Cleaning HX article

[Claygr1]

Could someone send me the link (or a copy) to a 2006 Mainsheet article on cleaning the heat exchanger?  I am an association member but the Tech notes on the website only go up to 2005.  We're running down an overheating problem and this is the next step in the odyssey.  Thanks!

[Ron Hill]

Clay : Take some Lime-a-Way cleaner and pour it in the outlet hose (bottom hose) from your raw water pump.  Let it it for about 1 hour and re fill it again.  That should get most of the crud out of it.   

[Ken Juul]

You should also remove the inlet end cap and check for broken bits of impellers.  Apparently the POs of my boat weren't very careful.  When I was tracing down my overheating problems I found pieces of 4 or 5 blades in mine.

[Claygr1]

Thanks for the responses!  Would you mind indulging some not very knowledgeable questions about the interior workings of the heat exchanger?

I understand the basic concept is that the raw water is pumped through the heat exchanger to transfer heat from the coolant.  I also understand that they are separate systems so that there is no mixing of the coolant and the raw water.  Seems logical so far. 

However, does the coolant go through the tubes in the heat exchanger or does the raw water?  Another post (as well as Nigel Calder's book on Diesel Marine Engines) I saw indicated that the coolant goes through the tubes.  If that is the case, how does coolant come out of the drain where the zinc is inserted?  And isn't the purpose of the zinc to attract the corrosive elements in the raw water so it doesn't get deposited elsewhere in the engine.  How would that work if you are inserting the zinc into a space where coolant drains? 

And perhaps more to the point, is the Limeaway cleaning the outside of the tubes and the interior walls of the heat exchanger or is it cleaning the interior of the tubes?  I get that it is intended to get rid of the scale, etc. that is deposited by the raw water so the answer to my questions in the preceding paragraph would answer this one as well. 

And just let me state off-topic for the moment that I love my boat and think this association is a fantastic resource.  I don't share the same opinion of the Universal M25XP owner's manual, however. 

[Claygr1]

Ron, one additional question - do you flush the Limeaway out with water in between the two fillings? 

[Stu Jackson]

Clay, to answer your own question, all you have to do is take the zinc out.  What kind of water comes out, raw water or fresh (antifreeze) coolant?

You're exactly right about it works.

The tips & tricks part comes that when the insides of the HX (outside the tubes) are all cleaned out with the Limeaway, it is important to continue to check the incoming tube where the hose from the raw water pump goes to the HX.  There's cold water hitting the hot HX right there, and very often deposits build up within that first inlet tube.  Ron's been successful with th Limeaway, I choose to remove the HX and check it out at least once a year.  Recognize that it's not something I love to do, but it's relatively easy and usually has to come out because I'm messing with something else and it's always in the way!   

[Ron Hill]

Clay : When you use Lime-a-Way you don't need to flush.  Just start the engine after you reconnect the hose and you'll be OK.   

[Claygr1]

Sounds great - thanks again!

[joe feyder]

I followed Ron's instructions to use Limeaway to clean the raw water side of the heat exchanger.  We  have a Yanmar 30GM and it is very easy to fill using the raw water pump outlet hose.  My neighbor in the marina also recommended cleaning the coolant side of the heat exchanger using radiator cleaner purchased from an auto body store.  I have not seen this step mentioned by anyone.  Does anyone have thoughts or experience as to whether this is worthwhile?     

[Ken Juul]

It certainly couldn't hurt.  But most of the radiator cleaners I have seen require at least one complete flush of the system prior to refilling with a new 50% antifreeze mix.  Makes it quite a bit bigger and messy job.  If you are that concerned I would just remove the HX, take off the end caps and immerse the whole HX in Lime Away.  Rinse well and reassemble.  Then you can be sure that any impeller blades or broken pencil zincs aren't the problem.

[Ron Hill]

Joe : You'll go a long way to keeping the sediment build up out of the HX if you flush it with fresh water.  When you know that you aren't going to use the boat (starting the engine) for a week or two take a 5 gal bucket and fill it with fresh water.  Remove the raw water intake hose (after shutting off the thru hull) stick the intake hose in the bucket of fresh water, start the engine and flush the system with fresh water.

You can take the HX to a radiator shop and they will "boil it out", but simple Lime-a-way does the job with out having to take everything apart!!  A thought

[Stephen Butler]

We store on the hard for 9 months out of the year, and always flush with fresh water before leaving our C34. Also, we have been using Ron's lime-away solution for 5 years, with excellent results.  Suggest you give it a try.

[SeaFever]

I created a fresh water flush mechanism by adding a (T) fitting between my through hull and the raw water strainer. The output of the strainer goes to the input of the raw water pump on the engine. I converted the end of the T so I could connect a garden hose to it. The purpose of this fresh water flush system is to allow for easy flushing of the raw water passages including the HE with fresh water while at the dock. I also added another ball valve in this circuit so while the engine is running at idle, I can close the through hull stop cock and open the valve to the hose and switch from sea water to fresh water. This is a bit more convenient than the use of the bucket since we can run the engine longer by connecting the hose. You do need to remember to turn down the pressure of the water in the garden hose as that may be quite a bit depending on the location. This mechanism can also be used with the bucket of water and will not require removing the hose from the through hull stop cock.

I am taking some friends out for a sail this weekend. I can take and post a picture if it is of interest to people here. Although the fresh water flush is pretty common and many of you may already have something like it.

[Stu Jackson]

Hose pressure should never be used on the raw water side.  The bucket method should always be employed.  Maine Sail wrote this up, and the reasons for it, on the co.com website.  I'll see if I can find it.  It may also be on his own website.

[Stu Jackson]

Here it is:  read Reply #32:

http://forums.catalina.sailboatowners.com/showthread.php?p=577754&highlight=bucket