Motor temp – 450 CTA 8.3

[Dean Brown]

I’m new to diesels , notably the 450C. Purchased and sea trialed the boat (sea Ray 420 DB) in Dec. At the sea trial and engine survey the motors ran in the mid 170’s at cruise and 160-162 at idle. Now As I compare to other 450 C they seem to run about 160 at idle and at cruise. Fast forward 7 months both motors run 175-180F. At cruise Could it be that I have 180 thermostats? Nothing was noted as out of the ordinary with temps at survey and they have been consistent. I don’t have a baseline on history of the motors but plan to do a full maintenance of the cooling system at the end of the season.

Topic

[Gerasimos]

Old topic but figured it may be better than starting a new thread. 6CTA’s I did my aftercoolers last winter and was running at 160 on both at cruise. One was horrible corroded ended up getting a new one from you guys.  Only at WOT would they go to 170ish. A few days ago my gauge was spiking to 180 for a split second and then dropping back down. Almost looked like a gauge electrical issue because of the speed of the up and down. Then I started paying more attention and at cruise my port side engine (older aftercooler that was serviced and pressure tested a year ago) and realized that at cruise around 2000ish RPM it seems to hover between 165-170, wheras my starboard engine (new AC) is steady at 160. 

I opened up the HX without removing it (top cap) and saw some old chunks of zincs in there clogging, so I removed, and did a 8 hour barnacle buster flush which seemed to clean them up as best as I could see. Still running the same temps with the bit of a flicker on that gauge that shoots up to 180 and then backt o 165 (this happens at below cruise as well which is why i figure its an electrical issue. Also happens to my RPM gauge when idling sometimes it just says 0 rpm for half a second)

Aftercoolers were good a year ago when looked at. Did freshwaster flush every weekend when boat sat, so kind of stumped at what to look at next. Also, hoping to not have to have down time mid season for 5-10 degrees more at cruise while I troubleshoot this. Is there a problem running these at 170 at cruise? Our season is so short here and this could take a few weeks to chase. 

[Keith Giller]

Motor Temp

I have the same motors with 160 T Stats. With an IR gun they run at about 172-175 degrees but as you’d expect the gauges hold at 160.

[Mike Uliasz]

Here’s the Aftercooler bench service link:

Cummins Marine Aftercooler Maintenance

Need to check the heat exchangers too. Did you change the zinc’s in the after cooler and heat exchanger this season? If not they could have dissolved and clogged the raw water tubes. This is what my boat looked like when I purchased 2 years ago, one engine was running 190 on a plane, fine at idle.

[Gerasimos]

Long time lurker here.

Same issue, but on my port side engine online. Last season both engines ran around 160. This year the day after we launched I noticed port side runs around 170-180. I will check the impeller but water flaw out of the exhaust looks equal on both sides visually. How do you “clean out” the saltwater cooling system? Is this a ridlyme flush?

[Anonymous]

It sounds like you have the 160 degree T stats. I would recommend that you clean out the entire Saltwater cooling system and replace the impeller and get your baseline readings when everything is clean. Even tho you are not running hot.

[Author]

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