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Open Roads Forum  >  Tech Issues

 > Onan hot hot hot

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onrecess

Boca Raton, FL

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Posted: 06/30/19 02:39pm Link  |  Quote  |  Print  |  Notify Moderator

I had trouble with my gennie dying for years. I spent a couple thousand at CW, they called in onan twice, kept it for many months. I pulled the fuel pump and replaced it. Runs great. I drove 200 miles across Florida, 90 degrees. No problems. Coming home, I stopped for gas. I shut it off (it exhausts under the fuel filler door.)mWhen I went to start it, no joy. I went to shange the oil. I could barely keep my hands on the cover to pull it. I had to hold the dipstick with a rag, it was too hot too touch. I drove a few minutes to let it cool. After ten or fifteen minutes it started right up. No problems after. I can shut it off and restart, but sitting long enough to fuel up it gets too hot. I looked under it to see where air goes in... There is a perforated metal part where the oill filter and drain is. There is metal plate behind it (touching). There's a pan that covers almost the whole bottom, and the perforated part disappears over that, with a 2" gap the length. Is it open under? I assume there is a fan, is it belt driven? Seems awfully hot. Is this normal? Does your gen set get that hot?


Tom Anderson
2005 GeorgieBoy 35

onrecess

Boca Raton, FL

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Posted: 06/30/19 02:51pm Link  |  Quote  |  Print  |  Notify Moderator

I checked the carb altitude, it is set to 0, where I am. I started it, there is a lot of air coming out the air exit by the muffler. Someone somewhere mentioned a summer/winter switch, but I don't see one.

TEXAS

Centerville Tx

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Posted: 07/12/19 06:55am Link  |  Quote  |  Print  |  Notify Moderator

Onan has been building generators since 1925. Would be nice to know which one you have. Model and serial number would help.

This is the reason generator techs like myself left this site. People asking for help. But not telling us what they have.

dougrainer

Carrolton, Texas

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Posted: 07/12/19 07:49am Link  |  Quote  |  Print  |  Notify Moderator

Your Onan is AIR COOLED. Also the Altitude adjustment is for the Fuel/air mixture at the CARB. Has nothing to do with cool air circulation. Doug

apr67

Tallahassee, Florida

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Posted: 07/12/19 08:59am Link  |  Quote  |  Print  |  Notify Moderator

Mine (5.5k hgjab) is the same way. It gets hot as hell under the cover. Onan has a procedure in the installation manual to test that the hot exhausted air isn't being re-ingested for cooling. However I personally don't have the tools for that.


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DownTheAvenue

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Posted: 07/12/19 09:05am Link  |  Quote  |  Print  |  Notify Moderator

One thing to think about is that the generator should be disconnected from any load and run to cool off before shutting down. Shutting it down immediately while under load just makes more heat to be dissipated.

MEXICOWANDERER

las peñas, michoacan, mexico

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Posted: 07/12/19 01:02pm Link  |  Quote  |  Print  |  Notify Moderator

HOT HOT HOT?

Push ambient air into the generator compartment

[image]

and...

it cures the ambient generator compartment hot tamale syndrome.

onrecess

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Posted: 07/12/19 03:49pm Link  |  Quote  |  Print  |  Notify Moderator

The gennie is a 5500 Marquis Gold HG JAB.
Thanks for the fan post, I am considering that and an air scoop under the coach.
And the cooling off. I've never done that.We are usually running two ACs, because of the heat in FL and back and forth to Texas. I'll be sure to do so in the future.

* This post was edited 07/12/19 04:02pm by onrecess *

CoachFiver

Upstate NY

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Posted: 07/22/19 01:01pm Link  |  Quote  |  Print  |  Notify Moderator

Alright I have to post, hoping by posting here, I can get some feedback over starting a new post.

I have a 2013 Raptor toy hauler 410 LEV with onboard Onan 5500 RVQG EVAP. When temp outside is hot(85+) generator will run until it gets good and hot and shut down. I've done a tone of testing, replace fuel filter, fuel pump, I run good premium gas, and done a lot of testing. It is definitely vapor locking. And I've proven it. It is because of the tremendous, and I mean unbelievable amount of heat that builds up under the generator between generator and ground. And yes there is plenty of room between generator and ground. That is also the same area where the fuel pump and fuel lines reside. I'm looking to resort to 1 of 2 options. Option #1, remove the generator, install a slide tray, reinstall the generator and then when using it in 85+ degree weather, slide the tray out so much more air can circulate. Option 2, and I did do some testing of this during the weekend. To build a heat deflector that pushes the high exhaust temperature air away from the cavity under the generator that houses the fuel pump, fuel lines and intake tube.

Out of all the Onan's I've had I've never had one run this hot, and i'm talking so hot you can't touch anything behind the front cover. This cannot be normal.

shastagary

minnesota

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Posted: 07/22/19 04:08pm Link  |  Quote  |  Print  |  Notify Moderator

from the installation manual
Quote:

Hot Air Recirculation Test A representative installation of the genset must be tested to determine that the genset will not overheat due to recirculation of hot air back into the genset.
8.4 Test Requirement The rise in inlet air temperature over ambient air temperature must not exceed 15°F (8°C). A rise in inlet air temperature indicates hot air recirculation. If the rise exceeds the requirement,steps must be taken to reduce recirculation to an acceptable level.


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