Onan Generator 13.5kW

[charleshett]

On a Trader 57’ with an Onan MDKBD 13.5kW Generator. Having an issue with it. Has only been running for 50/60mins then cuts out (with no power load) - presents as Error 58. Seems to over-heat.

We’ve checked generator, coolant and bled out air-locks. Seems to start OK when cold just doesn’t run for long.

Also checked water intake and cleaned that. Then (earlier today) only ran for 2 mins now showing Error 7.

Any ideas much appreciated.

 

[O C Diver]

When you say, "It seems to over-heat", do the mechanical gauges say the engine is over heating or is that the error code?

If the mechanical gauges show the temperature within operating range, you may have one of the temperature sensors in the auto shutdown circuit going bad. There should be a sensor for coolant temperature and one for exhaust temperature.

Ted

 

[charleshett]

When you say, "It seems to over-heat", do the mechanical gauges say the engine is over heating or is that the error code?

If the mechanical gauges show the temperature within operating range, you may have one of the temperature sensors in the auto shutdown circuit going bad. There should be a sensor for coolant temperature and one for exhaust temperature.

Ted

It was from the Error Code. We’ve check raw water strainer and can see a 1-way valve before the water pump. We think the 1-Way valve not operating and will bypass that.

Any ideas on why there is a 1-way valve?

 

[O C Diver]

Before bypasing the one way valve, run the generator and look for water existing the exhaust on the hull. The manual should have a specification for how many gallons per minutes should be passing through the raw water system. Also, you should be able to see water flowing through the seawater strainer.

If you can put your hand in the water of the exhaust, it shouldn't be hot without and electrical load.

Ted

 

[charleshett]

We’ve had a v.hot hour in the engine room and the Error7 sorted. (Removed faulty 1-way valve & short pipe from pump to heat transfer had a kink). Back to Error Code 58.

We’ll look at the Temp. sensors in the morning (night time here). Presumably only solution is replacement?

 

[Lepke]

Error 7 is low raw water flow and 58 is high exhaust temp.


Check the raw water impeller. Check the flow from the seacock. Make sure the exhaust is clear where raw water enters.

 

[charleshett]

Thank you Ted & Lepke. We’re removing the flow sensor (sits between the raw water pump and heat exchange). We think that’s the problem. Presumably the Coolant and Exhaust sensors will activate and stop the generator if there is over-heating.

 

[charleshett]

We’re checking the Spindle on the WaterPump - does it turn clockwise or anti-clockwise?

Is it possible the Impellor could be installed the wrong way round (we had a new impellor installed in port recently) and if it was installed the wrong way - what would happen?

 

[O C Diver]

Generally it doesn't matter which way the impeller is installed, the blades will flex in the correct direction to make the pump work properly.

How many hours are on the engine and is this the original raw water pump? Pumps wear out over time and a part in the pump called the "compression fork" can also wear down. As the fork wears down, you get reduced flow. If you've taken the cover off the pump, take and post a picture to the thread. It's much easier for us to offer opinions based on pictures.

Ted

 

[Lepke]

If you have the stock pump, there's a replaceable wear plate. Also the cam is replaceable, too.
Most cams can go in reversed for opposite rotation. If you've had the pump apart, make sure it's set correctly. Most raw water pumps can be used in either direction. The only change is the cam direction.