Rebuilding an Onan B43G (Part 1) External Tear Down

[@jasonkeith674]

Thank you for this video! I recently brought home an old Lincoln welder, with an Onan. It took me a while to get the numbers off it, due to the wear and tear. I got it to turn and even burped a bit yesterday, and hopefully with the help of your series of videos on the engine, I can bring it back to life. Thank you.

[@pisby1]

Thanks for the awesome video, I'm considering doing this for an Onan from a wheelhorse.

[@jamesdepaul3410]

Long bus, but good

[@speedbuggy7240]

mmrbeef thank you for the vid. I have a question. I have a b48g off a Cub 982. I bought a NOS onan with electronic ignition. I believe it is for a John deere. I already know I have to change the oil pan and starter. But the flywheel on the new onan is larger and won't work. My question is will the flywheel off the older onan with points work on the newer onan with electronic ignition? Any help would be greatly appreciated. Thx

[@mmrbeef]

The flywheels from the B and P series are different. I’d need to sit down with a book and do some serious thinking to see how the parts could interchange.

[@timclose7789]

Where’s the best place to get a overhaul kit for these engines ?

[@mmrbeef]

Generally I point folks to Onanparts.com. My recommendation is to take the engine apart and figure out what you need then order the parts. In many cases you do not need a full rebuild kit.

[@timothylongmore7325]

Have you ever seen a 20 hp off a welder. I have one that I want to turn into a sawmill. I was wondering if i could put a 1" pto on the front. The back output shaft is 1 3/8 shaft and can't find a clutch pulley to fit. Also the back fan/flywheel is broken , lol. I'm going to take the front cover off tomorrow and see if the flywheel is the same as the one your working on in this video. Any input would be great , thanks

[@mmrbeef]

Honestly I am not sure about the fitment on the sawmill. Onan had a lot of different specs for these engines. Try McMaster Carr or Motion Industries if you are looking for a pulley. Rather than an electro-magnetic clutch you could build a tension style clutch.

[@timothylongmore7325]

@@mmrbeef Thanks for the reply. I pulled the flywheel screen off the front of the engine. the flywheel looks the same as the one your working on ... except theres only two bolt holes tapped on the center pto mount. I'm going to get the axle that bolts on there and see if lines up with whats there. I might be further ahead to change out the flywheel as I'd have to pull it to machine it anyway. I did throw a battery on it and started it. No back flywheel blower on it and it ran great.

[@mackendw]

is there any specific type of thread sealant one should be using for those bolts that go into the crankcase for sealing them?

[@mmrbeef]

I’ve always used pipe paste that is rated for oil. I would not recommend Lock Tite or any types of silicon product I case you have to get them back out.

[@051570orion]

you wouldn't happen to have another one of those electric PTO's laying around ?

[@noahlechner1036]

My tractor smokes a lot, do u think it could be anything else other than rings.

[@jser4822]

Where is the cheapest place to buy the parts for rebuild? thanks

[@jackjjames]

Lefty loosy, righty tighty. (Muffler)

[@richardhileman3228]

Good job rebuilding Onan B43G engine. Can you tell me where you got the OEM parts from. Thank you

[@mmrbeef]

You can source many of them from Cummins dealers, Onanpart.com, and Boomer's Onan. Boomer you will have to call but its worth the call to talk to him and tell him what you need or ask what he suggests.

[@michaelaugustson7725]

jacks small engines

[@JeffreyMyers_]

Thanks for these videos. I have a 318 with this B43G motor and what I think has a fuel issue. I don't have much fuel in the filter (barely any in fact). I put a new filter on every year before the season starts. It started dying last season when I was getting it ready and worked fine until the end of last season. Runs great at idle, then as I'm running it it seems to want to die and choking doesn't seem to help. Not sure if the pump needs to be replaced or something else. I want to make sure because Deere sells them for $90 I think? What are your thoughts and maybe point in the direction of your fuel videos for them so I know what I'm doing also, thanks!

[@mmrbeef]

I would check the "fuel line" that serves as the pulse line for the fuel pump. Often times that line is cracked leaving very little pressure for the pulse pump to move fuel. If you have not replaced it there is a high percentage chance that will be the problem. I would also encourage replacing all the fuel lines at the same time.

[@mmrbeef]

Here is one of the reassembly videos. kzbin.info/www/bejne/o6fFl5SBi6yBd8U

[@ts89540]

I picked up a 318 with the B34G last year. A 1984, I think. Anyway, I was having a similar issue. Replaced filter, still seemed to not be getting any fuel. I had both electric and vacuum fuel pumps, so got rid of vacuum pump, and only run electric. Tested fuel delivery into filter and out of filter and it was fine. Issue persisted; started fine cold, ran for 15-20min, then would stall out, unable to restart, but when cooled down, would run fine for another 15-somin. Repeat. What it turned out to be for me was heat soak of the coil. It had an aftermarket coil from a motorcycle. I tested the spark when hot, and it wasn't good. I replaced with a Deere coil, and did the wires, plugs, and points and condenser, and haven't had an issue since.

[@stratsforever]

Do you have an extra B43G governor spring? I can't find one anywhere.

[@mackendw]

it's only $[ALOTTACOIN] at john deere ;)

[@buder5116]

hi need help before i start grinding im aslo going to try my first rebuild :D the muffler is stuck even after bolt removed welp i been hamering all over it but dosent work and there some dang rust smudge everywhere in 1 of the piston stupid rain the engine managed to run but startor is stuck same for carburator so it was shuted off how can it run with that much smudge :S i difinitly going to take it apart since the valve aslo need cleaning

[@buder5116]

aslo how do you dismantle the carburetor from the intake manifold :S its stuck together even after bolt removed wasup with my engine getting everything stuck together

[@mmrbeef]

The carb is attached to the manifold via two bolts on the bottom of the carb. I think you will need a 1/2' wrench. The rust sounds to be from the cylinder walls. You are correct for wanting to take it apart.

[@buder5116]

@@mmrbeef thanks :D do you know where its said the real model of the engine? the plate number lead to nearly nothing i dont find a ( p216g) kind of number anywhere on it i can only gather more part number and cross reference

[@buder5116]

@@mmrbeef if you can i would like to know the diameter of those valve seen in pt2 11:47 so i can help finding more clue about the variant on my engine good chance its too late now though xD

[@buder5116]

@@mmrbeef what the torque for the valve timing cover? (where the 3 gear are)

[@speedbuggy7240]

mmrbeef I think my new onan is a onan preformer 20

[@PhatboyHD88]

Buddy im kinda disappointed ,,, with all that crud on the engine ya really should have cleaned the engine completely off so it is contaminant free for reassembly ,, using first a air hose ,,then either a steam genny or brake clean if a steam genny isnt available ,,,,, all that dirt on there with both intake and exaust ports open all that debree sure to get in there..

[@mmrbeef]

All the components were cleaned and the engine block was run through the dishwasher before we assembled anything. So it was clean when we started reassembly.

[@railfanjames7699]

Well this also consult with the Onan p220g?

[@mmrbeef]

Yes, there are a few differences but not a lot.

[@railfanjames7699]

@@mmrbeef what differences are there?