Onan 1,000 hour service questions

[CWHTRAINS]

I am coming up on the 1,000 hour service point for my Onan 7500 QD. In order to perform this service, I have to remove the generator from my motorhome. Since this is a fair amount of work, what other items should I plan on replacing in addition to the coolant fill cap, thermostat and gasket, fan belt, and upper and lower radiator hoses? In looking at my parts manual, there are also the following hoses: 1. Fill neck hose, 2. overflow hose, 3. two air bleed hoses and 4. a lower engine hose. Are these hoses under pressure and subject to deterioration? I will not be able to see them until I take out the generator, but need to order the parts ahead of time in order to do the job. Some where in my system there is a small leak occuring within the inside of the generator which only seems to occur when genrator is not being used. My first thought is just buy all of the hoses and gaskets used and replace everything and maybe even all the clamps while I have it out of the motorhome.

Any thoughts, hints and suggestions on performing this maintenance?

[RVhauler]

In view of the amount of work involved. I personally would replace everything that you have stated

[RV Mech Tech]

Clayton -any chance of retrofiting a slidout drawer for the Onan when its out? - I've seen a Class A with the front clip seperate and unboltable and with some fabrication was made to open and a slidout for the genset was installed - makes you wonder why the manufactures would make a MH that requires removing the genset that size and weight for service- have pulled many a smaller Onan and Generac and that's not too bad but did one Onan QD - not a lot of fun - what are they charging you to re & re the genset?

[Rex]

Replace all the hoses. On mine there were four. Replace the water pump while you have the unit out of your coach.

Be careful of the three bolts holding the coolant tank. They are the ones closest to the start panel. They are a different length than all the others in the top cover.

[CWHTRAINS]

Right now I am planning to do the removal and re-install myself. I may ask for a price at the Onan dealer here in Indianapolis where I will get the parts from. Has anyone else paid to have theirs removed and re-installed?

My son has a 1,200 pound motorcycle life which I can borrow to raise and lower the generator unit which weighs 462 pounds. For those that have removed one, what did you do to disconnect the fuel supply coming into the generator and keeping it from leaking or draining more fuel from the tank while it is disconnected? When I replaced the original fuel filter at 500 hours it was somewhat a messy affair. One suggestion to me was to simply use a pair of vise grips on the hose coming from the tank to the generator.

Any other tips on removal and re-install would be appreciated. Can this be done by one person, or do you need a second person to help move things around?

[RV Mech Tech]

Clayton - you can do that with the fuel line but after it's disconnected put a bolt in the end of the hose with a clamp and remove the vise grips- there is an auto tool thats available with two flats on the end so as not to damage the hose but you can use the vgrips temporarly - there will always be some fuel that will drip down so have a catch pan ready - also make sure there is no fuel pressure in the lines by cracking the fitting on the fuel filter if you can - best to make sure of this on any fuel system -(always wear eye protection and gloves- any fuel getting on your skin is not a good idea and can cause sickness) - do not run the fuel system dry as you may have trouble starting it later -(there is a fuel bleed fitting on most late model diesel generators if required ) - always have a second and third person if possible when removing and reinstalling something this heavy - a second set of hands and eyes is always helpfull to avoid accidents and make the re & re easier - also disconnect your coach batteries as you will have to disconnect the starter power cable and associated wiring - make note of which bolts go where for the generator - best to have a couple of boxes and notepad when you are doing this and make note of which bracket goes where and in which position - I have seen two identical coaches with the same generator and one had the support brackets bolted in and the other brackets were welded in!! - so look at your installtion first and make notes if required - saves time when reinstalling - also the generator is going to be on the lift so if you will not be able to do anything underneath if the lift is in the way so if you want to do an engine oil or fuel filter change do it before removing - I have a portable generator stand that I made that makes it easier to repair the gensets and I can also run the unit and test them before installing back into the RV- you could do this with a remote fuel tank and battery as well to check and make sure everything is o.k before installing (if the mortorcycle lift is sturdy enough - yours is for 1.200 pounds but make sure the platform is wide enough so the genset won't tip to one side ) - when you have the genset exposed you can clean the generator and engine radiator with compressed air - you won't beleive the garbage that comes out - use low air pressure ( you can use a pressure regulator in line with the hose) and keep your distance from the radiator as not to damage it - your engine is liquid cooled but the generator is air cooled and it pulls in a lot of dust etc. when running - I always clean anything I can with the genset exposed and inspect everything for any signs of leaks or damage.

[Rex]

Clayton I had a lot of work done on mine and have pictures that may be of some help. If you would like them let me know rbdtanasi @ yahoo dot com and I will send them to you.

I watched the tech pull mine. They used what looked like a large motorcycle lift. It had two bars projecting out front and was a bit awkward for them to use but it worked. Then only had to move it about six feet. They also left it on the rig to do the repair work.

Mine had lost the control board at 800 hrs so I had the 1.000 hour work done at the same time. In the pictures it may look more like an erector set than a generator. On the top there is a removable plate and inside there there is a lift point where you could hook a chain hoist to pick it up. On my Monaco, the generator could be slid out almost half way before the lift needed to be under it.

Be sure and use PB Blaster on the four base mounting screws for several days before you pull them. The tech broke all mine and had to drill them out. The exhaust pipe will be the most difficult thing you have to remove off the rear, other than the mess from the fuel lines. The tech plugged the fuel line and put a clamp on it. He still got lots of fuel on his hands and shirt.

[Gary RVRoamer]

I've got 1772 hours on my Onan QD7500 and it has the original filler cap. hoses and belt. I inspected everything 18 months ago while doing a major service (mine is on a roll out) and everything looked and ran fine, so decided not to do the hard stuff (the belt is a real pain, even to get a look at).

Your generator is younger than mine (January 2004 ), so I don't think you have to worry about belt and hoses yet. They aren't worn out, and they aren't old enough to be tired out. I believe strongly in maintenance, but the Onan schedule looks to me to be ultra-conservative.

[CWHTRAINS]

Just an update on progress so far. Stopped at our Cummins/Onan dealer on Friday morning here in Indianapolis and they did not have any of the hoses or other parts in stock, so I am waiting for them to come in. What I do know is that something is slowly leaking as there is a coolant drip out of one of the weep holes in the bottom of the generator base. Funny thing is, the over flow tank seems to be slowly draining empty, even though I am not running the generator. I did not order a replacement tank as I wanted to examine the current one first, once I can open the generator covers after removal of the generator from the coach. Dealer told me $174 for a new overflow tank!

[Norm4015]

The overflow tank on my Onan 7.5 started leaking. I removed it and found a crack about 1 1/2" long starting at a lower hose connection on the left side. I removed and cleaned the tank and applied some plastic sealer and it has held for six months.