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7500 Onan

busyguy
Explorer
Explorer
I posted this on IRV2 and didn't get much response. My QD7500 Onan is not on a slide and has to be dropped down to take the cover off to gain access to the engine and internal parts.
I was wondering if anyone has cut the outside cover portion off and then used hinges or brackets to re install it. Would make it a lot easier to do some maintenance on the internal workings.
Any thought on this?
Busyguy
15 REPLIES 15

busyguy
Explorer
Explorer
Thanks Bounder39zman
I only have access on the left side of my gen set. But I appreciate your info.
Busyguy

bounder39zman
Explorer II
Explorer II
Had one of these in a Bounder, no slide tray. at around 5000 hrs I pulled it (dropped it out the bottom!) The only modification I made was to cut out a hole, 12x12 or so in rear panel, then got a piece of diamond plate aluminum to cover the hole, installed with nut-serts, so I could change belt if necessary in the future, without dropping entire set. Of course I did full P.M. maintenance while out, including belt, hoses, coolant sensor, water pump and thermostat, valve adj., etc, etc.
The commercial units do have a service door, but I doubt that it would help with the gen stuffed up in the RV . They can be very useful if gen slides out, gives good access to fuel filter and oil filter. The commercial units are identical to RV units, with the exception of having a 12v battery charging system installed.
I do work on these gennys for a living, and usually will always change the belt and water temp sensor, every time I have a unit out of the coach for whatever reason.

FIRE_UP
Explorer
Explorer
busyguy wrote:
Fireup
Just got around to reading your post. Thanks. I was thing of taking the whole side panel off and then hinging it where it bolted to the top panel or maybe cutting a door in the left side. I have plenty of room to open a door off the gen set as it is in a compartment with a large access door on the left side.
Not taking any action now. Just an idea that crossed my mind.
Thanks for your input and for all the others who responded.
Busyguy


Roger that Sir. Do take pics if you manage to move forward with this project.
Scott
Scott and Karla
SDFD RETIRED
2004 Itasca Horizon, 36GD Slate Blue 330 CAT
2011 GMC Sierra 1500 Ext Cab 4x4 Toad
2008 Caliente Red LVL II GL 1800 Goldwing
KI60ND

busyguy
Explorer
Explorer
Fireup
Just got around to reading your post. Thanks. I was thing of taking the whole side panel off and then hinging it where it bolted to the top panel or maybe cutting a door in the left side. I have plenty of room to open a door off the gen set as it is in a compartment with a large access door on the left side.
Not taking any action now. Just an idea that crossed my mind.
Thanks for your input and for all the others who responded.
Busyguy

FIRE_UP
Explorer
Explorer
busyguy wrote:
I posted this on IRV2 and didn't get much response. My QD7500 Onan is not on a slide and has to be dropped down to take the cover off to gain access to the engine and internal parts.
I was wondering if anyone has cut the outside cover portion off and then used hinges or brackets to re install it. Would make it a lot easier to do some maintenance on the internal workings.
Any thought on this?
Busyguy


Busyguy,
I applaud your thoughts and intent on this. The QD7500 is not overly complicated to work on but, it is encapsulated in its somewhat cumbersome housing. I know, I've had mine pretty much ALL THE WAY TORN DOWN. And it's not just "changing the belt" that's a concern here. In fact, the belt is normally the least of anyone's problem with a QD. The infamous "temp sensor" is way more of a chronic problem than the belt or, oil pressure sensor or, even the thermostat.

I feel for any QD owner who does their own work on them but, does not have them on a sliding tray as we do. It's really a tough situation when major work is needed and, you have to go through great lengths to remove the gen set, just to start to work on it. A slide makes that soooooooo much easier.

Now, as for you wanting to "re-design" your QDs outer housing by cutting it at strategic places and placing hinges there, well, that would not be a problem at all. YOu will NOT CHANGE ANY COOLING AIR CHARACTERISTICS whatsoever. If you think about, the side paneling or panels, are there to encapsulate the entire gen set and, also help to provide correct channeling of cooling air.

Simply by slicing the paneling at bend points or, anywhere you'd think would be strategic to place hinging, would not have any effect on the channeling of that cooling air or, any part of that gen set operation, as long as the paneling, with hinges, is still placed where it was before any mods were performed. There is a plastic bulkhead that runs fore and aft that is also, a main component in air channeling. It is basically sealed, end to end with the front and back panels and, top to bottom with those upper and lower outside body panels. If done correctly, your hinged panels would have zero effect on air cooling.

But, also if you think about it, have you reasoned it out and pictured what you'll gain with your plan? I mean, with the QD up in its cave, there's usually not much "extra" room around it, especially to hinge a side panel up and out of the way, so you can perform any surgery on that QD. I get what you're thinking for sure. I'd do it myself if I thought there would be gain from it. Good luck.
Scott
Scott and Karla
SDFD RETIRED
2004 Itasca Horizon, 36GD Slate Blue 330 CAT
2011 GMC Sierra 1500 Ext Cab 4x4 Toad
2008 Caliente Red LVL II GL 1800 Goldwing
KI60ND

Preacher_Man
Explorer
Explorer
busyguy wrote:
Thanks to all for your input. I may never do this but, it has crossed my mine and I see that some of the earlier Quiet D sets did have an access panel in the side.
My set runs great and I won't mess with it. Thanks again.
Busyguy


The commercial units do have an access door on the side. I've never seen one in person, so I'm not sure how they are configured inside.

Colorodo Standby Generator
Mark Walter
J-Angel Productions
Web and Media Company
2004 Sportscoach LE 376 DS
Cat 3126E, Allison 3000

Preacher_Man
Explorer
Explorer
WOW, 30K hours. I thought I had a lot at 3500. Still on original fan belt.
So my 7500 has picked up a slight oil leak. Coincidently with an oil change but it’s not at the filter, it’s above the filter.

It’s weird, it leaks about a third of a quart over a few days then almost stops. It doesn’t appear to leak while running.

Knowing what you know, what might you suspect?


According to the parts breakdown there are a few items above the filter that could cause an oil leak. The injector pump is one area as well as a block off plate or two as well. You'll need to pull the covers to see what it is for certain.
Mark Walter
J-Angel Productions
Web and Media Company
2004 Sportscoach LE 376 DS
Cat 3126E, Allison 3000

busyguy
Explorer
Explorer
Thanks to all for your input. I may never do this but, it has crossed my mine and I see that some of the earlier Quiet D sets did have an access panel in the side.
My set runs great and I won't mess with it. Thanks again.
Busyguy

Big_Katuna
Explorer II
Explorer II
Preacher Man wrote:
My 7500 is also not on a slide. I use a hydraulic table to pivot (remove the front mount bolts and 1 on each side in the rear) the unit down for anything other than oil or coolant flush. My unit has a little over 30K hours on it. We had the radiator rebuilt, changed water pump and belt. I'm on my 3rd water pump and belt. I change the thermostat as a matter of habit if I'm that far into it. Link for the table from Harbor Freight - hydraulic table

We also changed the oil pressure sending unit last week. That turned out to be a fairly significant job. We had to pull the radiator, muffler and fiberglass firewall (for lack of a better term) to get to the switch since it's buried in the right rear portion of the block. Of course it was a mess, but we got it all cleaned up and going.

The biggest thing would be not changing any of the characteristics of the cooling air flow. If you do, it will overheat and eventually cause damage. It's like changing the characteristics of a fan shroud. Normally it causes more issues than it's worth. Honestly, I think you'd be better off spending the $170 at Harbor Freight for the hydraulic table for as little as you'd need to remove the top.


WOW, 30K hours. I thought I had a lot at 3500. Still on original fan belt.
So my 7500 has picked up a slight oil leak. Coincidently with an oil change but it’s not at the filter, it’s above the filter.

It’s weird, it leaks about a third of a quart over a few days then almost stops. It doesn’t appear to leak while running.

Knowing what you know, what might you suspect?
My Kharma ran over my Dogma.

Preacher_Man
Explorer
Explorer
My 7500 is also not on a slide. I use a hydraulic table to pivot (remove the front mount bolts and 1 on each side in the rear) the unit down for anything other than oil or coolant flush. My unit has a little over 30K hours on it. We had the radiator rebuilt, changed water pump and belt. I'm on my 3rd water pump and belt. I change the thermostat as a matter of habit if I'm that far into it. Link for the table from Harbor Freight - hydraulic table

We also changed the oil pressure sending unit last week. That turned out to be a fairly significant job. We had to pull the radiator, muffler and fiberglass firewall (for lack of a better term) to get to the switch since it's buried in the right rear portion of the block. Of course it was a mess, but we got it all cleaned up and going.

The biggest thing would be not changing any of the characteristics of the cooling air flow. If you do, it will overheat and eventually cause damage. It's like changing the characteristics of a fan shroud. Normally it causes more issues than it's worth. Honestly, I think you'd be better off spending the $170 at Harbor Freight for the hydraulic table for as little as you'd need to remove the top.
Mark Walter
J-Angel Productions
Web and Media Company
2004 Sportscoach LE 376 DS
Cat 3126E, Allison 3000

Tom_Barb
Explorer
Explorer
I believe I'd simply drop it once and put a kevlar belt on it and be done, every thing else is done from the bottom.
2000 Newmar mountain aire 4081 DP, ISC/350 Allison 6 speed, Wrangler JL toad.

busyguy
Explorer
Explorer
I do all my own maintenance on my m/h. If I can spend a few hours making it easier to get to the engine on the gen set and be able to change the belt and thermostat why wouldn't it be worth it.
Beats dropping the unit for a minor repair.
Thanks for the replies

larry_cad
Explorer II
Explorer II
You can change the oil, oil filter, fuel filter, air cleaner, and flush coolant without removing the cover. You cannot change the belt. So, is it worth the trouble?
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