Carver Owners Forum

'06 41 CMY Gas Volvo Penta 8.1s with a Kohler 7.3 ECD-CB generator. Last fall when we purchased the boat there was an issue with the generator. During the repair, the technician told me that the raw water from the heat exchanger exits the boat through a hull fitting in the bottom of the boat because there was no water coming from the generator exhaust on the port side of the boat.

This season I am having issues with the generator restarting after it has been running for say an hour or so. Last weekend I ran the generator for more than six hours straight with no issues. Note, that the generator starts immediately on the first start. If I initiate a shutdown (not an auto-shutdown of the generator) the generator will not restart unless it sets for some time. The error code I get on the restart is UU (Under Voltage) which I do not believe to be accurate. Yesterday as I was continuing to diagnose the issue, water started coming from the generator exhaust on the port side of the boat for the very first time since we purchased the boat. This led me to believe that up until yesterday, the thermostat may have been stuck hence the generator temperature was too high for a restart.

My question is, on the Kohler 7.3 ECD-CB on an '06 41 CMY, does water from the heat exchanger exit the boat through the bottom or through the exhaust on the port side of the boat?

Thank you for your help!

Normally the raw cooling water is mixed with the exhaust at the exit. This cools the exhaust and keeps noise down. The wet exhaust goes typically goes to a fiberglass canister-type silencer/muffler and then exits the boat. You should have a nice bubbling stream of water through the exhaust when the engine is running, regardless of thermostat or engine temperature. You don't see them a lot, but some boats have an underwater generator exhaust and some have gas separators. Centek seems to be the leader in specialty exhaust systems - check this out if you think you have an underwater or gas separation system: http://www.centekindustries.com/wp-cont ... pdf?x62515

Here is a link to the manual for your generator - the exhaust system is Group 116. http://ourcayoloco.com/docs/tp5987.pdf

Note Kohler makes the generator, but others make the exhaust system that connects to it!

I do believe your generator is a closed cooling system, thus your thermostat should not be an issue. I believe your raw water cooling system was not performing and should have been exiting the side exhaust port. You may want to try descaling your generator with a product I just used on my engines call RydLyme. It opened up the entire system and things on the raw water cooling side seem to be performing much better and no more steam out the exhaust. Good Luck with your issue.

AlexHardesty wrote:Source of the post My question is, on the Kohler 7.3 ECD-CB on an '06 41 CMY, does water from the heat exchanger exit the boat through the bottom or through the exhaust on the port side of the boat?

Check your boat manual, you may have the gas separator type as has been mentioned, raw water out the bottom gas out the side.....post a pic of the muffler.....I am sure someone else here has this model and can come in.

Correct... the generator is a closed system... Based in the what I see in the engine room there is hose from the "silencer" (fiberglass canister) to a bottom through-hull (raw water outbound from the heat exchanger) and another (also from the silencer / fiberglass canister) to the port side of the boat (gas exhaust). I have never had water exit through the port side exhaust until recently. Any idea what may have broken or changed to cause water exiting through the exhaust?

Unusual to see a gas separator exhaust on a gas generator, but I suppose it does exist. The only reason you should see water out the exhaust gas side of one is if the sea cock on the water drain is closed or somehow obstructed. The idea of the system is to quiet the noise caused by the water splashing out the exhaust when at anchor.
The other issue you are having could be related to a known heat soak issue. The exhaust temperature sensor sits on top of the SS catalytic converter. When the engine is running, it is nice and cool and all is good. At shut down, the high heat of the catalytic converter rapidly heats the temperature switch and it can activate. Left alone, it will cool off and re-set after 1/2 hr or so.
Be sure you have the latest version of software, it has a 30 second inhibit to the exhaust temp so the sea water can cool it down a little before it allows the controller to sense it.
On the EKD models they switched to a flow sensor switch and eliminated the exhaust temp switch.
Try running the generator with no load a few minutes before shut down and this will cool the exhaust a little.