2008 kohler 5ecd running hot

Dustin Swayne

New Member
Jun 1, 2019
3
Hendersonville, TN
Boat Info
330 Sundancer 2008
Engines
Twin 496 Mercruiser w/Bravo III Drives
I have searched the forum and found many posts but I haven’t found an answer to normal operating temperatures for a kohler 5ecd with a 195 degree thermostat. Has been running at 213-215 degrees with ac, battery charger, fridge all running. Hasn’t shutoff but after reading other posts I feel that is too hot.

I have replaced thermostat, bled system many times with bleed screw, flushed heat exchanger, replaced anode, checked and replaced oil, even changed fresh water pump even though after taking that booger off it seemed to show no wear and was turning, water impeller is good, water flow looks good over side of boat and temp is not hot maybe luke warm.

so what is the normal operating temp? I’ve seen a manual with 195-219 listed but it seems if I’m running 213-215 with cooler lake temps it will overheat in summer once it warms up. Any advice is much appreciated!
Thanks!
 
Last edited:
So while I am running the generator with fridge, batt charger and a/c my gender digital readout in cabin is 213-215 degrees, is that normal?
 
I dont know the normal running temperature when all those items are on but logic tells me it should always run at the thermostat temperature as long as the system is operating normal and without any worn or blocked parts. With that being said, remove your line behind your impeller and look carefullly in the heat exchanger for old fragments of and old impeller. That will impede water flow and would make it run a tad bit hotter than normal. I assume you have checked and cleared the strainer and intake? Including making sure the valve is operational?
 
That's what I was thinking too, so around 195 degrees.

I did flush the heat exchanger when I pulled it. I checked the strainer (clear), checked the impeller and lines look clear with no growth. When I pulled the zinc out it was all mashed in there and only a nub came out, I worked to get the loose pieces out and cleared hole to insert a new one. Shook and heard no pieces were still in there. Seems like good flow.

I have noticed when I shoot the heat exchanger tube closest to the thermostat, before it opens it seems great as expected around lake temp, then it opens, and you can see the temp rise as expected, however, instead of seeing it cooling down tremendously as it approaches the middle, it seems it is really hot right in the middle of HE and then goes down again towards the end where it goes back into the manifold (when I say goes down, it is around 185 to 195 degrees. Is this because of an airlock?

I feel like I have bled this system plenty, but maybe my method is wrong. I have tried opening the bleed screw and filler cap while running to let fluid run out even while burping the hose coming off the side of the bleeder screw, then refill. crank again let air bleed and before it starts coming out tighten bleed screw and put filler cap back on. Have tried this numerous times. So frustrating...But it comes with the boat. I remember the simpler times when I had my 240 sundancer w/o genny... Thanks again for any help you can offer.
 
That's what I was thinking too, so around 195 degrees.

I did flush the heat exchanger when I pulled it. I checked the strainer (clear), checked the impeller and lines look clear with no growth. When I pulled the zinc out it was all mashed in there and only a nub came out, I worked to get the loose pieces out and cleared hole to insert a new one. Shook and heard no pieces were still in there. Seems like good flow.

I have noticed when I shoot the heat exchanger tube closest to the thermostat, before it opens it seems great as expected around lake temp, then it opens, and you can see the temp rise as expected, however, instead of seeing it cooling down tremendously as it approaches the middle, it seems it is really hot right in the middle of HE and then goes down again towards the end where it goes back into the manifold (when I say goes down, it is around 185 to 195 degrees. Is this because of an airlock?

I feel like I have bled this system plenty, but maybe my method is wrong. I have tried opening the bleed screw and filler cap while running to let fluid run out even while burping the hose coming off the side of the bleeder screw, then refill. crank again let air bleed and before it starts coming out tighten bleed screw and put filler cap back on. Have tried this numerous times. So frustrating...But it comes with the boat. I remember the simpler times when I had my 240 sundancer w/o genny... Thanks again for any help you can offer.

Good morning Dustin,

we’re you able to determine what the normal
Operating temps are for your genset?

I run a Koehler 7.3 ecd on my boat, and am wonder the same; what are the normal operating temps?

If anyone can provide this info using a laser temp gun, that be great. Please post the temperature for the following parts;

The Left and right side of heat exchanger, the coolant hose, and the temperature of the exhaust water as it exists the boat.

Also, should the exhaust water be cool, warm or hot?

Thanks in advance!
 
That's what I was thinking too, so around 195 degrees.

I did flush the heat exchanger when I pulled it. I checked the strainer (clear), checked the impeller and lines look clear with no growth. When I pulled the zinc out it was all mashed in there and only a nub came out, I worked to get the loose pieces out and cleared hole to insert a new one. Shook and heard no pieces were still in there. Seems like good flow.

I have noticed when I shoot the heat exchanger tube closest to the thermostat, before it opens it seems great as expected around lake temp, then it opens, and you can see the temp rise as expected, however, instead of seeing it cooling down tremendously as it approaches the middle, it seems it is really hot right in the middle of HE and then goes down again towards the end where it goes back into the manifold (when I say goes down, it is around 185 to 195 degrees. Is this because of an airlock?

I feel like I have bled this system plenty, but maybe my method is wrong. I have tried opening the bleed screw and filler cap while running to let fluid run out even while burping the hose coming off the side of the bleeder screw, then refill. crank again let air bleed and before it starts coming out tighten bleed screw and put filler cap back on. Have tried this numerous times. So frustrating...But it comes with the boat. I remember the simpler times when I had my 240 sundancer w/o genny... Thanks again for any help you can offer.

Good morning Dustin,

we’re you able to determine what the normal
Operating temps are for your genset?

I run a Koehler 7.3 ecd on my boat, and am wonder the same; what are the normal operating temps?

If anyone can provide this info using a laser temp gun, that be great. Please post the temperature for the following parts;

The Left and right side of heat exchanger, the coolant hose, and the temperature of the exhaust water as it exists the boat.

Also, should the exhaust water be cool, warm or hot?

Thanks in advance!
 
Good morning Dustin,

we’re you able to determine what the normal
Operating temps are for your genset?

I run a Koehler 7.3 ecd on my boat, and am wonder the same; what are the normal operating temps?

If anyone can provide this info using a laser temp gun, that be great. Please post the temperature for the following parts;

The Left and right side of heat exchanger, the coolant hose, and the temperature of the exhaust water as it exists the boat.

Also, should the exhaust water be cool, warm or hot?

Thanks in advance!
 
My 7.3 ECD runs at 195-197 at all times regardless of any load conditions. This is the normal operating temperature of this unit. It’s higher because it keeps the emissions lower. My unit is 40 hours old so it is brand new and works perfectly.
 

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