Trojan Boat Forum

as I mentioned, I switched over to the overside and bought a Tiara (nice boat fwiw) with a Kohler generator. You guys were always very helpful in the past, so I will ask about my genny issues. I have a 2006 Kohler 7.3 e marine genny in the my boat. It starts and runs fine, makes good water, good electric, but after 4-5 hrs it wil shut itself down. I think due to heat. Any way, so far we have changed the fuel pump, the fuel filter, the impeller, and we have back flushed the closed loop system. When we back flushed the system we did get some old 'ears' off an impeller, as well as a few barnicals (the boat was in salt water, and now is in fresh). We are thinking we need to re back flush the closed loop system again, and see if there is more 'junk' in there. Your thoughts?? Thanks in advance!!

Flush out the raw water side with something like Ridlyme . I would pull the riser and clean it too

did you post this question on the hull truth forum?
did you do other troubleshooting that others had suggested?

does the genset start right up after it shuts down or do you have to wait for a while?
since it would be easy to check the shut down circuits on the oil,water etc it would be easy to jump those temporarily and see if the problem goes away or if it reoccurs.

Yes I did It does start but does not stay running. After an hour or so it will start and stay running
I would be afraid to run the Genny for hours without the sensors. It does run for hours

not saying run it for hours with them jumped, after it shuts down and if it wont start immediately then i would jump the sensors and see if you can get it going right away and not have to wait the hour or so till it would start again, if it starts and runs then you know where the problem will be
or using a dvm measure across them

What Prowlersfish said.

I had a similar problem when I bought my boat. I pulled off the hoses that dump water into the exhaust manifold, placed them into a bucket, then used an external pump to circulate something like Ridlime through the cooling system for a while. I obviously had good flow, as I could see what was coming out of the hoses. My overheating problem still existed. After further review, I discovered that, while the hoses were clear, the fitting that attached one of them to the exhaust manifold was plugged with silt. Yours may be partially blocked, and after a while the heat build-up is sufficient to trip the over-temperature switch. I also second the defeat-the-switch-when-you-experience-the-symptom suggestion to see if you can make the problem (temporarily) go away. If that solves the problem, either the switch is working (and the problem is cooling), or it is not working (and the problem is the switch).

Have you taken temperature readings with an IR thermometer? I have a Fluke-brand IR thermometer that I use constantly to check the status of things that are (or should not be) hot, such as my stuffing boxes. After running, they are basically engine-room ambient temperature, which is a good indication that they are not too tight, even thought they don't leak a drop. OK, one drop, once in a while. If you don't have an IR thermometer and are going to buy one, shy away from the $15 Amazon and Harbor Freight variety. I had one of each before I bought a real one. Since you want to compare multiple measurements on the same location, be sure to keep the device the same distance away each time -- spot size varies with the distance, and you could end-up reading something other than your intended target if you are too far away.

Please keep us posted -- it is what makes this forum work.

Thanks for the info. We have used a heat gun and all seems good. I try the other ideas and report back

x2 on all of the above. Sensors will interupt the ignition circuit; high exhaust temp switch, high engine temp switch, low oil pressure switch. An issue in the generator portion itself will cause the engine to stop running as well. There were ambient temperature issues also that precipitated the recommendation to run the blowers while the generators were running in an effort to reduce engine room temps during operation.

I'd be putting my money on the oil pressure sending unit (switch)

RWS

RWS wrote:I'd be putting my money on the oil pressure sending unit (switch)

RWS

Pretty common failure but usually when this component fails, it fails completely and won't be okay again after cooling off a bit. A typical symptom of the pressure switch failing is that the unit shuts down during operation and when trying to start up again the unit shuts down as soon as you let go of the start switch.

When the unit shuts down and you try starting again, does the engine run until you let go of the start switch or is it simply turning because of the starter? Back to basics here; as soon as it stops next time, you need to determine whether you're getting a spark or not. If you are, that's entirely different and should take you in the direction of fuel delivery or an issue with the generator section as some units will not run if output has failed.

i had a similar issue on mine.

new oil sending unit fixes the problem

just my own experience - maybe the hot oil thinned out and the change was outside the range of the faulty sensor

RWS

thanks guys!! I will try this, and report back!!!

my Kohler 5e came with a plastic water pump impeller housing. I had some overheating issues and found out the housing was the issue. Replaced it with the new metal housing and solved the problem. Have no idea if yours could be similar but figured it was worth mentioning. Good luck