Intake Manifold Temp alarm

[Joe Palermo]

I have a 540 QSC and just recently started to experience the IMT alarm. The DieselView display shows 160-170 degrees, which, from what I understand, is too hot. The other day, I pulled the endcaps on the cooler and found the water side to be rather clean. I did chip some calcium buildup out, but everything seemed to be in the ordinary. After putting everything back together, I went for a test ride. The temp stayed at 145 throughout all spectrums of the RPM range. I figured it was the calcium build up.

Yesterday, the boat idled for about 45min before running up. As soon as I got it on a plane, I got the alarm again and it remained at 165-175 all day (idle and running).

This morning, I had it at idle at the dock and it immediately went to 150, even though the motor was at 120.

Given all of this, could it be a dirty cooler? Im just confused how it ran at 145 one day and 175 the next. I have about 1200hrs on my rebuild. Thank you!!!

Topic

[Joe Palermo]

Fixed

Sorry I didn’t reply to this 3 yrs ago. lol. It ended up being a faulty sensor. 

[Steve Lewis]

Joe,

You indicated that you opened the end caps on the aftercooler……. What is your overall service regimen on the entire aftercooler? You are in warm Salt Water so the SBMAR team recommend that you bench service the AC ever 2-3 years as per their protocol. Also fresh water flushing after every use is highly recommended to keep things clean after the full bench service. Plenty of great info on this on the site.

An easy start is to have the AC bench serviced as you will then see with your own eyes the condition of the air side and be able to assess the full condition of the seawater side. Also you might want to clean or replace the IMT sensor.

Cummins Marine QSC/QSL Intake Manifold Temp (IMT) & Boost Sensor Location

Some “relatively easy” places for you to start Troubleshooting…….

[Author]

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