6CTA Port Cruising Temp 170

[Gerasimos]

2001 6CTA’s on a Tiara 3800 Open I did my aftercoolers last winter (18 months) 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 freshwater 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.    My next step was going to be an IR gun to shoot the temp when I have a moment.

 

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[Gerasimos]

I have the mechanicals so I can’t see my fuel burn but I am WOT at 2600ish RPM at around 30-31kts. I’m pretty confidence I am propped correctly. I think this slightly higher temp is this clogging of the aftercooler as it looks to be wiping out like 20% of the water flow. I don’t know what caused the white buildup, but the rubber impeller parts getting through could definintely have caused this. My issue now is that core is stuck in there good. Had it 24hrs under kroil will try again tomororw. Was able to get it out a bit but I am about 1/8″ left until I bring the lip out from the top enough to “grab” it fro under the lip. Wont budget. The other one sat in kroil overnight and slid out with some gentle impact.

[Rob Schepis]

Yes, that is the bottom of the aftercooler as evidenced by the condensation port.

[hifirush]

I’m no expert, but one thing that stands out to me is that the “clogging” of that AC seems to be on one side and I’m curious, is that the bottom when installed? I have the same boat and have done my cleanings after buying the boat 2 years ago. It is time for me to do it again this year. My temps are pretty solid, but as Steve Lewis mentioned, the parameters can go to 182, which mine have never done, but have come close, at 179. That turned out to be the AC, HX and the fuel cooler needed servicing. This year while I had her in the yard for yearlies, I took 2 inches out of the props and what a difference it made, since I have the 6CTA480CE’s. The boat is like a whole new boat now. It jumps on plane and I used to think it was pretty good before. I am getting better fuel burn at cruise, which is now 29MPH at 2200 with a wind and against the tide, I’ve seen 31MPH. But the one thing I really noticed the temps. They stay under 165 even at a hi cruise, which is now 29-31 MPH and I can easily run her 2300-2400 and the engines hardly break a sweat. If I lumber along at 2100 I get 1.03 MPG and the temps are solidly at 159-161, that’s it. Are your engines propped right? 

[Gerasimos]

So its been 2 years since I replaced an aftercooler core and serviced them. Yesterday I took the afteroolers out for another service. Came out much easier than 2 years ago, but still did not slide out easily like the youtube videos show. Did Fresh water flushes relatively consistently. Well, turns out that I saw chunks of what looks like impeller rubber at the bottom of the housing when removing it on the Port Engine which could explain the overheat.

The pictures look worse than expected considering I did the service 2 years ago, any thoughts?

 

[pwrobert]

Since you are seeing erratic behavior on multiple non related gauges it is certainly an electrical issue. Also since the various gauges use different senders that would suggest a bad ground that they all use in common.<br />I have three different temperature senders on each engine  – the standard locations plus others Tony indicated as good spots to measuring. Their readings are similar but not exactly equal. Maybe a 5-8 degree F spread. One goes to standard gage, second to a Noland RS11 for NMEA 2000 display, and the other to another digital instrument/tach multi function display. Same with the oil pressure for each engine.<br />Regardless there should be a similar spread that shows they all agree in the general condition of how things are running. 

[Steve Lewis]

For comparison.  I have 6CTA 480CE’s.  I have 160F thermostats.  When running 2240rpm my port engine is 159F and my Strbd engine runs 167F.  when I am off plane and running hull speed both temps become even around 156F.  In my opinion this is right around the opening temp of the T-Stat so I would expect some open/close activity. but that might not account for a short spike……….

I just had new cylinder heads, SMX Water Pumps and cooling circuit service.  Temps were not even before all of that and they are not even after all of that…….

As for running at 170F on a 6CTA?  Not a problem at all.  I looked at the 6CTA CPL2172/8089 data sheets and the T-Stat range for open is 160F- 182F.  So if you are cruising at 170F you are in the range.  I would not worry.

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