7000 Onan gas generator help

Nick_Siebert · 05-26-2022, 10:21 AM

On hot days, open the generator compartment door and prop the cover on the generator open to allow the hot air to vent out, I sell a lot of these generators in trailers and this is a common issue. They get hot and shut off.

John Duzac · 05-26-2022, 11:48 AM

Thank everyone for the information. Your comments has given me plenty of insight.

Joe Martens · 05-26-2022, 01:19 PM

Placing a fan on the generator should help. Not sure what weight oil you run but I run 15-40 in mine.

SGSST109E · 05-26-2022, 08:01 PM

I was schooled on the 7k generator by a factory tech. Opening the compartment door is fine do not open the cover on the generator; They are designed to pull air in from the bottom and out the side where the exhaust is. There should be a baffle between the intake and the exhaust often trailer manufactures ignore that step, So the cold air intake pulls in the exhaust air over heating the generator; Shoot the exhaust and the air intake with a gun and you will see. I made a baffle on mine curves around the exhaust pipe deflecting the air away from the intake

Rich Biebel · 05-26-2022, 08:19 PM

All Onan’s are designed to run with the service door in place.
The air flow is dependent on the door being on and tight
They do not have a high temp shutdown but will shutoff and it is from the control board and or the fuel lines, carb etc getting to hot
Many installs of these units ignore the airflow issues that make running hot worse
A fan directed at the compartment and to blow the hot exhaust away from the cool air intake area usually will help
The cooler air is drawn in along the bottom front area behind the oil filter and to the left.
With it running there is a very strong suction there and can pull a rag right out of your hand
I’ve seen birds nests up in there and bags or debris.
The lower they are to the ground the worse it can be
These units rely on air to cool and heat routinely causes cylinder head failures
The guides loosen up, valves and springs suffer from the overheating and the oil turns to sludge around the spring bases.
I do head replacements all the time. Finished one yesterday. Third one I’ve done in a month.
Anything you do to reduce the heat being drawn into the machine is a big plus.
I’ve seen one machine on a sign truck from Miami area with head failure from running to hot and it had under 1000hrs
Was mounted on the side of the truck very low to the ground and obviously was run in a hot area….Miami !
I work on them all the time.

My own 4000 watt Onan’s also would shut down if they got hot.
A big pit fan blowing directly at my trailer compartment mounted unit stopped the hot shutdowns
Do not run Onan’s with the service doors off ! Like I said it disrupts the designed air flow and will shorten the life of your machine. That goes for any Onan

05-26-2022, 10:21 AM	#1
Nick_Siebert Junior Member Join Date: Jul 2007 Location: Wamego, KS Posts: 39 Likes: 55 Liked 66 Times in 12 Posts	Re: 7000 Onan gas generator help On hot days, open the generator compartment door and prop the cover on the generator open to allow the hot air to vent out, I sell a lot of these generators in trailers and this is a common issue. They get hot and shut off.

05-26-2022, 11:48 AM	#2
John Duzac Member Join Date: May 2005 Location: Covington, La Posts: 311 Likes: 63 Liked 83 Times in 20 Posts	Re: 7000 Onan gas generator help Thank everyone for the information. Your comments has given me plenty of insight. __________________ John Duzac D/S 4448 STK

05-26-2022, 01:19 PM	#3
Joe Martens Senior Member Join Date: Dec 2001 Location: North Olmsted, Ohio Posts: 788 Likes: 631 Liked 196 Times in 69 Posts	Re: 7000 Onan gas generator help Placing a fan on the generator should help. Not sure what weight oil you run but I run 15-40 in mine. __________________ Joe Martens AA/Stock 3969

05-26-2022, 08:01 PM	#4
SGSST109E Member Join Date: Jun 2007 Location: NJ Posts: 351 Likes: 62 Liked 126 Times in 61 Posts	Re: 7000 Onan gas generator help I was schooled on the 7k generator by a factory tech. Opening the compartment door is fine do not open the cover on the generator; They are designed to pull air in from the bottom and out the side where the exhaust is. There should be a baffle between the intake and the exhaust often trailer manufactures ignore that step, So the cold air intake pulls in the exhaust air over heating the generator; Shoot the exhaust and the air intake with a gun and you will see. I made a baffle on mine curves around the exhaust pipe deflecting the air away from the intake

05-26-2022, 08:19 PM	#5
Rich Biebel VIP Member Join Date: Jun 2007 Location: Northern New Jersey suburbs Posts: 2,314 Likes: 25 Liked 544 Times in 213 Posts	Re: 7000 Onan gas generator help All Onan’s are designed to run with the service door in place. The air flow is dependent on the door being on and tight They do not have a high temp shutdown but will shutoff and it is from the control board and or the fuel lines, carb etc getting to hot Many installs of these units ignore the airflow issues that make running hot worse A fan directed at the compartment and to blow the hot exhaust away from the cool air intake area usually will help The cooler air is drawn in along the bottom front area behind the oil filter and to the left. With it running there is a very strong suction there and can pull a rag right out of your hand I’ve seen birds nests up in there and bags or debris. The lower they are to the ground the worse it can be These units rely on air to cool and heat routinely causes cylinder head failures The guides loosen up, valves and springs suffer from the overheating and the oil turns to sludge around the spring bases. I do head replacements all the time. Finished one yesterday. Third one I’ve done in a month. Anything you do to reduce the heat being drawn into the machine is a big plus. I’ve seen one machine on a sign truck from Miami area with head failure from running to hot and it had under 1000hrs Was mounted on the side of the truck very low to the ground and obviously was run in a hot area….Miami ! I work on them all the time. My own 4000 watt Onan’s also would shut down if they got hot. A big pit fan blowing directly at my trailer compartment mounted unit stopped the hot shutdowns Do not run Onan’s with the service doors off ! Like I said it disrupts the designed air flow and will shorten the life of your machine. That goes for any Onan __________________ Rich Biebel S/C 1479 Stock 147R Last edited by Rich Biebel; 05-26-2022 at 08:36 PM.