2018 to see if they ran her up to WOT but the boat has thr 26x26 nibral props and is said to run 22-23 knots at 80% load. I know we need RPMs to really tell, but can anyone comment on whether that speed sounds in the proper range for that year/engine combo?
 
Bought our 2005 420db w/480ce’s w/26 x 26 nibrals on her. Fuel burn #’s were to high so had them modified to 26 x 25, fuel burn still to high. Modified again to 26 x 24 & cup removed, fuel burn now right on!
80% cruise speed is now about 20 mph.
That’s fully loaded & 800lbs of Freedom Lift & dinghy
 
I'm not close to the boat so cannot look at present time, but does anyone happen to know if we have a standard 3 prong 120 outlet in the engine room. I'm debating on putting a Twin Hornet engine room heater in there and getting rid of those problematic air heater assemblies on my engines. Any northerners have good luck in the shoulder seasons using a engine room heater versus the factory engine air heater assemblies?
 
I did not have one on the 44 but installed one on the bulkhead high behind the port engine exhaust mixing elbow. It is wired in the battery charger circuit so I did not install a new breaker.
Very convenient now though to have 110 power in the ER. I did put in a water resistant box.
Cheers
 
Bought our 2005 420db w/480ce’s w/26 x 26 nibrals on her. Fuel burn #’s were to high so had them modified to 26 x 25, fuel burn still to high. Modified again to 26 x 24 & cup removed, fuel burn now right on!
80% cruise speed is now about 20 mph.
That’s fully loaded & 800lbs of Freedom Lift & dinghy

wow, it sounds like this boat is likely way Overpropped then. He carries a big rib with a 40hp on the hydraulic platform too. How many hours were on your motors when you bought it? Did the Cummins tech have any concerns that it had been run like that for a while?
 
My 420 doesn’t have any 120v outlet in engine room either. If needed I would consider tying into washer/dryer outlet on back side galley cabinet under steps ahead of starboard motor. Boating in Florida now so disconnected air heaters after having to replace both alternators!☹️. I believe sbmar refers to and sells Wolvorine pan heaters as an option.
 

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