Overheating diesel engine

[chips]

My Chico 30 yacht has a Yanmar 2GM20 seawater direct cooling engine. Overheat alarm sounded when beating into wind, motor sailing.
Later found that thermostat had jammed half closed!
Thought I would fit temp sensor to show engine conditions. Can anyone recommend suitable unit for self installation?

[undercutter]

The only issue here is port size in the block or water jacket for installation as the sending unit and gauge will be matched set. A VDO sending unit and gauge in the correct temp range will be fine. I imagine you operating temp is 180deg F or 80C. This sending unit does not replace your over temperature switch.

[Sailmonkey]

Originally Posted by undercutter

The only issue here is port size in the block or water jacket for installation as the sending unit and gauge will be matched set. A VDO sending unit and gauge in the correct temp range will be fine. I imagine you operating temp is 180deg F or 80C. This sending unit does not replace your over temperature switch.

I agree, except for the temp. Raw water engines are closer to 160 to prevent salt from coming out of solution.


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[undercutter]

Originally Posted by Sailmonkey

I agree, except for the temp. Raw water engines are closer to 160 to prevent salt from coming out of solution.


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Really, My Perkins has always run at 180 but I have wondered whether it could be less to keep heat out of the cabin. Also, you've got to watch out when jumping in the shower after running the engine as that hot water can be scalding.

[Sailmonkey]

Originally Posted by undercutter

Really, My Perkins has always run at 180 but I have wondered whether it could be less to keep heat out of the cabin. Also, you've got to watch out when jumping in the shower after running the engine as that hot water can be scalding.

your perkins isn't direct raw water cooled if you've got a water heater plumbed to it, it's got seawater running through a heat exchanger with a coolant in the block.

The OP has an engine with seawater in the block.

[undercutter]

Ah, Missed the direct water cooled.

[four winds]

I'd like to add gauges as well. A good auto parts store would have a brand like vdo or equivalent.

For the water temp it would be an issue how the sender fits the block(length of thermistor tube), especially if retaining the warning light switch.

I have considered the plugs in the block for hot water heater connections might be used for the water temp sendor. Though I think the thermostat may affect flow to those passages. Still thinking how to go about this.

[Snowpetrel]

I like my engine watchdog. Its a fully electronic sensor system with an alarm. The benfits are its stand alone, it measures surface rather than water temp, and can read and alarm two different places. I have mine set for head temp and exhaust elbow temp.

It quickly shows if it salt water or coolant thats the problem.
http://enginewatchdog.com/tm4.html

There are a few other similar units about the place.


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[charliehows]

i recently replaced the temp. gauge sender on my 2qm20 with a $20 automobile sender unit - the problem encountered was finding one with a matching thread - ended up having to use a threadsealing product to make up for a slight difference in thread profile. Hasnt caused any leaks yet (about 1 year). A rare win - when was the last time you fixed anything on a damn boat for $20?

[basssears]

Originally Posted by Snowpetrel

I like my engine watchdog. Its a fully electronic sensor system with an alarm. The benfits are its stand alone, it measures surface rather than water temp, and can read and alarm two different places. I have mine set for head temp and exhaust elbow temp.

It quickly shows if it salt water or coolant thats the problem.
ENGINE WATCHDOG TM4, Audible Engine Temperature Sensor and Low Coolant Alarm

There are a few other similar units about the place.


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This one is a new one to me... seems attractive with the universal mounting instead of having to mess with thread in senders (I'm trying to have temp monitored in two places at once at it's a challenge).

You say there are other similar units, any others you considered?

[Snowpetrel]

http://engineguard.com.au/shop/

http://www.carsensors.com/Engine_Guardian.html

Here are a couple. My TM 4 works well and seems nicely made. It is not waterproof unfortunately.

[basssears]

Originally Posted by Snowpetrel

http://engineguard.com.au/shop/

http://www.carsensors.com/Engine_Guardian.html

Here are a couple. My TM 4 works well and seems nicely made. It is not waterproof unfortunately.

Where did you end up mounting the sensor for a good representative reading of engine temp? I suppose absolute temps aren't as important as just alarming when it's higher than usual

I could see using 2 sensor TM4 for engine & exhaust temps to good effect...

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[Snowpetrel]

I stuck one on the head near the forward cylinder because there was a handy lifting lug to bolt it under. This runs around 65 degrees celcius and alarms at 68 deg and it should also alarm even if the coolant leaks or boils.

I hose clamped the other onto the exhaust manifold. This sits around 20 degrees. It alarms around 25 degrees and is very sensitive.

The system alarms when I shut down the engine due to the exhaust warming up. This is a nice check, and a reminder to turn it off. At the moment it is wired independantly from the engine. The alarm is quite loud. I plan to hook up the oil presure sensor as well at some point.

A switch so you could add another sensor to monitor transmission temp would be nice. Maybe I will hook up a TM2 to do this.

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[Snowpetrel]

^^ edit, not the exhaust manifold, onto the mixing elbow where the raw water mixes with the exhaust gasses. It is clamped right up next to the rubber exhaust hose, but firmly touching the metal. Normally this is pretty cold, but if the cooling water stops it will rapidly rise up to a temperature that will melt the rubber hose. My TM4 should alarm pretty quickly in this case, hopefully well before the hose completely melts, and long before the engine overheats.

Also knowing what is overheating gives me a big headstart with the troubleshooting.

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[chips]

Thanks guys for all that feedback. Can't find suitable entry into waterway for a sensor so will mount engine surface type. TM4 looks good for my panel mounting.