3GM30F Operating Temperature

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Jun 4, 2004
812
Hunter 340 Forked River, NJ
I just installed an engine temperature gauge to replace one of the idiot lights on my Yanmar 3GM30F. I used a CruzPro T30 digital gauge with an over temerature alarm feature. The istallation was straightforward and I was able to use the blue/white sender wire from the old sensor to the pedestal. I used a Telflex 3/8" temp sensor and calibrated the gauge for that sensor. The gauge seems to work well and the engine temperature with the boat in the slip reached 153F and then leveled off. It's been too snotty to take the boat out on the bay but I did run the engine for a while at 2000 RPM. I'm wondering what is the normal operating temperature of this engine. The Yanmar manual say that the alarm signal comes on at ~202F. The water in the marina is cold this time of year.
 

Alan

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Jun 2, 2004
4,174
Hunter 35.5 LI, NY
Where...

...did you install the temp sensor? Is it in the fresh water/coolant side or the raw water side? The coolant temp is dependent on the thermostat setting. All other things being equal, the engine coolant will never rise above the temp that the thermostat is set at.
 
M

Miles

Cruzpro T30

Hi John, I installed a Cruzpro T30 on my 340 a few months ago. It sounds like you replaced your stock sending unit? I T-ed mine into the output hose to the water heater right by the engine block so I have two over temp alarms now. The Cruzpro seems to work quite well. Running in the slip the indicated temp. goes to 159 and pretty much sits there. Under way it runs a little higher, maybe 165 or so. I did notice that after being out overnight when the high output alternator is working hard to recharge the batteries the temp goes up to maybe 175 or so and then drops as the alternator load drops. This is a 3GM30F in a 1998 340 in the cold waters of the PNW so I bet your numbers are pretty close. I think the thermostat starts to open at 160 which is why the engine runs just under that until it gets more of a load. I programmed my alarm for 195, hope it doesn't get that hot. I give the Cruzpro a thumbs up, nice unit!
 
K

ken

operating temp

Alan I dont think there is a port for installing a thermostat on the salt water side. ??? where is your boat this summer ?? Ken
 
Dec 2, 2003
4,245
- - Seabeck WA
I've done scientific tests on the thermostat.

Well, actually I watched it open in a pot on my stove with a candy thermometer next to it. That's scientific! Mine starts to open at 159 and is fully open at 163. I find that no matter how hard I run my 3GM30F, my highest possible loading will never make the raw water at the outlet of the heat exchanger WARM. If it gets warm, something is very wrong.
 
M

Miles

That's interesting Fred

I didn't realize the range between starting to open and fully open was that narrow. I figured the thermostat wasn't fully open until 170+, glad to know otherwise. Nice experiment! I agree that the cooling raw water after the heat exchanger is never warm, there's so much flow it doesn't get a chance to heat up much.
 
D

Dan Johnson

John...

where did you source the Cruzpro unit from? What sensor was used and where was it plumbed into the system?
 
Jun 4, 2004
812
Hunter 340 Forked River, NJ
Installation information

Thanks for all the replies and comments. I got the CruzPro gauge from e-Marine, Inc. in Ft. Lauderdale, FL (http://www.emarineinc.com/) for $109 plus shipping. You can go the CruzPro site directly and read and download the T-30 owners manual at www.cruzpro.com/t30.html. I used the Telflex 3/8" NPT temp sensor (Telflex # 52320S009) and used it to replace the original Yanmar sensor in the thermostat housing. It was an exact fit and as I mentioned, I could use the blue/white original temp sensor wire that ran to the pedestal mounted engine panel on my boat(H340). I just disconnected it from the alarm circuit and attached it to the gauge. The gauge has a number of different programmable calibration settings for all of the major sensor makers. I am looking for a way to measure the coolant temperature directly to verify the accuracy of the gauge. I may just open the pressure cap and run the engine up to temperature and then stick a good thermometer in the coolant, hoping that it does not overflow. BTW, I set the high temp alarm at 200F.
 

AndyK

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Mar 10, 2004
195
Hunter 33 Salem, MA
same results here

I did the same thing myself this year. Replaced the idiot light with the Cruzpro T30. T-ed the new sender into the hot water heater feed line. My temp stays pretty much right at 155-160. This was all part of the the 3YM30 overheating issue (see archives) that I went through for the prior two years. With the replaced cooling core in the engine and the improved temperature monitor I did not overheat once this year with over fifty days on the boat including two longer trips of about 350-500 miles each. Andy
 
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