View Full Version : miller bobcat 225 needs engine
I recently bought a used miller bobcat 225g plus welder generator. It is powered by an onan P216 engine that needs to be replaced. Apparently onan is no longer being manufactured, and is very pricey if one can be found. I would like to replace it with a less expensive brand. Does anybody know what model Kohler or Briggs will interchange?
07-27-2005, 12:37 AM
hmmm, well I dont know but I can look into this, I have the 225NT and its got the kohler, one good engine. Wouldnt go with a briggs if I was you. but Ill see what I can get on the info.
07-27-2005, 12:44 AM
hmm when I searched on the owners manuals I found that the onan engine is a 16hp engine, the kohler is a 20 hp. Here is what Id do, go to the miller welds website and theres a link called ask the expert. You will want to pose your question obviously to him/ her as this way they can give you a definative answer without any bs involved. I would question regarding the kohler or another engine. Hope this helps.
Thanks for the help. I agree about the kohler thats the engine I'd like to put on it.
I'll check the miller website and post what i found out in case someone else is having the same problem.
07-27-2005, 11:54 PM
Been there done that. I have a 225G with a new Onan ...now. I had to go to ebay and get one, nothing local. Anything from the 16hp to the 25 hp WILL fit it. The extra hp will not hurt a bit. The trouble will be mating up the shaft of the engine to the rotor adapter. If you get a 16 or 18 hp Onan, just reuse the old shaft, providing it is servicible. Mine was and that is the road I took. It was less painful than adapting another engine. FWIW, I got a low hour P-216 for $600ish shipped.
Adapting a different engine can be done. Kohler was always my next choice since they are easy to get parts for. There are always lots on ebay as well...new and used. The next step will be to mate them up. Shafts will not match no matter how hard you look. You will need to make the generator part of the machine a stand alone unit. A member here did that by using the adaptor plate from an older AEAD model and braces down to the frame. Everything needs to be aligned perfectly, btw. The next step is to install a bearing in the adapter plate with keepers and fabricate a stubshaft to meet the new motor. The two shafts can then be mated up with flexible couplers..the kind they use on log splitters and such. Next step will be adapting a idle solenoid and wiring. That can be fun as well. After all this is done, any motor can be used in the future. .....Now do you see why I went with another Onan??
I'm sure this has brought up more questions. Fire away. I can provide pics etc.
07-27-2005, 11:55 PM
Do a search on Miller for my rebuild...it is titled Bobus Rebuildus.
I tried the miller answer man and the reply I recieved was " we do not support engine swaps." As far as I know onan engines are out of production. I Work in a pretty harsh envirornment and a more economical engine with better parts availability is the way to go for me. Is the shaft on the onan engine Iv'e got now tapered,threaded or keyed? The drawing in the owners manuel looks threaded, but i know most generator engine shafts are tapered. Once again thanks to all who donate information.
07-29-2005, 12:08 AM
If memory serves, you have a threaded shaft. You will not be able to match that shaft with another engine's shaft. They are specific to Onan. Get the engine family and serial number off the old one and give Onan a call. They will have the exact shaft size and specs for you.
You are correct, Onan is no more. You had an Onan/Linamar engine. The Onan's in production today are Onan/Robin. They are made by Robin and actually are a Robin engine. They may be a source for you as well. Robin is slated to drop the Onan handle very soon.
I thought of another mate up option. You can have a rotor adapter plate made by a machine shop that would be a direct connect to whatever engine you get. I considered this course, but was too expensive and would have taken too long. ( I was told 6 weeks min. by the machine shop...that and $7-900 ! :eek: ) You may have better luck, or can do it yourself. After that all you'll need would be an endbell to bolt to the engine and stator assembly together.
If you go with another engine brand, other than Onan, be prepared. A new engine will run from $1100 to 1400 and the extra work can easily add up to $6-700+. You will easily spend $2000 +. Kinda pricey for an old machine. I spent in the $1400 range for mine WITH an Onan. One thing you may want to do that I tried, is look at welder or generator repair shops. Try to find a similar machine with a bad weld side and a good motor. I found two, but they wouldn't part with them. I wouldn't be afraid of Onan as regards parts. I can get anything, anytime in San Antonio. There are tons of parts available....just no new or very few new engines out there. Be patient. It took me about four months of looking before I got mine. If money is no option, then plop down some $$ and blast. If not, look everywhere. FWIW, the Northern Tool in San Antonio has an Onan/Linamar 25 hp on the shelf right now for around $1300. Surplus center . com is a source as well as Tulsa Engine Warehouse.
Thanks, my engine is still running but it smokes more than i do.:laugh: I do have some time to explore all options. I'll keep lookin hopefully I'll find something before winter so I'll have a good project. Once again thanks to all for the help.
07-30-2005, 12:51 AM
If it is still running, the absolute most painless thing you can do is rebuild it. Even my stuck together, rusted solid engine could have been rebuilt...for a price. It ended up cheaper to replace than rebuild by almost 500 bucks! Your cheapest option is rebuild if you so desire. The P series Onans can hit 6k hours with the right care...several thousand without.
It only has 650 hours on it but unfortunatly the previous owner ran it at a sand pit with no air cleaner.:rolleyes: Not to good for the cylinders and rings.I priced rebuild parts from a local dealer and the total came to about 5-6 hundred dollars.I can pick up a new kohler commander for that. But like you said may be more work and money than to fix the onan. Miller welders are available with kohler engines surely one model will fit. I emailed kohler to ask their advice. Probably wont hear anything from them til monday. If not sooner or later I should come across a replacemant onan.
07-31-2005, 12:34 AM
You can get a Command 16hp+ for 5-600 bucks??????? Interesting ....very interesting since they retail for around twice that.
The shaft end is the key to the problem. You need to find the shaft number or code. More than likely, you will find the shaft doesn't cross over from Onan to Kohler...I have not seen a Miller shaft do it yet, but that doesn't mean one doesn't exist...just that all of my searches have come up empty. The Kohler engine wasn't offered until later in the Miller line. When they came up, the shafts and rotor adapters had all changed radically. The rotor assemblies are model specific, so they can't be switched around, unfortunately.
For example, my shaft is an Onan code 45BH. It was made specifically for Miller applications and just for the early Bobcats. No other shaft will cross over...just the 45BH will fit.
07-09-2006, 09:35 PM
Hello all I am new to this forum, but I am hoping I can find the help I need , I Just purchased a miller bobcat 225G from my boss after a 1yr of begging, it runs good but goes through oil due to rings I believe, I have looked and looked for a rebuild kit for the onan engine with no luck. and from what I have read here going with another engine seems like alot more money and time. I only paid $50.00 for the unit and can weld fine with it but I know the motor will give out sooner or later, so would like to rebuild it before it does. any help on where i can purchase internal engine parts for onan engines would be great.
07-10-2006, 01:04 AM
Hey, Crazzy. Welcome to the sandbox.:drinkup:
Where are you located and where are you looking? Onan kits should be plentiful still. Cummins has the rights to the old Onan parts and stuff, so check with the Cummins/Onan generator people. They should have them in stock and on the shelves. If not, that is a new one on me. I can get most any Onan part here. Cummins Central Plains here will get any part I need in quick order if they don't have it. Be warned, though....Onan parts are anything but cheap. I think they are cast in pure gold sometimes.:D
If you wanted to swap it, any Onan Performer series engine in 16 or 18 hp will be a direct fitup. You would just need to swap the shaft in it, that is all. That was the painful part for me. If you go higher in hp's, an adapter of some other adaptation will be necessary. Epay has lots of them all the time.
07-10-2006, 05:45 AM
I live in arkansas, but i see i have been trying the wrong places, looked all over the net and talked to the welding supply shops near me.
07-10-2006, 02:16 PM
Yup, welding supply shops are the absolute last place to look. If they repair and have sales, I stay away from them as well. They will undoubtedly try to sell you something instead of trying to fix the problem. I was told my machine was not repairable by my local supplier...oh, btw the new Bobcats are on sale now.:angry: :angry: :angry: I remind them of that every time I go back and the machine is on the truck. The machine is running like a top.:D
Look in the yellow pages for Onan generators. That should get you pointed in the right direction.:D
07-10-2006, 08:10 PM
Yes i remember seeing this pic in one of the other posts, tried to find that post this morning because it is exactly like the machine i just bought , mine realy needs a new face plate all the writting is faded out and unreadable, was wondering where you got yours from.
BTW, Thanks for your welcome, and your help.
07-10-2006, 09:54 PM
The face plate needs to be ordered by serial number from Miller. Your LWS can handle that one. They cost about 50 bucks....no more than 60. I had one idiot here that tried to sell me one at 120 bucks.:angry: The guy is a huge cheat and I have no idea how he stays in business. No one in welder repair here knows either. They all know he is a crook.....but I digress.
You had better hurry on that face plate. When I ordered mine last year, there were not many left. They pop up on ebay once in a while. A member here got one for a song practically. Less than half of normal pricing. Worst case, it there are no more, you can paint the original black and use a Mylar label maker and just make your own. That was what I had planned on doing if I couldn't get one.
The plate is actually three pieces. One big upper plate, a plate for the area around the lead connectors and a name plate below the lead connectors. Here is a pic of mine after it was put on.
07-11-2006, 07:23 PM
Ok thank you again, I just finished welding a little bit with the welder and am very excited I was finaly able to get it from my boss. Have wanted it for some time now, and I realy have doubts on the engine needing a rebuild it runs like a Champ and doesnt smoke at all. I was told it goes through oil but as i have said it doesn't smoke and runs like a champ. I just need to look into this face plate and watch my oil level as I use it.:D my face plate looks identical to yours, in the photo. just not as shiney LOL
also would there be a way to put a 220 outlet on this welder instead of the 40 and 2 110's? maybe one 110 and a 220?
07-11-2006, 10:37 PM
also would there be a way to put a 220 outlet on this welder instead of the 40 and 2 110's? maybe one 110 and a 220?
You mean like a full Kva plug? If so, there was a kit for it. Almost got one on epay two months ago. May just make one.
07-11-2006, 10:49 PM
yep thats exactly what i mean. i think i will start watching ebay for things also LOL
07-11-2006, 11:02 PM
Well, good luck. I have been looking for one for about four years and steadily for two. That was the first one I have seen. They were almost 80 bucks or more from Miller. You can piece one together for less than 40 maybe. Just need to get the wiring diagram. My welder repair dude showed me how he would do it. Seems logical, although I'd like to get Miller's design to compare.
Have you downloaded the manuals for the machine yet? You should, if you haven't already.
07-12-2006, 05:22 PM
Yes I sure have, mauals are my best friends. LOL
07-13-2006, 12:32 AM
In that case, go to the electrical circuit diagram. To gook up a full KVA plug, you need to connect #500 to one side and #53 to the other. Then the ground wire to the terminal where all the other grounds go. It is #33. That is how the Miller Service guy said to hook up a three prong, full KVA plug on my unit. Yours should be the same I believe.
02-22-2010, 11:02 AM
i realize this is a very old post, and you may not remember, but i have an old 225g that i would like to put the kva plug into. i have given up finding the old kit, so no issue with making my own, and i have reviewed the wiring diagrams from my service manual, and think i under where to place the spice and how to wire...my question is this, the existing wiring is all 12-14 gauge, surely that wont work on the kva? don't i need to bump that wiring up to 8-10 gauge to carry the amps? i have the machine apart, and ready to go...just have that bit of hesitation.
02-22-2010, 12:03 PM
I never ever saw the wiring on the full KVA plug. If in doubt, go heavier. 12 would probably do it, 10 would be safer.
02-23-2010, 07:21 PM
thanks, i will try the 10 and see what happens
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