• Mobile App For Android Now Online!

    Download it here. The app is searchable in the Google Play Store under Sailboat Owners.

    Sorry iPhone/iPad users, we are still waiting on Apple. :(

    Click the X in the upper right corner to make this go away

Anyone install a temperature sender in the heater line on a Yanmar 3GM30F?

Apr 24, 2006
868
Aloha 32 Toronto, Lake Ontario
I’m curious what temperature you are seeing? Ours never gets above 125 F.
The sender does protrude into the coolant flow and I have replaced the thermostat (first thing I did). I read somewhere that heater line temperature is reduced in order to prevent scalding - but I can’t find that post.
I checked the temp sender fitting and hoses after an 8 hour run and they were around 115 F. I realize they will be a little cooler than the coolant gliding in them but shouldn’t be that much after such a long run.
Chris
 
Apr 24, 2006
868
Aloha 32 Toronto, Lake Ontario
It’s engine coolant temp I’m interested in. My engine does not have an extra port to attach a sender so I did what many have done and made a fitting for the heater loop.
I was expecting 160 - 170 F temps.
Chris
 
  • Like
Likes: Joeniver
Apr 24, 2006
868
Aloha 32 Toronto, Lake Ontario
Thanks. I’ll ask my question there. Nobody has talked about the temps they are seeing yet.
Chris
 
Apr 24, 2006
868
Aloha 32 Toronto, Lake Ontario
None of the threads answer my question. They are all reading temp via replacing the temp switch with a temp sender. I want to hear from someone using a sender located in the heater/bypass loop as I’m curious if that is regulated to a lower temperature. In a car it would read the same temp as the coolant in the block.
 
Feb 14, 2014
5,627
Hunter 430 Waveland, MS
For your info, my 50 hp Thermostat is a 125°F type.

That seems to be what yours it too.
Why?
The surface of a Rubber hose at 115°F would be about right for 125°F flowing inside.
____
What is the concern?
Jim...
 
Apr 24, 2006
868
Aloha 32 Toronto, Lake Ontario
My thermostat (both old and new )is stamped 71 degrees C (160 F). That would suggest I’m not reading engine coolant temp.
 
Apr 24, 2006
868
Aloha 32 Toronto, Lake Ontario
I boiled the old stat and noticed something interesting. It’s a dual stat and the bottom disc controls flow into the heater/bypass loop. When cold there is enough pressure to lift the disc and let coolant through the heater/bypass loop. If you look at the pic with the stat open (165 F) the bottom extends putting more pressure on the disc, reducing the flow to the heater/bypass loop. This would suggest the heater/bypass loop runs cooler than the engine via modulating flow through it.
I think I answered my question but I’d still like to hear from others using the heater/bypass loop for engine temperature gauges.
 

Attachments

Apr 24, 2006
868
Aloha 32 Toronto, Lake Ontario
I found the answer!!!
3GM30F’s after serial # 5548 have the heater supply on the”block” side of the thermostat and (right out of my Yanmar manual) “throttle” flow in the heater/bypass loop. This provides faster warmup and less risk of scalding.

Prior to serial #5548, heater supply came from the other side of the thermostat. This caused a longer warmup as cool water was bypassing the thermostat via the heater. Once thermostat opens, coolant at engine temperature circulates through the heater loop.
So, it is correct that I’m seeing 125 F on the heater line while the engine is at 160 - 180 F.
If I had an older engine, my temp gauge would read engine temperature. I can move the heater supply hose as Yanmar just put a threaded plug in the old hole do they could use the same part.
Chris
 
Oct 26, 2008
4,991
Catalina 320 Barnegat, NJ
Mine is Serial # 22074 and the sender is mounted on a fitting to the water heater on the block side of the thermostat. Previous owner told me that temp gauge will always read less than engine temp and he always verified engine temp with a digital gauge when he was concerned. I didn't really put much thought into it until reading your post. Over the winter, I installed a new temp switch & new sender as well. My temp gauge typically shows about 150 or a little less when fully warmed up and running under load. Sender is installed on a tee fitting that comes off the block with a threaded copper pipe. I never thought about putting the sender where the switch is, but I think I would leave well enough alone.

Front.jpg
 

Attachments

Dec 19, 2006
5,727
Hunter 36 Punta Gorda
Look at T bird posts and what I was put tee into heater hose near thermostats I add sensor and have gauge at start panel in cockpit been working many years and came in very handy when had cooling problem and works real good with pretty accurate temp and rinses when a pro blew with the cooling and let’s me know when it starts to over heat and best thing ever added.