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Discussion Starter #1
Hi All,
Sorry for the lengthy post....

So my Onan CCKA has started running a bit rough, hot and seems down on power. After an hour or so of heavy mowing it starts backfiring, is really hot and loses much power.

Readjusting the carb yielded marginal results, but I really haven't run it very long since adjusting so I don't know how much it helped.The plugs looked light coffee colored. Really the only adjustment I made was to turn the load adjuster CCW about a half turn. (This does make the mix richer doesn't it?) It now accelerates quicker and is running smoother.
New fuel filter installed now also.

Had a nasty exhaust leak due to corroded gasket that I'm sure wasn't helping matters since it was leaking right next to the coil.

I assumed the coil that was on the machine was original since the dropping resistor was still in place. As Richard-tx says, these original coils are starting to give up the ghost due to age, so I thought the coil might be part of my problems.

I ordered a new coil. It is quite a bit longer than the coil that is on there and will require some mounting modifications. As I was tearing in to it to begin the replacement, I looked at the label on the coil which had been hidden from view and it said "Onan 166 0804 12V". Hmmm:confused: ....and it does not look that old now that I cleaned it up some.

I removed the dropping resistor and have reinstalled everything but have not yet turned the key. New items include spark plug wires, new wiring from coil to points, and new exhaust gaskets.

WILL IT BLOW UP with this coil now that I've removed the dropping resistor? :hide:

The information I found for the "166 0804 coil is that it "Fits some but not all CCKA."
I have owned this 816 for about a year and it has started quite well and run decent with this coil and dropping resistor.

I'd like to keep this old coil on it since the new one will require some modification to mount in a sensible manner.

Thought? Opinions?
 

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The 166-0804 is indeed the correct coil for your engine. Yes you need to take out the resistor for it is work properly.

The warning "fits all but CCKA" has to do with the mounting of it, not how it performs. I have that coil on my CCKA and it works great. I think you will find that the engine starts easier with the new coil. A hose clamp will hold the coil in place.

If the engine is running too hot, then that is usually a sign of too lean a mixture. With a load on the engine, try advancing the choke a little and see if it runs any better. If it does not then the issue isn't mixture.
 

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Discussion Starter #3
Thanks so much Richard!

I was hoping that coil would be okay without the resistor. I'll be testing a bit today to see how it runs now.
 

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Discussion Starter #4
Well I mowed with it for about an hour Sunday. After removing the dropping resistor, it started in about half the normal time. It really popped right off. Yes!

And it was definitely running smoother. Remember I also put on new plug wires, exhaust gaskets, and some minor rewiring.

For about the first 45 minutes it ran much like it's old self, except for seeming to still be a little bit boggy under more load like thicker/ wetter grass spots or turning uphill. And it still seemed quite a bit hotter than it used to be/ should be, but that could be me just being overly sensitive to something being out of sorts.
While it never lost power quite like it had, it did start backfiring and missing some toward the end of the run.

Later that evening I pulled the deck to sharpen the blades, grease spindles and check for something perhaps causing excessive load.

It was dusk when I went to put it in the shed, and it REALLY started missing. I hopped off and was looking at the engine and noticed severe arcing around the starboard plug boot. I've either got a faulty plug, plug wire or it may just need crimped tighter.

I've done nothing else with it yet.
 

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Change the plugs.
 

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Discussion Starter #6
New plugs installed.
Carb cleaned, flushed.
Timing checked statically. Looks to be dead on.

Have not checked the points or condenser
Have not adjusted valves
Have not changed head gaskets, or pulled heads to check for carbon buildup

On these CCKA carbs (Zenith) with the T handle load adustment screw, does counterclockwise make the mix richer?
This carb seems pretty resistant to adjustment. I could get excellent throttle response (like the manual says) throughout a wide range of adjustment. I kept unscrewing the T handle waiting for black smoke or for it load up, but after several turns it never changed. Also, the idle adjustment had to be nearly all the way in for it to run smoothest. The engine seems to be running well, starts quickly, good throttle response, good idle.
Is it still too lean? I have no idea.

I mowed with it for about 30 minutes and it started acting up again. It just got hotter and hotter, started with an occasional chuff chuff miss, and it soon started losing power in a big way and really missing.

I might be looking at a multi faceted problem. Perhaps the valves need adjustment. (Listening from the rear I can hear some pretty loud tapping that sounds like its coming out of the muffler, but cannot really hear the same tapping sound if listening from the sides). And the valves being out of adjustment could be causing the overheating thus causing the coil to breakdown.

Sound reasonable?

As far as I can tell, the intake has to come off to get the valve covers off, so I'll be ordering valve cover gaskets, intake gaskets, and will go ahead and get head gaskets too. Anything else I'll need?

One last thing... while watching it run today, the sun shine was on it at an angle where I happened see a pretty good haze puffing out of the breather tube, so I guess there's some blowby.

Well, at least I haven't really made anything worse yet. :fing32:
 

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If your CCKA is overheating then there are 2 common ways for it to overheat.

1 - poor air flow.
2 - too lean a mixture.

Some of the more common reasons for a lean mixture is a vacuum leak , a clogged carb, or possibly a fuel supply issue like a hose leaking air into the fuel supply. Did you try incermentally choioking the engine to see if it runs better when partially choked?

Poor air flow is usually caused by dirt, grass, dead mice, etc. in the cylinder and head fins.

If you are going to pull the heads, (not really advisable) you will need a good torque wrench.

You might consider replacing that Marvel VD carb with a Nikki carb. See Boomer for the details regarding that. He usually has a good guaranteed carbs in stock.
 

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One more thing.

DOn't run that engine with it overheating. You can overheat and destroy an air cooled engine. It is the same as running your car engine without coolant.
 

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Discussion Starter #9
Thanks for the reply Richard, it is greatly appreciated.

Fins are clear
Shrouds are all in place
The air flow is about as good as can be

All of the rubber fuel line is new except one short piece going from the tank to the steel line. (This was done after the engine started acting up)

I do not have a compressed air source to blow out the carb to be sure the passages are clear. But maybe before I call for a Boomer carb I'll take it to work and blow it out there.

Now something else just came to mind:
This all started after I decided to start a Seafoam regimen on the lawn equipment fuel. There has probably been less than one full tankful run through it since I started adding Seafoam to regular pump gas when I buy it.

I also changed the fuel filter at the same time.(Wix 33011)

I have just enough tools and know-how to be dangerous, and feel like I'm chasing my tail.
 

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First of all lose the Seafoam. If you have any gasoline in the tank that has that stuff in it, get rid of it.

If you want to put anything in your tank, put AVGAS in it.

Do the choke test. That will tell a lot.
 

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Hi Richard, what is wrong with Seafoam; I have read others on here say not to run it. I have also read on other sites that I should run it in my Farmall Cub to help clean out the "gunk". Is it a engine size reason?
 

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Seafoam is basicly a bunch of alcohol according to the MSDS sheet; Pale Oil, Naptha, IPA. In trying to keep alcohol out of a motor by using E free gas.. why put some right back in I believe is what Richard is trying to say.
 

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I guess I should tell you what those three things are...

Pale Oil - Kerosene or Diesel fall into that list
Naptha - Naptha
IPA - Isopropyl Alcohol
 

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Hi Richard, what is wrong with Seafoam

Do a google search for "seafoam sucks". 'nuff said.

This falls under the category of finding out why something should NOT be done.

Putting a pink coat on a goat might might sound like a good idea but....


 
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