Onan Quiet isel Shutting down

[Ericbsc]

I have a 10kw qd. When I bought it used last year i opened all windiws and ran 3 carrier 13.5 ac's for 12 hours as a test. Passed with flying colors. I put it in a box with fresh air across unit. It picks up its air under the unit. On the way to MS in 90 deg. heat shut-down according to the blinking light for high coolant temp. Thought the belt was loose. Found out when I got home that the rubber isolator in the harmonic balancer had come loose. Luck it did not do any damage. Replaced it, the temp sensor on the thermostat housing. Checked the thermostat in hot water. Opens and closes fine. Took the entire unit apart and cleaned rvery connector, and applied dielectric grease. Started it up and ran all three for over over 8hrs with no problem. Started out last weekend with three airs running, got about 15 mi. before shut-down!! It looks like the po put a new water pump on. Could be related. It does not kick the breaker.  What am I missing. The cummins dealer wants $150.00 to look at it and WOULD PREFER I REMOVE IT AND BRING IT TO THEM. Guess I should bring lunch to LOL!!

[Len Silva]

If I'm understanding you correctly. it works OK when parked but overheats when underway.  That's either because it is in a low pressure area under the bus or you are recirculating hot air back into the unit.  There is no way the Cummins dealer is going to find that problem.

Show us some pictures and read the Onan installation instructions very carefully, I think between us we can find the problem.

[bevans6]

I agree it sounds like the install, and I think that a great article for the mag may well be how to install generators so they get cool air in from a high pressure area and dump hot air out to a low pressure area...

Brian

[Ericbsc]

It shut down sitting still also. I thought the same thing until that happened.

[Ericbsc]

Unless the quiet diesel is mounted up front there is no way to avoid the low pressure under the bus. I have tried a scoopunder the bus and on the side. Neither helps.

[steve wardwell]

had the same kind of overheating prob 2 years ago when it was real hot outside  I went through sensors and stats. we are pulling air from one side of the  floor with a blower through the gen box and out the opposite side through the fan and rad box it was a  Wrico set up . we solved the prob by doubling the intake area (I mean its a BIG area, maybe 36x36 stretch mesh) and built a false floor  as ducting.  no probs since

[edroelle]

The cooling was likely designed "just good enough" under lab conditions.   Pressure differentials, obstructed cooling flow, enclosures, and weak fans can contribute to your problem.  I prefer to over design, and avoid problems.

Options
Increase size of radiator substantially
Remote larger radiator and use large squirrel cage (furnace)  fan.
Enlarge air openings
Add a booster fan
Provide clean cool air to the radiator, not warmed air that has passed over the engine

Ed Roelle
Flint, MI

[robertglines1]

had simular problem for  a year thought it was overheating...fuel line was getting hot and fuel pump pressure dropped..wrapped fuel line and all is good....just a very remote possibility...I know way out there....Bob

[JackConrad]

   When I installed our 10 KW Powertech, I looked at the heat sources. obviously, the largest source is the radiator and the next is the muffler. I removed both of these from the generator compartment. The radiator is remote mounted in the rear of then OEM spare tire compartment with a 12 volt electric fan. The muffler is installed under the coach just in front of the drive axle.
   The compartment has passive air intake from the side of the coach that enters the compartment near the floor and active air exhaust through the floor via 3 bilge blowers that pull air from the top to the compartment (hot air rises). Per sensor instaqlled near compartment ceiling, compartment air temp is usually about 10-15 above outside air tempersature.  Jack

[Ericbsc]

The unit is enclosed from the factory. The radiator is flat on the floor of the unit facing the front of the bus. It has a large squirrel cage fan on the engine where the regular fan would be. the discharge is angled toward the rear of the bus. The muffler is enclosed in the unit. I have it in the middle bay on the drivers side. I have the compartment double insulated with mass loaded sound block, 2" foam, .062 aluminum, and 1" absorbing foam. I have a 350 cfm. squirrel cage fan pulling air across the unit. It is pretty cool even when hot outside. It did die while on the road in MS. and would do nothing. I wiggled the harness and it started. I did clean every connection in the process.

[Len Silva]

I guess the next step is to actually verify the temperatures to be sure it's not a bad sensor.

[Ncbob]

Voltage regulator.

NCbob

[Ednj]

My Onan did this also.
The problem turned out to be the battery.
My generator does not charge the generator start battery.
When the battery gets low, it will still start the generator but will die and give the over heat code.
Ed

[thomasinnv]

i just installed a 7500 watt unit in the otr condensor compartment just behind the front tire.  it is a factory boxed rv type unit, which draws cool air in through the floor and exhausts back out through the floor also.  am i going to have the low pressure zone problems that you all are talking about?  or should it be ok being that close to the front of the bus?  should i be concerned?

[Charles in SC]

Eric, could it be a bad temp sensor, sender, connector, it sounds like you have covered a lot of the other things. Is your fault code a level one or level two? On my Onan the level two codes are a lot more detailed.