oil cooling for Twin Disk marine gear

[bernardi2004]

My 2004 Nordic Tug 32 has a Twin Disk marine gear. The gear oil (originally spec'd 30 weight, now 40 weight) is sent thru a cooler using raw water loop. The gear oil temperature reaches about 120 Fahrenheit and does not go any higher.

But I see that the Twin Disk "manual" states that the normal operating range is 140 F or above, never to exceed 200 F.

Should I be concerned that I am regularly running my gear oil too cold by 20 F?? Since the boat was not built with any thermostating of the oil loop going thru the cooler, I assume that in 2004 the company did not find this important.

Thank you.

 

[Mac2]

First thing I would do is buy a laser thermometer to verify the gauge reading. My gauges show different readings from the engine room compared to the helm gauge.

 

[bernardi2004]

First thing I would do is buy a laser thermometer to verify the gauge reading. My gauges show different readings from the engine room compared to the helm gauge.

Thanks. I am not familiar with that. Is there a brand or model I should look at?

 

[C lectric]

No brand from me. You can have decent units for $40 or a whole lot more.
What is important though, at least to me, is the distance that the meter can read the temp accurately. Some have to within inches of the target, some can be several feet away and accurately determine the temp. Read a bit about the cone of reading or some such title.

The mfgr. should tell you how far away you can be to get a decent reading.
All meters have a cone of reading and to not exceed that distance. The bigger the cone the better and farther away you can be and still get a good reading.

However the smaller YOU can keep that cone the better, period, or the meter will tend to average the temps of what it sees. Smaller, the better.

 

[DDW]

I've enquired directly of Twin Disc tech support this very question, as it is common to Nordic and American tugs (my AT34 turns just over 100 most of the time). Their response was that it is not a lubrication concern, rather if it is running too cool the shifting may be abrupt. He did advise using 30W (or whatever the lowest weight listed on the placard) in this case. He also advised using a single weight oil, as he said in their testing even modern multi-weights shear down under the hypoid gears quickly to the lower number.

 

[bernardi2004]

I've enquired directly of Twin Disc tech support this very question, as it is common to Nordic and American tugs (my AT34 turns just over 100 most of the time). Their response was that it is not a lubrication concern, rather if it is running too cool the shifting may be abrupt. He did advise using 30W (or whatever the lowest weight listed on the placard) in this case. He also advised using a single weight oil, as he said in their testing even modern multi-weights shear down under the hypoid gears quickly to the lower number.

OK, good info. Thanks.

 

[sean9c]

My Twin Disc is the same, it's heat exchanger uses raw water and runs cool. There is no thermostat so your options to raise the oil temp are reduce the amount of water going through the heat exchanger, which is hard to do or reduce the size of the heat exchanger. I've done nothing.
I think you're also supposed to use non-detergent oil

 

[Mac2]

Thanks. I am not familiar with that. Is there a brand or model I should look at?

No brand to recommend. As stated above, there are ranges of distance for accuracy. Generally the closer the better. You can practice on areas of the engine you know match your other temp gauges to get a feel for the correct distance. Im thinking 1 to two feet. Im sure the range goes up the more you pay.