seuadr 488 #1 Posted March 15, 2021 Once upon a time, (7 years ago) a handsome young prince I picked up a motor replacement for my 520H. it was not the right motor, though! link to the original debacle! i found a couple parts motors to fill out the short block and decided to get a gasket set and then had a second child and promptly forgot about the whole thing. Fast forward to this year, when my onan started smoking noticeably, not just on start up by often under load - i mean like burns enough oil in an hour to go from full to empty on the dipstick bad. i was thinking about a predator repower, and then digging around in the barn for something else completely i came across the box with motor in it and felt dumb for having forgot about it in the first place. Then i came on here, and read that the N52M was longer than the p220 and thus wouldn't fit in a motor swap - but - i actually measured them, and, i think it will - the p220 from edge to edge of the sheet metal mid motor is ~21" and ~13.5 inches wide at ~19 inches tall. the parts N52M (doesn't have a muffler, so that is a bogey in this) in the same spot is only an inch longer, and an inch wider. and with the air cleaner that is currently on it it is about a half inch taller. looking at it, i think i might even be able to adapt the p220's air cleaner to it as it is a bit indented and so a little lower profile. i'm going to pull that baby out and see if i can get it lined up (and better measurements) i have an extra hood from a 518 that i could utilize to make it a little taller if need be as well, and there is a little room for more motor under the hood front to back - so this could work out! pictures to come once i dig these guys out (i have a full set of tins for a N52M, a motor i bought as "junk" a motor i bought as "running" and the NOS short block i bought from ebay 7 years ago - so quite a bit to dig out from behind my camper and other assorted junk valuable pieces of history. 4 Share this post Link to post Share on other sites
ebinmaine 67,687 #2 Posted March 15, 2021 Well I don't have an Onan or anything even close to being modern considering our newest tractor is a 74.. But I'm interested to see what's going to happen so I'm just going to sit down over here and follow along. Share this post Link to post Share on other sites
seuadr 488 #3 Posted March 16, 2021 Here are my two donors The left one was sold as bad for parts, the right as running. Here is the short block Size comparison Looks pretty promising, boys! Gonna focus on the supposed runner first, as it is also the most complete which should help in determining the location of stuff on the NOS short block. Besides, if it looks solid, i may transplant it and use it until i can make the parts for the junker pretty to put on the short block. I'll need a full gasket set, new plugs, wires, a bunch of harness replacement, carb rebuild kit and points at the very least. Probably a replacement fuel pump ( may just go electric like the p220 currently is) The runner came with an extra starter and carbs hidden under the motor on the pallet, BONUS! 1 Share this post Link to post Share on other sites
onanparts.com 181 #4 Posted March 16, 2021 The CORRECT way to do a Repower! 2 Share this post Link to post Share on other sites
seuadr 488 #5 Posted March 16, 2021 (edited) 9 hours ago, onanparts.com said: The CORRECT way to do a Repower! hey - the "runner" motor is a N52M-GA 0199/35808 and the short block is a 170-43 87.. now, because it is a short block, i'm guessing that what i need are the gaskets for the "runner" since that is going to be where the vast majority of my transplant parts are coming from. what is the appropriate gasket set from your site for that? do you have other components like the points, condenser and coil (i do not yet know if i need a coil - it may be fine, but i am assuming the points and condenser need replacing) i'm going to need a carb rebuild kit too, but i haven't determined what carb is on it yet. i dunno if you can tell from the spec number? (it looks a whole lot like 146-0662) Edited March 16, 2021 by seuadr Share this post Link to post Share on other sites
onanparts.com 181 #6 Posted March 16, 2021 I have most anything you will need new parts wise. First, Parts manual here: http://www.skilledcrafting.com/onanfiles/940-0252 Onan N52M-GA019.9 (spec A-B) Industrial Engine Parts manual (10-1983).pdf If you need the service manual use the contact page on my site and I'll email it to you. Looked at your old thread...YES! Disassemble the short block, clean, inspect and reassemble with good lube. You already were planning that, and it's been 7 years since you got it...:) 1 Share this post Link to post Share on other sites
seuadr 488 #7 Posted March 16, 2021 Well, got the carb, intake, linkages and tins off today, but i don't have a puller that will fit that flywheel so i am stuck until i get one tomorrow. Looked down at the intake, not sure what happened there: Flywheel looks ok Just one little nick there, think that'll be just fine. Share this post Link to post Share on other sites
seuadr 488 #8 Posted March 16, 2021 Look at this! What a great idea! I'm going to be putting my remote filter kit on this unit, so, it doesn't help me much but i wonder if the later onans have the same bolt holes to attach it? Share this post Link to post Share on other sites
seuadr 488 #9 Posted March 18, 2021 (edited) More disassembly! Any tips on getting the fricken dipstick tube out? Maybe it will come easier once the oil pan is off? Steering wheel puller worked great! Magnets look good too.. No burn marks or broken down insulation (looks like) Oil pump - i assume this looks good? I didn't disassemble it further, not knowing if there is any springs in it.. Looks like the pto is electric? Iridium plugs, SWANKY! This cylinder doesn't look bad either.. Edited March 18, 2021 by seuadr Share this post Link to post Share on other sites
seuadr 488 #10 Posted March 18, 2021 So, i can feel slight waves at the top of the cylinders on the "runner" engine. one cylinder is cross hatched, The other is not? Looks pretty clean! Got the electric pto - thing - off. Doesn't seem to work, i am reading 0 ohms between what i am assuming is the power plug and the frame. It has a number on the back: 104-0264 but i couldn't find much of anything on it. Started taking apart the other motor - found out what was wrong - exhaust valves were stuck, not moving. Haven't dug in any farther to see "why" Woof, this one is grimey, but the stator might be ok! Next i gotta decide how to clean up the heads, covers and tins for transplant as well as paint. There are two screens for the flywheel, one on the flywheel, one on the shroud - thinking over painting most of the shrouds black, but that inner screen red. Might look sharp? Thoughts on painting the block vs leaving it au natural? Share this post Link to post Share on other sites
seuadr 488 #11 Posted March 18, 2021 Did a little digging - looks like the "runner" was off a bolens mower. Found a MTF post about rebuilding them - looks a whole lot like mine, except you know, not rusty as hell.. Share this post Link to post Share on other sites
oliver2-44 9,765 #12 Posted March 19, 2021 On 3/17/2021 at 7:17 PM, seuadr said: I don’t have any Oman knowledge, but on a Kohler single I would say that piston/cylinder has some blow by going on. When you see a piston that has carbon on most of it but a clean partial moon shape like that, it’s a textbook picture of blowby. I would have a machine shop measure that cylinder or at least use @953 nut method of using a piston ring to do a rough ck on it. This cylinder doesn't look bad either.. Share this post Link to post Share on other sites
seuadr 488 #13 Posted March 19, 2021 5 minutes ago, oliver2-44 said: Oliver, thanks for the advice! Fortunately I'm not going to be using that block, was just curious about it. I have a NOS short block - i just need the external bits. Share this post Link to post Share on other sites
seuadr 488 #14 Posted March 20, 2021 @oliver2-44 i just realized your name is oliver 2-44(or i guess, more accurately i just realized that is an oliver 2-44 ) that is kinda funny - i have your tractors ancestor - an oliver 550. here she is getting picked up from the seller a few years ago: currently need to rebuild the steering, thinking of sending it to texas to get done. was a great little worker for the last couple of years, though, and i have no reason to believe she won't be great once the steering gets sorted back out! Share this post Link to post Share on other sites
seuadr 488 #15 Posted March 20, 2021 @onanparts.com @ebinmaine @oliver2-44 Well, i'm getting my gasket set today looks like - so i guess it is time to start looking at the NOS block. what i am unsure of is what i should. this is a NOS motor, it had a letter to the dealer inside and was sealed in cosmoline. I'd like to check as much as i can without possibly messing something up or re-assembling something critical wrong (just had a K301 grenade because it looks like the person that rebuilt it put the oil hole in the wrong spot!) i have a set of feeler gauges on hand, and i am sure i could get ahold of a caliper pretty easily. based on things i've read about other's motors in the past i want to check things like valve clearance - but i am unsure what else? Thoughts? Share this post Link to post Share on other sites
ebinmaine 67,687 #16 Posted March 20, 2021 I don't any specific familiarity with the Onans. Just general engine knowledge. Perhaps @ZXT or @WVHillbilly520H could chime in. 2 Share this post Link to post Share on other sites
seuadr 488 #17 Posted March 20, 2021 2 minutes ago, ebinmaine said: I don't any specific familiarity with the Onans. Just general engine knowledge. Perhaps @ZXT or @WVHillbilly520H could chime in. thanks - me either. not only am i not a professional, i'm not even a gifted amature! 1 Share this post Link to post Share on other sites
Tuneup 1,433 #18 Posted March 21, 2021 Late responding to the Wednesday post about the piston top - my P216 was much worse and start-up smoke was bad. Rings worn bad enough that a puddle of oil would form. Engine was abused - really dirty inside. They don't run on sludge very well. Share this post Link to post Share on other sites
seuadr 488 #19 Posted March 21, 2021 In the process of cleaning up the flywheel shaft i noticed a couple nicks like this one: Can i sand those down a bit or should I not worry about them? I don't want to significantly change the size of the shaft. Share this post Link to post Share on other sites
seuadr 488 #20 Posted March 21, 2021 Heads are all carbon free! Tins are coming out nice too! Share this post Link to post Share on other sites
seuadr 488 #21 Posted March 23, 2021 Nice and clean, time for the oil pan. (Yeah, i noticed i forgot the oil pickup - of course after i got the pan on...) Does this gear look too worn? Remote filter adapter plate: Oops - those fittings are not going to work.. i think that might be a pressure cutoff switch, or could be a pressure transducer? Coming together good, though! Share this post Link to post Share on other sites
ZXT 2,401 #22 Posted March 25, 2021 On 3/20/2021 at 12:39 PM, ebinmaine said: I don't any specific familiarity with the Onans. Just general engine knowledge. Perhaps @ZXT or @WVHillbilly520H could chime in. My experience with Onans is about the same as yours. I've changed a head gasket on one and that was it. Share this post Link to post Share on other sites
seuadr 488 #23 Posted March 25, 2021 Well i checked the valve clearances and the play in yhe crank, those were the only things i really saw in the manual. Then i set the static timing and started sticking it all back together. A lot of unknowns on this one - i cleaned the carb, but haven't been able to find any initial settings for it, so went with the ole 1.5 to 2 turns out. Dont know if the stator works (but it doesn't show shorted and looks sound) dunno if the starter works (but i have so..) We'll see i guess! 😁 1 Share this post Link to post Share on other sites
seuadr 488 #24 Posted March 25, 2021 So the hardware store had no map, no oxygen, no more propane and i had a hankering to fix that cracked exhaust so i took unusual measures. Preheating for about 15 mins Not great, but i haven't brazed in 15 years and all they had was 5/16 rod so, considering the availability of means, i am satisfied. Thought i might have some cold spots, but once brushed and ground i think it is solid. 1 Share this post Link to post Share on other sites
seuadr 488 #25 Posted March 26, 2021 Evidently i have nelson mufflers? Not too bad! 1 Share this post Link to post Share on other sites
