6BTA thermostat

[Ron Lemire]

Greetings

I plan on replacing my thermostat on my Cummins 6BTA. ( I’ve replaced all hoses, and cleaned the heat exchanger and the after cooler ) per the instructions on this site.

I see Seaboard has 2 different temperature thermostats to choose from.

I have a trawler and I typically Cruse at 7 knot’s. The previous owner has a note next to the temperature gauge indicating 170 degrees. ( It typical runs about 160-170 degrees )

What temp thermostat do you recommend? 190 degrees or 160 degrees?

What should my max operating temperature be?

Thank you for your time.

Ron
Mystic CT

Topic

[Ron Lemire]

Thank you very much.

Ron

[Rob Schepis]

At your cruise speed temps would stay at 180 or a tad under and anything over 180 is cause for a concern that something on the sewater or coolant side is not up to snuff and some repairs or maintenance are due. You can save the 4 letter words for when you start approaching 195, 200…!

As to increase WOT rpm a prop adjustment would be in order – reducing blade pitch (or cup).

Here’s some reading on propping and engine loading:

https://www.sbmar.com/articles/engine-life-vs-engine-loading/

https://www.sbmar.com/articles/propellers-move-boats-engines-just-turn-them/

[Ron Lemire]

Thank you I really appreciate your help. Can you tell me what you think the maximum operating temperature will be with 180-degree thermostat? At what point should I get worried?

I will check the gauges as you recommended to make sure that they’re accurate.

If the RPMs are not correct how do I correct the RPMs? Do I need to change my prop or do I need to make an adjustment on the engine?

Sorry for the novice question.

Ron

[Rob Schepis]

Good pic. WOT rpm of 2,700 would be low for this engine. The 2,800rpm 330’s should be propped to see an easy 2,900 with the boat fully loaded. Get a handheld photo(laster) tach and verify your dash tachs and your true WOT rpm. Not super critical based on how you run your engines but it should still be propped correctly…

[Ron Lemire]

I’ll resend the picture.

[Rob Schepis]

180 tstat is right for you. 160’s for those that like to run at high cruise (on plane vessels). No pic was attached to your post?..

[Ron Lemire]

My mistake, the tstats are 160 and 180 degrees.

I usually run around 900-1000 rpm. WOT is 2700 if I remember correctly.

I’ve attached a picture of the engine nameplate.

6BTA 5.9M

[Rob Schepis]

Choices would be 180 or 160. Not 190. Probably the 180 but what rpm do you normally cruise at? And what exact engine? rated rpm? Your WOT rpm when loaded up as you use the boat?

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