Bad purchase?

[stuppy62 58]

I recently picked up a 520H with only 716 hrs. on it and it ran and drove on the trailer just fine. Brought it home and went over it thoroughly, changed oil, new plugs, adjusted hydro drive, etc.. Reinstalled the mower and tried mowing some early grass that needed trimming and it had no power. The motor really didn't run rough or sound bad to me. I drove it back in the garage and pulled the plugs out to check compression. Well, the rear cylinder had 90 PSI, the front cylinder had 0 PSI! What the heck! I gave up on working on it for the day, got back to it today thinking it might be a stuck valve, nope, busted connecting rod! The rod is not slapping around or anything, quiet! I quit working on it again to maybe get some of your opinions on where to go from here and best case scenario.

[WHX?? 51,784]

Well now that just down right sucks... looks like a PO wasn't keen on checking/changing oil. That cylinder looks rough but might be saved. The way I see it you have only two options, rebuild or replace/repower. Third option is parts it out to try and recoup yer investment but not keen on that but get it.

I would pull the motor apart and check things out and figure out what parts would cost and go from there. Since it ran after it threw the rod chances are good nothing else was busted up in the crankcase. 

Good luck and keep us posted.

[The Tuul Crib 7,339]

Can’t say it would have been a bad purchase of course depending on what you paid for it. Could be an easy fix or a costly one . 700 hrs is not a lot depending on how hard it was run. A little more tear down to see what is going on and what could be done.

[stuppy62 58]

Is it possible the connecting rod could have broke and didn't do any other damage?

[WVHillbilly520H 10,376]

1 minute ago, The Tool Crib said:

 Could be an easy fix or a costly one . 700 hrs is not a lot depending on how hard it was run. A little more tear down to see what is going on and what could be done.

Unfortunately it's an Onan and that means it's a bit more costly than your average Kohler or Briggs opposed twin.

[WHX?? 51,784]

39 minutes ago, The Tool Crib said:

 Could be an easy fix or a costly one

Breaking news  Cribs.... there usually no such thing as a cheap repair for an Onan. 

 

40 minutes ago, stuppy62 said:

Is it possible the connecting rod could have broke and didn't do any other damage?

Anything possible when they let loose Stuppy... ventilated blocks...destroyed cams... possibilities are endless. Odd thing is they often sometimes let loose on shut down when she's stopping meaning low rpm..  Good thing is it ran after the rod headed to Gilligan's island. Big thing is don't run it anymore till we find out what actually went south. Looks like you got that covered by the head off. Again pull the motor apart. We are gonna need to see the condition of the crank journals. 

[stuppy62 58]

I'll start the tear down tomorrow after work. thanks for your opinions! I'll keep you posted.

[WHX?? 51,784]

Please do .. no shortage of Onan experts here.

[ericj 1,579]

that's why I almost always run a compression test before I purchase it, at a minimum try and feel each exhaust pipe to see if both are getting hot.

 

From the decals I'd say it's at least a 94 or newer and in overall fair shape. If it where me I put it on the back burner and wait for a cheap 520 to come along and then do a motor swap, unless you got it cheap enough to put the forward swept axle and gear reduction steering on something else. ggod luck

 

 

 

 

eric j 

Edited April 18, 2019 by ericj

[stuppy62 58]

Well, I got it apart finally, been busy with work. It looks like to me the connecting rod nuts came loose because they were laying in the oil pan. Severe damage to the crank shaft, but it may be salvageable, not sure how I want to proceed. A donor engine would be the easiest fix, but if I repair this one at least I'll know what I have. On the up side the valves look good and the block is not harmed. I did find an Onan P220g listed for sale that claims to have new connecting rods a year ago, but valve seats have since gone bad, so it's a none running engine. If this motor did have CR's replaced then you would think pistons & rings would all be good as well. My question is would all parts be interchangeable for the P220g?

[WildmanC120 613]

I would probably show back up at their door with the tractor if it was me. 

[stuppy62 58]

Wildman, I agree, but I got other attachments with it that make it worth what I paid.

[stuppy62 58]

So, can any of you Onan fan's tell me if the parts(connecting rods & crank shaft) are interchangeable on these P220g's?

[onanparts.com 185]

9 minutes ago, stuppy62 said:

So, can any of you Onan fan's tell me if the parts(connecting rods & crank shaft) are interchangeable on these P220g's?

 

Rods are the same on the all the 18HP & 20HP engines. Cranks are the same internally and at the flywheel end. It's the PTO end of the crank that varies. Length, diameter etc.

[GMan 82]

You should stay with one pulled from a Wheel Horse to be sure the PTO end is the same dimensions (dia. & lgth.) as yours. I know the cranks in the 518 WH series would also work. Stay away from the cranks pulled from the WH 516 & 416 series as those have a different stroke and longer rods. John Deere used a lot of Onans but they had a 1 7/16" PTO shaft end diameter. Call Boomer at 651 437 2826 M-F 10-7 S-S 12-6 cent time. He is an Onan guru and likely has anything you need for your repair. If you would prefer to contact him by email is address is: (boomers_influence@yahoo.com). His real name is Robert Kummer. He's a down to earth guy, easy to talk to and doesn't make you feel upside down just because you might be unknowledgeable about Onan's...................Hope this helps.............Gary

[stuppy62 58]

Thanks onanparts and Gman, that's the information I'm needing right now! 

[onanparts.com 185]

2 hours ago, stuppy62 said:

Thanks onanparts and Gman, that's the information I'm needing right now! 

You're welcome! :)

[GMan 82]

15 hours ago, stuppy62 said:

Thanks onanparts and Gman, that's the information I'm needing right now! 

You're welcome...........glad to be of help............Gary

[stuppy62 58]

Well, I've done some searching this week for getting my Onan running again on 2 cylinders and I've come to find it kinda pricey! The machine shop would bore the cylinders, turn the crank, R & R the valves and remove a couple broken head bolts all for about $300. That didn't seem to bad. The problem is the new Onan parts to do it right would be $400 or more(no offense onanparts.com). I can't justify putting $700 into an old tractor! So I guess I'll be looking for a donor engine.

 So in the meantime I'm hauling my dad's 60" zero turn back and forth from his house to mow my lawn. Also, the lawn looks terrible when I use his mower!

Not sure of my next move?

 

[WildmanC120 613]

20 minutes ago, stuppy62 said:

Well, I've done some searching this week for getting my Onan running again on 2 cylinders and I've come to find it kinda pricey! The machine shop would bore the cylinders, turn the crank, R & R the valves and remove a couple broken head bolts all for about $300. That didn't seem to bad. The problem is the new Onan parts to do it right would be $400 or more(no offense onanparts.com). I can't justify putting $700 into an old tractor! So I guess I'll be looking for a donor engine.

 So in the meantime I'm hauling my dad's 60" zero turn back and forth from his house to mow my lawn. Also, the lawn looks terrible when I use his mower!

Not sure of my next move?

 

I think you are better off spending the money and doing it right.  If you pick up another used one you are just putting yourself into the same boat. Fix it, take care of it and run it another 30 years. 

[Sarge 3,465]

To rebuild one of those twin cylinder Onans - $700 is pretty cheap. Consider what it is and try to find any engine that has the true torque and horsepower in that range for a replacement - those engines are pretty much non-existent. Even the best series of new replacement engines aren't nearly as well built, nor will last half as many hours. You are far better off investing in the older engines if you can get a quality rebuild done versus trying to find anything built today to even fit into that application - the new engines are basically disposable anyway. You can research through some of the repower sites/companies that offer direct replacement "kits", but be prepared for some serious sticker shock. 

 

Sarge

[stuppy62 58]

You both make valid points and I probably will rebuild it, it just stings a little to pull the trigger on a rebuild!

 

[WildmanC120 613]

1 minute ago, stuppy62 said:

You both make valid points and I probably will rebuild it, it just stings a little to pull the trigger on a rebuild!

 

Yes I am sure it stings. But if the rest of the tractor is good then you will have a quality machine for many years.  You can't replace that machine with anything newer for less than a few grand easy.  

 

I bet it would be $500 to find a used tractor with a running motor and it will probably have over 1000 hours on it.  How was it treated before you?  The sand is running out of the house glass.  $700 to me seems awesome for that rebuild. It cost me that for a cheap harbor freight 22hp predator. 

 

It would cost you somewhere in the 1600 range just for a Briggs vanguard repower kit.  

[Sarge 3,465]

Considering the prices of these kits, and the work involved to cobble it together to work -

https://repowerspecialists.com/products/wheel-horse-520-with-onan?variant=6979132817431

http://www.smallenginewarehouse.com/Repower-Old-Equipment/Wheel-Horse-520H-Category/

 

That would truly hurt.

 

Sarge

[stuppy62 58]

Ouch! yeah, I'm not doing that!

I found on CL a 518 with Onan 18 SXL, considering buying and temporarily repower my 520 till I get my motor rebuilt. I'm considering this purchase for 2 reasons, obviously for the motor , but also, it comes with a tiller that I would like.

Question though, would this motor be a direct swap, wiring harness etc.?