Cleaning Man CR900 heat exchangers

$8k just to clean the heat exchanger seems very high. I usually clean them myself but i would think they should be no more then $800-1000 to have them cleaned professionally.

It is a little complicated to remove, clean and replace them and more labor intensive than most motors because you have to take several things off to remove and reinstall them. I would NEVER and I mean NEVER go through the trouble of cleaning them with barnacle buster for $8k. I would have them electrostatically cleaned at a shop and pressure tested. Do have your aftercoolers cleaned at the same time. However, I've seen MANY MAN owners go much longer before cleaning the heat exchangers if the engines are running at correct temperatures due to the expense.

Agreed. Unless your are still under warranty. then you have to follow Man's schedule. I have the older 820's. When I had my 1000 hour done, my quys in Mystic said they we "CLEAN". so if your temps are good don't do that expensive work with a wash.

On a positive note, if you have the extended warranty you should be covered on the repair to your heat exchanger they will have to do when they go to take it apart. Let the pro's do it this time because the CR engines have an issue with the header tank that needs to be updated.

How's that work?

An alternative many use is to circulate Barancle Buster or Rydlyme through your heat exchangers without removing them. A recirculation setup that circulates solution directly through the aftercooler, heat exchanger and trans cooler is an effective way to descale and clean the seawater side. Of course the aftercooler needs to be removed and inspected periodically. I also use my setup to clean the genset and AC seawater lines.

That's what you get for $8K.

Although I have not used him, Overtemp Marine does "dockside heat exchanger cleaning". I have spoken with the guy a few times and he seems to know what he is doing. His pricing is $1K to do 2 900 MANs and he will do the genset with the left over cleaning solution.

For $8K I assumed the mechanic was removing the exchangers. It is hard to believe someone would charge $8K to circulate solution dockside, aftercoolers not included! But then I have CATs and not MANs.

It is amazing what lurks at the other end of a cell phone call.

But you are right, 8K is amazing. Heck, I would do it all day long for $7500.

Effective????? hardly.

8 times out of 10 on heat exchangers I've seen pulled, it's broken off zincs and debris that are restricting waterflow and not scaling. Barnacle Buster and Rydlime do nothing to remove zincs and broken off impellor blades, etc etc.......

While YMMV, I have found that changing impellers on an annual basis or as required by maintenance schedules prevents impeller failures. Also using and maintaining appropriate intake screens reduces debris significantly. There have been several threads over the years on the repected boatdiesel web site about the use of descaling agents and circulation systems. I have also read some nice studies by the US Navy evaluating descaling agents and their optimum concentrations for circulation during seawater system maintenance.

It is not to say that heat exchangers should never be removed or cleaned, but an annual or biannual descaling is an effective way to reduce scale and maintain optimum running temperaures. I monitor WOT RPMs and look for any sign of temp creep, especially in diesels that are marginally cooled or producing very high HP/liter.

Also, hydrochloric and phosphoric acid, the primary ingredients in Rydlyme and Barnacle Buster respectively, are well known to dissolve zinc which is why you must remove all zincs when performing a system flush. I think small broken off pieces of zinc are likely to be dissolved or significantly reduced in size.

Not really, I've seen heat exchangers taken off after rydlime or barnacle buster is used and still hasn't cured the overheating problem. It seems to do a pretty good job on the scaling, however the zincs and impellor blades tend to be intact and were the problem to begin with. Especially the tube style heat exchangers, the zincs get trapped in the tube and it would take a very long time for rydlime or barnacle buster to try to disolve it. Honestly, on a lot of motors, the heat exchangers come off fairly easy and not much longer than everything you have to do to remove zincs, hook ends on whatever it is to circulate the stuff, etc etc.....plus it's always good to pressure test various coolers.

I am not sure about big diesels, but what I do every few years on my Crusader heat exchangers is mix a solution of muriatic acid. In my case, two gallons of water for every gallon of acid. I remove the raw water intake hose and put it into the bucket with the three gallon solution and let the engine suck in the solution. I shut down the engine and let sit for 30 minutes of so. Re-attached the raw water intake hose to the thru-hull and fire up the engine and flush out the acid solution. Keeps my coolers and risers clean. You will have to replace any zincs that are in the coolers if you did not remove them before the cleaning.

In addition to the heat exchangers, the valve adjustment and head bolt re-torqueing is very important as is checking the injectors at the 1000 hour mark.......on MAN's.