EPS Kubota Generator - Running Hot

[Haney]

I have a 2007 MCI J4500 conversion that has an EPS Kubota Generator.  On the last couple trips out, it has started running hot.  I have read the post about air locks.  I ordered a new water pump and thermostat for it and I am gonna install.  While I have it drained, what do I need to do to make sure I don’t get an air bubble.  Looks like on top of my Thermo housing, the line is tied back to my fill tank on the front of the engine.  Is this correct?  Also, should I run a thermostat?  I’m it may not even have one in it.  First time working on it.  My fill tank in the front seems to be lever with the radiator too.  Also, do I need that catch can?  I’ve never seen anything in it.  Thanks in advance.

[Haney]

Pic 2

[thomasinnv]

Yes you need the "expansion tank" it is there for a reason. When the generator is running and up to temperature the coolant will expand. The reservoir gives the coolant somewhere to go, and as the genset cools down and the coolant contracts the radiator will then draw coolant back into itself. You say you never see anything in it, have you checked the radiator coolant level when the genset is cold? I also have a Kubota which did not have an expansion tank when it was installed. It would end up low on coolant after several heat/cool cycles and the temp would start rising under heavy loads. Once I installed the expansion tank I never had to add coolant again and no more rising temps under heavy loads.

Top off your radiator and put some coolant in the reservoir and you may see a significant difference. Make sure the cap is in good shape and the overflow hose is good or it won't do its job.

[Haney]

Thomasinnv, Thank you so much for the reply.   I think I may have miscommunicated.   The silver tank that has the radiator cap and is also plumbed in with a hose from the thermostat housing I know I need.  I think this acts as an expansion tank for the radiator.  I was questioning if I need the white plastic overflow jug zip tied to the side.  Just wanted to make sure I communicated correctly.   If I keep that jug, I don't think I need the vent hose off to the side.  I want to keep all the fluid in that white jug, correct.  If it is vented, then I don't think it will work.  Right?    Also, It appears to be lower than the radiator fill line.   Would this make a difference?  What is the correct height for it to work correctly?

[thomasinnv]

The vent hose coming off the side of the overflow is just exactly that, a vent hose. It allows air in/out of the expansion tank so that the radiator can pull/push coolant as it needs. If you pull the cap on the overflow there should be a hose that drops down into the bottom of the tank. This is the side that should be connected to the radiator. The vent hose should just connect to the top of the cap. As long as the radiator is properly sealed and the radiator cap is functioning correctly the height of the overflow tank doesn't really matter. With the large tank on top of the radiator you don't necessarily need the expansion tank, but I would keep it as it lets you check the coolant level at a glance without having to worry about radiator being under pressure if it's hot.

Definitely keep the little hose running from the top of the tstat housing to the radiator. It bleeds off any trapped air, basically acting as a steam port.

[luvrbus]

Those Kubota engines are bad about the water pump impeller going bad.My ESP 20kw the surge tank and recovery tank were the same it didn't have separate tanks you add coolant in the same tank,most of the newer vehicles are the same no separate tanks 

[Haney]

What temp thermostat should be in this system.  This one has a 160F.  Seems low to me for some reason.  Thanks

[luvrbus]

160F is the norm they don't fully open till around 172F

[Haney]

Thank you!