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Blackdiamond's avatar
Blackdiamond
Explorer
Jul 11, 2013

Onan Quiet Diesel 7500, Coolant leak

Onan Quiet Diesel 7500, Coolant leak. I have a leak that I traced to what looks like either the overflow tank or a hose at the overflow tank but I can't get to it.

Looking at the right cover (which is facing the front of my MH) I removed all the outer screws and the screws where the rad cap is and I can shimmy it off a few inches on the back of the gen (passenger side for me) but it hangs up in the front (DR side) like there is a hidden screw under the panel.

Anyone that has replaced their overflow tank have any insight or tips that could help me out?
Class A
  • Jamboree89's avatar
    Jamboree89
    Explorer
    Jul 11, 2013
    Is you generator on a slide, if so, easiest access is to remove top cover.
  • Blackdiamond's avatar
    Blackdiamond
    Explorer
    Jul 11, 2013
    No slider...dealer wants around $1100.00 because they say the whole front cap needs to be removed. If I can just get that panel off I can do it.
  • JackMS's avatar
    JackMS
    Explorer
    Jul 12, 2013
    You can't do much with the gen in its spot. I have had mine out twice. Not too hard. I removed the front acces door, on coach, not the whole front cap. Look to see if yours is removable. I can have my gen out in about 30 mins. The first time I slid It down some ramps onto a trailer. Used an ATV with a winch and a pulley under the coach to get it back up the ramp. Used a forklift the second time. It actually slides on its foundation pretty easy.
  • John___Angela's avatar
    John___Angela
    Explorer
    Jul 12, 2013
    Blackdiamond wrote:
    No slider...dealer wants around $1100.00 because they say the whole front cap needs to be removed. If I can just get that panel off I can do it.


    Seems pricey. Fleetwood front caps come off easy. 20 minutes for a Revolution with two people. Not heavy, a bunch of screws and rivets to remove and off it comes. We had to remove ours to work on the temp sensor of the Onan.
  • vance's avatar
    vance
    Explorer
    Jul 12, 2013
    I've got the same problem. Rather than remove the tank, my plan is to buy a tank that I can mount outside the generator, disconnect the hoses from the hold tank and hook to the new one.
  • cat199's avatar
    cat199
    Explorer
    Jul 13, 2013
    I have the same problem. If I fill the tank up it will it will loose coolant until there is a 1/4-1/2 inch in the bottom of the tank then I never loose any more coolant.
  • smlranger's avatar
    smlranger
    Explorer
    Jul 13, 2013
    The recovery tank is probably cracked...it has been reported before. I did a full service on the Onan 7.5 on my previous coach (Journey on FL chassis) and used a motorcycle jack to drop the genset out from under the coach. On most DP's without a slide out for the genset, you generally have to remove the genset from the coach to get inside of it. If you can remove the fiberglass clip on the coach and have no frame obstructions in the way, you might be able to work from the front but getting that top off the Onan would still be tricky.

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