Generator rebuild cost question

[Charlie and Martha]

I am facing hefty repair costs for my Onan 7500 generator. It was overheating and shutting down (self protection). After doing some preliminary searching as what could be wrong I came up with:

1. Water Pump bearings or water pump in its entirety
2. Water Pump Belt
3. Impeller Replacement it is 7 years old
4. Temperature Sensor (while it's out)
5. Required Gaskets
6. Coolant
7. Removal Costs
8. Re-installation Costs
9. Rebuild Labor costs
10. Filters and fluids (while it is out).

Assuming all of those parts are bad or while it is out of the coach replacing obvious service items, what approximate costs am I facing for the repair?

My coach has a static mounted generator (no slide) so it will have to be removed from the coach and reinstalled. I am assuming based on the cost of parts plus labor I am looking at slightly under $2500 including fluids and filters while it is out.

Does this seem about right?

[ByeTheWay]

Mine needed a new Stator. R&R, parts, Test under load at a cummings dealer in Tolleson AZ was $3500. They told me I could buy new for twice the price plus installation.

[Charlie and Martha]

Nice of them to offer the new one....lol Yeah, nothing is cheap on an RV. I guess that's the way the mop flops.

[hclarkx]

A fellow on here about a year ago had major repairs on his cummins/onan by cummins to the tune of a bit under $2000. A year later (I guess out of the repair warranty) he was back with problems and plunked down $5000 for a new unit. I guess I'm saying the obvious, that if the repair cost gets anywhere near the cost of a new unit, go for the new unit. I wonder if there are aftermarket rebuilders like there are in the automobile industry ... where your old unit is a core for a rebuilt unit.

[tommar]

A water pump is not a major thing IMHO. I've done many water pump jobs during my life... had a Mustang with a 351C that seemed to eat a WP every 16 months. Got so I could do the job fast! I also did a WP job on an Onan 20KW marine genny and got er done as well. The main expense you're facing is having to remove the genny due to it not being on a slide. That's labor intensive and not a job I would or could tackle. If your genny has not been damaged due to overheating, it's worth doing even with a complete removal. If there's a strong possiblity of overheat damage, a whole nother thing. Cummins/Onan is gonna charge a premium price for all this. I'd call and search around for a mechanic willing to tackle the job. It's just a WP in the engine, not the generator components. In other words a simple mechanical repair. While you're at it, replace the hoses and belts, plus have the genny radiator inspected, flushed, and cleaned, and of course, new coolant. I'm not understanding what the impeller is that you refer to. There is an impeller in the water pump, but that's part of the WP and I don't think it can be replaced meaning that the entire water pump would need to be removed and replaced in order to fix the impeller; it's integral to the WP.

[Dav L]

When one says a generator needs to be rebuilt...I am assuming Pistons, rings, rod bearings, main bearings et al.

Replacing a water pump isn't a rebuild.

Anyway, If that's all that's wrong, then that's a half day of work and very doable.
Who did the diagnosis?
So, it's overheating....doesn't sound like it's a sensor. A water pump might be the case especially if it has a replaceable impeller.

https://www.amazon.com/185-2236-1852.../dp/B07ZRF78VV

Not positive that's yours.
Put a new belt on, do an oil / filter change and give it a test.
that's way less than $2500 of work.

[Spk64]

Was coolant recently changed on generator?
Very easy to get an air lock and cause overheating. Refilling coolant requires a specific procedure.

Air lock may not be correct term but the issue is lack of proper filling complete cooling system with coolant.

[Dav L]

BTW, if the unit is shutting down (self protection) due to overheating, that tells me the temperature sensor is doing a fine job and doesn't need to be replaced.

Now, if the unit is NOT overheating (by actual temperature) and is shutting down, then possibly the temp sensor is bad and you don't need a water pump et al as the engine is running at normal temperature.

Does the engine shut off due to temperature all the time? Or once in a great while? If the water pump is bad, it likely would overheat all the time (within ~20 minutes of the engine starting if the pump has total failure).

Proper diagnosis is Step 1 before estimate of repairs.

[AZDave]

I see you list Tucson as your location. Call Arizona Generator (480) 257-5288 and talk to him. He is a certified Onan tech with a mobile service. He did a great job diagnosing and repairing my 7500 at a very reasonable cost. I know his rate is better than the Onan dealer. He is based in Phoenix but may go to Tucson as well. If nothing else he will provide some great insight to your problem.

[Charlie and Martha]

Thanks everyone,

We were fulltime for four years and when the virus hit, We chose to get off the road at that point and took a Casita Apartment in Tucson. We were faced with storing the coach but instead decided put it on consignment for rental in Phoenix. The generator failed before going out for a rental (it was ran for an hour after the previous rental with no problem). Since I am nearly two hours away and our temps (and Phoenix) have been in triple digits for over two months I opted to authorize repair at Le Mesa RV in Phoenix.

The service manager there has been very active in keeping me informed. He says that the temp sensor and the impeller are both bad (as of this past Friday). I priced out all the parts required and it looks like parts are about $990=/-. He stated the total bill as $2300 to pull the generator out of the coach (no slide) do the repairs and re-install the generator.

You can bet if the weather was more co-operative I would have been doing this work. But, at 70 I thought better of it. I will post up when I get the final bill.

[Dutch Star Don]

You didn't respond to the one question, had the coolant been changed recently before you rented it? Very common, as stated, they get an air lock and you have to keep bleeding the air out before it will quit overheating....don't ask how I know.

[Charlie and Martha]

Originally Posted by Dutch Star Don

You didn't respond to the one question, had the coolant been changed recently before you rented it? Very common, as stated, they get an air lock and you have to keep bleeding the air out before it will quit overheating....don't ask how I know.

Oh sorry Don, I forgot and meant to answer that question. No, the generator coolant was changed in early 2019 and has run flawlessly since. We did have an air lock problem with our engine in late 2020.

We had to take out the radiator and intercooler because of a severe build up of slobber tube emmited oil. After it was reinstalled about a week later it overheated and that problem was traced to an air bubble in the system. But, nothing like that on the generator.

I appreciate the thought and question though. We are hoping that the unit is repaired soon, peak rental season is about to roll around. Also, we need a break from sequestering ourselves. We need to get out and do some camping.

[Craig36]

I had been quoted by two different repair centers that it would 3-4 hours to pull and then reinstall my gen that has a slow coolant leak. My Cummins center said they MIGHT be able do it quicker, but said time varies on each job, and they get $190/hr.

[Charlie and Martha]

Originally Posted by Craig36

I had been quoted by two different repair centers that it would 3-4 hours to pull and then reinstall my gen that has a slow coolant leak. My Cummins center said they MIGHT be able do it quicker, but said time varies on each job, and they get $190/hr.

I was quoted $175.00 an hour...so not far off.