Our newest engine is equipped with an Onan 7.5kw diesel generator. This Genset is in an enclosure atop the pump house. We have been experiencing problems with the unit shutting down after running for 20 to 30 minutes. The Onan reps claim it is overheating due to a lack of ventilation. The apparatus manufacturer states that they have not received any complaints from departments with similar setups. Currently, after only 48 hours of running time on it, the generator needs a new voltage regulator and a new rotor. It had been discharging 160 volts instead of 120 volts. Looking for any feedback from anyone who may have had a similar problem or feedback on experiences with Onan products.
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Thread: Diesel Generators
05-12-1999, 11:08 PM #1Chief51Firehouse.com Guest
05-13-1999, 12:37 AM #2e33Firehouse.com Guest
Should have bought a Honda, or gotten a PTO generator. No past experience with anything other than the above mentioned.
05-13-1999, 09:05 AM #3Dalmation90Firehouse.com Guest
Just kinda sucks when you tie the gasoline powered Honda into the truck's Diesel tank e33.
We run 2 7.5kw Onan Diesels, a 2.5kw Onan Gas, a 5kw Honda Gas, a 5kw almost-as-old-as-me Homelite, and a 15kw Harrison Hydraulic...no unusual/unexplained problems with any of them.
Have you tried to contact a Cummins service center instead of the Onan rep for a second opinion? (Cummins owns Onan...) It wasn't clear to me if the Onan "rep" was a local dealer, or factory person. Check out http://www.onanrv.com/dealers/index.htmlfor service centers...very few are at their "Level 3" certification.
[This message has been edited by Dalmation90 (edited May 13, 1999).]
05-13-1999, 10:57 AM #4STA2Firehouse.com Guest
05-13-1999, 11:04 AM #5e33Firehouse.com Guest
I was kidding, sorry.
05-13-1999, 11:12 AM #6STA2Firehouse.com Guest
We have similar setups for two of our generators on our Rescue Pumpers. They are in enclosures like yours above the pump panel. We use Onan generators that are 7.5 KW and have not had your problems. Ours are gas but are in complete enclosures except for ventilation slats on one side of the enclosure on the side above the pump panel. Does yours have ANY ventilation openings at all? Our concern with putting ours up top was the fuel situation. Our fueltank is at chest height behind a door for easy fueling and maintenance within the pump enclosure. We have a fuel pump system that pushes fuel up to the generator on top of the pump panel. I agree with the other poster about a second opinion. Check with someone else and see what they say. I would think if it was a ventilation problem that it would not take 20 to 30 minutes of running to shut down from overheating. It should happen sooner than that. Could be a fuel problem with either your filter or lines especially if it is above the apparatus fuel tank. Gravity is sometimes more difficult to overcome than engineers think. However, I also agree that PTO generators are the way to go and thats what we bought on our heavy Rescue unit just 6 or 7 months ago. I wouldn't condemn Onan just yet, could be a bad unit. Have you tried a different unit in the same location? Your the customer and if its new then make your dealer satisfy you with the problem. What type of apparatus is it on (Pierce, Sutphen, E-One, etc.)? If you know for sure that the voltage regulator was bad and had it fixed and it continues then the rep is probably on the right track. However your spec should include and your builder should include a WORKING generator. How old is the rig? Is it under warranty? Onan is a good truste name. Maybe talk to someone else higher up the food chain in the tech. or engineering dept. Be safe.
05-14-1999, 01:44 PM #7Chief51Firehouse.com Guest
To Dalmation90 & Sta2: Cummins Power Systems of Bristol, PA, who is working on our generator, has level three certification. I spoke with 4 technicians while there and they are all of the same opinion that the apparatus manufacturers are at fault for providing inadequate ventilation. Ours is on a 1997 KME Excel custom pumper. The enclosure is completely open on the radiator end and both the top and rider side is are louvered. Personally I feel that the unit was a lemon from day one. Luckily for us, it is being taken care of under warranty but that does not make up for our inconvenience. Perhaps we will look into the PTO type on our next spec. Two local companies here have them but have not been without their troubles. One burned out and another had a broken drive shaft. So much for modern technology. Thanks for the input, guys.
05-14-1999, 06:36 PM #8STA2Firehouse.com Guest
Chief one other comment. We have a 1984 Pirsch 1500GPM custom as a reserve in my volunteer dept. It has an Onan diesel generator in the officer side lower rear compartment which is totally enclosed and we have never had a single problem with it. The guys were always forgeting to open the compartment doors when it was a front line piece and ours never shut down. Now with it as a reserve and not recieving as much "attention" it is still fine. Just something else to think about. I agree with you though, I think you got a lemon from the beginning. Hope it works out for you. Be safe.
05-15-1999, 05:23 PM #9Mec28Firehouse.com Guest
We have one engine with the same size and type unit you are using. It is enclosed in a side compartment. We have to open both doors on compartment or the generator will overheat
.The compartment only has one small vent.
05-18-1999, 06:05 PM #10FyrtrksFirehouse.com Guest
We have a 10kw Onan water cooled unit on a 1997 Seagrave. Runs like a champ. I would like to have a one button push and forget start. I also think 10kw was overkill we only have 2kws worth of light, one cord reel and four outlets thats 8kw from each outlet.
West Elmira Fire Dept.
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