"IMT High" on Smartcraft (Cummins QSCs)

[jff]

I ran the boat today quite a distance, no problems. Went back to the dock and an hour went by, needed to start it again for a quick idle across the marina. When I started I got a System Error on the Smartcraft:


IMT High

showing for *both* engines. It lasted about 15 seconds and went away. I looked it up and if I'm reading the page right it means:

Intake Manifold 1 Temperature - Data Valid but Above
Normal Operational Range - Most Severe Level

doesn't sound good. However, I found it odd that it was on both engines. And it went off after about 10 seconds. After it went off I looked in the bilge, looked at the various screens and everything seemed fine. So just to see what would happen I idled around the marina for a few minutes, no problem.

Anyone know exactly what the error means, the implications, etc. ?

Thanks!
Jason

 

[sbmar.com]

Jason,

Do you have CMD Vessel View panels so you could actually "see" the intake temperature and monitor it?? What vintage are the engines and how many total hours??.

IMT is just that.. Your intake manifold temp was exceeding a predetermined parameter.. In this case it's about 175F........Could be a glitch or you may have an issue....................Further investigation is needed to figure out what caused it.. The aftercooler is fed by seawater and the issue, if you actually have one, is usually related to it (filthy aftercooler on the air side) or the seawater flow.. All other temps are good? No excess steam from the exhaust?

Care to send me some pics from all around your engines showing all ? Focus on the turbo and aftercooler side on the engine..

tony@sbmar.com



Tony

 

[jff]

I do have the vessel view screens and the manifold temps look fine to me. I've used the boat now twice since that alarm without incident so I'm not sure what it could be - maybe some kind of wiring glitch, sensor problem, etc. These are Cummins QSC 511's, 2005 (in a 48DA). The engine exhaust seems normal. Can't send pics now as I'm heading up to NY for a trade show. Thanks for the advice!

Regards,
Jason

 

[themorganjane]

JFF, I had the same exact issue last year. Got a IMT on the PORT engine. However the smartcraft showed everything to be at normal temps. I silenced the alarm and finished the trip. Replaced the IMT sensor and problem no longer existed. Bottom line. Bad Sensor. $50 part. 2 minutes to replace. I think all that was required was a 7/8" Boxed end wrench.

 

[jff]

I didn't even know there was a IMT Sensor, do you happen to have any more details on exactly where it is, the replacement procedure, etc.? My alarm seemed to be on both engines though, so I'm thinking it wasn't both sensors. Today I got this back from a Cummins tech:

"There have been issues with these before where people will shut them off hot, then heat soak, and when they crank them back up they get the high intake temp alarms. This was FC155, but later cals ignore this temp until the engine is running again. Could also be clogged or plugged aftercoolers restricting flow cooling the air."

he's exactly right, I had just come in from a long run, shut down the engines but found out I had to move the boat so I fired them back up when this happened. I've used the boat twice since then with no problem so I think it was exactly what he outlined in the first scenario, shut them of hot and crank them back up when they are still hot. A few questions though:

- any idea what he means by "heat soak"?

- what is "FC155"? and what are "later cals" ?

Regards,
Jason

 

[themorganjane]

I think what they are saying is that when the engines get turned off or are run for a very long period, the sensors abosorb/soak alot of heat and get very hot and don't really cool down. If the engines are started back up then the sensors could be reading hotter temperatures than the actual temp of the intake. Regardless, this is exactly what would happen with me. It would only happen at the end of a day after a 3 to 4 hour run when the egines were lowered to troll speed or the next morning after I had completed a long 3 to 4 hour run the day before. Drove me crazy until I replaced the sensor. If you are actually getting a reading from both engines then I have no clue. I can't really imagine a situation wherer you get the same alarm from both engines at the same time. I found the smartcraft difficult to read correctly in an alarm situation, especially when this loud screeching alarm is going off. The sensor is located on the tip of engine on the intake. Has a 2 wire plug in connection on it. Order a new one then you will know which one it is. I might just buy a spare to have one on hand. I believe FC155 is fault code 155. I have a temperature gun that I would point at the sensor when it would go off and the temp gun would be reading normal temps. No idea what CALS is. Let me know how it works out.

 

[jff]

Thanks - I'm checking with MM to see about ordering two of them. I assume you replaced these yourself? Next time you are in your bilge would you mind snapping a pic of one and PMing me with it (or posting it here in the thread)?

Regards,
Jason

 

[jff]

I replaced both sensors last year and that seemed to do it, however this weekend the IMT High error came back. I had about a 45 minute run, turned off the engines, went and ate dinner and about an hour later turned them back on to go home again. The IMT alarm appeared to be for both engines. That was yesterday, today I used the boat quite a bit and no alarm. Strange that it would be on both engines (kind of makes me think it's more of a wiring glitch than sensor, hard to believe both of the 1-year old sensors aren't working properly - and if it was the aftercoolers I would think it would consistently be a problem right?). Just thought I'd post this update in case anyone had any new ideas ...

Thanks,
Jason