Case 446 engine info

[jimmyj]

You can get the manual for this engine at this site

Michael's Tractors (Simplicity and Allis Chalmers Garden Tractors)

The same engine is used in a bunch of stuff, I have two of them and the most important thing I've found is to have the timing spot on.

 

[kevinwak]

Wow. 5 minutes to shift. That is too long. Something is wrong or bent.

 

[kencunningham]

Do this and you wont have a problem or even have to get off the tractor to shift between hi and low. Let me preface this by making sure that you understand that the tractor should be stoped to change between the two. If the lever will not move, that means that the gear teeth are hitting each other on the edges. Place the lever in nuetral and push forward on the travel lever and return it to the stoped position, then try to use the gear lever again. This should work in 1 or 2 attempts. Usually takes no more than 5 seconds to do this.

Here is a before and after pic of mine. Remember what you were told earlier, you will be required to actually work on this thing to make it work right, but there is alot of help to be found to help you along.

 

[Dr Natedogg]

That's exactly what I did and it worked. Thanks for your help. I have a whole new problem and not sure if it's major. While engine is running I checked the oil and it's bubbling and spitting and I put my hand over the top and there's huge pressure??? Any thoughts??? Would that be an intake leak???

 

[hydriv]

I don't know why you would try and check the oil of a running engine because it is not possible to get an accurate reading.

Inside the crankcase, oil is flying everywhere, thanks to all of the components that are spinning. Crankcase pressure is also common. If you want to know the true health of your engine, then you need to conduct a leak-down test as well as wet and dry compression tests. The results of those tests will give you insight as to how much wear is on the engine parts and which engine parts (if any) are worn to the point of being a problem.

Rebuilding an Onan engine has never been inexpensive and today the cost has risen to well above the $1000.00 figure, depending on how much of the work is done by the tractor owner. That said, a competent engine builder/machinist should be employed to assess the block, do the machining necessary and then re-assemble the basic engine. Adding the heads, flywheel, sheet metal, starter, coil etc are all simple tasks along with putting the completed engine back into the frame.

I'm not saying that you need a rebuild. What I am saying is that you need to find someone to conduct the above tests to determine whether a rebuild is needed NOW or in the near future. Until those tests are made, it's anybodies guess whether the problems you are having are major or minor. A leaky intake manifold can cause all kinds of havoc and that is a common problem. Issues with the governor spring can also cause the "hunting" you describe.

Engine diagnosis is a step-by-step process and it begins with making sure that the valve lash is set correctly, the points and plugs are gapped to spec and that the carb is functioning as it should.

As for the gear changing issue from Hi to Lo range, just rock your body back and forth when sitting on the tractor and it will also rock. it only takes a couple of inches of movement to synchronize the gear teeth so that they mesh. Using the travel lever to do this is not always advisable because you run the risk of chipping the edges of the teeth. If that happens, the chips can get pulled into teeth of the Hi or Lo range gear and smash those gears when they reach the cluster gear.

 

[kencunningham]

Not much chance of breaking a tooth off of the gear if its in neutral, but by all means, feel free to pull some muscle that you didnt even know existed by rocking around in the seat hard enough to move a tractor that in my case weighs well over 1000 pounds.

 

[Dr Natedogg]

Thanks for the info hydriv. I have some work to do. My mechanic that I got a chance to talk to told me to check and see how much back pressure is coming from the oil dipstick. I didn't mean I was checking the oil (haha), I'm new to engine work but not that new. I now how to check the oil but thanks for making sure. I see how it sounded when I re-read it.

The engine just won't run smooth. I changed both spark plugs and it stopped "hunting" which I don't understand and now it just dies and smoke comes out the top of the carb when it does and it wreaks like gas. It's almost like it's flooding but still not running right while it runs. If that makes any sense. I'm gonna phone a mechanic and have him stop by my place. Any more suggestions would be appreciated

 

[hydriv]

Thanks for the info hydriv. I have some work to do. My mechanic that I got a chance to talk to told me to check and see how much back pressure is coming from the oil dipstick. I didn't mean I was checking the oil (haha), I'm new to engine work but not that new. I now how to check the oil but thanks for making sure. I see how it sounded when I re-read it.

The engine just won't run smooth. I changed both spark plugs and it stopped "hunting" which I don't understand and now it just dies and smoke comes out the top of the carb when it does and it wreaks like gas. It's almost like it's flooding but still not running right while it runs. If that makes any sense. I'm gonna phone a mechanic and have him stop by my place. Any more suggestions would be appreciated

I would check to see if this engine has a brass float or the composite float in the carb's float bowl. The composite ones have a tendency to swell with the crap they call gasoline today and then they rub on the sides of the float chamber.

 

[hydriv]

Not much chance of breaking a tooth off of the gear if its in neutral, but by all means, feel free to pull some muscle that you didnt even know existed by rocking around in the seat hard enough to move a tractor that in my case weighs well over 1000 pounds.

Ken,
When you switch from Lo range to Hi range, you are moving the cluster gear along the splined shaft that belongs to the drive motor. If you move the travel lever to make the motor spin, then you are also making the cluster gear spin. Trying to engage a spinning cluster gear into a stationary range gear does have the potential to cause tooth damage.

 

[kencunningham]

Obviously i wasn't clear enough, moving the gear selector out of nuetral should only be done after the travel lever has been returned to the stop position. This is the way i do it and there is no gear grinding going on, if it was i wouldnt be doing it. I suppose if the travel valve were out of adjustment or damaged in some way that allowed the motor to still recieve oil when in the stopped position this could be a problem.