Leak from 3YM30 and other issues. :(

Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
After motoring to the pumpout and then under the crane I discovered a lot of fluid in the engine pan under my 3YM30. I cleaned it up then watched to see a slow drip form on the bottom of the pulley on the end of the crankshaft. Uh oh, a bad main seal I thought. But it doesn't look like oil. I extracted some oil to see if maybe there was water in the oil but it looked good. The drip was around a drop every two minutes. I could not see or feel where it originated. So I put a paper towel under it and went back a week later to cover the boat. I took the picture while watching and no longer saw a drip. But there was a fair amount of fluid, what I think is engine anti-freeze. And now it looks like it came from farther back else it puddled and just backed up. Not sure how to isolate.
To boot the yard took my Nexus anemometer off at my request. The cups were gone and the direction indicator has bad bearings. :( Leak.3YM30.jpg Nexus.Anemometer.jpg
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Sorry about the rotated picture. It is good in my picture folder. Don't see a way to fix it here.
 

sailnc

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Sep 6, 2014
30
Hunter 37C New Bern, NC
Could it be as simple as a leaking seal on the freshwater cooling pump? I had that problem early this year and ended up replacing the pump; may rebuild the old one sometime as spare.
 

Jeff

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Sep 29, 2008
195
Hunter 33.5 Carlyle Lake in Central Illinois
Not sure what color your antifreeze is...orange I assume. In my engine pan the color
in your picture means a diesel leak since my antifreeze is green.
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Doesn't taste or smell like diesel thankfully. Thought about the pump but it would be more watery, less viscous I think. Have a sample in a zip lock but not sure how to test it.
 
May 12, 2004
1,502
Hunter Cherubini 30 New Port Richey
Doesn't taste or smell like diesel thankfully.
Now, I have tasted the water in the bilge on occasion to test for fresh or salt but engine fluids? You are braver than I am, Ed.
BTW, does look like coolant. I have the 3YM20 and your hoses look like they are getting old and possibly brittle. Could have something to do with it. Just my $.02.
 
Sep 20, 2006
2,912
Hunter 33 Georgian Bay, Ontario, Canada
Now, I have tasted the water in the bilge on occasion to test for fresh or salt but engine fluids? You are braver than I am, Ed.
BTW, does look like coolant. I have the 3YM20 and your hoses look like they are getting old and possibly brittle. Could have something to do with it. Just my $.02.
Ed's on Lake Erie, only salt around is in the margaritas. The "brittle" appearance was Yanmars brilliant idea to paint the engines after the hoses were installed. I have the same appearance on mine, pita, as the paint chips get everywhere.
 
Sep 20, 2006
2,912
Hunter 33 Georgian Bay, Ontario, Canada
Ed, colour looks like rusty water on the raw water side? Can't think of anywhere else that colour could be from?
 

Dan_Y

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Oct 13, 2008
514
Hunter 36 Hampton
My 3YM30 is leaking engine coolant (yanmar pink in my case) from the o-ring in the rear cover of the heat exchanger. I jammed some paper towels under the rear of the heat exchanger to prove where the leak was. Maybe yours is leaking from the front, just behind the alternator, where it's difficult to see. I was going to simply change the oring but a yanmar mechanic said it was better to pull the heat exchanger off as a unit (6 long bolts) and take the core to a radiator shop for cleaning then pressure test. Also, the sleeve that's pressed into the top of the heat exchanger (radiator cap fits on it) leaks as well. So it might be another source to look at. Has the fluid level in the overflow tank changed after this event? I look at mine when checking the oil and belts before an outing, and have seen it slowly drop over the summer.
 
Jun 8, 2004
994
C&C Frigate 36 St. Margarets Bay, Nova Scotia
If you're into tasting boat fluids (and I am not recommending it!) antifreeze tastes slightly sweet. I would bet on AF - leaking shaft seal on the coolant pump maybe. Is that the coolant pump behind the top belt pulley? If so, its right above the crankshaft pulley and might be the source of the drip you saw.
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Could be it Jim. I have some 50/50 Prestone in the garage. I put some in a zip lock with a piece of paper towel to match the one that I brought home. I think they are the same. Just can't see how the drips form on bottom of crank pulley. But that is the pump directly above. I have the parts manual in my reading stack. :)
 
Jun 8, 2004
994
C&C Frigate 36 St. Margarets Bay, Nova Scotia
Ed, there is often a weep hole on those coolant pumps (can't say for sure on a 3YM30) and if the shaft seal leaks, that is where the fluid comes out...and if the weep hole lets the drip fall on the crank pulley below, you may have traced your leak. Also, sometimes the drip will stop when the shaft is not rotating. Good luck with the troubleshooting!
 
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Oct 22, 2014
20,993
CAL 35 Cruiser #21 moored EVERETT WA
weep hole on those coolant pumps
I had that issue on my Perkins 4017. Back when I knew nothing about my engine I told the BMW self named "Mechanic" of the spray, he found nothing wrong. The pump eventually blew when the seal and the bearing failed. Then it was an easy problem. Fired the BMW and spoke with the engine dealer. They found me a replacement pump. Installation was like working on a car only laying on your side with your head below your shoulders. The install went smoothly and the engine has not hiccuped since. This one action appears to have solved the PO's over heating problem that plagued his use of the boat.
 
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