3018 Onan

Troubleshooting, rebuilding, repairing Onan engines.
TLD89 United States of America
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3018 Onan

Post by TLD89 »

I have a 3018 Onan that finely gave up with 2400 hrs on her last year. Motor locked up before that she was getting slowly harder and harder to start. Tuning over slowly then starting like maybe main bearings or piston rings seized up?? What do you guy think. I did go to 10 x 40 oil for a season.
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DavidBarkey Canada
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Re: 3018 Onan

Post by DavidBarkey »

TLD89 wrote: Sun Dec 19, 2021 9:05 am I have a 3018 Onan that finely gave up with 2400 hrs on her last year. Motor locked up before that she was getting slowly harder and harder to start. Tuning over slowly then starting like maybe main bearings or piston rings seized up?? What do you guy think. I did go to 10 x 40 oil for a season.
Like all flat heads , could be getting harder to start due to carbon build up on the head . The other thing is it could have been a worn out starter making it harder to start and the lock up is quince-dental . Now that being said , I assume from your first post that you have not taken anything apart yet . I have an old Jacobsen in the shop that was given to me (grandsons project ) . They told me the motor had locked up , they had remove spark plugs and air shrouds but could not get the crank to move . By the time I got it it had been open to the elements for some time and had rust damage in bottom of the cylinders . 18 hp BS HOP twin . A real shame because the motor before the rust damage was in great condition . The cause of the lock up was the Electric Clutch main freewheel bearing seized up and help the crank from turning . Before condemning the engine as you did not describe any bang or knocking , pull the clutch off and the pump free enough to clear the coupler . Also pull the spark plugs as excess fuel can hydro lock the engine . Heres hoping it is just a bad clutch in one and wrong fluid or seized spindle in the other and you can fix both .
Please do let us know how you make out .

Dave
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Re: 3018 Onan

Post by ssmewing »

If the engine is getting worn out, they actually spin faster than a newer engine because the compression is lower.

You have something else that caused it to stop turning over. Intervals do not tighten up as they get used.
TLD89 United States of America
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Re: 3018 Onan

Post by TLD89 »

Dave, Thanks I will look into that no I haven't done anything yet, it did have a knock when staring for the past couple years and the starter has less then 30 hrs on it. Cleaning up the 3118 that I got Sat. and Winterizing boat this weekend.

Terry
DavidBarkey wrote: Sun Dec 19, 2021 9:27 am
TLD89 wrote: Sun Dec 19, 2021 9:05 am I have a 3018 Onan that finely gave up with 2400 hrs on her last year. Motor locked up before that she was getting slowly harder and harder to start. Tuning over slowly then starting like maybe main bearings or piston rings seized up?? What do you guy think. I did go to 10 x 40 oil for a season.
Like all flat heads , could be getting harder to start due to carbon build up on the head . The other thing is it could have been a worn out starter making it harder to start and the lock up is quince-dental . Now that being said , I assume from your first post that you have not taken anything apart yet . I have an old Jacobsen in the shop that was given to me (grandsons project ) . They told me the motor had locked up , they had remove spark plugs and air shrouds but could not get the crank to move . By the time I got it it had been open to the elements for some time and had rust damage in bottom of the cylinders . 18 hp BS HOP twin . A real shame because the motor before the rust damage was in great condition . The cause of the lock up was the Electric Clutch main freewheel bearing seized up and help the crank from turning . Before condemning the engine as you did not describe any bang or knocking , pull the clutch off and the pump free enough to clear the coupler . Also pull the spark plugs as excess fuel can hydro lock the engine . Heres hoping it is just a bad clutch in one and wrong fluid or seized spindle in the other and you can fix both .
Please do let us know how you make out .

Dave
TLD89 United States of America
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Re: 3018 Onan

Post by TLD89 »

Dave, you were right about bad clutch took the old one off and 3018 stared up. I have been looking around for new one what would you suggest?

Thanks Terry



TLD89 wrote: Sun Dec 19, 2021 10:43 am Dave, Thanks I will look into that no I haven't done anything yet, it did have a knock when staring for the past couple years and the starter has less then 30 hrs on it. Cleaning up the 3118 that I got Sat. and Winterizing boat this weekend.

Terry
DavidBarkey wrote: Sun Dec 19, 2021 9:27 am
TLD89 wrote: Sun Dec 19, 2021 9:05 am I have a 3018 Onan that finely gave up with 2400 hrs on her last year. Motor locked up before that she was getting slowly harder and harder to start. Tuning over slowly then starting like maybe main bearings or piston rings seized up?? What do you guy think. I did go to 10 x 40 oil for a season.
Like all flat heads , could be getting harder to start due to carbon build up on the head . The other thing is it could have been a worn out starter making it harder to start and the lock up is quince-dental . Now that being said , I assume from your first post that you have not taken anything apart yet . I have an old Jacobsen in the shop that was given to me (grandsons project ) . They told me the motor had locked up , they had remove spark plugs and air shrouds but could not get the crank to move . By the time I got it it had been open to the elements for some time and had rust damage in bottom of the cylinders . 18 hp BS HOP twin . A real shame because the motor before the rust damage was in great condition . The cause of the lock up was the Electric Clutch main freewheel bearing seized up and help the crank from turning . Before condemning the engine as you did not describe any bang or knocking , pull the clutch off and the pump free enough to clear the coupler . Also pull the spark plugs as excess fuel can hydro lock the engine . Heres hoping it is just a bad clutch in one and wrong fluid or seized spindle in the other and you can fix both .
Please do let us know how you make out .

Dave
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DavidBarkey Canada
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Re: 3018 Onan

Post by DavidBarkey »

TLD89 wrote: Tue Dec 28, 2021 3:33 pm Dave, you were right about bad clutch took the old one off and 3018 stared up. I have been looking around for new one what would you suggest?

Thanks Terry



TLD89 wrote: Sun Dec 19, 2021 10:43 am Dave, Thanks I will look into that no I haven't done anything yet, it did have a knock when staring for the past couple years and the starter has less then 30 hrs on it. Cleaning up the 3118 that I got Sat. and Winterizing boat this weekend.

Terry
DavidBarkey wrote: Sun Dec 19, 2021 9:27 am

Like all flat heads , could be getting harder to start due to carbon build up on the head . The other thing is it could have been a worn out starter making it harder to start and the lock up is quince-dental . Now that being said , I assume from your first post that you have not taken anything apart yet . I have an old Jacobsen in the shop that was given to me (grandsons project ) . They told me the motor had locked up , they had remove spark plugs and air shrouds but could not get the crank to move . By the time I got it it had been open to the elements for some time and had rust damage in bottom of the cylinders . 18 hp BS HOP twin . A real shame because the motor before the rust damage was in great condition . The cause of the lock up was the Electric Clutch main freewheel bearing seized up and help the crank from turning . Before condemning the engine as you did not describe any bang or knocking , pull the clutch off and the pump free enough to clear the coupler . Also pull the spark plugs as excess fuel can hydro lock the engine . Heres hoping it is just a bad clutch in one and wrong fluid or seized spindle in the other and you can fix both .
Please do let us know how you make out .

Dave
I do not have any Onans or Cases with electric clutches , everything I have done is standard riders . Some of the old clutches are rebuild-able . Check and see if the bearings are staked in or are in with clips . But if $$ is no object , the Extreme clutches are great and rebuild able . Other than that , without having it in my hands to measure it up I would order a direct replacement from one of the Case parts dealers down there . Maybe some of the other guys who have had to change clutches can give better insight on this . Happy you were able to get it running .

Dave
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Harry United States of America
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Re: 3018 Onan

Post by Harry »

I had a manual clutch on my 446 with a BM48 Onan. It was the older clutch that used shims to adjust not the EZ adjust which is in my 444. I picked up on C/L an electric clutch that was off a JD lawn tractor. The clutch hub on the Case was one and an eight and the clutch was for a one inch. I had the hub shaft turned down to one inch and assembled it on the Onan. I use it for snow blowing only and it has worked flawlessly.

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Harry
1973 444, 1974 644, 1976 446, 1977 646, 1986 226
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