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Heat Exchanger Service Question...

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Can anyone advise what kind of service/frequency the heat exchanger requires in a universal 5416 16 hp freshwater cooled diesel engine. The engine is working fine, not overheating or causing any problems, but I want to ensure it keeps working.

Our heat exchanger was leaking, so we replaced it about 4 years ago (about 300 engine hours since then). I have regularly replaced the pencil zinc in the heat exchanger, but haven't done any other flushing or cleaning. I understand that they can gradually corrode or get mineral deposits that need to be removed periodically, but I'm not sure how quickly that occurs. I have heard that a small (1/4inch) dowel pushed through the internal rods can work, or immersing in muriatic acid can work.

Does anyone have any experience/advice to keep it working properly?

Thx.

Frank
 
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Kerry Kukucha

Member II
Frank:

I had my exchanger serviced about 2 years ago - had it sent out to a radiator shop & they "boiled" it out & also repaired a leak. I seem to recollect reading that when your engine temp. starts exceeding optimal range (185 degrees for a 5432/M-40), it is time to get the exchanger serviced. So far & after >200hrs, temp is still OK.
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Thanks for your reply, Kerry. That is helpful information, but I would like to be a bit more proactive, and not wait for my engine to start overheating. I'm thinking that there must be a normal or recommended service interval--like every 500 engine hours. If anyone has any additional information like this, I'd love to hear from you.

Thanks again.

Frank
 

bayhoss

Member III
Frank,
It depends upon the water that you are in. If you have a high salt content or high degree of marine plant life, then pull the heat exchanger at years end. Then pull the caps in half of that time and check for the return of salt deposits. Are you using a raw water strainer? If not, I would recommend the installation of one to prevent the plant life entry. I would not use a cleaner as strong as muratic acid on the thin walls of the tubing. I use the wire brush of a small caliber gun cleaning kit to clean the inside of the tubes.

Hope this helps,
Frank
 

erobitaille

Member II
Frank,

Finding a radaitor shop that actualy cleans and repairs radiators is getting harder and harder, most shop today just replace the radiator and charge and arm and a leg.

Boling a radaitor is actually imerrsing it in a WEAK acid bath and heating to break up deposits. If your exchanger is not leaking soaking in a solution of very hot water and 1/4 - 1/3 cup muaratic acid to 5 gls of water ( 5 -10 minute soak) and a wood dowel will clean it up very well note if the paint starts to come off the exchanger too much acid you just want to break up the salt deposits. Flush with plenty of water several time. I clean mine about every two years ans I typicaly run about 185 full throttle on my M-40
 

Frank Langer

1984 Ericson 30+, Nanaimo, BC
Thanks for this very helpful information! I do coastal sailing in British Columbia, so salt water. I do have a raw water strainer, and I change coolant every couple of years. The engine is running well, with no sign of overheating, but I think I'll try to do as you suggest, just for peace of mind.

Thanks again!

Frank
 
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mherrcat

Contributing Partner
I would also like to pull my heat exchanger and check it out. Engine is not overheating and I change the zinc every 4 to 5 months; thats about how long it takes for it to be eaten down about halfway. (When I bought the boat my ex-partner tried to tell me there was no zinc in the heat exchanger, "They don't have them anymore" he said -- idiot.)

The gun cleaning rod/brush sounds like a good method to use. I imagine a rod for a .177 or .22 cal. would work. What size brush do you use?

When you remove the h/e how much coolant is lost? Do you have to plug the hoses while the h/e is off the engine? When you replace the h/e and replenish coolant is there any "bleeding" process necessary?
 
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bayhoss

Member III
For HX for my Universal M12 I use a .17 and I use a copper brush. The softer copper will clean but not harm the brass tubing in the HX. I don't know the diamenter of the tubing for the larger engine but I would think that either the .17 or .22 would work. The tubes in mine are about 4mm which is roughly (very roughly) about 1/6 or an inch. My HX has a removeable cap at either end and this makes cleaning the outer tubes much less trouble. The thing to watch out for is not using a brush that is too large and having to force it into the tube. The loss of coolant is minimal - I use a small coffee can to catch the content of the HX and hoses. And, yes some bleeding will be required. I just remove the cap, crank the engine and wait for the bubbles to finish. Then top off with additional coolant.

Hope this helps,
Frank
 

selous

Inactive Member
I did some extensive research into this about a year ago when I bought my boat.I used to be in the air conditioning business and in air conditioning pickling you use muiratic acid which is very aggressive but not a problem when used on the copper coils found in marine air conditioners.
I use a bucket with a submersible (march) pump in a bucket below the H.E and attach a hose to the inlet of the H.E and a hose to the outlet led back to the bucket.In the bucket I use a 50/50 phosphoric acid/water mix and circulate for an hour. Works like a charm and will not harm the alloys used in most modern H exchangers which contain some nickel.
 

selous

Inactive Member
It's the smallest submersible,little maroon colored pump.about 120 gph if I recall correctly.lc series. No the phosphoric is mild and will not harm the pump at all. When we serviced A/C units we used the same pumps for a year or more with muiratic acid before they eventually shorted out internally.
Once done just empty the phosphoric and circulate some fresh water for a minute or two.
 
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