Help with a flooding issue. 416-h. Looking for doctors in the house..

[jchris 27]

Background- Been on the hunt for my first horse relentlessly for weeks,  hours daily spent trying to "rescue " a survivor for a decent price. Lept abruptly at a 416-h with hydro lift. She's all there but looks to some degree like she spent 5 rounds in the ring with Mike tyson in his prime with parts "rearranged". Looking for some doctors in the house and I'm willing to perform the remote "surgery " as specified. When in need you lean on the specialists ;)...

 

Her issue- beyond, and somewhat in spite of, her neglect she runs.....sort of....and poorly. She starts,  but choked and only on full throttle,  otherwise she floods out. The only way, yet unproven as mentioned by the previous owner,  she runs is full throttle with the deck engaged. 

I've had her briefly running ( less than a minute) but then she stalls.

 

My observation- the " patient" entered the "exam room " ( my garage)  and seems to be intact,  all "appendices" are there. In general in decent shape for her age but with issues that can be "medically solved " with "surgery " to which I hopefully "deffer to "specialists" in this field for advice. Her cough of fuel is the pressing issue,  and thereafter we with move on to "cosmetic surgery " where I have a specialist "on staff" lol.

 

As a "general practitioner" in the mower field,  I'm Versed in small engines and my "diagnosis " leads me to believe this is a carburetor issue,  but the "Onan" patient requires a "specialist ", specifically you :). 

 

Docs, what do you specifically believe is your "diagnosis " and your recommended treatment ( what steps would you take to start)?

 

 

[953 nut 55,188]

I am not a doctor but I am very patient!         Sounds like your patient is suffering from fuel starvation.

First step would be to remove the fuel hose from the tank and drain it then give it a visual inspection. It there is ant derbies in the tank it can prevent fuel flow.

Install a new fuel hose with filter and verify that you have fuel flow from the tank to the fuel pump. DO NOT use gas with ethanol in it, this site will guide you to stations in your area that have pure gasoline,   https://www.pure-gas.org/

Now connect the fuel line to the pump and confirm that toe pump is functional.

Next step should be a thorough cleaning of the carburetor. 

OH,   one more thing we request of all new members;          

[jchris 27]

5 minutes ago, 953 nut said:

I am not a doctor but I am very patient!         Sounds like your patient is suffering from fuel starvation.

First step would be to remove the fuel hose from the tank and drain it then give it a visual inspection. It there is ant derbies in the tank it can prevent fuel flow.

Install a new fuel hose with filter and verify that you have fuel flow from the tank to the fuel pump. DO NOT use gas with ethanol in it, this site will guide you to stations in your area that have pure gasoline,   https://www.pure-gas.org/

Now connect the fuel line to the pump and confirm that toe pump is functional.

Next step should be a thorough cleaning of the carburetor. 

OH,   one more thing we request of all new members;          

Pics soon to follow!  Today is a busy day but I will try to do both( fuel lines and photos). I will advise,  at this state,  she has a "face perfect for radio ".

[lynnmor 7,305]

This statement;( "She starts,  but choked and only on full throttle,  otherwise she floods out.") makes no sense.  Flooding means too much fuel is getting in and the need for the choke means not enough fuel.  Regardless, it appears that the carburetor needs to be properly cleaned.  The information can be found in the Onan Service Manual.

[jchris 27]

14 minutes ago, lynnmor said:

This statement;( "She starts,  but choked and only on full throttle,  otherwise she floods out.") makes no sense.  Flooding means too much fuel is getting in and the need for the choke means not enough fuel.  Regardless, it appears that the carburetor needs to be properly cleaned.  The information can be found in the Onan Service Manual.

After re-reading that your right. I've been told she will only stay running if all attachments are engaged and she is at full throttle. Anything less than full throttle she dies. I have only had limited time to play with it as she ended up in the surgical room late yesterday evening. Will try to get more info for diagnostics later today 

Edited June 8 by jchris
Clarity

[ebinmaine 67,420]

 

 

 

Here's a link to a list we put together for several levels of checking over a tractor. 

It's broad and covers multiple types. 

 

 

 

 

 

 

We've reached a point because of ethanol fuels that many (most?) machines need the ENTIRE fuel system either replaced or correctly cleaned as part of the routine maintenance. 

Remove and replace ALL fuel line. 

Remove and clean fuel tank. 

Replace fuel tank outlet and grommet. 

Remove and rebuild (clean) carburetor AND FUEL PUMP. 

I put caps there for a reason. Fuel pumps seem to be ignored too often lately. 

 

It's likely your tractor will be happy to perform once that's done. 

 

 

[lynnmor 7,305]

4 hours ago, jchris said:

After re-reading that your right. I've been told she will only stay running if all attachments are engaged and she is at full throttle. Anything less than full throttle she dies. I have only had limited time to play with it as she ended up in the surgical room late yesterday evening. Will try to get more info for diagnostics later today 

First thing it is not a "she" and not a feminine product like is sold at big box stores. 

 

Since it may be starving for fuel, remove the fuel line at the fuel filter and direct it into a container to see how much it pumps while cranking the engine.  Of course take all precautions to prevent a fire.

[953 nut 55,188]

3 hours ago, lynnmor said:

First thing it is not a "she" and not a feminine product like is sold at big box stores.

At this point his 416 is being cantankerous, uncooperative and undependable.                   He, the 416, is exhibiting its femininity.  Once he has been shown some love and attention HE will exhibit more masculine characteristics.                 Hope my wife doesn't see this post.      

[adsm08 2,046]

14 minutes ago, 953 nut said:

At this point his 416 is being cantankerous, uncooperative and undependable.                   He, the 416, is exhibiting its femininity. 

 

The new Hybrid Explorers are like this. Best part is all those VINs contain the character sequence WOMNA.

[jchris 27]

I appreciate the assistance really,  but one word used ( she) seems that hilarious? 

[lynnmor 7,305]

13 minutes ago, jchris said:

I appreciate the assistance really,  but one word used ( she) seems that hilarious? 

When using the words she or her 17 times it does get to be a bit much. 

[jchris 27]

2 minutes ago, lynnmor said:

When using the words she or her 17 times it does get to be a bit much. 

Point taken. Let's try to focus on the issue now, alright? 

 

Edited June 9 by jchris

[oliver2-44 9,729]

1 hour ago, jchris said:

Point taken. Let's try to focus on the issue now, alright? 

 

Focus      

O Young Grass Hopper, I too keep relearning,  "Focus" is a challenging request for this crowd!

But, ultimately everyone will do anything possible to help you get your tractor running.

So far I'm just a Kohler guy, so I'll leave it to the Onan Clan.

Edited June 9 by oliver2-44

[jchris 27]

On 6/8/2024 at 12:28 PM, lynnmor said:

First thing it is not a "she" and not a feminine product like is sold at big box stores. 

 

Since it may be starving for fuel, remove the fuel line at the fuel filter and direct it into a container to see how much it pumps while cranking the engine.  Of course take all precautions to prevent a fire.

Had a chance to work on it. Pulled the fuel line off the filter post the fuel pump to test as mentioned. Flow non-existent. Continued to crank, fuel line freed of debris,  pump began pumping fuel. Reattached. Fired up and ran. Drove briefly. Parked it.

 

Next will be to power wash it ( needs it) then drain the tank, clean and flush it, change the fuel lines and filter. Then standard maintenance (oil, rear end, belts,  blades, air filter ECT) but on another day. Just glad it runs for now.

[ebinmaine 67,420]

2 minutes ago, jchris said:

Just glad it runs for now.

 

 

Niiiiice! 

[Bill D 1,916]

Nice.  Plan on a complete fuel system overhaul.  New fuel line, filters, tank shutoff with built in screen and tank grommet.  Run a compression check on each cylinder (throttle wide open and choke open when testing).   Plan to take the top off the carb and clean the carb, possibly more than once.

[jchris 27]

All maintenance items acquired Yesterday with a tremendous wealth of information gleaned from this site. In addition,  I was able to obtain a new-to-me 36" deck that I drove 6 1/2 hours round trip to pick up. Gonna be a full day of cleaning,  polishing and doing the PM's that most likely have been ignored. 

[Bill D 1,916]

Please consider purchasing a membership.  This will allow you to post unlimited pictures which will make it easier for us to help you.  When trying to help someone diagnose an issue long distance a picture can be worth a thousand words.  

 

If you haven't done so already, check the transmission mounting plate for cracks.  I've seen a few of those on high hour, abused machines.  If it's cracked that may change your long term plans for the machine.  

 

I have two P216 Onans.  In addition to the fuel system renewal items I like to do the following:

 

Change the plugs wires.  The originals are 30 years old.  I use solid core wires. 

 

Run an additional 14 GA wire from the positive terminal on the starter to the voltage regulator/rectifier.  This takes the charging load out of the 9 pin connector.  With some silicone spray and patience you can push it thru the harness sleeve on the engine.  Add a fuse.  Two 14 GA wires will fit in a yellow female spade terminal at the rectifier.

 

Change the Headlights to LED.  This lessens the load thru the 9 pin connector.

 

Clean the 9 pin connector. I use a pin to spread the male pins apart slightly to help insure a good connection.  I prefer to use Noalox on these pins.

 

Clean the cooling fins.  Brake clean and an air gun are your friend.  Plan to fix any oil leaks.  Be sure the rubber seal on the outside of the oil filter is in place.

 

I'm sure I forgot something.  I'm sure others will chime in 

 

 

 

[jchris 27]

Well maintenence done and she ran beautiful for roughly 3 hours. It took some coaxing but after awhile it purred.

 

 

Then I think a catastrophic incident happened. 

 

It began to sputter,  then died. Less than a second after it shut off a lazy flame was coming out of the exhaust for a few seconds. 

 

I tried to restart it, and the starter tries to engage but won't turn over. No loud bangs when it shut off, nothing . 

 

[artfull dodger 394]

More Onan things to maintain.  one, if the rubber grommet to seal the cylinder tin to the oil filter body is missing, replace it ASAP!  Very important to keeping that rear cylinder cool.  Next up, Onans have adjustable valve lash and this must be checked and adjusted every 250 hours of operation.  Failure to do so can result in valves not fully closing causing cylinder imbalance between the two and overheating the hardened valve seat.   Cylinder imbalance can cause a rod to throw, and overheating the valve seat can cause it to pop out of the alum block.  This is especially common on the 20hp Onan more than the 16 and 18 hp version due to a larger bore leaving less block to act as a heat sink.  You can download the Onan engine service manuals online to see the procedure to set the valve lash.   When you change the oil, shine a flashlight in there and look for oily buildup under the flywheel and the cylinder fins from leaking crankshaft seal ect.  You want the fins dry and clean.  Only work the engine at full rpm, 3600 +or- 50rpm under load, ie mower deck engaged.  Onans are a beast but are more particular in their upkeep and during overhaul compared to a Briggs or Kohler of the same vintage.  They come from the generator world, they move a lot more air when compared to other brands as many times they are mounted under an RV ect.  They are like a sports car, where a Kohler is the Chevy truck you just cant kill.  That said, I love my Onans, have 2 of them and nothing beats the throaty roar of a finely tuned Onan at full throttle!  

 

[lynnmor 7,305]

6 hours ago, artfull dodger said:

More Onan things to maintain.  one, if the rubber grommet to seal the cylinder tin to the oil filter body is missing, replace it ASAP!  Very important to keeping that rear cylinder cool.  Next up, Onans have adjustable valve lash and this must be checked and adjusted every 250 hours of operation.  Failure to do so can result in valves not fully closing causing cylinder imbalance between the two and overheating the hardened valve seat.   Cylinder imbalance can cause a rod to throw, and overheating the valve seat can cause it to pop out of the alum block.  This is especially common on the 20hp Onan more than the 16 and 18 hp version due to a larger bore leaving less block to act as a heat sink.  You can download the Onan engine service manuals online to see the procedure to set the valve lash.   When you change the oil, shine a flashlight in there and look for oily buildup under the flywheel and the cylinder fins from leaking crankshaft seal ect.  You want the fins dry and clean.  Only work the engine at full rpm, 3600 +or- 50rpm under load, ie mower deck engaged.  Onans are a beast but are more particular in their upkeep and during overhaul compared to a Briggs or Kohler of the same vintage.  They come from the generator world, they move a lot more air when compared to other brands as many times they are mounted under an RV ect.  They are like a sports car, where a Kohler is the Chevy truck you just cant kill.  That said, I love my Onans, have 2 of them and nothing beats the throaty roar of a finely tuned Onan at full throttle!  

 

The 16, 18 & 20 horsepower engines all have a 3.250" bore.  The maintenance schedule for valve adjustment is 1,000 hours, but I think that should be reduced a bit because of the varied use in a tractor.

 

[jchris 27]

I'd like to thank everyone for this assistance. I did have it running but I believe it now has had a major mechanical failure inside the engine. ( see onan p216 post in the engine section of this forum).

 

It will be sent down the road as a donor for a future owner. Again,  thanks everyone. 

[artfull dodger 394]

The preferred rule of thumb and taught at the Onan engine school years ago when B and P series engines were nearly new was every 250 hours, adjust the valves and decarbon the heads and piston tops.  Only the RV gensets on propane got a different decarbon vs normal gas.   Every Onan I have owned or worked on and opened up at 500ish hours had valves way out of adjustment, usually tight to the point that one or both were being held slightly open all the time.  One should hear a little valve train clatter at low rpms when its set to the book spec.