3GM30F operating temperature follow-up

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Jun 4, 2004
812
Hunter 340 Forked River, NJ
I wrote a week or so ago asking what was the normal engine operating temperature for the Yanmar 3GM30F engine. I had a new temperature gauge and was getting readings up to 180 degrees F at RPM’s above 3,000. Fred Ficarra wrote that my engine was running too hot and suggested that I should clean the heat exchanger among other things. Last weekend, we had the boat out on the bay and I began to get engine temps above 180 whenever I ran over 2,000 RPM. Something was wrong but we had plenty of hot water for the dishes that night. Keeping with the rule to check and fix simple things first, I stared at the beginning of the cooling system before tearing apart my heat exchanger and exhaust elbow. My thru hull was clear and the sea strainer was empty. There was good water flow from the thru hull and no evidence of an air leak. Even though I had installed a new impeller at the beginning of the season (April), I removed the raw water pump from the engine and took off the back cover. The impeller was in pieces. Two vanes were missing and the remaining were badly cracked but still attached enough to pump a little water. I am sorry to report that the impeller was one of those new Globe brand, blue rubber, “run-dry” impellers with less than 15 hours of service on it. I replaced the impeller with a new Yanmar replacement unit and a new “O” ring. I found the two broken vanes stuck in the raw water entrance port to the heat exchanger and was able to easily remove them with a tweezers. We took a short trip this week and of course, the wind was right on our nose both ways so I had to motor to and from our destination. I motored a total of five hours directly into a 12 to 20 knot head wind, at 2,800 RPM, towing a dinghy at from 5 to 6 knots. The engine temperature stayed between 156 and 159 degrees all day. There was no steam at the exhaust. Lessons learned? The wind always blows directly from where you want to go and the normal engine temperature for the 3GM30F Yanmar (on my boat) is at or below 160 degrees F.
 

GuyT

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May 8, 2007
406
Hunter 34 South Amboy, NJ
Could your exhaust gush indicate

to you that there was not enough flow. I always listen to the gush every 2 to 3 seconds to make sure of flow. I like to hear a gurgle and a hefty spit. If I have a clog, it gushes out every 5 or 6 seconds. Great job troubleshooting!!
 
Dec 2, 2003
4,245
- - Seabeck WA
John, thank you for the feed-back!

I was clinging to your every word as I imagined myself traveling to Desolation Sound day after tomorrow. ;D (but my wife will wait and fly up in August) Sorry to hear of the impeller failure. I was planning to buy those. But good for you! Hey! Check out my latest drag strip run with my Camaro. It's at the bottom-front of my web site. The 11's are a breath away.
 
Dec 25, 2000
5,048
Hunter Passage 42 Shelter Bay, WA
Hi Fred, what's your sail plan to Desolation?

We usually sail to Cornet Bay, through Deception Pass, then over and up San Juan Channel with a clearance at Bedwell. Terry
 
Jun 4, 2004
812
Hunter 340 Forked River, NJ
Exhaust Gush

On my boat - 2000 H340 - the exhaust port is just above the waterline on the underside of the scoop transom. That and the fact that my boat squats somewhat by the stern makes it almost impossible to check the water coming out of the exhaust. Thinking back, I recall that the engine may have had a deeper and more hollow sound while running hot and I should have known then that the water flow was not good.
 
Dec 2, 2003
4,245
- - Seabeck WA
Terry, as I type, I'm looking at the tide charts

and wind speeds on the nose that are all ugly until later in the week. Hmmm. Do I really want to get beat-up for a looooong time? I think I'll play it by ear. And if I wait until Saturday when conditions are favorable, I CAN RACE MY CAR AGAIN Friday night! :) As far a routing, I usually go right up the Sound, duck into Cattle Pass and if early enough, clear at Bedwell. If it's late, anchor across from Friday Harbor then clear in the morning. Oh, we just talked to a friend last night who's been stuck in Nanimo for three days waiting for the gail to subside. Record temps this week too so that gail will go for another day or two.
 
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