Engine Temp

Chief RA · Jun 1, 2015

Big Fish: Have no clue why the inboard crew are not posting and reinforcing your temp readings. Having run many sports cars in my time, from that reference I would expect that is about right for a water cooled engine. Of course that is just an educated guess on my part as I run an outboard on my boat. Maybe someone will chime in. Stu?
Chief

Stu Jackson · Jun 1, 2015

OK, Chief. I'll give it a try.

What is your thermostat rating? They usually make two: 160F or 180F. If it's a 180F thermostat, then your temps are OK.

They stamp the thermostats, but they do it in degrees C!

Ralph Johnstone · Jun 1, 2015

Big Fish said:
The temp is running around 180-200 degrees is this to hot?

Maybe a bit on the hot side, specs call for 160-185. If this is a constant running temp, the first place I'd look is at your temp. measurement device.

Chief RA · Jun 1, 2015

Thanks Stu, I couldn't cover this one. Ralph, sounds like you can add to this to help. Thanks guys, Chief

woodster · Jun 1, 2015

Big Fish said:
I have a retro fitted 21 hp yanmar diesel in my hunter 27 with a fresh water cooling system.The temp is running around 180-200 degrees is this to hot? If so where do look first to remedy the situation?
Regards
BF

is this a two or three cylinder yanmar and if so could you tell me what the model is plz

Claude L.-Auger · Jun 1, 2015

On most 2 & 3 cyl. Yanmar GM engines, thermostat begins to open at 71 C (160 F) and is fully opened at 85 C (185 F). As Stu says, sometimes you'll find a higher temp thermostat allowing the engine to run hotter.

woodster · Jun 7, 2015

check the raw water pump impeller and also the t stat and make sure you have the valve open when running if that does not do it you may have to open up the heat exchanger and service it it should run at 160 to 180 degrees when fully warmed up

as cool as your water is up there it should take a long time to heat up and then it should run at what ever temp your t stat is + or - 5 degrees you have very good water for cooling up there

Ralph Johnstone · Jun 7, 2015

Big Fish said:
So I gradually increased the rpms up to 2200 and the temp hit 210 and I shut it down. To hot? Suggestions?
Thanks as always.
BF

The fact that you temp. rises excessively with load shows that there is a blockage to the raw water flow. Follow Woodster's recommendations and you're on your way.

In addition, don't know if you're just pointing out that 2200 RPM is the start of the overheating but it should be at 80% of 3600 RPM = 2880 RPM for normal running.

Sailor_Jeff · Jun 7, 2015

I also want to suggest, in addition to the recommendations above you ensure good water flow sometimes things grow on the hull and obstruct the water inlet, also the strainer may be clogged. Both of these can damage the impeller. (Of course).

Nelsonhow · Jun 8, 2015

My GM 10 was running hot. I'm raw water cooled and I thought checked everything.
I checked the hoses, thermostat, pulled the head o check the cooling passages and even ran Redylime me theough the engine to descale it. I replaced the impeller thinking that the rubber vanes may have separated from impeller hub. I also replaced the pump face plate. (It looked a little worn). After all was said and done I traced the problem to
A bunch of small mussel shells in the raw water intake thru hull between the the hull The ball valve. I think the descaling and
Pump face plate also helped.

Recheck the temp
Check ALL hoses
Check the thermostat in a pot if boiling water to make sure it's open.
Check the they hull BEFORE the ball valve
Replace the impeller and check the face plate
DESCAlLE

woodster · Jun 8, 2015

Big Fish said:
Wooster:
Excuse my ignorance but what valve and location please?
Thank You
BF
PS: I will be away until the end of the week but will investigate when I return and will post what I find.

the seacock valve that feeds your raw water pump its usually at the rear of the engine mounted to the hull

Nelsonhow · Jun 9, 2015

On my 1978 H-27. The thru hull for the engine was in front of the motor to the left looking aft. There was no sea strainer. There was a 90 degree fitting with the ball valve attached to the fitting. Then there was a hose nipple attached to the ball valve.....the mussel shells were in the 90 degree fitting before the ball valve...

kloudie1 · Jun 26, 2015

Reading high.. couple of things that ya have to keep in mind when using an infrared thermometer.. 1 the reading is of the outer skin where the sensor is looking.. If you have a fairly thick rubber hose which is a good insulator, you might read the temperature of the skin of the hose which will be close to ambient in the engine box, and not the cool water inside.. an extreme example would be to measure temp on outside of fridge .. you'd get something lower than room temp but not the cold inside temp. 2. The readings depend on a surface property called "emittance" which is how much heat the sensor can see coming out of the thing that you are measuring. Something kinda dull will always give a better measurement than something very shiny..

Measure the seacock body (if bronze) to get a better measure of the incoming water temp..

Stu Jackson · Jul 5, 2015

BF, there are only three things in the system: the sender, the gauge and the wiring/connections. Check the connections, each end. Gauge checks are easy: Google Teleflex gauge check and find it on the internet, easy to do. If both those work, then it's gotta be...? You guessed it!

Engine Temp

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