Onan QD 7500 Generator Mystery
Hello. So, I have a 2006 Fleetwood Revolution LE with the Onan QD 7500 Generator. Last winter, last trip out the generator would start, run for 5 minutes and then shut off. It would start righ...
Forum Discussion
We have a similar QD8000. Previous owner did not survive it well, and when we bought the coach and then ride to start using the generator. We had some problems to start with:)!
-Replaced the temp sensor, as the OEM unit had a problem due to incompatible metals, and would fail early.
-Only 14 months later, 114 outside while in Bishop, CA. Same shutdown, and error code. This time I dug a bit deeper, found out the sensors had a problem, and that a revised replacement part was available. I had conversation with the parts department as I was trying to order the newer 'revised/improved' part number - as they kept insisting that I should use the OEM part number. Amazingly, it took the Cummins Site Manager stepping in to help me (He'd walked by a few times and observed our conversation.). He asked the Parts Manager if it was true that an upgraded replacement part was available. Parts Manager said yes. And the Site Manager said to order me that part, overnight if necessary - and to send all remaining OEM parts back to Cummins the main warehouse.
-I went ahead and ordered two these, because I have a non slide out generator, so lots of labor hours to drop it out of the front of our coach to work on. The shop I was working with installed one of the new parts normally, I had the second temp sensor metal "C Clamped" to the water line Return manifold. And had these A/B wired in. A = normal location heat sensor. B = C clamped to return manifold heat sensor. (The shop made me sign the invoice that I assume all responsibility for the modification from stock.). So now, once or twice a year, I test that my 'Over Ride B C clamped sensor still works.
I did this, because I until I knew for sure that the revised heat sensor was going to fix the problem of premature failures, due to the incompatibility of the metals reactions - I wanted a 'back up plan' to keep the generator running. IF it were to shut down, and IF the error code indicate Over Heating. I would check all fluids, and inspect the fan belt was properly working. IF the answer was yes, I'd then switch over to he B C Clamped sensor, and fire generator back up. Due to the B sensor not reacting to the coolant and different metals, it should last forever:)!
When you are in the high temperatures of the desert areas. Having a 'false error shutdown' of your Generator/Roof Top AC - can really be very uncomfortable, and possibly dangerous to those with medical conditions.
One last comment. About 2 1/2 years after I did the A/B modification, with the revised Heat Sensor, a buddy of mine had is QD7500 heat sensor go out. He went to a Cummins/Onan shop, and they replaced the sensor (And flushed the generator radiator too.). When he was telling me this, I asked if they used the new improved sensor for the repair. He pulled his receipt, and I compared the part number they had installed to my receipts. His receipt indicated they had installed the OEM sensor... Apparently they're were still using up old stock... This was 6 years ago now, and when I talked with Cummins Northwest about this during a visit. They looked up the old Part Number, and it now shows no longer available...
SO - OP, if you find you need a new sensor for sure. Good chances you will get the new latest and greatest improvement. I only share this story here, because I was told that the original OEM sensor is still available for sell in Mexico...
Expensive repair, twice, due to faulty design on a component. The fun of RV ownership!!!
Best to all,
Smitty
-Replaced the temp sensor, as the OEM unit had a problem due to incompatible metals, and would fail early.
-Only 14 months later, 114 outside while in Bishop, CA. Same shutdown, and error code. This time I dug a bit deeper, found out the sensors had a problem, and that a revised replacement part was available. I had conversation with the parts department as I was trying to order the newer 'revised/improved' part number - as they kept insisting that I should use the OEM part number. Amazingly, it took the Cummins Site Manager stepping in to help me (He'd walked by a few times and observed our conversation.). He asked the Parts Manager if it was true that an upgraded replacement part was available. Parts Manager said yes. And the Site Manager said to order me that part, overnight if necessary - and to send all remaining OEM parts back to Cummins the main warehouse.
-I went ahead and ordered two these, because I have a non slide out generator, so lots of labor hours to drop it out of the front of our coach to work on. The shop I was working with installed one of the new parts normally, I had the second temp sensor metal "C Clamped" to the water line Return manifold. And had these A/B wired in. A = normal location heat sensor. B = C clamped to return manifold heat sensor. (The shop made me sign the invoice that I assume all responsibility for the modification from stock.). So now, once or twice a year, I test that my 'Over Ride B C clamped sensor still works.
I did this, because I until I knew for sure that the revised heat sensor was going to fix the problem of premature failures, due to the incompatibility of the metals reactions - I wanted a 'back up plan' to keep the generator running. IF it were to shut down, and IF the error code indicate Over Heating. I would check all fluids, and inspect the fan belt was properly working. IF the answer was yes, I'd then switch over to he B C Clamped sensor, and fire generator back up. Due to the B sensor not reacting to the coolant and different metals, it should last forever:)!
When you are in the high temperatures of the desert areas. Having a 'false error shutdown' of your Generator/Roof Top AC - can really be very uncomfortable, and possibly dangerous to those with medical conditions.
One last comment. About 2 1/2 years after I did the A/B modification, with the revised Heat Sensor, a buddy of mine had is QD7500 heat sensor go out. He went to a Cummins/Onan shop, and they replaced the sensor (And flushed the generator radiator too.). When he was telling me this, I asked if they used the new improved sensor for the repair. He pulled his receipt, and I compared the part number they had installed to my receipts. His receipt indicated they had installed the OEM sensor... Apparently they're were still using up old stock... This was 6 years ago now, and when I talked with Cummins Northwest about this during a visit. They looked up the old Part Number, and it now shows no longer available...
SO - OP, if you find you need a new sensor for sure. Good chances you will get the new latest and greatest improvement. I only share this story here, because I was told that the original OEM sensor is still available for sell in Mexico...
Expensive repair, twice, due to faulty design on a component. The fun of RV ownership!!!
Best to all,
Smitty
