I was asking myself the same question about my 1953 DC-180. Turns out Kohler has a *very* nice unit but it'll set you back about $2200.... that's a bit much for me, I opted to rebuild.

 

Not uncommon for the Onan to break a rod and keep on running on the other cylinder.

Crank taper used is a 2.25 or total of 2.25" per foot on Onan crank type 45BG. Your crank is likely still good and if it were me I'd rebuild as nickel_city_fab did.

You can contact TJ (member onanparts.com) on his website http://onanparts.com/ for everything you need or give ebay a shot.

 

Thanks for the crank specs. Now is it a testament to Onan durability that they run with a snapped rod, or does it mean they are crap because it is not uncommon for them to snap rods?

 

I would think it would make an ugly noise running on one cylinder

If your not a fan of the rebuild ; harbor frate has a 22 HP on sale for $699 that looks like a KOHLER COMMAND or CH 650 and may directly fit with love joy's. I dont know about tapers and thought that was an ONAN thing but dont know for sure. I do know I shouldnt reccomend harbor frate stuf but if your in a jam it might help.

 

Aluminum rods often suffer from cyclic fatigue in higher hour engines. It's just a fact of their finite life whether in an Onan, B&S, Kohler, Honda, etc.

You will likely find material transfer from the rod to the crank throw but this is easily cleaned up with progressively finer grits of sandpaper.

 

Apparently no one in the Buffalo, NY area rebuilds Onan engines. I called 6 places with no luck. The people who rebuilt them in the past said they will not touch them now due to parts scarcity and cost. They said the last couple they did cost $2500 to rebuild! So it is re-power or sell this whole machine for parts and buy a different used machine.

 

I am assuming of course that the current motor will need machine work which I cannot perform. If I could get by with a sand paper and cylinder hone rebuild, with new pistons, rings, bearings, and gaskets, it would probably cost under $500 to rebuild this Onan. Time is also an issue because I have 3 children all 3 years of age or less.

 

Do you have a B.O.C.E.S. or other vo-tech school with automotive or small engine course in your area?

They are always looking for projects to work on to give students exposure to and experience with different types of engines and equipment.

You typically supply the materials and they supply the labor and equipment to do the job.

 

Good idea! We have two in the area, one of which I attended in high school. They have mixed results with engine rebuilds though (my friends were in auto mech class and only one group got their rebuilt motor to run). I guess my next step is to tear it down and assess the damage now that my weekend side job is done. (Used the Ranger 8 to repair an outside wood burning furnace this weekend). I have to tear the motor down to get it separated from the generator anyway. Who knows, maybe I will luck out and it won't need any machine work?

 

I could do the rebuild for you if we were close to each other.

 

Nw Ontario is a bit of a drive, thanks though. I just saw a decent YouTube video with an Onan just like mine...shattered rod and piston, still ran. Doesn't look too complicated to rebuild. I will post pics of the tear down as soon as I get to it.

 

try either Stoelting Machine (niagara falls) or Northeast Machine in NT

 

Will do!

 

And you or they will need one of these to remove the crank gear without damaging it or the block in the process.

 

Duane does good work and has nice dedicated tools. This is what I made to remove the gear on my 216 Onan. Just be sure to use Grade 8 or better screws.

 

Thanks for the tips on the crank gear guys. I have been reading info posted by onanparts.com too so I saw the bit about the tapered crank on the generator side.
I am a bit eager to start this project as it will be a good learning experience for me. Never had a motor apart and back together before, but always wanted to.

 

Good news and bad news. The rotor stayed inside the stator housing when I pulled the motor off the chassis tonight, so that made life easier. I definitely have a shattered connecting rod and piston in there!

Looks like the cam and valves are ok, crank has a couple little dents in the journal that should smooth out enough with fine sandpaper. But the cylinder bore is another story! Looks like the wrist pin walked out and gouged the cylinder wall pretty bad.

Based on my field expedient feeler gauge measurements, that gouge is 10 thou deep, so it should bore out easy. Also it looks like 2 pistons, rings, gasket set, connecting rod, etc. would be at least $600... plus machine shop time. So I have a lead on another Onan that I would have to swap my tapered crankshaft into (would still cost me $200+ in gaskets to get that done). If that doesn't pan out, I will lean towards re-powering this welder. Which leads me toward my final question for those "in the know"....did the Ranger 8 machines have different mounting surfaces with the different motor options or are they all the same? The bottom doesn't look like a problem, but the rear bearing plate area on my Onan bolts up to the chassis where the tapered shaft meets the rotor and that does not look like a universal type of mount to me.

Will the Honda or Kohler options bolt up here?

 

From the looks of the photo, the gouge in the cylinder from the wrist pin appears much deeper than .010" ? You should have not ran the motor anymore after you heard the one side come apart. Do you have a set of telescopic gauges and a mic set to determine a more detail measurement?

 

I believe the whole problem was caused by the wrist pin walking out of the piston in the first place. Once it came apart the damage was done and all the chunks made their way to the oil pan. I do not have inside micrometers on hand but I do plan on aquiring a set to get a more accurate measurement.

 

I believe that mounting pilot and bolt pattern is an SAE standard.

Swapping cranks with another running engine is common and you just have to make sure the rods in the replacement are of the same journal size (Std., .010" under, etc.). If undersize you will have to have the crank turned down to match if it's still standard dimension. Also, to get the crankshaft out of a replacement engine you will need to pull the heads and piston/rod assemblies so you may want to consider new rings and a cylinder honing in the process.

I see you have at least one snapped off head bolt and you MAY be able to get the remaining piece out by welding a nut to it and turning it out that way. On these Onans I've been successful using this method and other times have had to drill/tap to address it.

On the cylinder scoring, keep in mind if the gouge is .010" deep then you're looking at .020" oversized pistons minimum and may need to go to the largest available .030"OS.

 

Not sure yet exactly what the other motor is (216, 218, 220?). It would be very good luck if I could just swap the crank, hone the cylinders, and put new bearings, rings and gaskets in. My current block is questionable for sure in regards to how deep the gouge is. Would probably have to go with .030 + pistons, which would just get too expensive compared to a replacement engine.
I actually have 3 snapped head bolts, 2 of which I can get my stud extractor on to, the other I will be doing the welded nut trick (done that lots of time).
I looked briefly online and found a couple new motor options too. How does this one look?http://www.smallenginewarehouse.com/356447-0397.html

 

Alternate motor is a p220. So cranks are same but rods are different?

 

No, cranks and rods are different due to the longer stroke. Sorry that I wasn't clear on that before.

A different stroke is determined by the crankshaft and compensated for by either a shorter/longer rod OR shorter/taller piston deck height (C/L of wrist pin-to-top of piston) presuming one or the other remains the same dimension for the different strokes.

 

So where the hell do I get a motor with the right tapered shaft?

 

Don't worry about the taper.

I've got a 4.8KW genset with a tapered input shaft that I repowered last year. Neither of the engines had a tapered crankshaft.

As long as the crankshaft goes about an inch into the armature, and leaves the brushes on the commentator (or slip rings) you're good to go. Just make sure to torque the draw bolt up sufficiently.

 

How much would you guys expect to pay for machine work on these engines if I wanted to re-bore the cylinders and maybe clean up the valves?

 

Again, check with your local vo-tech school as they may have the ability to perform the work or know of a reasonable source that can.

 

Times like this I wish I had a mill in addition to my drill press. A strong boring head in a mt3 drill press might still not be precise enough for boring the cylinders.

 

Totally my opinion and I have done this:

Pick up a cheap Predator brand engine of about the same size from the Chi-com place.

Bolt it up to the remnants of the existing equipment.

Run with it.

You'll be able to pay for 3 engines by the time you get the Onan rebuilt.

Or, do the research and get the right Honda engine. You'll pay about what rebuilding the Onan will cost, but you'll have a brand new Honda power plant.

Honda is still making parts for it's engines. I rebuilt a 5.8KW Honda genset engine and a Honda riding mower engine with factory parts from a local retailer.

Do what works best for your checkbook. Remembering that downtime has a price too.

 

The Onan has a date with a machine shop in Hamburg New York tomorrow. I finally found a place only a few miles away from home that wasn't intimidated by Onans. We'll see what they quote the job at. If it is as high as I expect, I will go with a new replacement. I really just don't want my engine being a vo-tech experiment, even if it saves a few dollars up front.

 

I was quoted about $150 for both holes on my Wisconsin engine, comes with a 3-yr warrantee. I'm buying the pistons and doing all the assembly work. Which means I'll be able to update my build thread in a week or 2.... Duane, I'll try to document mine as much as possible. Should only take a weekend to get it back together.

 

Keep us posted.

 

I am thinking mine may get just the damaged cylinder sleeved. We will see though. Is there any better places to source parts than onanparts.com? (Not that they aren't good per-se, they look top notch to me.)

 

Not sure, I'm not real familiar with Onan, but I know that they are good stuff. Check with these guys here: http://www.smokstak.com/forum/forumdisplay.php?f=1

I'm on the Wisconsin forum on another part of that site. BTW that is a *real* good site for all kinds of old engine info and mechanics tricks.