Onan 6.5 NHE oil leak

[Rickf1985]

Had the generator running on the Pace Arrow and noticed it was leaking oil. A pretty fair amount. It is being sprayed out the bottom by the fn but when shut down a pretty good amount runs off the drip tray under the oil filter. I also noticed that when it would not start for some reason which meant a lot of cranking that I had a fair amount of oil coming off of the drip tray. This is after sitting for a week so I know the oil was just coming out during the cranking. I see there is a oil pressure sender above the filter and I have seen these leak profusely on cars, have any of you had this problem with a generator? And where is the best place to buy the parts?

[ClydesdaleKevin]

I'm guessing that if you can remove it, you can probably match it up to one at either an auto parts store, or a tractor supply place.  Or look up the part number and get it directly from Onan/Cummins, but it will probably be a lot more expensive.

Kev

[Rickf1985]

I thought about crossing it over to an auto one but the problem is that I do not know the pressure rating on it. Since this generator does not have a gauge or idiot light does it have low oil shut down? Is that the purpose of the sender?

[M & J]

I think it is a low oil safety shutoff Rick.

[gpw9552]

According to my NHE manual it is the low oil pressure shutoff switch.

[Rickf1985]

Thanks guys, I have to try to get the side shroud off and see what is leaking in there. I will pull the filter and look in and see if it looks like it is that sensor but I am thinking I may have to go deeper. Getting the shroud off is going to be a real treat, this unit does not drop out the bottom or slide out. It has to be unbolted, exhaust removed, unwired and then lifted over the edge of the compartment.

[DRMousseau]

That is indeed a sensor/switch above the filter. One of many safety systems that likely contribute to the famously long life of these things. It prevents starting and running if oil pressure is insufficient. Yup,... these take a bit of cranking to start up. Can't even check for spark till oil pressure builds. Some have a temp sensor that shuts it down when too hot too.

Blowing oil under running pressure is never good,.... usually means a gasket or seal has failed somewhere. And getting it out and removing shrouds means that EVERYTHING will be oil coated and not easy to find the source since it likely can't be run then to see where it might be coming from. UGH!!! THEN,... locating parts if needed!

Looks like I'm gonna need a fuel pump, plunger seals dry and cracked with age. Maybe some starter parts too, surprising since there's only about 500hr on this unit. It's all fine now, but neither is good enough to be dependable and both will be needed soon. So I'm anxiously awaiting any info on good part sources here.

[Rickf1985]

There is only 124 hours on this unit. As long as I can get the on shroud off that is around the oil filter I will be able to get in there with a mirror if need be to find the leak. If you spray it down with Castrol Super Clean and then rinse with water the oil and grime will be gone. Let it dry real good and then dust it with baby powder. Start it up for very short runs and shut down and look for oil in the powder. Any oil at all shows up dramatically and quickly in the powder.

[DaveVA78Chieftain]

If you spray it down with Castrol Super Clean and then rinse with water the oil and grime will be gone. Let it dry real good and then dust it with baby powder. Start it up for very short runs and shut down and look for oil in the powder. Any oil at all shows up dramatically and quickly in the powder

   Will remember that one!

[DaveVA78Chieftain]

That is indeed a sensor/switch above the filter. One of many safety systems that likely contribute to the famously long life of these things. It prevents starting and running if oil pressure is insufficient.  Yup,... these take a bit of cranking to start up. Can't even check for spark till oil pressure builds.

Most Onans (e.g BGM, NHM, etc.) are designed such that the oil pressure switch is cut-out of the circuit when starting the engine so you should still be able to check spark and such during start.

In the case of the NHM, the start switch provides a ground to the run relay (K3) for starting.  Once started the oil pressure sensor switch closes so when you release the start switch the K3 run relay still has a path to ground.  If you loose oil pressure, the oil switch opens which de-energizes the K3 run relay.

I would need to specific model & spec number for a given onan set to describe how each one is done.

[Rickf1985]

I took a picture with my phone of the numbers but they are unreadable. The label is very worn, probably from someone washing the oil off. No, not me yet. Learned that lesson long ago, keep the cleaner OFF the labels!!! I will go back and get the numbers again if I can read them but I believe it is in the second series of spec numbers. Here is the picture I took.

[DRMousseau]

Now I really LIKE that powder tip!!!! Finding those oil leaks has been a pain of mine for YEARS!!! (for some reason, I'm finding an urge to help my buddy's by throwin' a hand-full of the stuff into the fan and coat EVERTHING in a cloud!!! LMAO!!!)

And it look's like Dave is the man for Onan!!! And Onan jus seems so much better than others I've worked with. Those oil safety switches are a real pain on other setups,.... "I had spark? NOW what's wrong??? grrrrr!!!"

And the folks behind the Cruise Air II are real nice,.... ALL installed appliances (including the generator) are listed on a nice label in the main closet and include full model numbers AND serial numbers!!!

[Rickf1985]

That is handy, saves time digging around for labels that are faded like mine.

[DaveVA78Chieftain]

Rick,
Did not see this until now.  6.5 NHE
Oil sender Onan P/N 309-322  (Cheap enough just have to wait for the mail)
http://onanparts.com/index.php?main_page=product_info&products_id=588

http://www.partsfortechs.com/asapcart/onan-3090322-oil-switch-for-rv-gensets-etc-p-322.html

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313.TR0.TRC0.H0.XOnan+309-0322.TRS0&_nkw=Onan+309-0322&_sacat=0

Fairly sure that last Model No. letter is an "E" so it is a Spec E unit
It was built in October of 1989 in Minneapolis, IN.

Spec D-F: points / round coil
G and later: Electronic Ignition / square coil

Only one bolt used to hold the oil filter adapter plate on so it might be loose.

[DaveVA78Chieftain]

DRMousseau,
You have a 4.0 BGE Spec C.  Make sure you grab the correct Service manual 965-530. 
The K4 start relay bypasses the normal run relay functions during "Start" so yes, you should have spark to the plugs during start operations.  Once running the K3 relay energizes which de-energizes the K4 start relay. The K3 relay is in series with the low pressure oil switch so will shut the unit down on low oil pressure.  The K3 relay however is dependent on the K2 relay which is energized by the generator windings.  All explained in the control section of the service manual 965-530

[DRMousseau]

Yes, Thanks Dave.

When my generator didn't start right away, I was about to check for spark. There's a lot on some that can prevent spark, that oil sensor is one, and I wasn't so sure of the system here. So I was jus gonna check when "PoP! POP!",.... startled me so bad I let off the switch!!! Knew I had fire then. Hit it again, and it fired up momentarily. Knew I had fuel issues at that time. THEN, I referred to the manuals and learned a bit more.

BUT,... no oil leaks!! Nothin anywhere!!! Never did! Nice and clean!!! The 2.5LK in the ol' Winnebago was a different story though. A filmy covering over everything below the cylinder. Appears that it's probably the valve cover gasket behind the carb, and wasn't a serious issue. Jus a oily coating and no serious leaking or dripping like Rick's. I'm removing this genny since it's a good runner and the ol' Winnebago will never see the road again. I'm gonna mount it up for portable use in emergency power outages. I'll clean it up and go thru it good then.

But Rick's leak sounds to be a bit more of concern, and I'm quite interested in this. Would like to know what he finds and what the issue is for future reference. A loose oil sensor is easily prevented, a cracked one means I may need to exercise a bit of care in that area. If this proves to be from another source, it might be something to watch for on similar models or include a simple preventative check in my routines. The twins do run a lot smoother with far less vibration to loosen things up.

[Rickf1985]

I will be sure too post up what I find if it ever stops raining. Wet and cold do not go well with severe arthritis.

[Rickf1985]

Rick,
Did not see this until now.  6.5 NHE
Oil sender Onan P/N 309-322  (Cheap enough just have to wait for the mail)
http://onanparts.com/index.php?main_page=product_info&products_id=588

http://www.partsfortechs.com/asapcart/onan-3090322-oil-switch-for-rv-gensets-etc-p-322.html

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2047675.m570.l1313.TR0.TRC0.H0.XOnan+309-0322.TRS0&_nkw=Onan+309-0322&_sacat=0

Fairly sure that last Model No. letter is an "E" so it is a Spec E unit
It was built in October of 1989 in Minneapolis, IN.

Spec D-F: points / round coil
G and later: Electronic Ignition / square coil

Only one bolt used to hold the oil filter adapter plate on so it might be loose.

Dave, I have been looking at the manuals and I see that both the parts manual AND the service SHOW one bolt but I count the holes and read the text and there are two bolts on that adapter.

From the NHE service manual.

OIL FILTER AND ADAPTER
Open the oil drain valve and drain the crankcase oil.
Remove the filter (see Figure 9-1) by turning counterclockwise
with a filter wrench. The low oil pressure
cut-off switch is installed in a threaded hole in the filter
adapter and may be removed if required. Loosen the two
capscrews that secure the adapter to the engine block
and remove the adapter and gasket.
Assembly is the reverse of disassembly. Use a new
adapter gasket and install so the two small oil holes are
aligned with theoil holes in the block. Gasket should be
installed dry. Coat the threads of each capscrew with
non-hardening sealer and tighten to recommended
torque.

[DaveVA78Chieftain]

Easy to miss that without one in front of you.  Oh, the parts list does say quantity of 2  D:oH!

[M & J]

 D:oH!