Onan

[Hydro 131]

Can't wait to see your modification. If I had it to do over again knowing what I know now that would be the first thing I would do with my Onan is vent the belt guard.

The second would be a cylinder head temp guage.

[jay in nc 210]

victory! i finaly loaded a picture. first time don't know if i will be able to do it again. here is the beltguard on my 518. i have enough material to do at least 30 more, pm me if interested. Jay

[Hydro 131]

AWESOME :greetings-clappingyellow:

[boovuc 1,090]

Hi Jay,

That is a great job! Very nice looks and I would guess very functional too!

[coldone 35]

It does look factory!

[jay in nc 210]

that is just cut & fit , mig welded & light grinding 1 light coat of primer & 2 light coats of farmall paint spray bombed,and i got rain drops in the paint when it blew under the shelter, customer parts will be better but i had to get it done that day! thanks for your praise everyone Jay

[BOWTIE 226]

HELLO GUYS, I JUST SOLD MY 1988 520H TODAY WITH 1200 HRS. IT RAN GREAT AND MOWED GREAT. I GOT IT USED AND DIDN'T KNOW THE MAINTANCE HISTORY ON IT. I ALSO HAD A 1991 416H ONAN WITH 1400 AND 1995 416-8 ONAN WITH 400 HOURS THEY RAN GREAT TOO. I PERFER THE SINGLE CYLINDER KOHLER MYSELF. IF YOU KNOW THE HISTORY ON THE ONAN TRACTORS THAT MAKES A BIG DIFFERENCE. KEEP THOSE COOLING FINS CLEAN!!!!! JUST MY 2 CENTS

BOWTIE IN OHIO

[BOWTIE 226]

JAY, I JUST SAW THE PICTURES OF THE VENTED BELT COVER. DO YOU SEEN THE DUST/DIRT BLOWNING THROUGH WHEN MOWING? IT LOOKS GREAT. IF I PICK UP ANOTHER ONAN TRACTOR I WILL DO THAT ALSO. I THINK I WILL MAKE IT LOOK LIKE THE LOUVRE HOOD IF POSSIBLE. THAT SHOULD HELP THE PROBLEM WITH COOLING..

BOWTIE IN OHIO

[canadian_diesel1964 0]

Bringing this thread back to life...My first post...Hello all...been reading about the 416-8 tractor...I just bought one and am ready and able to do any mods necessary to keep that back cylinder cool...such as venting the belt guard...and relocating the oil filter..using high end fuel with NO ethanol...I do all this stuff a lot so nothing is beyond scope...any ideas on if you can buy a relocation kit for the 216 Onan motor? Thank you!!

[boovuc 1,090]

:text-welcomeconfetti:

I just saw you brought this post back. There was a Remote Oil Filter "kit" that was available through Cummings but I do believe that they have been discontinued. Sears used some Onans in their higher-end Garden Tractors and there was a plate and remote Spin on Filter holder available through Sears for the BF Series and I think the P series. (Don't quote me on that).

We have a member here, (horsefixer), that bought some new filter housings and showed off his remote located filter on a February Posting. He wrote how he did the modification step by step. Search "Onan Remote Oil Filter" in the motors forum. Horsefixer did a great mod on his P220 and it's all spelled out on that thread.

Good Luck!

[canadian_diesel1964 0]

thank you I will search that up!

[artfull dodger 394]

Gonna fire this thread back up, IMHO as a professional mechanic, the remote oil filter's main help is getting the chance of oil leaks, mess from changing filter ect away from the cylinder head, not so much the extra heat. The cylinder jug is hotter than the engine oil, espicaly up near the head. The problem lies in the belt guard blocking cooling air flow, and the difficulty in cleaning the rear cylinder head and jug of oily gunk that tends to build up around the oil filter housing area. I have also seen Onans with crankshaft oil seal issues under the flywheel that go unnoticed till they plug up the cooling fins. Any air cooled engine doesnt like to be run hot, espicaly flat twins. What happens, as explained by an Onan factory rep is normaly one cylinder runs hotter than the other, that happens to be the rear on the WH but is usualy the side with the filter mount as it usualy has the most build up from oil leaks, seepage or careless oil changes making a mess and not cleaning up. When that cylinder gets hot enough, the piston rings loose thier temper causing a loss of compression on that cylinder. If the loss is high enough when compared to the opposite side, the engine goes out of balance and the resulting harmonics will kill the connecting rod on the weak cylinder normaly. I have seen B and P series Onan twins with over 5000 hours on them in RV gen sets. But look at the enviroment they run in, normaly cleaner, service is usualy done when the RV is getting serviced, so its done by the book. They dont get run in an envrioment full of blowing grass and dust. I would see more valve seats coming loose than blown rods. And those were not that common either. Onans are pricey to overhaul, but Kohler is getting up there in recent years with a pretty good price hike in OEM parts. That being said....Jay are you still doing belt guard mods?? I may be getting a 518 and would like to get one of the modified belt guards if I end up with it. Thanks Mike

[JackC 617]

artfull dodger, thanks for that information. There is a serious effort underway to develop a temperature monitor device that will alert the operator to the over temp conditions that result in engine failures. See the tread "Onan twin cylinder head temperatures".

It is also not a bad idea to take the air cleaner off periodically to clean off the crud build up that occurs on the back cylinder and that is not easily visible with the large air cleaner covering the block.

In my view wheel Horse did not provide sufficient protection for a relatively high performance engine stuck in a very tight space on tractors with large mower decks blowing large volumes of grass and dust out the same side as the high volume air input cooling system for the aluminum engine.

[mavfreak 11]

My setpdad has a johndeere 318. This past spring he had me go over it and was complaning of lack of power. the engine started but took forever to do it. did a compression check had 80psi on one cyclinder and 70 on the other (wet test) checked the hours on the meter just shy of 2200hrs. (was told that hr meter hasn't worked for some time). He has owned this tractor since 99 had 1025hrs on it when he bought it. He rearly changed oil and never tuned it up.

I torn it down to to see if it was worth rebuilding. The cyclinders was shot the crank was out of spec, the valves were so bad the seats were beat out.

Found a company that offered remans. $2500.

He went ahead and put the reman on it. Like my stepdad said he isn't going to find a tractor with all the attachments that he has for the johndeere for that kinda money.

I have heard many of bad things about Ohan engines but I think this one proves that they can run even with bad maitance.

on a side note when I checked into rebuilding this one many parts were not availible, the crank was one and oversized piston was another.

[artfull dodger 394]

Ever since Cummins got ahold of what was left of the Onan company, they really havent been interested in doing much with it. Parts prices are outragious for many parts. Thier ring prices are on par with Kohler OEM, $40 a side roughly for new ring sets. But many hard parts like oversize pistons, crankshafts ect can be impossible to locate. Could you have had the crank turned 10 or 20thou undersize? Last I knew one could still get undersize rods. There is a local gentleman, does mostly JD spec Onans but can overhaul others. Offers turn key rebuilt Onans for around $1300, mostly again JD spec for 318/420's. The WH Onan install isnt the tightest I have seen, take a look under the hood of a 446 Case/Ingersol. Underhood muffler, full covers over both heads with a 90' deflector at the end to keep heat off the operator's legs. I see way more Case tractors with Onan issues than WH, JD or Sears. Keeping up with valve adjustments, cylinder head decarboning and keeping the engine clean are the keys to long lifespans in Onans, or any air cooled for that matter. Onans are just a bit more maintance sensitive than a Kohler or a Briggs. But when in proper tune, they are a site to behold and hear. They have a throaty roar to them that no other flat twin has. I like thier block design over the Kohler KT and Mag series, only thing I would have like to see is replacable cylinder jugs like the Kohlers. I hate the two piece crankcase on the KT and Mags. Mike

[zeedubbya 18]

In my humble opinion the Onans are the best gas motors ever put in garden tractors. I agree with all of what artful dodger said. Consider--two of the most revered garden tractors in history have had Onan motors in them. The JD 318 and the 520H. Not to mention the Sears lineup that some consider the best and the Case 446-448/ingersoll 4016, 4018 etc., Having owned 3--Case 448, 318 and 520h I believe they all have their own set of pluses and minuses. The constant item on all three is the motor though. It can't be a coincidence that if you go onto any of the collector websites for these brands nearly every person has or aspires to have one of these for a worker. That's a testament to Onan. I've found with all of them if you keep them clean and do the maintenance as recommended they run great. Just my 2 cents.

[artfull dodger 394]

For a bit of triva, how many here have seen a Vtwin Onan??? I have seen 2 of them, basicly imagine the flat twin with the cylinders pulled up into a V style but with OHV's, the rest of the block looked much like the late P220's. We got a pair of Miller welder/generators in that had Onan Vtwins in them, 20hp. Shame that Cummins decided not to pursue them any further. The owner said that they were one of the last Onan powered welders sold by Miller. The engines had both Cummins and Onan names on the engine tin work. My last year working at a dealership with access to dealer pricing on parts, Kohler OEM parts were getting right up there with Onan. K series parts were fast going NLA from Kohler with only whats in the warehouse left. Thankfully Stens has taken over in the aftermarket, but I have heard both good and bad on thier hard parts like pistons and rods being of spotty quality. I try to use OEM whenever I can. If your gonna do it once, just like Duke on his snow chucker 520h, go whole hog and do it right. Even if it takes longer to afford all the correct parts. Kohler K series will tolerate being run low on oil and being run hot, Briggs have to have very regular oil changes or they start to fall appart fast, Onans will not tollerate being run hot, being run low on oil or other abuse that has spoiled owners of the K series Kohlers. Onans are more like your car, you change the oil and filters on a regular basis and maintain it, or it doesnt last...period! But that being said, I love Onans, on my buddies showroom clean restored 318 he got lucky, the PO put a Linmar/Onan replacement in it, has less than 500 hours on it. Other than needing a new carb from sitting for a year at the dealership, which is sitting on my shelf to install when it warms up a bit. Basicly, once you start seeing blue smoke on throttle up, start a fund to overhaul cause its coming soon, plan on 800-1200 bucks depending on block work and whether you do the labor or not. I normaly dont replace rods or piston heads unless an overbore is needed or other issues with bearings being out of spec. Many times if you go thru them when the first sign of oil burning is seen, a simple hone, fresh rings and bearings, espicaly cam bearings, fresh oil pump and a good clean up is all it needs. And contrary to popular belief, there is no issue with having that opening in the rod just above the big end. Jaguar sports car have this feature, it lightens the load on the bottom end bearings. I do believe most all the replacement rods nolonger have this opening. I will replace my belt guard with one that has an opening for cooling prior to mowing season. Doubt it will be an issue in these below freezing temps. Cheers Mike

[dwcphoto 7]

Hi Guys,

I'm back with another Onan question. I have a WH 518 and it's been running quite well. I put a voltage regulator in the past summer, but the volt meter on the tractor has not changed much. It does keep running, though, as before it would drain the battery and quit.

I recently took the battery off and charged it as it was weak from sitting in the cold. I finally put the snowblower on last week. Here's the thing now. The battery will turn the engine over well enough, but doesn't want to fire cold. I put the jump battery on to assist so I don't run down the tractor battery and bang, it fires right up. Any ideas?

Thanks very much. Happy New Year. dwc

[zeedubbya 18]

If you think it's an issue with the voltage regulator do some reading in the electrical section of the forum. Maybe ask your question over there as well. Member Save Old Iron frequents there and is a professor emeritus in all things electrical. He is a living legend on here.

[artfull dodger 394]

Awhile back someone posted that they were not sure why Onans moved way more air thur their cooling system than the same Kohler size twin. To find that answer, you have to look where you find probably 75% or more of the Onan twins, in gen sets, mostly on RV's, fire trucks and standby stationary for residential homes. When tucked up under an RV in a litle cubby, or in a compartment on a fire truck with just mesh vents on each side. You need to move mass quantities of air to keep these engines cool. Onan designed the flywheel blower set up to really move the air!!! When they started putting them in GT's the air movement was seen as an advantage in hot climates, but there was a flip side we all see now, it sucks in more dust and debris. Add to that a minor oil leak or just a grimy block to start with and you are set up for a massive failure sooner rather than later. Onans are high performance engines, they have features not available on most other flat twins of the times like adjustable valves. There is a reason you see Onans in RV gensets and not Kohler or Briggs. Even the Onan singles, which are not very common are really nice high performance engines. Cub Cadet put one of the singles in the 2000 series shaft drive cubs, the tractor is usualy junk by now, typical MTD tin foil metal and frames, but the engines still run like a champ. Would make a nice engine to put in a small WH when repowering. Anything we can do to keep them cooler, be it oil coolers, remote oil filter set ups ect will help. But in that respect, someone needs to come up with a boxed retrofit kit that can be installed by the average WH owner, one that cannot fabricate their own brackets and mounts. It should be designed to use exhisting bolts or bolt holes to ease installation. Belt guard vents and regular inspection of the front of the cylinder jugs for debris or oil leaks should be in every Onan owners maintance schedule. I would say treat it like your car, but then I know people that absolutly beat the living snot out of everything they own. Cheers Mike

[mavfreak 11]

Ever since Cummins got ahold of what was left of the Onan company, they really havent been interested in doing much with it. Parts prices are outragious for many parts. Thier ring prices are on par with Kohler OEM, $40 a side roughly for new ring sets. But many hard parts like oversize pistons, crankshafts ect can be impossible to locate. Could you have had the crank turned 10 or 20thou undersize? Last I knew one could still get undersize rods. There is a local gentleman, does mostly JD spec Onans but can overhaul others. Offers turn key rebuilt Onans for around $1300, mostly again JD spec for 318/420's. The WH Onan install isnt the tightest I have seen, take a look under the hood of a 446 Case/Ingersol. Underhood muffler, full covers over both heads with a 90' deflector at the end to keep heat off the operator's legs. I see way more Case tractors with Onan issues than WH, JD or Sears. Keeping up with valve adjustments, cylinder head decarboning and keeping the engine clean are the keys to long lifespans in Onans, or any air cooled for that matter. Onans are just a bit more maintance sensitive than a Kohler or a Briggs. But when in proper tune, they are a site to behold and hear. They have a throaty roar to them that no other flat twin has. I like thier block design over the Kohler KT and Mag series, only thing I would have like to see is replacable cylinder jugs like the Kohlers. I hate the two piece crankcase on the KT and Mags. Mike

I've heard that Cummins released the prats rights for aftermarket companys to make them. Is this true and if so then Onans will be around longer.

[artfull dodger 394]

I have recently seen voltage regulators made by Stens for the B and P series Onans, much cheaper than the $100 that the OEM part was selling for. Cummins releasing parts rights to the aftermarket should make overhaul and general maintance much cheaper than it has been. Should be more inline with Kohler KT and Mag series twins once the aftermarket catches up. Very good news to hear! Mike

[leeave96 487]

For a bit of triva, how many here have seen a Vtwin Onan??? I have seen 2 of them, basicly imagine the flat twin with the cylinders pulled up into a V style but with OHV's, the rest of the block looked much like the late P220's. We got a pair of Miller welder/generators in that had Onan Vtwins in them, 20hp. Shame that Cummins decided not to pursue them any further. The owner said that they were one of the last Onan powered welders sold by Miller. The engines had both Cummins and Onan names on the engine tin work. My last year working at a dealership with access to dealer pricing on parts, Kohler OEM parts were getting right up there with Onan. K series parts were fast going NLA from Kohler with only whats in the warehouse left. Thankfully Stens has taken over in the aftermarket, but I have heard both good and bad on thier hard parts like pistons and rods being of spotty quality. I try to use OEM whenever I can. If your gonna do it once, just like Duke on his snow chucker 520h, go whole hog and do it right. Even if it takes longer to afford all the correct parts. Kohler K series will tolerate being run low on oil and being run hot, Briggs have to have very regular oil changes or they start to fall appart fast, Onans will not tollerate being run hot, being run low on oil or other abuse that has spoiled owners of the K series Kohlers. Onans are more like your car, you change the oil and filters on a regular basis and maintain it, or it doesnt last...period! But that being said, I love Onans, on my buddies showroom clean restored 318 he got lucky, the PO put a Linmar/Onan replacement in it, has less than 500 hours on it. Other than needing a new carb from sitting for a year at the dealership, which is sitting on my shelf to install when it warms up a bit. Basicly, once you start seeing blue smoke on throttle up, start a fund to overhaul cause its coming soon, plan on 800-1200 bucks depending on block work and whether you do the labor or not. I normaly dont replace rods or piston heads unless an overbore is needed or other issues with bearings being out of spec. Many times if you go thru them when the first sign of oil burning is seen, a simple hone, fresh rings and bearings, espicaly cam bearings, fresh oil pump and a good clean up is all it needs. And contrary to popular belief, there is no issue with having that opening in the rod just above the big end. Jaguar sports car have this feature, it lightens the load on the bottom end bearings. I do believe most all the replacement rods nolonger have this opening. I will replace my belt guard with one that has an opening for cooling prior to mowing season. Doubt it will be an issue in these below freezing temps. Cheers Mike

I remember the "V" shaped Onan engines and I'm 99% sure they were rebadged Subaru/Robin or Kubota engines - not an Onan.

[artfull dodger 394]

Something like that, it was kind of Onan's last breath as a seperate company making engines. Sadly the quality wasnt there. Both units ended up with P220's after to many frequent flyer miles in the shop for constant issues. I wanna say they were rebadged Subaru/Robin units. I dont think there were that many rebadged either, dont seem to see many of them atleast. They did have a little of that signature Onan throaty roar when at full power, definatly were still different sounding than the Kohler, Vanguard and Kaw Vtwins were normaly saw in the shop. Just a shame to see an excellent engine company fad away. Even the older teccys werent to bad once you got past thier carb issues. My dream engine is a combination of the Kohler KT/Mag series and the Onan P series. I like Onan's block design, much like a Kohler K series single, hate the two piece block on the kohler KT17/Mag18's ect. But like the ablity to swap out a bad jug on the Kohlers. So, take the base Onan block, make the jugs replaceable seperate of the main block, it would make repairs so much easier when only one jug dies. Mike