6BTA5.9 M1 Water Transfer Tube Temperature

[James DeCristofaro]

I have twin 1991 6BTA5.9 M1 250hp engines in a trawler. About 2020 hours each, run well. Purchased boat December 2017. (see Oct 29 post for more background info).

I got some good feedback… posted a question after… never got a response…trying again. I’ve set aside a couple of days and would like to drain/flush/replace coolant on both motors.

The water transfer tube under the heat exchanger, after over an hour running at the dock, with temp gauge reading close to 175 F, feels very warm to the touch at the forward end and cold at the aft end near the coolant drain plug.

Question – does that necessarily indicate that the T stat is not open? Any other ways besides temp gauge to verify the T stat is open or closed?

Thanks. Appreciate any feedback/experiences.

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[James DeCristofaro]

Corey,

I’ve had the boat less than a year, and have not replaced the thermostats. And based on my experiences/conversations with the previous owner, the local Cummins dealer, and local diesel mechanics, I’d be very surprised if the thermostats were anything but the standard 180F – but I don’t know for sure. That’s why I was asking the question about the water transfer tube cold being on one end and warm on the other; and if there were other ways of knowing the thermostat was open.

[Corey Schmidt]

James, what temperature thermostats do you have on the engine? 180F or 160F?

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