Onan 10kw Routine Maintenance

[zmotorsports]

Thought I'd show some pictures of the routine maintenance that I just performed on our Onan 10kw HDCAA Spec-A generator.  I can post a video of the service as well after I edit it, if that would be of interest.

 

Our genny now has just over 3k hours on it and time for another valve check so I thought I'd incorporate some other maintenance in with it such as another V-belt replacement and fuel filter.  I did the oil and filter service in November when I did the overhead and LOF service on the chassis engine so that item was good on the genny.

When we purchased our 2003 Monaco Dynasty back in Feb. 2007 the original owners had used it quite heavily as it had 55k miles on the coach and just over 1200 hours on the genset.  I figured based on some of the neglect the rest of the coach was exhibiting that they more than likely didn't get around to having the valve clearance check completed at the 800 hours that Isuzu recommends.  Now I've worked on a lot of these Onan gensets over the years between my old Kubota powered 7500 watt in our '91 Beaver Contessa, the Perkins powered one in my aunt/uncles late 80's Beaver Marquis and both my cousins in their late 90's Signature and early 2000's Country Coach so I have a pretty decent feel that these "can and do" go further than the 800 hour interval before needing valves adjusted.  Most I've worked on don't need any valve adjustments to close to 2k hours and from what I gather, most people will never see those kinds of hours on their gensets.  However, we used our coaches for racing as well as duning and snowmobiling so we ran our generators a lot as did my aunt/uncle and cousins as we all sledded together over the years.  The Onan 7500 in our last coach had just over 5k hours when we sold it and my aunt/uncle had around 15k hours on their first Beaver Marquis when they sold it and around 7k on their mid-90's Marquis when my uncle passed.

That being said, my mind just can't let things go.  I did the initial valve check on my 10kw Onan when we purchased the coach back in 2007 with just over 1200 hours.  The valves all were within spec. right at .008".  I replaced the V-belt and other maintenance items at that time as well.  The Isuzu engine got an oil and filter change @ 100 hours rather than the 150 recommended in the service manual.  I heard many years ago in the industrial world that most equipment that uses hour meters uses a 45 MPH calculation as a comparison.  Now whether or not that is the "engineered" calculation or nor, for some reason that has stuck with me so I have opted to change fluids on my generators @ 100 hours for the past 32+ years of owning RV's and it has served me well.   For many years that equated to a couple of oil changes per year as around 200 hours on the generators per year was a good average.  Nowadays, I don't think I put more than about 15-20 hours a year on, it that.

 

I did another full-service including V-belt and valve clearance check @ 2000 hours and found the valves only being tight by about a thou. is all.  I did adjust them at that time and put them back to .008" which is the factory spec.   We racked up a lot of hours on the generator in those first 8 or 9 years of ownership but over the past 9 or so years we barely put over 100 hours on it as we sold all of our race toys, sleds and sand toys between 2012 and 2014.   I have changed the oil about 4 times in the last 9 years or so and 100+ hours as I change it every other year while doing the chassis engine but with it now passing the 3k hour mark I figured the V-belt and fuel filter had some time on them, even though low hours so I would just do all of those on a routine maintenance check.

 

 

 

Covers removed to gain access to the engine as well as the blower fan and V-belt from the backside.

 

Be careful with the plastic blower housings as they get a little brittle with age and usage.

 

With the blower housing removed as well as the aluminum blower fan I now have access to the V-belt.  The alternator was loosened from the topside.

 

The old belt looks almost new.

 

Backside shows little to no wear or cracking.  I could have easily run this belt some more but with a new belt only about $15 and it's sitting on the bench it was senseless not to install the new one this deep in.

 

New belt going on.

 

I did notice upon removing the plastic blower housing that I had a small amount of contact between the aluminum blower fan and the housing.  Nothing severe but enough I didn't want to continue on.  After installing the blower fan I added some .050" thick washers to the 6mm studs that hold the blower housing to space them off the fan a very small amount.  I left the blower housing off until after the valves are checked.

 

Belt and fuel filter part numbers.

 

Had I been thinking back in November when I changed the oil and filter on the generator, I would have also replaced the fuel filter at that time as it has much easier access without the oil filter in the way.  It's not terrible with the oil filter on the engine, but is sure opens things up a bit more without.  I stuffed an absorbent pad under the fuel filter to catch any fuel that spills out of the lines and old filter.  I like to crack the nut on the mounting stud loose then lightly tighten back before going at the fuel lines.  Once the fuel lines are loose enough to remove by hand then quickly swap the filters to minimize spillage.

New NAPA Gold (Wix) fuel filter being installed.

 

Fuel lines tightened up and mounting stud secured.  

 

Absorbent pad removed and bottom of cabinet wiped clean chased by some brake cleaner and compressed air.

 

With the V-belt and fuel filter completed I can focus my attention on the valve clearances.  I left the back cover off and the blower housing until after the valve check because it is easy to turn the engine over using the blower fan.  Just be cautious as the aluminum fan has some sharp edges so grasp it firmly enough that your hands don't slip, or wear gloves when turning it over.

 

I am impressed with just how clean the inside of the engine is with >3000 hours on it.  Inside looks like new.

 

The FSM states the procedure to check/adjust the valves by using the notch and timing mark on the crankshaft pulley to the block but visibility is so awkward that I have found by using the overlap method and only being a 3-cylinder engine it is pretty easy to know which cylinder has the camshaft on the base circle.  The procedure is as follows:  with an intake valve and exhaust valve open on two cylinders, the third cylinder is on the base circly of the cam and can be checked and/or adjusted if needed.  Then turn the engine over until the next two cylinders have valve being compressed and the one that both valves are closed is on base circle and can be checked/adjusted and so on.

 

I also like to mark the top of the adjusting bolt once I verify that valve is correct and I have put a wrench on the jam nut to verify it is tight.   I then mark the top of the adjuster with a paint pen and move on.  This just helps me to avoid missing one.  It may be hard to tell in the picture but last time I marked the adjuster screw with a white paint pen and even though some paint had worn off, this time I used a yellow paint pen to avoid confusion.

 

Once all valves were verified to be within spec., which they were all spot on @ .008", I then could clean the rocker cover in the solvent tank and install the new gasket.  Here is the part number for the OEM rocker cover gasket.

 

Old gasket removed and new gasket being installed.  If you look closely you can see notches in the gasket groove.  The gasket has corresponding tabs that fit into the notches so make sure they are all properly seated otherwise you can almost guarantee yourself a leak.  Another suggestion is to not push along the gasket when installing as this pushed the gasket to the direction you are going and stretches it somewhat from the direction you are coming from, therefore the tabs will not properly align with the notches.  After laying the gasket out on the cover push the gasket straight down into the groove.

 

Gasket installed and the cover ready to go back on the engine.

 

Cover bolt torque specification is 1.4-3.6 ft/lbs.  I torqued them all to 20 in/lbs. first round starting at the middle and working my way outward in a criss-cross pattern, followed by a final torque of 40 in/lbs.

 

Before starting the engine, I pulled the plug from the spark arrestor.  I primed the fuel system and started the engine and loaded it slightly then kept covering and opening the carbon port to extract as much soot or carbon as possible.  

 

 

After reinstalling the plug back into the spark arrestor I used compressed air to thoroughly blow off the engine and cabinet before reinstalling all of the covers and double checking fluids.  I also installed a new radiator cap and tested the coolant before stuffing the generator back into the nose of the coach and calling that job done.

 

Hope this was helpful as it really isn't that terrible of a job.  Just a bit dirty and awkward at a few steps.  

 

I can also post up the video when done if that would be helpful although I think the pictures covered it pretty well.

 

Thanks for looking.

 

 

 

 

 

 

 

 

[Ivan K]

Nice write-up. I have done the same to our Isuzu couple of years ago and had the same observation and solution to the shroud clearance. I had to do I bit of plastic welding as it had some cracks too. Ours has over 4k hours so I also replaced the collector, brushes and rotor bearing. Couple of the injection pumps had a leak while on the road but only need new orings to stop that.

[zmotorsports]

48 minutes ago, Ivan K said:

Nice write-up. I have done the same to our Isuzu couple of years ago and had the same observation and solution to the shroud clearance. I had to do I bit of plastic welding as it had some cracks too. Ours has over 4k hours so I also replaced the collector, brushes and rotor bearing. Couple of the injection pumps had a leak while on the road but only need new orings to stop that.

 

Thanks.   I replaced brushes several years ago when I had an intermittent issue on ours.  I would lose exciter power shortly after startup and after putting a scope on it to watch the signal from control module I determined that the signal was sporadic from the module.  Replaced the module and good to go.  While testing I was getting some funky readings through the brushes and to take them out of the equation, ended up replacing them, even though I didn't think that was the issue, more preventive than anything but upon removing them they looked nearly like new so that was wasted money.  That was around 2500 hours or so.  Even on the super high hour generators of my aunt/uncles I had not seen any bearing failures or rotor/stator issues so that gives me comfort knowing how durable and reliable they are.

[96 EVO]

No issues with your overflow tank?

Before I tossed mine and went with a generic can style, mine had split at almost all of those nut recesses!

Wasn't me overtightening them, I feel they were all overtightened at the factory 😣!

[Indydyne]

Mike,

Thank you for another super informative write up. I look forward to the video!

[zmotorsports]

Here is the video I posted over the weekend.

 

 

[2003 Dynasty]

Great resource Mike.  I have the same coach/year but a 7.5kw Onan.  Any idea how different the layout is for the 10kw vs 7.5kw, and thus the servicing differences?  I have changed oil/filters but not the belt or checked valve clearances (but have had those done by service tech).  Thanks for sharing the expertise.

[jacwjames]

18 minutes ago, 2003 Dynasty said:

Great resource Mike.  I have the same coach/year but a 7.5kw Onan.  Any idea how different the layout is for the 10kw vs 7.5kw, and thus the servicing differences?  I have changed oil/filters but not the belt or checked valve clearances (but have had those done by service tech).  Thanks for sharing the expertise.

I just changed the belt on mine.  Layout in general is close but my 7.5KW has a different fan.  I had to take off the top and rear panel to access but I left the rear panel in place and just tipped it back.  Hardest part was getting the 4 bolts off the pulley to remove the belt, no good way to hold the pulley from spinning.  Tried using a strap wrench but finally had to resort to using a channel locks on the pulley to hold it in place.  No real instructions in the manual on that.  Maybe someone else can provide a better solution. 

[zmotorsports]

1 hour ago, 2003 Dynasty said:

Great resource Mike.  I have the same coach/year but a 7.5kw Onan.  Any idea how different the layout is for the 10kw vs 7.5kw, and thus the servicing differences?  I have changed oil/filters but not the belt or checked valve clearances (but have had those done by service tech).  Thanks for sharing the expertise.

 

Thank you.  As Jim mentioned, they are similar but different.  The Onan 10kw has more in common with the 12.5 than any other.  The layout is similar but fan layout is slighlty different between the 7.5kw and the 10kw as well as the spark arrestor plug location.  Some 7.5's also access the oil filter and drain plug via a removable panel on the bottom vs. the side.  As for the intervals to check things like belts and valves, they are pretty much the same service intervals.

 

54 minutes ago, jacwjames said:

I just changed the belt on mine.  Layout in general is close but my 7.5KW has a different fan.  I had to take off the top and rear panel to access but I left the rear panel in place and just tipped it back.  Hardest part was getting the 4 bolts off the pulley to remove the belt, no good way to hold the pulley from spinning.  Tried using a strap wrench but finally had to resort to using a channel locks on the pulley to hold it in place.  No real instructions in the manual on that.  Maybe someone else can provide a better solution. 

 

Jim, using an air gun or cordless gun zips the bolts out quickly and easily without worrying about the pulley turning under the belt. No need to have to find a way to hold the pulley.

[jacwjames]

2 hours ago, zmotorsports said:

Jim, using an air gun or cordless gun zips the bolts out quickly and easily without worrying about the pulley turning under the belt. No need to have to find a way to hold the pulley.

Tried a an air impact, wouldn't budge the bolt.  Had to use a socket/ratchet and small cheater bar.  No real good way to hole the pulley so I had to improvise.

[zmotorsports]

25 minutes ago, jacwjames said:

Tried a an air impact, wouldn't budge the bolt.  Had to use a socket/ratchet and small cheater bar.  No real good way to hole the pulley so I had to improvise.

 

WOW!  That's only a 10mm bolt so it shouldn't be that tight, maybe 50-55 ft/lbs. roughly.  I just use my cordless impact, but I'm surprised an impact gun wouldn't break it loose.  Hope you didn't tighten it back that tight?  I would worried about pulling the threads out of the hub.

[jacwjames]

Nope, didn't go back that tight.

[Joint Venture]

Your timing was perfect. Was planning on a full service of our 10kw gen set first week of May. Was wondering if there was more to have completed then just oil and filter. Now I can give the tech at Freightliner a list of what I want done. Our 10kw only has 1400 hours but I don't find anything in the records the PO had that shows any previous service. 

[Ivan K]

In your generator manual should be list like this one.

[Joint Venture]

11 minutes ago, Ivan K said:

In your generator manual should be list like this one.

I wish I had such a manual as the owner's manual has very little in the way of service paperwork for either the engine, trans or gen set. Thank you for the lists of required service on my 10kw gen set.

[Ivan K]

You can download your model specific Onan manuals here

https://www.cummins.com/generators/rv-generators/rv-generator-manuals

[zmotorsports]

13 hours ago, Joint Venture said:

I wish I had such a manual as the owner's manual has very little in the way of service paperwork for either the engine, trans or gen set. Thank you for the lists of required service on my 10kw gen set.

 

As Ivan mentioned and attached the link, most any manual is available for these gensets.  Using model and Spec and you should be able to download the manual(s) for your specific unit.

 

 I printed out copies of the various owner's, service and parts manuals and put them each into 3-ring binders in which I carry in the coach for reference when out on the road if necessary.  Also have them saved to my external hard drive at home.

[Joint Venture]

9 hours ago, zmotorsports said:

 I printed out copies of the various owner's, service and parts manuals and put them each into 3-ring binders in which I carry in the coach for reference when out on the road if necessary.  Also have them saved to my external hard drive at home.

I'm going to take your suggestion and purchase some binders for just that. Great idea, I've down loaded many manuals on my laptop but that is useless should it crash as is a possible.  Nothing like paperwork when a problem occurs.

[zmotorsports]

13 hours ago, Joint Venture said:

I'm going to take your suggestion and purchase some binders for just that. Great idea, I've down loaded many manuals on my laptop but that is useless should it crash as is a possible.  Nothing like paperwork when a problem occurs.

 

Plus, I'm old school in the fact that I still like and actually prefer paper service and parts manuals.  The ones I download to my hard drive are my backups.  

[bryan browne]

Great article and video, I have a 2007 with 10kw, Is there other parts I should carry, I see people ask about thermostats and sensors. I carry filters and a belt but would add parts to have in emergency. thanks

[zmotorsports]

2 hours ago, bryan browne said:

Great article and video, I have a 2007 with 10kw, Is there other parts I should carry, I see people ask about thermostats and sensors. I carry filters and a belt but would add parts to have in emergency. thanks

 

Thanks Bryan.  As for your question, I would say it would depend on what your particular maintenance program looks like.  There is no way you can carry all of the parts with you that could "potentially" fail, unless you carried an entire spare unit.  Sensors can and do fail, as does most everything else but keeping a close eye on things, looking at them more than once a year and being in tune with your rig will go further than me (or anyone for that matter) telling you what you should carry.

 

About the only part for the genny that I carry is a belt and that's just because I had a good used one to toss in a storage bin.  Other than that I don't carry other spare parts for the generator itself.  Now if I were going on an extensively long trip such as to say Alaska, I may bring along another air filter and possible a fuel filter but not sure about anything else, other than a very thorough preventive maintenance before leaving the driveway.

 

Sorry, that probably doesn't answer your question very well.  Maybe others will be able to give you a list of components to carry along.

[96 EVO]

My 10K has been reliable enough I don't carry any spare parts for it other than extra oil, and coolant.

All maintenance is performed on it while I'm at home.

[Ivan K]

I am with Mike on this, I only carry few things based on my previous failures. A couple of good used belts, fuel filter and pair of brushes just because I have them for next time. I also have a set of those 'special' Injector pump orings because they failed on our last trip and I ordered extras. Our 3LD1 pumps had PITA penta bolts that I replaced for regulars to save myself a hustle on the road. I haven't heard of anyone else having leaks at those pumps on a generator but 2 of mine did, at around 4k hours.

[Tom Cherry]

Whatever one feels he needs….he carries.  The list of spare parts for my Onan 8.0 was less than $75 ….maybe a few years ago.  Now, that is the belt, sensor, thermostat and gasket.  Always have spare oil and air….

How much brushes for the 10 would be….no idea.  So for maybe $100 MAX. .I can do, or let a shop fix anything that would shut me down….and not have to wait on stuff shipped in.

Our travel may be different.  We plan a 6 - 8 week trip.  Up to 9K PLUS miles….like from NC to West Coast to NW to ND and then Elkhart.  

We had GK’s flying in to SFO then daughter into SEATAC (Seattle/ Tacoma) the. Back out and son into Spokan and out somewhere further East.

Our plans are tight and we have 6 months out reservations for critical campsites…..and also tours and plays and whale watching and pageants…

Had a tire failure and kept on track…otherwise DW drives from Reno to SFO as GK’s coming in.

Never had a bobble with my Onan.  Eventually, it gonna need to PM.  but I DID have an issue at home….and had a leak.  So, tech put in new Thermostat….wish they would have called….then minor PM with my parts.

The parts listed were what the most experienced and full timers that started and joined this site said they carried….

NEVER thought that simple post would morph…..Oh WELL!!!

[bryan browne]

Mine is a 10kw and i have looked on the part breakdown drawings looking for the part number for the water temp sensor and have not found it. thought for sure it would have something on the cooling section drawings for location and part number but not there either. 

Update: I did find it on the thermostat assembly breakdown Page 40, Part # 193-0318, thanks again

 

Edited April 12 by bryan browne