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Onan motors? good? bad?

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#1 oliver2655 OFFLINE  

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Posted January 02, 2015 - 01:58 AM

i have owned a few onans over the past few years and have not been too lucky with them. i used to have a couple onan motors in a couple sears garden tractors. although 1 tractor was a parts tractor, the other was usable. i did end up getting it to run and it ran good sometimes but no matter what i did it never seemed to be very consistant at running good for long periods of time. i eventually got rid of those and we now have a wheel horse with an onan motor. this one appears to be much more reliable to run. i have been told there are certain models of onan motors to stay away from? is this true? if so what models were most reliable? i love the sound and power of these motors but i am half afraid of buying one if it is non running.

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#2 KennyP ONLINE  



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Posted January 02, 2015 - 06:05 AM

I have 3 Onans and am very happy with them.

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#3 toppop52 OFFLINE  

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Posted January 02, 2015 - 07:32 AM

my favorite sound from a garden tractor is an Onan twin!

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#4 GTTinkerer OFFLINE  


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Posted January 02, 2015 - 07:50 AM

They say if I have nothing good to say about something I should stay quiet so please ignore this post.

#5 JDBrian OFFLINE  


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Posted January 02, 2015 - 07:58 AM

A lot of them are still out there running great but many have been run hard and not maintained. They are just worn out in a lot of cases. I find that is the case with most older tractor engines these days, not just Onans. If a tractor is 30+ years old and has been used for 40-50hrs a year, it's engine will be pretty tired at that point, especially if it wasn't well maintained, no matter what the brand. The other issue with Onans is the parts are harder to find and quite expensive, at least in this area. 

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#6 Oldford OFFLINE  

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Posted January 02, 2015 - 09:21 AM

This guy has a lot of onan knowledge and parts.


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Posted January 02, 2015 - 09:32 AM

I have never owned an ONAN, but I have Wheel Horses, and read a lot of problems with the ONAN on the WH GT's.


I think the biggest problem is the engine sits in the GT with the crank shaft right/left, and the rear cylinder gets too hot because of debris in the "cooling tins". This excessive heats makes the valve seats loose and fall out of the block, thus poor running!


If you keep it clean and well maintained, no issues, as long as there are no issues when you get it.


As I said, I have neve owned one, but I do like the sound of them running.....running well that is.

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#8 noclue OFFLINE  


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Posted January 02, 2015 - 11:20 AM

i have an onan in my 1655, it runs so well i don't want to mess with it!   the fuel pump and carb float went bad so the previous owner put an electric fuel pump on it. like i said it runs so well i don't want to mess with it!

#9 glgrumpy ONLINE  


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Posted January 02, 2015 - 12:11 PM

The BF's I think? were used in the Sears and had cheapy carb and intakes on them. Once you know any brand's problems, you can fix right away and be back in shape. Onans are known to have poor plastic floats, replace with brass. Intakes on some are split tinny metal and they come apart and leak air causing issues. Fix those and good again. Hardest part I found was the cost of parts. Found a few sources, but most were individual parts and no sets like plug wires as example. Price for one was what I would have liked to pay for pair. Coils are odd two post for plug wires and hard to find orig type.  I gave up on my Sears and got it running enough to drive and sell and that is last of an Onan for me. Case guys really have to learn how to fix, many Case tractors had those as stock engine.

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#10 Bud OFFLINE  



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Posted January 02, 2015 - 12:16 PM

I too have a mf1655 with the Onan. I have put more money in the carb and fuel pump than the whole 1655.  I gave up and took it to a mechanic. He said the engine runs great but they just don't have enough vaccum to run the pumps properly. He said get a cheap electric fuel pump. I did and it runs fine now, although I haven't run it much since putting it on. I would have to say I like the Kohlers better, but I have had more of them.

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#11 MH81 OFFLINE  


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Posted January 02, 2015 - 12:52 PM

I have three Onans. Two 18's and a 19.9
They are some of the easiest starting, most reliable engines. My 19.9 starts twice as easy as my 16 or 8 Kohler and at least a thirds easier than my 12 teccy's. it runs sweet too.

The 18's start easy, but one has a bad choke so I have to give it a squirt of ether. This engine has had zero love all of its life and its visible. The oil change was a cringefest.

I will watch for more so I have spare parts, but I am not afraid of them, just wary that they can have the same issues as any engine and are (usually) more $ to fix.

#12 Leonard VanCamp OFFLINE  

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Posted January 02, 2015 - 01:26 PM

The biggest thing with Onans is to keep them clean. I have a JD 420 with a B48G and my one relative has two 318's, one with a B43G and the other a P218. Like KC9 said the biggest issue with the Onans in these tractors is usually the right cylinder, you need to keep the fins clean so you get good air flow because once they get hot the valve seats come loose. Onans are used in a lot of welders and generators and many still run good, mainly because they are not in a as dirty environment as a lawn and garden tractor.

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#13 A.C.T. OFFLINE  


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Posted January 02, 2015 - 04:54 PM

I have three, 2 JD's 318 and a Case 448. As mentioned the sound is awesome. If engines never broke down, really like the Onan over a Kohler. But they do break and repairs are much higher on the Onan. Have had more starting problems on the Onan's. Also mentioned these guys are getting pretty old and have been rode hard and put away wet (not by me but p.o.)  Just think if I could go back in time and have bought these GT's new............ And the Camaro and then......kids.

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Posted January 02, 2015 - 06:53 PM

The Onan P series in my Massey 1655 has been good to me. Starts up pretty easy and runs strong. Only thing I don't like about it is that it surges sometimes. I have tried adjusting the carb several times to tune it out but nothing seems to work. It's not even enough to really bother anyone.