Community Forums

JimM68 · 03-13-2010, 09:29 AM

I'm going over my onan genny getting ready for camping season.

I bought a "real onan" oil filter, $13 bucks! Ouch. For next time, is there a crossreference to something that can be bought at napa or autozone?

Is it safe to gunk and hose this thing?

Besides changing the oil, what else chould I do to it?

Is there a manual I can download somewhere?

Genny is an Onan 5500 gas, a 1999 model. It's not the fancy one with the full greenish cover, the engine kinda sticks out the right side, and it has a black cover over the electrics.
I'll get a model nomber and post a pic in a lil bit.

JimM68 · 03-13-2010, 09:32 AM

Oh... almost forgot. this morning, it cranked right up and ran great. I put both A/C's on, first one, waited a minute for the shed light to quite flashing, then switch ed the other. Genny took the load without even a change in sound!

Toward the end of last summer, genny was running like crap. Surging badly under load, lights getting dim and bright, a/c's tripping off, just plain nasty.
I don't want this happening again, wish it would happen now so I could fix it!

Today, it's 47 degrees and very damp.

Clay L · 03-13-2010, 10:10 AM

I get my filters at Cummins dealers for $7 or $8.
I bought a service manual from a Cummins dealer.
As I recall the oil change interval is each 100 hours or once a year whichever comes first.
The air filter is supposed to be blown out at 100 hour intervals I think. I am not sure about that but it's easy to do so I blow it out each 100 hours.

There are two fuel filters on mine and I replaced them both at 100 hours. I don't remember the next replacement interval but I think it was way out there or "as required'.

I have carefully washed mine with RV wash and a hose.

AFChap · 03-13-2010, 10:43 AM

The spark arrestor is suppose to be cleaned out at every oil change, but I do mine probably every other. Mine takes multiple extensions on a socket wrench, about 20" as I recall. Just remove the plug, run the generator with the plug out for around 10 minutes, and replace the plug. If it has not been out in awhile, it will be very tight.

Yours likely has different filters than my Onan 7.5 diesel, but if you take your Onan number to a NAPA store you should be able to get a cross reference to their NAPA Gold and maybe others. My service intervals are 150 hr/1 yr oil (3qt) & filter and clean spark arrester; 500 hr/3 yr Air filter & Fuel filter; 1000 hr change coolant & hoses

For my Onan 7.5 diesel
- oil filter options are Onan 185-5409 or 0122-0833 $16.49 / NAPA Gold 1064 $8.03 (by Wix) / Fleetguard LF3591 / Deutsch D370 / Donaldson P550726 or P55-0162
- Air filter Onan 0140-2897 apx $17.99
- Fuel filter Onan 0149-2513 / NAPA Gold 3063

H. Miller · 03-14-2010, 11:05 AM

On this site (iRV2) go to Cummins section...... There will be a "sticky" called "gen. maint. & manuals" Then "follow the yellow brick road".

JimM68 · 03-14-2010, 04:50 PM

Quote:

Originally Posted by H. Miller

On this site (iRV2) go to Cummins section...... There will be a "sticky" called "gen. maint. & manuals" Then "follow the yellow brick road".

awesome and will do. changed the oil and filter. Checked the plugs and air filter, they looked fine. no clue how to do the spark arester, will follow the yellow brick rd.

Wizard · 03-14-2010, 06:17 PM

The Onan oil filters have a special, I think its a bypass on something built in, and my manuals tells you not to substitute with a standard filter. I'll get the manual out soon and post the exact wording.

My manual states also that the fuel filter is not user replaceable, did mine anyway with Onan fuel filter and didn't have any problems.

JimM68 · 03-14-2010, 07:29 PM

yellow brick road not a lot of help, all current models, nothing 10 years old.
Generator is running very well today after it's long sleep, but was surging badly toward the end of last season.
She spent the winter with a full tank of gas, well juiced with stabil. I drove the coach with the genny running for 30 minutes to make sure the stabil was well circulated.

JimM68 · 03-15-2010, 09:25 AM

There is a square head threaded pipe plug going into the bottom of the muffler, it looks impossible to get a wrench on, I can see it thru the airlfow slots but there isn't an access that I've found.

TW · 03-15-2010, 10:10 AM

Hello Jim, I go ONCE a year to Cummins here and have my GEN Service done... I used to do the service myself, but I'm getting tooooo lazy (means old) and I have it done now....
I always used ORIGINAL PARTS on everything.

TW

gresults · 03-16-2010, 10:34 AM

I just parts for my Generac here.. Found prices to be very reasonable.. https://www.generator-parts.com

RV Mech Tech · 03-17-2010, 11:04 AM

JimM68 - check with your local tool supplier for a square ended socket that will fit over that plug- (it's a standard pipe plug)- you may have to go to Snap-On or Mac tools or a local industrial tool supplier that sells to the HVAC industry- some of those plugs like yours are almost impossible to get at on some of the older gensets- if enough carbon builds up in the muffler/spark arrestor then it can actually plug up enough to stop the engine from running (extreme case) - as far as maintenance goes you can do all of it yourself including and especially cleaning the unit- these gensets are air-cooled and you would not beleive the dirt that gets pulled into and around the generator and engine cooling fins - I take care of several rental RV's and almost each and every time one comes back the generator has to be cleaned - what I do is get a longer than standard air nozzle and used compressed air to blow out in and around the generator and engine- (make sure you wear safety glasses and ear protection) the engine draws cooling air over the cooling fin area and the generator also does the same (air runs through the inside of the actual generator) and over time stuff will accumalate in there - you may not be able to get all of the areas but put that air nozzle anywhere you can and you will not beleive the garbage that comes out- keep doing this along with regular oil changes and filter changes along with tune-ups and fuel stabilizer and the genset will last for many running hours - I have been able to restore several in the past to running condition just by doing that - you are also using the correct procedure to load the generator- start, let it warm up (to stabilize) and then put on your loads one by one - and do the same when shutting off as well - had a customer last year who purchased a Forest River Georgetown with a Generac 5500 watt genset- kept turning the generator on and off with both front and rear A/C's on - he burned the generator out (Generac replaced under warranty) but starting with loads on caused the damage - Onan used to have their manuals online but now you have to purchase them- maybe another member on this forum may know where to download them from but I have not found any sites yet- Generac did the same on their site last year but there are a couple of site you can get them from- if you do get one from Onan take all the info especially the Spec number from the generator sticker - they will need this as the Spec number tells them what the generator was used for and that manual wll have the correct wiring diagrams for your specific unit.

Tincup · 03-18-2010, 07:46 AM

Here's another site for Onan and other manufacturers generator parts

Generator Parts for Generac, Kohler, Onan Generators

Ray,IN · 03-21-2010, 08:56 PM

Bad gas is a huge factor for rough-running engines, especially when not ran for a while. I add the proper amount of fuel system cleaner about every 3rd tank to help combat rough-running and slowed response to governor action.