What Is the Right Operating Temperature ?

[Alecadi]

I hope somebody can help me on that.

My 35 Endeavour is fitted with a Yanmar 3HMF.
The engine is probably the original engine from 1984.

What should be the normal operating temperature on this kind of engine?
It regularly shows between 140 and 155 F , rarely 160 F, at between 1200 to 1500 rpm.
Never above, even when motoring for hours....

Is that normal? I thought this kind of engine would operate more in the 180 F.
This "low" temperature could harm the engine?

Is it a thermostat problem (stuck open) ?

Thanks for the help.

[delmarrey]

First we need to know more about the motor. The temp should be between 160 & 190º F. And, I assume it has a heat exchanger.

Is your coolant clean?

Have you tested the gauge & sender? (most common error)

Have you checked the thermostat?

How long has this been happening?

[Jim Cate]

Critical info: is it raw water cooled, or does it have a heat exchanger? If raw water, the temps you quote are correct, if fitted with a heat exchanger, something around 180 F is correct.

Cheers,
Jim

[Alecadi]

Tough questions... ;-) I'm very ignorant in this kind of things....

I have the boat since last June and it has been like that since.
This can harm the engine?

I think it is raw water cooling fresh water (coolant) so I supposed this is a heat exchanger?
Coolant is clean.
What and where is the gauge sender in a yanmar 3HMF? how do we test it?
We'll check the thermostat

Thank you both.
Alec

[delmarrey]

Originally Posted by Alecadi

What and where is the gauge sender in a yanmar 3HMF? how do we test it?
We'll check the thermostat.
Alec

Here is an excellent thread that Gord posted a long while back.
http://www.cruisersforum.com/forums/...sting-645.html
This should get you going for this. Note: There is a difference between english and metric gauges. Yanmar has a mixture of both. Water temp is usually english oil pressure is metric. So consider the readings.

Parts list: http://www.yanmar.com.au/qrg/3hmf.pdf

Here's the Manual (part 1 & 2), if you don't have one. If not, you may want to save these on your computer.
http://www.sailkismet.com/Notes/ryan1.pdf
http://www.sailkismet.com/Notes/ryan2.pdf

The oil pressure switch is under the oil filter. See page 14-13 of the second pdf download.

[lannen]

Howdy, I've got a 1985 40 Endeavour... Mine, and I think all of them did, came with Perkins engines. But enough of that...

Do you notice it running cooler in colder weather (winter water temps) and warmer in the summer (Florida bath water)?

Or is this a constant temp throughout the year?

Also, you might check here: Endeavour Sailboat Owners Forum

[Alecadi]

Thank you Delmarrey, very usefull.
And thank you all for the comments and tips.

lannen: so far I didn't see much of a notable difference between summer and winter.

[djmarchand]

Engine coolant temps depend on several factors.

Raw water cooled engines (raw water in the block passages) operate at lower temps because seawater will precipitate salts and foul the engine over 150-160 degrees. So they typically have a thermostat set at 145 or so.

Older fresh water cooled engine have a lower "radiator" cap let off pressure and typically have thermostats that begin to open in the 160 degree range. These engines operate in the 170-175 range.

Newer fresh water cooled engines have a higher pressure cap and have thermostats that open at 175 or so. They typically run at 180-190 at high cruising load. The 15 lb pressue cap increases the boiling temperature to about 225 so there is plenty of headroom for wot or some heat exchanger fouling.

[Alecadi]

A friend of mine gave me a good idea: he told me to buy an infra red thermometer with which I could accurately measure the temperature while under way.They can be purchased for under 30$ from Harbour Freight- The brand is Centec. He said they are very good and quite inexpensive.With it I could check the exact temperature and see if it's a sender/gauge problem before going further. Anybody has had experience with that kind of device?

[delmarrey]

Originally Posted by Alecadi

A friend of mine gave me a good idea: he told me to buy an infra red thermometer with which I could accurately measure the temperature while under way.They can be purchased for under 30$ from Harbour Freight- The brand is Centec. He said they are very good and quite inexpensive.With it I could check the exact temperature and see if it's a sender/gauge problem before going further. Anybody has had experience with that kind of device?

There are good ones and cheap ones. I used them for measuring compressor case temps. But they will not measure the water temp inside unless the motor had been running for over a half hour, then it would be fairly close depending on the air circulation around the motor.


.

[Mark Johnson]

Originally Posted by delmarrey

There are good ones and cheap ones. I used them for measuring compressor case temps. But they will not measure the water temp inside unless the motor had been running for over a half hour, then it would be fairly close depending on the air circulation around the motor.


.

After installing a new thermostat, I got one of these IR thermometers, and took readings all over the top of the engine, near the thermostat housing, after running hard for 45 minutes. (Under load)

I was told by Mac Boring, that it should reach about 180 degrees, which it did.

BTW, "long term" running at below 2,500 RPM is death to a Yanmar...

Mark

[delmarrey]

Originally Posted by Mark Johnson

BTW, "long term" running at below 2,500 RPM is death to a Yanmar...

For certain sizes of motors.

[Alecadi]

Delamarrey: Can you be more specific? which size of motors are we talking about?
Thanks

[delmarrey]

Originally Posted by Alecadi

Delamarrey: Can you be more specific? which size of motors are we talking about?
Thanks

I see you have a 35' boat so those numbers are probably OK since you have a higher RPM motor (25-40hp). Larger motors may not even goto 2500 RPM's. 2500 is about cruising speed for my 3JH4E, which starts to redline at 3000. But economically, 2000 is the best fuel wise.

Which motor do you have?

[Jim Cate]

Originally Posted by Mark Johnson

BTW, "long term" running at below 2,500 RPM is death to a Yanmar...

Mark

If this is really true, one wonders why Yanmars have a good rep in the sailing world. Seems to me to cross that marque off my potential buy list. Anything that finicky doesn't belong on a cruising boat IMO.

Cheers,

Jim