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-   -   How hot does your diesel run? (http://www.sailnet.com/forums/general-discussion-sailing-related/103120-how-hot-does-your-diesel-run.html)

tspooner 08-30-2013 11:43 AM

How hot does your diesel run?
 
A few weeks ago I posted a cooling question and received a lot of good responses from a lot of good people on this forum. I had installed a water temperature gauge for my Yanmar 2GMF to better judge how hot the running temperature was versus the original alarm set up. The guage issue was indeed a result of the supplier selling me the wrong sending unit. After checking all water delivery systems, both salt & fresh I feel confident that the flow is working as it should. After about 20 minutes of running the engine at the dock under load the temperature guage is showing about 185 degrees. The infrared gauge is showing around 178 degrees when pointed at the cylinder head near the injectors. I'm tired of just using the motor to get in and out of my slip for daysails and was still hoping to get away for a week of sailing up the coast. However I'm paranoid about having to use the engine for extended periods if the wind doesn't show up! These readings seem high and are a concern to me. Does this seem right to you? How hot are these diesels supposed to run?:confused:

johnnyquest37 08-30-2013 11:46 AM

Re: How hot does your diesel run?
 
My M-35B runs between 160 and 180, according to the temp. gauge at the helm.

Tim R. 08-30-2013 11:52 AM

Re: How hot does your diesel run?
 
178 at the cylinder head is fine. What temp do you get when you point it at the top of the thermostat housing? That is the most accurate reading you will get of the fresh water side. You could be running normally if you have a 180 thermostat installed.

eherlihy 08-30-2013 01:38 PM

Re: How hot does your diesel run?
 
My Universal M25 runs at 180F exactly.

A couple of weeks ago I was motorsailing through heavy chop in 'Vineyard Sound (trying to get to Cuttyhunk before dark), and did not realize that the angle of heel on starboard tack was great enough to partially lift the intake out of the water. After about an hour, I heard the "beep, beep, beep..." of the temperature alert (for the fist time ever), and quickly shut down the engine. I looked at the temp gauge, and it was no more than 185F. I checked the coolant level (which was high), oil level, raw water strainer, and the impeller, and found that all was OK. We changed tack, and sailed in to the outer harbor. I started the engine to get into the inner harbor, and all worked as it should.

I am glad to have both an audible alarm and a gauge.

Bradhamlet 08-30-2013 02:02 PM

Re: How hot does your diesel run?
 
Each Yanmar is different, my 3GM is raw water cooled and the alarm starts buzzing when over 150 however some fresh water cooled motors will buzz their alarm at 200. So You might call a Yanmar tec to find out what yours will buzz at.

Brad
Lancer 36

Tim R. 08-30-2013 02:42 PM

Re: How hot does your diesel run?
 
Quote:

Originally Posted by eherlihy (Post 1081851)
My Universal M25 runs at 180F exactly.

A couple of weeks ago I was motorsailing through heavy chop in 'Vineyard Sound (trying to get to Cuttyhunk before dark), and did not realize that the angle of heel on starboard tack was great enough to partially lift the intake out of the water. After about an hour, I heard the "beep, beep, beep..." of the temperature alert (for the fist time ever), and quickly shut down the engine. I looked at the temp gauge, and it was no more than 185F. I checked the coolant level (which was high), oil level, raw water strainer, and the impeller, and found that all was OK. We changed tack, and sailed in to the outer harbor. I started the engine to get into the inner harbor, and all worked as it should.

I am glad to have both an audible alarm and a gauge.

Ed, you should verify your gauges accuracy before assuming it is correct.

capta 08-30-2013 02:57 PM

Re: How hot does your diesel run?
 
The important thing to remember with temp gauges is that they may not be an exact reading of the true temp (off even 10 or 15 degrees), but the changes are very significant. For instance, once the thermostat has opened it should come up to a normal operating temp (usually 180ish) and remain there. If the temp fluctuates w/ a change in RPM's, dropping at lower RPM's or rising as you go up, you have a cooling problem. If it begins to creep up (not in a day but over successive trips) from whatever is the normal operating temp, your impeller has probably lost a few vanes.
After a bit of time you will have a good idea of your normal operating temp reading on the gauge and can keep an eye out for changes. Your engine should run at the same temp for half an hour or 20 hours; time should make no difference.
There are odd times, usually in extreme conditions, where the engine is working much harder than usual and the temp can go up a few degrees, but it should never go above 200 (from 180ish), no matter what. I hope you also have an audible alarm, because a plastic bag or something else could cause a blockage in the line and the temp will go up very quickly to damaging levels, unnoticed on the gauge.

Omatako 08-30-2013 04:06 PM

Re: How hot does your diesel run?
 
Quote:

Originally Posted by Tim R. (Post 1081813)
You could be running normally if you have a 180 thermostat installed.

That is the intelligent answer.

What thermostat is installed? If it is a 180F then that's where the engine ought to run.

Most engines, marine or otherwise run at around 85C (185F, sorry I am metricated :o) as controlled by their thermostats.

Closed circuit cooling systems can run hotter because they are pressurised and the boiling point of water is higher when under pressure. As a general statement, engines run more efficiently the hotter they run which is the primary reason for pressurised cooling systems. Raw water cooled engines will run on a cooler thermostat because there is no pressure but they should still run at the temperature regulated by the thermostat. Lesson over.

So if your engine is running at considerably less than 185 (or whatever the rating of your thermostat) then you should be concerned because it is less efficient and is probably experiencing accelerated wear. And your thermostat has either been removed or is stuck open.

overbored 08-30-2013 05:24 PM

Re: How hot does your diesel run?
 
both raw water and recirculated water cooled engine run at the same internal temperature
they both burn diesel. the metals used are the same and the oil is the same. in fact they are the same engines. the reason they run a lower temp thermostat in the raw water cooled engines is because the thermostat needs to open and start letting in raw water at a lower temp so the metals will not be allowed to heat up to high and then get shock cooled by the cold raw water. on a 2GMF the thermo is set to start opening at 159 and full open at 185 degrees F. the raw water models use a 108 to 125 degree F thermostat

Seaduction 08-30-2013 05:32 PM

Re: How hot does your diesel run?
 
'FRESH' WATER SYSTEM


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