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Onan Quiet Diesel 7500, Coolant leak

Blackdiamond
Explorer
Explorer
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?
03' Fleetwood Southwind 32VS
Enclosed Trailer hauling the toys
05 525 EXC KTM
15' FE350s Husqvarna/KTM
07 Rhino, long travel, 4 seater
8 REPLIES 8

smlranger
Explorer
Explorer
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.
2019 Grand Design Solitude 384GK 5th wheel. Glen Allen, VA

cat199
Explorer
Explorer
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.

vance
Explorer
Explorer
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.
vance
2007 Coachman Encore
330 HP Mercedes
Honda CRV toad
"If you see our children, PLEASE don't tell them where we are"

John___Angela
Explorer
Explorer
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.
2003 Revolution 40C Class A. Electric smart car as a Toad on a smart car trailer
Life is not measured by the number of breaths we take but rather by the moments that take our breath away.

JackMS
Explorer
Explorer
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.
2005 Holiday Rambler Neptune 34pdd, Cummins ISB 300, Allison 2500MH, Onan 8.0QD
Prior Toad-2001 Chevy 2500 CC 4WD
Toad-2012 Honda CRV, Blue Ox Aventa II

Blackdiamond
Explorer
Explorer
Seems no one has had this issue before......
03' Fleetwood Southwind 32VS
Enclosed Trailer hauling the toys
05 525 EXC KTM
15' FE350s Husqvarna/KTM
07 Rhino, long travel, 4 seater

Blackdiamond
Explorer
Explorer
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.
03' Fleetwood Southwind 32VS
Enclosed Trailer hauling the toys
05 525 EXC KTM
15' FE350s Husqvarna/KTM
07 Rhino, long travel, 4 seater

Jamboree89
Explorer
Explorer
Is you generator on a slide, if so, easiest access is to remove top cover.
1998 Monaco Dynasty
Scion Xb
Collin and Alfie the dogs