3GM30F WHAT IS PROPER TEMPERATURE

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Aug 25, 2007
43
Hunter Hunter 34 New Rochelle N.Y.
A 3GM30F What is the proper temperature the engine should be running at? I had an overheat problem and am looking at the gauge every 3 minutes, Ive got to chill out. Thanks Richard
 

RichH

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Feb 14, 2005
4,773
Tayana 37 cutter; I20/M20 SCOWS Worton Creek, MD
180 deg. F with fresh water cooling.

Up to 200 deg. F if you are 'pushing' the engine with a high working load. Check the water flow at the exhaust outlet at the stern with a bucket and stopwatch. The 3GM30 'raw water cooling flow rate should be at ~3.5 gallons per minute with the engine at 1400 rpm. Anything significantly less than this value and you have a blockage/restriction, etc. somewhere. Get yourself a 'non-contact' infra-red thermometer and 'profile' the engine and all its components .. (under load and at your normal cruising rpm) so if you perceive a 'problem', a quick check with an IR thermometer will quickly show the area of problem. Be sure to 'profile' the heat exhanager under steady state conditions so you have a record for the values between inlet and out of both raw and fresh water loops .... will indicate when its stime to 'clean out' the exchanger. An IR thermo can be used to monitor stuffing boxes, engine transmissions, alternator bearings, etc. etc. etc. A decent IR thermo will be at ~$35.00 Seawater rapidly fouls heat exchangers and exhaust manifolds, etc. when the seawater gets above 145 degrees. When was the last time you 'pickled' (cleaned out) the raw water side of the cooling circuit. Use a commercial descaling compound to remove the carbonates inside the raw water side of the engine .... not plain 'acid' as that will dissolve 'base metal'. Rydlyme or Marsolve are good marine descalers.
 
M

Miles

IR Thermometers

are very handy, I second the suggestion that you get one. The thermostat on my 3GM30F starts to open at 160 and that's pretty much where it stays unless I'm running it hard and the alternator is charging hard in which case it might get up to 170-ish. I believe the over temp alarm is supposed to go off at around 192 which is still below a temperature that would do any damage.
 
Jul 1, 1998
3,062
Hunter Legend 35 Poulsbo/Semiahmoo WA
Tip: Doesn't necessarily read exact temperature

An IR thermometer will not necessarily measure an exact temperature because what it senses depends on the color of the object being read; therefore, a correction factor needs to be applied. If you buy a new one this should be stated in the instructions. I would guess that any correction factor you might have should be less than 20% and probably only around 5% or slightly more so it isn't a big deal unless for some reason an exact temperature is needed. However, in most cases and exact temperature is not needed and a relative temperature is good enough. One place that I track readings is on the mixing elbow. I've got readings from just before I cleaned it and then after. Now I can monitor when it needs cleaning again by just takeing readings from time to time. Draw a sketch of the mixing elbow area and where the readings are taken so you have something to work with in the future. Another area that was interesting was maping the temperature of the counter top around the refigerated ice box. This was very interesting! I now have a drawing of the counter top with reading locations that show where the heat loss is. Another nifty use was to check the temperature of the disk brakes on the car. Heck, I've even used it to help with my wife's cooking! Wikipedia link to IR thermometers: http://en.wikipedia.org/wiki/Infrared_thermometer
 
R

Rob

Thermostat

Doesn't the temp depend on the thermostat? I know with cars you can change the running temp by changing the thermostat that has a different "opening" temp.
 
Jun 2, 2004
1,077
Several Catalinas C25/C320 USA
Temp

My engine (same model) runs about 170...although I doubt the guage is very accurate.
 
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