Onan choo choo

[xstang77 2]

First time poster long time listener. Just picked up a free 416-8 after having to work through a lot of none working electrical and having to jumper the coil to the battery I can occasionally get it to start however when it does it seems like it wants to run away at really high rpms and smokes white smoke like crazy/smoke out the whole garage and when you turn down the throttle it eventually dies out,anyone have any ideas? Oil looks kind of milky gray and noticed they rigged this electric pump on with no Markings on it, thanks in advance for any ideas!

[JoeM 7,874]

Change the oil quick! Even if you put some off brand cheap stuff in for start up and test. Milk is good for cookies.

 

Might be a Facet  fuel pump. May work better mounted lower. They push better then pull.

 

Sounds like the carb needs a good cleaning. 

 

 

[xstang77 2]

1 hour ago, JoeM said:

Change the oil quick! Even if you put some off brand cheap stuff in for start up and test. Milk is good for cookies.

 

Might be a Facet  fuel pump. May work better mounted lower. They push better then pull.

 

Sounds like the carb needs a good cleaning. 

 

 

Grabbed some cheap 10-30 to throw in I'm hoping it's a facet 1-2 psi was initially concerned it may be a higher pressure pump make it billow white smoke,I'll try moving it down to the side of the case instead,you think a dirty carb would make it pour whitish gray smoke like that? Seems to actuate and squirt fuel in the bore ok as I crank it

[lynnmor 7,313]

 

You have multiple issues; a fuel pump with unknown pressure, dirty oil, possible worn out engine, probable flyball issue and dirty carburetor.

 

Start with a compression test to see if you have a healthy engine and we can go from there.

[xstang77 2]

Flyball issue? Going to check float and change oil today unfortunately dont have my compression tester with me but maybe by tommorow I can borrow one,haven't seen an engine smoke quite so much without it being major internal issues,are these known to smoke when they have the notorious valve seat issues?

[Tuneup 1,433]

You have a 16 so less likely to have the valve seat issue that plagues the 20. The slipping flyball spacer will cause it to run away. You can hold the governor lever to see if you can stabilize the running but have to hope that the previous owner didn't let it run away like that. Oil in the muffler would smoke but not immediately. Yes, compression test at the start.

[johnnymag3 2,520]

Replace it with a Kohler....Problem solved !!!

 

Just my .02 cents

 

[lynnmor 7,313]

6 hours ago, johnnymag3 said:

Replace it with a Kohler....Problem solved !!!

 

Just my .02 cents

 

Great idea, perhaps you can supply a free Kohler to replace the Onan that xstang77 got for free? 

[lynnmor 7,313]

9 hours ago, xstang77 said:

haven't seen an engine smoke quite so much without it being major internal issues,are these known to smoke when they have the notorious valve seat issues?

 

A bad valve seat won't cause much smoke, you really need to do that compression test.  If you get a low reading, it is time to pull the heads.  My concern is that the previous owner allowed the engine to runaway to the point of damage.  Valve seat issues, bad rings and loose flyball spacers can be the result of overheating caused by owner neglect.  I have seen very few major issues with an Onan that were not caused by neglect, some people can break an anvil.

[kpinnc 12,124]

If the compression is even decent, a 16hp onan is worth saving. I'm not the biggest fan of the P220, but the 216 is a good engine.

[tom2p 2,394]

 

runaway rpm , white smoke , milky gray oil .... ouch - does not sound good 

 

 

a properly maintained Onan will run for thousands of hours 

 

semi-maintained Onan (like mine unfortunately ; semi-neglected ? ) will run around 1000 hours and then you cross your fingers  lol

 

abused and neglected Onan like most other engines can and will suffer an early demise 

 

Edited May 30, 2021 by tom2p

[tom2p 2,394]

2 hours ago, kpinnc said:

If the compression is even decent, a 16hp onan is worth saving. I'm not the biggest fan of the P220, but the 216 is a good engine.

they are very similar

 

is it due to difference in the engine - or due to the operator / lack of maintenance  ? 
 

Edited May 30, 2021 by tom2p

[tom2p 2,394]

2 hours ago, lynnmor said:

Great idea, perhaps you can supply a free Kohler to replace the Onan that xstang77 got for free? 

and make it a KT Series 1 

lol

 

[xstang77 2]

Pulled plugs today,front cylinder plug was soaked,turning it over I can clearly feel theres barely any compression in that one cylinder,hoping to just repair the cause and run it 

 

[xstang77 2]

If anyone has any pointers or parts let me know,is it a pain getting in and pulling heads etc. On these old onans? My experience is in automotive. It has roughly 850 hrs.

[kpinnc 12,124]

1 hour ago, tom2p said:

they are very similar

 

is it due to difference in the engine - or due to the operator / lack of maintenance  ? 

 

The P216 and P220 are nearly identical, but the 220 tends to lose valve seats and pretty much destroy itself. I assume the 220 may run hotter, which contributes to the problem.

 

Obviously proper maintenance usually equates to longer engine life. But I wouldn't mow in August with my 520 without an oil cooler and the beltguard mods to improve cooling. I would not worry so much with anything using a P216 engine. They have a much lower failure rate.

[lynnmor 7,313]

1 hour ago, kpinnc said:

 

The P216 and P220 are nearly identical, but the 220 tends to lose valve seats and pretty much destroy itself. I assume the 220 may run hotter, which contributes to the problem.

 

Obviously proper maintenance usually equates to longer engine life. But I wouldn't mow in August with my 520 without an oil cooler and the beltguard mods to improve cooling. I would not worry so much with anything using a P216 engine. They have a much lower failure rate.

 

I mowed acres from 1991 to last year with a 520/60" without issue and did no modifications.  With the massive flywheel pumping out a lot of cooling air, I see no need to alter what is there.  A member did a study a few years ago and found no significant temperature difference between the front and rear cylinders indicating there is no need for belt guard holes.  Overheating is usually caused by air being blocked by debris on the screen or inside the housing.  An often neglected area is under the engine where the cooling fins for the oil pan may be plugged solid with oily crud.

 

I bought a spare engine that was abused and found a loose valve seat.  I caught it in time and was able to fit the .010" oversize seat.  That engine appeared to have the original oil and oil filter and the cooling fins were completely packed by mud daubers as well as other debris.  There is no shortage of people that waste everything.

[johnnymag3 2,520]

12 hours ago, lynnmor said:

Great idea, perhaps you can supply a free Kohler to replace the Onan that xstang77 got for free? 

All he has to do is ask....I may have an extra floating around....

 

I save Kohlers....Onans go to the boat anchor dealer when the crap out !!!  

Edited May 30, 2021 by johnnymag3

[Horse Newbie 7,075]

I love my Onan P220 because it makes my Wheel Horse gallop !

[kpinnc 12,124]

10 hours ago, lynnmor said:

That engine appeared to have the original oil and oil filter and the cooling fins were completely packed by mud daubers as well as other debris.  There is no shortage of people that waste everything.

 

That is definitely a good point. Most of us here over-service these old machines and spend lots of time and research coming up with ways to preserve them. Even if some of those ways just make us feel better. Unfortunately you are correct though, most people did not even keep minimal service routines on them. 

[xstang77 2]

Update,plug was soaked checked compression,rear cylinder 120lbs,front cylinder absolutely nothing...

[lynnmor 7,313]

58 minutes ago, xstang77 said:

Update,plug was soaked checked compression,rear cylinder 120lbs,front cylinder absolutely nothing...

Pull the head, it is an easy job.  Take a photo of the damage.

[xstang77 2]

Well I'm really impressed it ran at all,enjoy the carnage fellas. Ps if anyone has any parts please let me know,thanks.

[kpinnc 12,124]

Whew that is rough! 

 

Still might be salvageable. Gonna take some new stuff, but if the block is good I would rebuild it. First time I've seen a 216 like that.

[Crazyredhorse 295]

wow looks like that rod smacked that piston couple 100 times after it let loose