Higher temperature in port engine

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Higher temperature in port engine

Postby kainebob » Sun Aug 25, 2019 9:53 am

[attachment=0]082619.jpg[/attachment]:wink: Our 36 classic has twin Cummins 6bt engines with about 3600 hours. The port engine runs significantly hotter and I am worried about doing damage. I changed the impellers even though they were not damaged and the Sea strainers were cleaned. Anyone have any ideas?
Bob: "...Nothing's free in Waterworld..."
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Last edited by kainebob on Mon Aug 26, 2019 11:58 am, edited 1 time in total.
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Re: Higher temperature in port engine

Postby Berger » Sun Aug 25, 2019 10:20 am

Check your heat exchangers.
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Re: Higher temperature in port engine

Postby gsanchez » Sun Aug 25, 2019 10:44 am

You may want to confirm the temperature sensor and gauges are working correctly by comparing the engine temperature when measured with an infrared thermometer.

But, as Berger suggests, the heat exchangers are a the usual suspects here. Have these ever been replaced or cleaned out?

You can take off the end caps of the exchangers and see if they are clogged.
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Re: Higher temperature in port engine

Postby FrugalWife » Sun Aug 25, 2019 3:47 pm

And if the heat exchanger is clogged you can do a quick & dirty clean out with a copper rod from the hardware store. Be sure to file the end round to avoid any damage internal to the exchanger. I do this nearly every year just to prevent a clog. The sacrificial zincs tend to throw off pieces as they degrade and if the impeller fails on the raw water pump some pieces of rubber can make their way into the heat exchanger too.
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Re: Higher temperature in port engine

Postby westiculo » Mon Aug 26, 2019 7:53 am

Agree with gsanchez. Check the temperature sender/gauge/wiring.
I just tap on the temperature gauge until it reads what I want it to read ;).
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Re: Higher temperature in port engine

Postby kainebob » Mon Aug 26, 2019 12:01 pm

Thanks everyone. I will remove the heat exchangers and clean them out.
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Re: Higher temperature in port engine

Postby Chesapeake » Mon Aug 26, 2019 5:32 pm

Not to confuse things, hopefully, but that port temp looks pretty normal for a 6BT @ 2200 rpm's. If anything, the stbd is running cold. Is your stbd motor plumbed to a hot water heater heat exchanger? You still might benefit from boiling out the exchangers anyway, but see if you can get an IR thermometer and point it at the water temp sending units on the motors. If the stbd temp is low there too, then maybe the thermostat isn't closing or is a colder rating.
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Re: Higher temperature in port engine

Postby bill.read » Tue Aug 27, 2019 11:23 am

I agree with J.R. Good "Chesapeake". Our 36 Classic also has twin 6BTs with 820 hours. I clean the heat exchangers using the rodding technique and "Salt Away". Cruising at 1700 RPM both engines are at 182 degrees. Increasing RPM to 2000 increases operating temp to 190 degrees. You do not have to remove the heat exchangers to clean them. Follow the instructions listed in the Cummins 6BT manual if you have it. If not, I can provide a copy of the instructions via PM. Be aware that the torgue specifications are incorrect. You will need #2 Cummins heat exchanger kits for the end caps. Contact Seaboard Marine in California for assistance if needed. https://www.sbmar.com/ They will set up an account for you with your engine specifics and assist with your needs. Do not rely on the web site for a complete listing of parts available. Talk to them directly.
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Re: Higher temperature in port engine

Postby Cruising » Tue Aug 27, 2019 9:48 pm

Depending upon how old your heat exchangers are I would replace them. I have a cleaned one as a spare but in my estimation if they are 15-20 years old they are throw away items.
Contact Lenco on Long Island. They are excellent to work with.(I’m not connected with them- just a very satisfied customer)
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Re: Higher temperature in port engine

Postby AllanKay » Thu Sep 05, 2019 8:24 pm

I had the same issue since buying this boat 2015. Although I changed impeller, cleaned out my heat exchanger, changed coolant, properly refilled to get air out, changed thermostat, etc.... nothing worked ... port ran up to 10 degrees hotter. I even bought a candy thermometer for checking the readings I was getting. Finally, while changing the impeller (again) the solution presented in 2018. This time I checked my intake hose to the oil cooler and it was clear, so no pieces of rubber blocking it. Then I decided to check the intake hose on the raw water pump but couldn't get it off, so I explored inside the pump with the impeller out. There was some seaweed in there, not a great deal, but stuck at the initake of the impeller port. Now it runs exactly as the stbd engine.
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Re: Higher temperature in port engine

Postby gsanchez » Sun Sep 08, 2019 5:39 am

As mentioned below, bits of old impellers can get stuck in the most improbable places and reduce the raw water flow.

I am not familiar with the Cummins engine but on my Onan generator I found several rubber vanes in an elbow right after the pump that had probably been there for years. When I cleared them the water coming out of the exhaust noticeably increased.

I wonder if you can visually compare the water coming out of the the two exhausts and see if there is noticeable difference.
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Re: Higher temperature in port engine

Postby bpbyrne » Sun Sep 08, 2019 10:02 pm

that stbd engine reading looks very low...as suggested..verify with a thermometer gun from Home depot or your favorite auto parts store...
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Re: Higher temperature in port engine

Postby 3240 » Thu Jan 23, 2020 7:25 am

I had the same problem. It was the thermostat.
And it was the thermostat on the cold engine. I thought one was too hot, but it was the otherone that was too cold.

Quite easy to test; make a longer full speed run. If both engines temperaturers line up the same as the hotter engine, possible problem is the cooler ones thermostat.
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Re: Higher temperature in port engine

Postby denogail » Fri Jan 24, 2020 8:16 am

I learned this trick from a marine air conditioner service, in cleaning the condenser of a marine AC unit, which is a heat exchanger of sorts for the feron.

I prep two 5 gallon buckets....one with water, and the other with a 50/50 mixture of water and muriatic acid. Next, I have a small rule bilge pump, wired to two alligator clips with a 10 foot wire, for positive and negative. Hooked to the bilge pump is a hose of the right ID that will fit the pump and the inlet to the first main heat exchanger from the raw water pump. This hose is long enough to get from there back to the bilge pump which is in the bottom of the acid bucket. (You will not hurt the bilge pump) My 135's have 3 heat exchangers in series, the main heat exchanger, the oil cooler, and the transmission cooler. (removing the hose from the RW pump to the heat exchanger..to be replaced back when finished)

Then remove the hose from the exit of the transmission cooler (the hose that puts water in the exhaust mixing manifold) and connect another hose..long enough to get back to the acid bucket. You now have a closed loop system to pump the acid mixture through all the heat exchangers. Pump for a few minutes, and notice the instant color change in the acid water. After a few minutes, disconnect the power from the BP and move the pump and discharge hose to the fresh water bucket, and turn it on again, to flush the acid. Walla...clean heat exchangers.

Foot note...remove all zincs BEFORE acid flush..replace removed zincs with temporary plugs that fit. Replace with new zincs.

I find that this process is much, much less work, easier, then physically removing heat exchangers from the engines...after the proper hoses are reinstalled, start the engine to further flush for a few minutes and to check for leaks..
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