My Tractor Forum banner
1 - 20 of 26 Posts

·
Certified Technician
Joined
·
8,606 Posts
Discussion Starter · #1 ·
P218G engine, about 1800 hours on it, uses some oil...

Has always run fine, never had this problem, then one day I noticed that when I revved it up it seemed to accelerate too rapidly and reved up to nearly 4000 rpms. I let it sit and cool, and when I retired it, it revved to 3450-3500 and was fine, did it multiple times, ran fine. after running 4-5 minutes, when revved it would want to run faster and overrev some when accelerating before abruptly ceasing to accelerate.

Governor isnt dragging, its not sticking anywhere and I tried a new non sloppy governor/carb rod...helped every so slightly, but it didnt fix it.

I put in 10W40 oil and some engine restore, this, for whatever reason seemed to help more than anything, but after a couple hours, the problem has come back and now, after 4-5 minutes warming up, it will run faster than it should and wants to overrev when accelerated.

I know the governor is a plastic disc sitting on the cam gear with steel balls in slots, with the governor having a bowl shape, and a disc sitting over the balls, also with a bowl shape...faster it revs, it pushes the balls out, pushes the disc out, which pushes the governor closed. Id think it it were a governor problem, heat wouldnt have much if any effect on it, if it lost a ball, it would overrev all the time.

Im at a loss on this one...Im not sure where to go with it, Im not really willing to tear it down to the front cover only to find its all perfect inside. If Im taking it that far, Im rebuilding it, and I really would love to sell it without rebuilding it, but I dont want to sell it like it is and have the new owner sitting on a ticking timebomb.
 

·
Registered
Joined
·
3,151 Posts
Could it be some sort of carburetor issue? ie, flooding/float problem?
I had a Tec powered snowblower that had a bad float/needle/seat, making the throttle/governor useless.
 

·
Registered
Joined
·
1,614 Posts
My guess is that the plastic cage for the governor balls is not tight on the cam hub. When it comes up to operating temp, it begins to lose it's grip on the cam and slows down, relative to the cam.

According to Onan, the cam w/gear must be replaced as a unit. But, others have reattached these. I don't remember exactly how, but look over on WFM.

Or, if you want a good used replacement, send me a PM.
 

·
Premium Member
Joined
·
5,741 Posts
Even if it was an intake leak, the governor would close the throttle to compensate. I'm with antiqueetc, the governor drive is slipping. Last year I picked up a Kawasaki FH500V engine used on commercial WB's to fix and resell. I test ran it before I took it apart (always do this) to see what I had. It only ran on one cylinder. The problem was a broken intake manifold gasket. When I revved it up, it took right off, the governor wouldn't control it. I checked the static adjustment, it was OK. When I pulled the sump, the plastic spider that drives the balls was missing its two drive tangs.
 

·
Certified Technician
Joined
·
8,606 Posts
Discussion Starter · #10 ·
Okay, so If I pull the engine (again) and pull the stator and such..And unbolt the front cover, Im basically at the governor right?
 

·
Certified Technician
Joined
·
8,606 Posts
Discussion Starter · #11 ·
If the Retainer is no longer keyed to the cam gear, how does that make it not react rapidly enough when accelerating hot? And also run faster hot vs cold?
 

·
Super Moderator
Joined
·
44,896 Posts
Pull the flywheel and gear cover and that should give you access to the governor cup assembly

With the gear cover removed, the governor cup can​
be

taken​
off after removing the snapring from the camshaft
center pin. Catch the flyballs while sliding the cup-off
(Figure
10).

Replace with a new part any flyball which is grooved or​

has a flat spot; the​
ball spacer if its arms are worn or
otherwise damaged; the gear/ spacer assembly if loose
on gear hub, and the governcup if the race surface is
grooved
or rough. The governor cup must be a freespinning
fit on the camshaft center pbiunt, without any

excessive play
 

·
Registered
Joined
·
1,460 Posts
ok a monthago I was having this same issue, I talked o a local Onan pro and he asked me wha oil I pu in it, I told him 15w40, he said "get it out and put in 5w30 or 5w20 Mobil 1 with a splash of Seafoam...He said the thicker oil interfers with the gouvenor balls ???
So...I did wha he said and guess what...it runs perfect now and has for over a month..go figure
 

·
Premium Member
Joined
·
2,207 Posts
red, and cvc
the fly ball retainer NEVER was keyed to the shaft.
the early ones were steel and pressed on the gear hub.
THEN onan saved a few pennies, and made them from plastic,
but they were still pressed on the shaft. ( they split )
then they made a slot in the gear, and had a tang on the retainer.
when you remove the LITTLE snap ring, be ready,
most likely it will fly a long way.
cvc.
if you look at your operators manual,
it will tell you that 5/20 is from -20 to +20
5/30 is from-20 to + 50
in other words i do not agree with your ONAN guy,
as to what oil you should use.
thank you. boomer ( the used onan engine parts guy )
 

·
Registered
Joined
·
1,460 Posts
that mentality was very popular when these were made but in later years good mechanics learned that thicker oil was NOT better, in small engines or race cars.. Look at race cars that run 0w20 and run alot hotter than these tractors.
Its ok to disagree but I have 5w30 in mine now and it runs great, no more surging or reving up when warm...the thinner oil allows it to flow when and where it should, run what you like but I run what works ! Again these manuals were printed 30 yrs ago,
 

·
Registered
Joined
·
1,460 Posts
You are falling into the trap thinking the thicker the oil the better it protects. A while ago a bike magazine compared 10W-30 oil against a 20W-50 oil they rigged a bike with temperature sensors throughout the engine, then they ran the bike up and down a canyon road. What the found that the thicker oil ran much hotter, hot enough at the main bearings to reach the flash point for mineral oil. Makes sense when you think about it, oil must flow to carry away the massive heat load of the main and other internal bearings. If it does not flow freely it cannot do its job. The thinner oil flows better,faster and removes heat twice as fast as heavier oils...

This was taken from a web site re; oil weights
 

·
Certified Technician
Joined
·
8,606 Posts
Discussion Starter · #17 ·
One odd thing is, it started doing this very suddenly.

Its just so strange, you can crank it cold...idle it for 25-30 seconds...pull it wide open and it will run about 3400 or so, and over the next 5 minutes, un touched, be running 3800, and if you idle it and rev it, revs to 4000 rapdily and smoothly, then down to 3800.

It feels like, and I know some of you have experienced this, but...a Stickly governor linkage. Its like it reacts and it takes an instant for the flyballs to overcome to sticky governor link, and it finally kicks it down to the right speed.

But its all moving freely.
 

·
Registered
Joined
·
1,460 Posts
exact same way mine was doing it, the thick oil makes the balls stick, hey try it, waht will it cost for 2 qts of Mobil 1, splash of seafoam, and a new filter...Mine runs like a top now !
 

·
Certified Technician
Joined
·
8,606 Posts
Discussion Starter · #19 ·
I dont even want to think about how bad its going to smoke on thinner oil...

I guess Ill just have to sell it as is, or rebuild it. I just needs to figure out where the point of diminishing returns is. If I put 400 into fixing the smoking problem, is it worth 400 dollars more in value?

There is a 316 for sale locally, no smoke, unrestored but very nice, for 600obo...kinda sad.
 
1 - 20 of 26 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top