Onan genset quits

[Bobby P.]

My Onan genset shuts down after about 5 to 8 seconds of running. I get two blinks on the indicator which suggests low oil pressure. I checked the oil level and it was a bit low. I put in 4 ounces of oil. Tried it again with same results. The oil level was a little higher so I put in another 4 ounces. Same results. Dipstick didn’t read to the quite full mark so I put in another four ounces. Same results. Any suggestions? Generator ran strong all night long the day before with normal shut down process.
Thanks,
Bobby

 

[Bobby P.]

FIXED!

This is the Onan QD 4/5 kw genset with the white sound shield.

Just want to give an update. I was able to fix the shut down problem (was throwing a 2 blink code, which is low oil pressure).

I first tried changing the oil and refilling with the exact amount. No change. Start up, run for 5-8 seconds, shut down and throws the code.

Yesterday I changed the oil sending unit (no easy task). That solved the problem.

I am certainly no Onan genset mechanic, but I have personally fixed several problems on this genset. Also, my last boat had the same exact genset (for about 10 years) and also performed multiple tasks, including all standard maintenance. I am adding this because hopefully others can learn from my "hard knocks" learning experiences.

Best to all,
Bobby

 

[barling]

Bobby,

Thanks for sharing. Where and how do you get the parts?

 

[FWTMD]

Good job, and thanks for the heads up. A few questions:

1) How did you isolate that as the problem? Thinking just an educated guess, after insuring oil was there?

2) Difficult to do, how? Mostly a case of difficulty of access, or more?

 

[Bobby P.]

I isolated the problem of the code for oil pressure by first checking capacity (didn't want to trust the dipstick) by emptying it into a ziplock bag and then measuring. I then started with new oil, measuring the exact amount. Although there could have been other problems that set off "oil pressure" as a code, there were not other symptoms leading up to that, ie, blue smoke, water in oil, etc. Replacing the oil sending unit was the next cheapest thing to try. And it worked.

In terms of difficulty... I had to remove most of the sound shield and contort my body into the space between the engine and the genset. I actually sit down in there and turn my torso to the right to work on the genny. I get comments from my wife, "What are you doing in there again with her..." or when I'm done, "You smell like her again." Evidently she wears 'ode to diesel and oil' perfume. I get caught every time!

But anyway, have to remove alternator belt, pulley, bracket and water pump, just barely get wrenches in there. This is the same order of things I followed I changed the starter and replaced the impeller.

In terms of where to get parts, I've use Amazon for the fuel pump (which i didn't need to change but wanted aboard as a spare). When I needed a starter I went to a place that sold Onan gensets. They want over $400. I ended up purchasing it at a shop that repaired starters. It's a little kubota engine, so they ordered my the starter for that $150. Worked perfectly. For the impeller, you can get that almost anywhere. Our own FM parts department has it at the same price as everyone else. I plan to order one each year with my other things I purchase from them as regularly maintenance on the big engine.

As an FYI, I hear a lot of complaints about different gensets. Even though I've had much to fix on this one, I still stand by it. The problems I have were due to water infiltration in a salt water environment, not the genny itself.

The Onan Marine QD 4/5 kW Generator is an outstanding performer, small, quiet, can run both a/c units, etc. I had the exact unit on my last boat for over 10 years and if I needed a new generator of this size, I would buy one again in a heartbeat.

 

[RMarkSampson]

Old post but thought I would jump in as this is what I am currently working through my own GENSET frustration. My generator would cut off after 15 seconds or so. Three flashes signified an error code - which when you hit the stop button once - flashes would change to 5 then 8 - or error code 58. Book says "high exhaust temp." That seemed unreasonable as the unit had not even really started running yet. I then tried to dig into the problem onboard - but there is no yoga class that would allow me to solve this without hanging upside down like Houdini. I was also seeing a lot of rust in the drip pan and soot spread around inside the white enclosure - so I opted for plan B, fully remove the GENSET from the boat in order to do a more complete inspection, repair and rehab.

Removing the GENSET was actually fairly straight forward. At 370 lbs you will not be able to budge anything without appropriate lifting tackle. So first, I unplugged the GENSET electrical connections, 12V, raw water, and fuel line/return - all somewhat simple - and then the four bolts that held the generator in place. I actually remove the 12V connections at the stern thruster so there would be no dangling 12V power connections - and I wanted to keep the boat operational during the rehab. I did cut the exhaust hose - so I will replace that upon installation. I also temporarily detached the trim tab reservoir and raw water washdown pump to make room so the GENSET could swing aft about 8 inches. Also, applying full left rudder moves the aft steering control rods out of the way. I then used a strong A-frame ladder and a 1/2-ton chain hoist to lift the GENSET (two lift points) out of the hole where the rear seat folds forward. I lifted it high enough to place the GENSET on an extension ladder laying across the cockpit gunwales (I first laid furniture pads and 2x4's down to protect the fold-out seats. My boat is on a lift so it was a simple thing to lower her so the extension ladder rested on the dock too - allowing me to use four 1/2 PVC pipes to roll the GENSET across to the dock. I kept a safety chain attached to the GENSET, just in case. I then used the A-frame ladder and chain hoist again to load the GENSET on a rolling table - heading to the garage.

The GENSET is now where I have complete access to everything once removing all the enclosure panels. I did lift the GENSET one more time in the garage to remove the drip pan from underneath. Depending on the price to replace the drip pan, it may be taken to a sandblast/powder coating company for a $250 rehab. I'm also replacing other common maintenance items without the need to swear, sweat or contort oneself.

Oh, the fault code shut down problem. Yep, that was an interesting finding. Pre-me, someone jumpered the High Temp Exhaust switch so the GENSET did not have that sensor/protection anymore. However, the weight of the jumper wire sagged down and was rubbing against the spinning generator flywheel which finally cut the wire - so it essentially it unjumpered itself causing an immediate error 58 code. Poor access sometimes leads to poor fixes...

 

[Bobby P.]

Very impressive!

The Onan generator is a great machine. I had the exact one on my last boat and it ran perfectly for 10 years.

Now that you got it out, check everything. I also had a screw from the sound shield chafe a wire on the electric side. I had the machine running great. Overtime I would put it together it would start, and then shut down when I engaged the electric.

Now that I got the bugs worked out on this one, she runs like a top.

BTW, I did all my work with genset in place. I used to get made fun of for being 5'5" and wirey. Not anymore!

Good luck!
Bobby P.

 

[RMarkSampson]

My follow-up. GENSET is back on the boat and running great. It was a project that took some time (~three/four weeks I think) - but I also wanted to take the time to really give the GENSET a good inspection and learn all the maintenance access points for future on-boat work. Boat was fully operational during the rehab - other than unable to run the air conditioning while underway or at anchor. Inverter handled other 120V loads.

I actually tossed the rusty drip pan into my recycling bin - and new one from Cummins was only $280, not much more than if I would have gone the sandblast/powder-coat route. I'm sure I could have just wire wheeled it and used a couple cans of spray paint - but I went for new. I rehab'ed the motor mounts that were also rusty, but they cleaned up fine. Fuel pump also worked fine but its mounting bracket had rusted away - I save my $150 for a new fuel pump by cleaning it up (including grinding away what was left of the mounting bracket) and painting it. I attached it back to the drip pan using tie straps. I also rehab'ed the oil sender - it lives right under the one drain petcock which may have been opened for winterizing, causing a little rust on the oil sender. New impeller, fuel and oil filters - simple access, simple job. I did decide to install one bolt holding the impeller pump backwards - now the nut is located at the front of the engine so it should be easier to remove and pull the impeller pump off the engine so I can replace the impeller outside of the engine compartment.

One additional add-on item - most of the soundproofing on the white enclosure was flaking apart and falling off. I bought a roll of new soundproofing online and also some silver "cool tape" - and then just matched the shape to the old stuff I scraped off. Soundproofing has a silver side toward the engine - and a glue backing on the other side.

Before reinstalling the GENSET I also removed the generator platform from the boat that was stained by all the rust - painted it top and bottom with a good marine enamel. Also, if you get that deep into a GENSET rehab - also spend a few moments ensuring those two drain channels at the rear of the bilge are clear. Easy to get rid of obstructions without the GENSET/platform in the way. Finally, removing the cockpit bench seat make it easier to reinstall the GENSET into the hole - but getting to the hinges afterwards to reinstall the nuts is a bit of a challenge.

Per the problem that shut down the GENSET and initiated my rehab effort. A new high exhaust switch was about $80 - I assumed the old one was inoperative since someone took the effort to jumper past it. I did not want to troubleshoot and heat it up and test for resistance changes. Plus, the book did not have any specs on those ohm values. I did route the wires around the top of the wire bundle in order to keep it well away from the spinning generator flywheel. Ounce of prevention...

Wife was on the dock watching me start the GENSET for the first time. Alas, it did not start. She rolled her eyes and when back into the house. Oh yeah, I forgot to turn the fuel valve back on - flip, and the GENSET started right up. Hey honey, it works!