Heat Exchanger

[GILow]

Originally Posted by WindLove

Maybe if I don't have a problem I should leave well enough alone but.... Recently I went to a discussion on Diesel engines and the guy said one of the most important routine maintenance tastes is to remove and clean the heat exchanger. He said the little tubes would get clogged and the engine would start to overheat.

I think it's been years since the heat exchanger has been removed. If everything seems to be working fine, is this something I should proactively do. How difficult is it to remove the heat exchanger, and what is involved in cleaning it. Is this something better left to a mechanic?

Any advice?

The thing about heat exchangers is that they can be only just coping, and you won't know till it matters.

For instance, if you usually run the engine at around 50% power, the heat exchanger may keep the engine temp reasonably steady, despite being quite clogged. However, the first time you need 60% or more from the engine, you find that it no longer has the capacity to dissapate the generated heat at the rate required. Bingo, boiled engine, just when you REALLY don't need it to boil, since sudden needs for more power are generally not matters of choice. I suspect very few of us decide to throttle up to near top power just for the fun of it.

Also, some, like mine, have sacrificial anodes that need to be replaced quite frequently. I don't actually know how long my anodes will last, we have not had the boat long enough, but I have read estimates between 6 months and a 6 years. Time will tell.

I just cleaned mine last week, and the whole job took less than four hours, including draining the cooling system (into the bilge.... oops!) taking the core home, poking out the passages with a copper rod (mostly pretty clean) fizzing it in MILD hydrochloric acid (ok for my type, don't know if this is safe with what you have), neutralising it in backing soda, cleaning the rubber seals, replacing the two zinc anodes (unknown age but pretty well gone), refilling the cooling system and finally pumping out the mess in the bilge with my niftly vaccuum oil extractor.

Did it make a difference? No way of knowing really. But nice to know the HX is as efficient as it can be.

Matt

[DeepFrz]

Did it make a difference? No way of knowing really. But nice to know the HX is as efficient as it can be.

That is the whole reason for preventative maintenance, isn't it. The maintained item is working the way it was designed to work. Plus you know it is working the way it should and that equals peace of mind.

[GILow]

Originally Posted by DeepFrz

That is the whole reason for preventative maintenance, isn't it. The maintained item is working the way it was designed to work. Plus you know it is working the way it should and that equals peace of mind.

I agree with every bit of that paragraph, except I'd replace the word KNOW with the word HOPE.

[coldar1]

I'm a bit of a novice in this area. I have 2 X Volvo Penta D2-55 engines with sail drives. Only the starboard engine has a heat exchanger, so we only make hot water on the days we run the starboard engine - we normally run engines day about to try and balance engine hours. What is involved in putting a heat exchanger on the port engine as well, apart from the hoses involved which I can figure out?

[FlyingCloud1937]

Wherever Sarah

Most engine manufactures request an engine flush on/and at antifreeze change, at least every two years.

So if every 2 years you pull the tube bundle and give it a low acid wash, when you change the anti-fr... then you should be be golden.

Hoses harden with time, so if you are past a five year hose then it's time.

Preventive maintenance, short fuses catastrophic failure.


Lloyd

[FlyingCloud1937]

You would be having 3 heat Ex's

One for each engine, sea water-to-fresch makes 2, and one for the domestic HW.

Lloyd

Originally Posted by coldar1

I'm a bit of a novice in this area. I have 2 X Volvo Penta D2-55 engines with sail drives. Only the starboard engine has a heat exchanger, so we only make hot water on the days we run the starboard engine - we normally run engines day about to try and balance engine hours. What is involved in putting a heat exchanger on the port engine as well, apart from the hoses involved which I can figure out?

[GILow]

Originally Posted by FlyingCloud1937

Preventive maintenance, short fuses catastrophic failure.

That's practially Haiku.

[Nicholson58]

Our Westerbeke (1983) was new-to-us about 8 years ago. We had periodic overheat issues I handled by making the prop pitch flatter & increasing the rpm. - Not an option for most people. I finally removed the end caps. (raw water in the tubes; glycol in the shell). The exchanger tube side is 4-pass. The first pass quadrant is coolest so growth is more liely to be possible. The other three passes have elevated water temperature. I discovered small shells blocking some tubes and a deposit of calcium in the bores of some of the 1st pass tubes. Long skinny bronze, SS and mohair brushes cleaned out most but I eventually took it to a radiator shop for proper cleaning and pressure test. We fortunately had a spare exchanger in the inventory so the cleaning, $60 bucks, was not a big deal.

The boat came from Florida and we are on Lake Michigan so our growth problem here is maybe zebra muscles but they don't do well in the copper & heat and/or algae slime. About two times per summer season I run a cup of clorox through from the strainer and let it rest in the engine for about 5 - 10 minutes and then motor out a few miles to sail. The most amazing crud shoots out the exhaust after this application.

You should at least inspect the tubes. A spare exchanger on board is good if you will be inconvenient to repair facilities when it craps out. If no PM has been done to this engine for a very long time you might spring for a GOOD mechanic to check it over. There could be other items waiting to surprise you.

I had one other revalation when I serviced ours. I also removed the exhaust manifold which doubles as the glycol tank. There was a place where the aluminum wall seperating the glycol from the hot exhaust was nearly eroded through. I had our welder fill it in and dress off the mating surfaces on the mill. Could have been a real mess.