Miller 225g welder replacement engine

[jayste]

Hey, thanks for all the valuable information. I'm in the stage of figuring out which direction I need to go. I'm thinking worst case is rebuilding. Adapting another engine may have it's hurdles but cost of rebuilding might not be feasible. If I could find a replacement engine from a generator that would be great. Especially if it was only 160.00!!

 

[onanparts.com]

Another issue with trying to use a genset is the starter. On early models battery voltage is applied to windings in the genset to make it "motor" or spin and start the engine.

On later models the starter is mounted to the adapter that connects the generator head to the engine. The ring gear is located inside the adapter. Onan engines used on tractors and welders have the starter mounted to the engine block in several locations and engage the ring gear on the flywheel.

The BGD 4.5KW series gensets use the same internal parts as a P218G. Rods, pistons, valves, cam etc. Your Bobcat should have a P216G. Swapping the internal parts from a BGD to your block would give you an 18HP engine.

My experience over the last 20 years is mainly with the Onan engines used on tractors and welders. BG, BF, B43, B48, P216, P218, P220, P224 etc.

I just picked up a BGD genny for parts and will be stripping it down soon. I'll let you know if in fact the PTO end of the crank is the same type of taper as the miller bobcat.

 

[BobG_in_VA]

......
My experience over the last 20 years is mainly with the Onan engines used on tractors and welders. BG, BF, B43, B48, P216, P218, P220, P224 etc.

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I've got a '99 Trailblazer with the P220 Onan on it. I picked it up "used" about 3 years ago with 11 hours on it...I was told by the Miller dealership that sold that unit originally that those Onan engines are known to last well over 4000 hrs with decent maintenance...Can you confirm that??/PS: I still only have about 60 hours on it....Thanks for any info. BobG in VA

 

[onanparts.com]

4000 hours is about average with normal maintenance before an overhaul would be called for on the Onan Performer series engines.

Definition of an overhaul on Onan engines with no issues other than burning oil.

Valve job and replace rings. Polish crank and put it back together. As long as the pistons, bore, rods & mains are within specs, this is true more often than not, that's it.

Unlike some other brands the Onan is not a disposable engine. It's designed to be rebuilt many times, and even though production ended in 2004 all the parts required to keep them going are still being produced and are made right here in the U.S.A.

 

[jayste]

Onanparts.com, sounds great. Keep me posted on the parts you're talking about. I'd like to tap into your knowledge on this internal part swap to obtain the 18hp rating if the costs are feasible.

 

[BobG_in_VA]

4000 hours is about average with normal maintenance before an overhaul would be called for on the Onan Performer series engines.

Definition of an overhaul on Onan engines with no issues other than burning oil.

Valve job and replace rings. Polish crank and put it back together. As long as the pistons, bore, rods & mains are within specs, this is true more often than not, that's it.

Unlike some other brands the Onan is not a disposable engine. It's designed to be rebuilt many times, and even though production ended in 2004 all the parts required to keep them going are still being produced and are made right here in the U.S.A.

Thanks for the info....looks like I'm gonna have to start looking for someone to pass this unit on to after I'm gone...BobG in VA

 

[onanparts.com]

Another issue with trying to use a genset is the starter. On early models battery voltage is applied to windings in the genset to make it "motor" or spin and start the engine.

I just picked up a BGD genny for parts and will be stripping it down soon. I'll let you know if in fact the PTO end of the crank is the same type of taper as the miller bobcat.

Update:
I stripped the BGD down today and discovered a few things. The PTO taper is "close" but not the same as the crank used on the Miller welders. The genny tapered crank is a little longer and smaller in diameter. So no go in that department.

The block is identical to those used on the welders. The mounts are there to hang a starter for use with the normal flywheel ring gear setup. The timing cover does not have the stator mounts drilled and tapped but the ignition module mounting location is tapped.

Mounting points for the welder adapter at the block are the same and will bolt right up for a miller.
So bottom line is to use a BGD genny as a donor you would need to use the following parts off the welder engine.

Starter, oil base, timing cover, exhaust/muffler, intake and carb, crank, rods, flywheel, ignition components, shrouding.

If your crank is ok or can be turned then a BGD donor would work fine if your block is junk or shot.

 

[jayste]

Onanparts, see email correspondence from me through your website. Thanks for the information and I hope between your parts and whats left of my engine we can get this thing going without too much hassle.

 

[Stimw]

I found a good web site that has good Onan discussions, a lot of other engines too. Antique Engines Antique Tractors Steam Engines and Old Iron if you go to forums, down near the bottom is Onan.

 

[jayste]

Ok. Thanks for responses. I'll check it out.