New Heat Xchgr. Ouch.

After our trip last month from Carrabelle to Clearwater, I decided to change the coolant on our pretty new to us 2005 mainship. Twin Yanmar 4lha-stp. I noticed that the coolant in the stb motor was no longer pink but was clear/cloudy.

The boat had very low hours on her when we bought her, about 200, and I've seen evidence of very little routine maintenance, so I figured the coolant had never been changed and had gone bad. I replaced it with new elc coolant.

Last week after running from Clearwater to Sarasota I did an engine check and found salt water in the expansion tank.

When I pulled an end cap off of the HE water poured out. I tried pouring water into the day tank and it poured out as fast as I could pour it in. This was Friday afternoon first day of our delivery/cruise to Stuart.

Luckily Florida Marine Power (they are great) the local Yanmar service provider managed to get me a new HE in just a few hours. $1,500 later we were back in business.

John at Marine power said in 15 years he has never seen a Yanmar HE fail like that, that it was a bad part failure and a fluke in his opinion. Aren't I lucky?

All told, saltwater ran through or sat in the engine for about 6 days, best as I can figure. Should I be worried?

I am going to flush it a couple more times and replace the coolant now that the boat is in Stuart for a while.

Doug

How do you know it was only 6 days? If you are sure it was only 6 days, I wouldn't worry about it as the antifreeze will re-stabilize the fluid in there.

I did an engine check before we left Carrabelle, and it was fine. I didn't check the coolant when we got to Clearwater, but I changed it about a week later. and didn't run the engine again until we left for Sarasota. Found the problem that afternoon in Sarasota.

At this point worring won't solve anything, flush a few times with water and then fill with ELC, after a season change out again.

Flush it with Cascade dishwasher detergent mixed with clean fresh water. It will clean out your fresh water system very nicely and there will be no suds to deal with when you flush it out with fresh water.

So why did the cooler fail? Important to know to avoid the same from happening again and hopefully save its twin. Several possible "whys."

My thought as to why it failed was that the pencil zincs were not changed on a regular basis, if at all, which scares me for the other side and the oil cooler.

the mechanic from Marine Power said no, that this was a tube that either split entirely or somehow broke completely in half. He said that zincs would have resulted in pinholes and a gradual slow leak or series of small leak. This was a complete, catastrophic failure. The water poured right through it as fast as I poured it in. He said he had never seen that before.

I hope he is right.

Antifreez Is changed on time in the engine because it becomes acidified.

YOURS WAS IN THE ENGINE , UNCHANGED , FOR FAR TOO LONG.