Changing the Air filter on an Onan 4kw generator

Post your general and technical information, questions or responses in this forum. Viewing messages is open to all with no registration or log-in required. Prior to posting a new message or a response to an existing message, registration or login is required. Please do not post FOR SALE or WANTED ads in this section!

Moderator: bfadmin

Post Reply
User avatar
BFrees
Posts: 39
Joined: Sat Sep 02, 2006 9:56 pm

Changing the Air filter on an Onan 4kw generator

Post by BFrees »

I may be making a mountain out of a mole hill here, but looking at the Onan generator in my '02 coach it seems to me that in order to change the air filter you have to remove the GENSET from the coach. It doesn't look like there is enough room to loosen the bolt and slide the housing and filter far enough to the right to be able to remove them and change the filter. I'm hoping I'm wrong.

Onan Model # 4BGEFA26101P Serial # J990 998833 in a 2002 24 ft. RSB.

Seems crazy to me they would design it that way..... ????

Before I start my own DIY program here, I thought it might be a good idea to check in with you folks and find out what I can about the whole process before I try to re-invent the wheel.

My fear is if I start disassembly, can't change the filter and can't re-align parts due to space constraints, I'll need to go back to the mechanic @ $90/hr. and be paying thru the nose to change the filter and fix my mistakes. The mechanic, by the way, is quoting me $200 for an oil & filter change along with an air and fuel filter replacement. I have no idea if this is a good quote or not. He says he knows the secret to replacing the air filter without dropping the unit, but is, understandably, reluctant to share this knowledge.

Is there a special "technique" or is this guy BSing me?

I would be able to do this job myself for $36 ( for parts) and my time.... I'm retired...... $36 vs. $200, I'm thinking its worth a shot.... ???

Any input on this issue would be greatly appreciated.

Thanks in advance,
Ed Coyle
Feel free to contact me direct @
coy88@comcast.net
Ed & Ann Marie
2002 24' RSB
User avatar
whemme
Posts: 2110
Joined: Mon Aug 15, 2005 8:05 pm

Post by whemme »

Ed,

I have changed the air filter in the past on my Onan 4.0 KW generator in my 2002 BF 26' RSB coach but did not drop the generator to do it. Since it was some time ago, I can't remember the details but I seem to recall that is was a tight fit to get my hand in the limited space provided to remove the old filter and install the replacement.

I will try and look at my generator tomorrow and post more info after I jog my memory.
Bill Hemme - Spencer, Iowa
E-mail: whemme@earthlink.net
2002 Born Free (Ford E-450 V10) 26' RSB
2016 VW Golf GTI - toad
User avatar
whemme
Posts: 2110
Joined: Mon Aug 15, 2005 8:05 pm

Post by whemme »

Ed,

Here is more information on changing the air filter in your Onan Emerald Plus BGE generator.

I will be the first to say that replacing this air filter is not an easy job. There is room to insert a box end wrench or small 1/4" drive socket wrench between the right side of this air filter box and right side of the generator enclosure but not much.

In my opinion the best way to remove the air filter box is to you a closed end 7/16" box wrench to remove the bolt shown. Most box end wrenches have a slightly angled tilt on the end of the wrench which will permit you to get the end of the wrench on the recessed head of that bolt.

When the bolt is completely loose - pull it out to the right as far as possible with the bolt still inserted into the filter box. Then pull the filter box with bolt and filter towards you removing it from the generator.

Replace the air filter element with new and I have listed 3 brands and P/Ns below:

Onan - P/N 140-2379
WIX - P/N 42362
NAPA - P/N 2362

On my generator's filter, there was an additional 1/8" thick yellow foam filter element stretched over the filter itself. Remove that element from the old filter, wash it in water with detergent, then rinse it in clean water, and then re-install it on the new filter.

I found it best to remove the air filter box with the box end wrench but to reinstall the filter and box with a 1/4" drive socket wrench with 7/16" socket.

Now here is really the hard part. With the air filter box removed, you will notice an air hose that was connected to the rear of the filter box. This hose is for the warm air supply into the air box. You will notice two holes on the rear of air filter box. The left side hole is oblong and is for the cold air inlet. The right side hole is round and is the hole in which the warm air supply hose should be inserted when re-installing the air filter and box - only this step is really difficult to accomplish in my experience. You would be lucky if this hose would happen to insert itself properly in this round hole when re-installing the air filter and box. If you aren't lucky, then the only way the hose can be inserted is to drop the generator down so that you can have enough rear access to get you hand back there to insert the hose manually.

The cradle holding the generator is hinged in the back. Put a hydraulic floor jack under the front part of the generator cradle and jack up just enough to support that part of the cradle. Then remove the two lower support bolts located near the bottom middle of the generator and then slowly lower the jack and the front of the generator will lower and tilt down enough to get you hand in behind the air filter box to insert the warm air hose into the round hole.

Any others out there that might have a simpler method to do this job, please post it below.
Attachments
View of air filter box located in the upper right side of Onan generator.
View of air filter box located in the upper right side of Onan generator.
Onan Generator Air Filter Box.jpg (36.2 KiB) Viewed 9524 times
View showing 7/16" hex bolt that must be removed to replace air filter.
View showing 7/16" hex bolt that must be removed to replace air filter.
Onan Generator Air Filter Box-1.jpg (29.39 KiB) Viewed 9526 times
Bill Hemme - Spencer, Iowa
E-mail: whemme@earthlink.net
2002 Born Free (Ford E-450 V10) 26' RSB
2016 VW Golf GTI - toad
User avatar
BFrees
Posts: 39
Joined: Sat Sep 02, 2006 9:56 pm

Post by BFrees »

Bill,

Thank you so much for the very detailed (with pictures, no less) description of this process.

I've decided to go ahead and give it a try. I'll definitely be feeling much less nervous now that I have a clear picture of how everything is going to play out.

Looks like it has the possibility to get a little tricky, but at least I know "it is doable".

It will be a while before I can start. I'm going to order the parts from Onan. I'm thinking of getting their 15-40w OnaMax oil for it. Any thoughts?


I'll keep you posted as to how it all works out if you'd like.

Thanks again, your input has been a big help,
Ed
Ed & Ann Marie
2002 24' RSB
User avatar
whemme
Posts: 2110
Joined: Mon Aug 15, 2005 8:05 pm

Post by whemme »

Here is additional information on how to lower (tilt down) the Onan generator in order to make it easier to replace the air filter element by provided better access the 7/16" bolt on the right side of the air filter box. Also, dropping the generator will most likely be required in order to reconnect the warm air supply hose to the round hole in the back side of the plastic air filter box or in order to replace the back side spark plug.

A detailed procedure to properly lower you Onan generator is posted in the Technical Library section below under the topic Lowering Onan BGE Series Emerald Plus Generators in your B/F or you can click on the following link to go there directly: http://www.bornfreervclub.org/bulletin_ ... php?t=2355

This post edited by whemme on 7/25/2010.
Bill Hemme - Spencer, Iowa
E-mail: whemme@earthlink.net
2002 Born Free (Ford E-450 V10) 26' RSB
2016 VW Golf GTI - toad
User avatar
BFrees
Posts: 39
Joined: Sat Sep 02, 2006 9:56 pm

Post by BFrees »

Bill,

Once again "thank you" for all your time and expertise.

You really have gone "above and beyond".

I really appreciate it.

Ed
Ed & Ann Marie
2002 24' RSB
oliverpsmile
Posts: 271
Joined: Thu Dec 18, 2008 2:46 pm

Post by oliverpsmile »

Bill

Is it possible and prudent to unplug the cables before lowering the GenSet? Are there any other connections that the practitioners should know about it (gas hose or some other cable harness for example)?
Oliver P Smile
2005 26ft RSB
User avatar
whemme
Posts: 2110
Joined: Mon Aug 15, 2005 8:05 pm

Post by whemme »

The fuel feed line to the generator is a flexible rubber hose coming to the generator near the hinge point at the bottom rear of the carrier - so this connection is not compromised when raising and lowering the generator. The electrical cable is the only thing that needs to be disconnected at the male-female connector joint shown in the photo in my post above if you need to lower the generator beyond a certain point. This connector joint has two locking tabs that must be depressed in order to separate the two connectors.
Bill Hemme - Spencer, Iowa
E-mail: whemme@earthlink.net
2002 Born Free (Ford E-450 V10) 26' RSB
2016 VW Golf GTI - toad
Post Reply

Return to “General and Technical Information, Questions, and Responses”