Heat Exchanger

[Pourhouse]

Does anyone have advice on flushing the sea water system?

 

[pleeson]

Turn off the valve between the thru hull and the strainer. Take the top off the strainer and run a fresh water hose into it while running the engine. After a few gallons, turn off the engine and the water and replace top on the strainer. Remember to open the valve to the thru hull again before running the engine again!

 

[Pourhouse]

How about with barnacle buster.

 

[knotflying]

I think barnacle buster may be overkill, especially if you use the engine a lot and flush regularly.

 

[Pourhouse]

I need it. My engine is running hot.

 

[joempo]

Some time ago, somebody suggested running Cascade dishwasher detergent through the sea strainer, using the same process as pleeson used. I have not tried it yet, but will "someday". 😉

 

[knotflying]

I need it. My engine is running hot.

I would use Rydlime to do the correct job. You need to create a closed loop and circulate it intermittently for a while. It does a great job and is non toxic. You can dump the used liquid down the toilet. I was able to create the closed loop and pumped it using the washdown pump. You will also have to remove your impeller and put the cover back on without the impeller so that the solution can pass through easily. It will not flow with the impeller in.
Rich from Roam and I did both of our boats with good results. Here is a link to the procedure we used:

http://www.tugnuts.com/viewtopic.php?f=5&t=4766&p=34718&hilit=engine+flush#p34718

By the way, are you sure it isn't another issue causing your high temperature? Did you check the impeller? Is the flow to the strainer good? Having used your boat on the loop I would be reluctant to think with all that use that you would already have a clogged heat exchanger. It could be a faulty heat sensor or a stuck thermostat, but a stuck thermostat is rare.

 

[LAKERtoo]

... is there a way to clean the heat exchanger on an R21 3YM Yanmar without taking it apart ?? .. seems like a good maintenance item for any heat exchanger .. Rob

 

[knotflying]

I am not as familiar with the R-21' but I don't see why you couldn't do it the same way I did the R-27 procedure.

 

[jroyle]

I need it. My engine is running hot.

I seriously doubt your heat exchanger is clogged, but I've been wrong before. My engine was running 10 degrees hotter than normal. I decided to don my wetsuit and check under the boat. The raw water intake was clogged with barnacles inside and out. My ex-dive service was cleaning just the waterline and everything else was covered with barnacles. My experience of 30+ years of boating is that heat exchanger problems arise after ~10 years of wear and tear.

 

[Barry Cohen]

I have not tried it yet, but others at my club flush with fresh water, fill with white vinegar from the grocery store, let sit for a couple of days, drain, flush with fresh water, and fill with antifreeze. Great results.

 

[doke01]

Mack Boring recommended Rydlyme when I took the diesel training there for cleaning exchangers. That being said, a restricted thru hull or dirty raw water filter is more likely the issue. I replaced the whole raw water thru-hull with one that didn't have a strainer cover and was straight through (no 90 degree bend). The raw water through hull intake strainer isn't not worth having in place since they cause more trouble than they fix. Now all that I need to do is close the valve, remove the hose and use a wooden dowel, purchased for just this purpose, and push it through the thru hull while opening the valve. Barnacles and blockage removed without getting wet! Gotta love that.

Quick back story... a huge mass of sea grass was sucked up into my intake and it took over two hours in rough, tidal water anchored out in the middle of nowhere to remove it. Not going through that again...