Onan 5500 Quiet Diesel question

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JSC51

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Apr 20, 2019
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Hello all. New to the forum and this is my 1st post ... in fact it is my principal reason for joining the forum.

This is the start of our 5th year in a 2005 4 Winds Chateau (35' Super C on a Chevy Kodiac chassis).

Changed the oil in the Generator today and ran into a situation that I've never experienced before. When it came time to add the new oil (CF4, 15W40) I manged to get the full 2 quarts down the fill tube only to see fresh oil running onto the ground.

Your first thought is probably the same as mine; dummy left the drain line open ... nope. Checked the oil filter and that was tight too (engine is not running either). Oil is dripping from 2 drain holes in the bottom of the Generator Pan under the fill tube. I'm guessing that I put less than a pint on the ground. Dipstick showing about half way between "Full" and "Add" marks.

After mulling this over for a couple hours and looking at Onan Maintenance and Parts Manuals, I can only think of a couple reasons:
1. Oil fill tube has become dislodged from the engine block.
2. Oil fill tube has a crack in it.
3. Oil backed up while I was filling.

Please let me know if you've experienced or heard of a situation like this as well as your recommendations. I'm not going to run the gen-set until I get the cover open and spilled oil wiped up.

Thanks

Jack 


 
 

Drewd

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I'm assuming you ran it for at least 15 minutes to get the oil warmed up to temp before draining it?

Did you measure how much oil came out? 

Did you remove old oil filter and prefill new one with some of the new oil?

15w40 is like molasses and needs to be poured in very slowly so the air it displaces has time to move.  If you fill too fast, you may have air entrapment which is not uncommon on small engines and this can cause it to backup.

I'd check the oil level, ensure it is full, run generator again, check for leaks, and check level another again after it is turned off.

Most commonly available 15w40s are conventional oils (not synthetic) and although not an approved viscosity, there is no harm in using 5w40 oil in your generator.  It will be much easier to start (higher cranking speed when it is cold outside) and should actually protect your engine much better, and it pours MUCH better than 15w40. 

 

Gary RV_Wizard

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I lean toward the back-up, for the reasons Drewd described. 

With the oil level between Add & Full, there is no reason not to run the genset and circulate the oil. Then top off.  our genset has a diagnostic fault code for low oil pressure, so no worries about damage due to insufficient oil.
 

Henry J Fate

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A bad filler tube is fairly common in your genset. If it turns out to be bad, a replacement plan should be a priority and will be contingent on access.
 

WILDEBILL308

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I am inclined to believe it just burped some oil out from the backed up air. Was it leaking out on the ground before? Try filling it slowly and see if you can get it to take the oil.
I run Shell Rotella T6 5-40 in my diesel generator.
Let us know what happens.
Bill
 

JSC51

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Apr 20, 2019
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Drew, Bill, Henry, Gary

Thanks for the input guys. Yesterday being Easter, I didn't have a chance to dig any deeper into the issue. I did however have a few minutes under the rig and can report that the oil has stopped dripping from the bottom of the gen-set case ... probably less than 1/2 pint total spillage. I also got some oil-dry dispensed to soak up the spilled oil and was able to locate a large inspection plate (about 12" x 12") on the control panel end of the gen-set. I hope I can get a clear view of the engine block and filler tube from here and I should also be able to mop up any remaining oil once the inspection plate is removed.

Responding to some questions/comments that you tossed out:
- No oil leakage prior to this. Bottom of case was dirty but dry as a bone.
- Once I get any oil that might remain inside the gen-set case wiped up I will recheck the oil and fire up it up.
- Yes, gen-set was run for 10 or 15 minutes to get the oil warmed up before draining.
- I did not measure the amount of oil that was drained.
- Oil filter is mounted horizonally and was installed without pre-filling to avoid spilling oil (so much for protecting mother earth when Murphy is on the prowl).
- Haven't reinstalled access plate for oil filter yet so that I can inspect for leaks with the engine running.
- Assuming that the oil sump is still indicating between the full and add marks, I'll make up the difference with 5W40.

I'm headed out of town on business today. Will post again after I craw back under RV next weekend.

Thanks Again

Jack 
 

JSC51

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Apr 20, 2019
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Henry

You indicated that a cracked filler tube is pretty common on this gen-set. What is the tube made of; metal, plastic? Do you have any 1st hand experience in replacing?

Thanks

Jack
 

Gary RV_Wizard

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Don't know about your QD 5500, but the horizontal oil filter on my QD 7500 was impractical to prefill.  At best you might get 1/3 fill in the small filter, just a few ounces. Not worth the effort, in my opinion. Besides, pre-fill or not would seem to have no relationship to your spill.
 

Henry J Fate

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I have not replaced the tube in the 5500 but it appears to be fairly easy if you can get to it. Here is the best link I could find.

http://www.irv2.com/forums/f54/onan-5500-quiet-diesel-generator-oil-fill-dipstick-tube-165256.html
 

JSC51

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Apr 20, 2019
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I dropped the RV of at Cummings Service Center in Baltimore.

Got a call yesterday that they inspected the gen-set and found that the oil is leaking from where the oil fill tube enters the engine block. Repair involves removing get set from coach, removing some or all of the external pieces that makeup the gen-set housing, cleaning up spilled oil, replacing damaged parts, reassembly, reinstalling into the coach.

Bill will be approx. $1300. 

If you see Mr. Murphy, that guy with the law is named after him ... kick him where he kicked me please.

Jack
 

Henry J Fate

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That stinks. Sorry about that. Ask them to save the old filler tube so you can look at it. Also, ask them if the replacement tube is any different than the one they took out. I believe they used a poor choice of material for the stock tube. It dries out and isn't resistant to the temperature swing it is exposed to. I would be a little reluctant to use the same stock part for a replacement. You could call Cummins to see if they resolved the problem.
 

JSC51

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Apr 20, 2019
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Henry

I did ask that they save all the parts that are being removed/replaced. My thoughts are going down the same path as yours.

Coach should be ready to pickup next week. I'll let you know what the fill tube looks like.

Jack
 

sinapu

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Jul 31, 2019
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Jack,

I'm actually going through the same exact thing you did in my 2006 Jayco Seneca ZX . I've read about everyone's nightmares with this issue, very curious to hear what you found out.

Roger
 

Scott Morneau

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May 28, 2020
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I found out about this issue after buying a 06 Seneca with the QD 5500.  Difficulty with re-insertion of the dip stick prompted a search on the issue. 

What i found was it requires access/ removing the gen from the MH,  an expensive repair, with no good upgrade to the failed fill tube.  Furthermore, some of the new style dip stick assemblies , that were suppose to be a fix, came apart and caused catastrophic engine failure.

I ran across a fellow RVer with a QD5500 in Colorado and asked him if he was  aware of the issue .  He was already a victim of the failed fill tube and explained to me the problem was NOT keeping oil in the engine
but rather getting oil into the engine through the tube.

Well that got me thinking...if i can get the oil into the engine without the tube can i dodge the big service bill or DIY ordeal.

So i hooked a section of hydraulic hose to the oil drain valve and i now use a funnel to fill it through that hose.  I DO NOT USE THE DIPSTICK ANYMORE.  I fill and check the crankcase level by using the hose.  It takes  2 qts to fill.

To check the level i have a high level mark on the side of the generator and the hose is long enough to raise or lower it by the mark to see the level in the end of the hose.  A small funnel is jammed into the hose and held above the mark to fill.  This is actually easier than trying to get oil into dipstick tube. 
A plug in the end of the hose keeps the dirt out and ALWAYS close the drain valve when not checking, draining, or filling.

So far this has been working.
 

Dustdevildan

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Jan 13, 2022
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I have a 2006 Jayco Seneca with the QD5500. Has run fine for quite a while, but started showing an over-temp code. Topped off the coolant, and that went away. While I was at it, checked the oil. Bad move. These dip sticks are awful. You can't get a good read on the level. Appeared low, so I put in half a quart. Still low, so another half. Then another and another. Looked just a bit high, so I started the generator, and it cranked slowly. Suspected overfill, so THEN I consulted the manual. The odds were that it was not actually completely dry, so I came to the conclusion it was over-filled. Drained it all, and refilled with new oil exactly 2 quarts. Runs great, but smokes badly. I suspect I have a slug of liquid oil in the exhaust. Initially threw a couple of low-frequency codes and shut down, but it runs continuously and very smoothly now. Just smokes. Taking it in, as I don't have the ability to drop the genset from the chassis for service. Don't believe the head gasket is blown, since it still seems to be full of both oil and coolant. I feel like a bonehead for continuing to add oil, but the dipstick wasn't registering a reliable level, and it appeared to still be below the minimum. If anyone has figured out how to reliably read these dipsticks, let me know. Because this has been a problem ever since we bought the MH. Likely looking at a $1000 bill.
 
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