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Discussion Starter · #1 ·
Just cracked another starter bracket on the 420 last night. This is the third time this has happened and all occurred from mid-summer on in less than 200 hours. They have all cracked at essentially the same spot. Right next to the two bolts for mounting the starter to the block.

There are ~1200 total hours on the tractor without incident to the starter...that is, until this summer.

So something other than the starter must be the culprit, but I'm puzzled.

The obvious first thing that came to mind was the ring gear. Checked the ring gear and it doesn't seem all that bad for number of hours that are on the tractor. Took the ring gear to Deere as well, and they too didn't think it looked bad.

Anybody have any thoughts or theories??

I'm really at a loss.

Thanks,
Kevin
 

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Kevin,

Well I have plenty of theories, so here is one possibility. I repaired a 420 that had the starter jammed against the flywheel. When I discovered I would have to remove the engine to get to the starter, I went to plan B. I got a prybar to turn the flywheel and the starter released. The problem was that the gear on the spline shaft that engages to the flywheel was dragging.

All I did is spray some Liquid Film (Lubricant and anti-corrisive spray) on the spline and gear. Start a few times and then respray a couple times. The gear is spring loaded to allow it to turn as it attempts to engage the flywheel teeth. If it cannot freely turn it can jam against the flywheel and this may be what is causing the mount to break.

If your starter does not engage the first time you attempt to start, this is a symptom of the gear dragging. You can see the starter and flywheel if you remove the air filter cover. I always spray the spline when I change the air filter.

Just My S.W.A.G.

George of Buford


PS SWAG = Scientific Wild Asss Guess
 

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Discussion Starter · #3 ·
Dragging on the ring gear was on possibility we we were thinking as well. Since there were 3 different starters, we ruled out starters being the issue.

This last time, I had borrowed a used ring gear from a tractor a guy was parting out.

Now that the emotions have died down since the last starter broke, I realized that the problems started occurring ever since I had Deere re-sleeve the pistons to get the compression back up within specs.

Deere dealer verified the timing and compression in the cylinders were right on.

After spending hours taking the engine out to replace starters and swap ring gears, I decided to cut my losses and put a Honda engine in.

New ring gear is something like $600 which I wouldn't have a problem spending if I knew that would solve the problem.

Kevin
 

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Kevin,

Whenever you are troubleshooting something, always ask yourself what has recently changed.

After I replied to your question, I thought that another possibility was that the timing may be off. Since your dealer checked it, I would temporarily rule it out. If the compression is too high, the gas will pre-ignite similiar to a diesel engine. If the gas ignites early, this may be what broke the starters. The cure for this is to run a higher octane gasoline.

Sorry you gave up, but I know the feeling.

Let me know if you want to sell the engine.

George of Buford
 

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Discussion Starter · #5 ·
Running a different fuel would have been interesting to try.

I also changed out the x-members in the drive-shaft u-joints...boy did that ever make a difference.

And another thing I'm mulling over that I didn't think too much of at the time, there was an engine mount missing in the back. Threads are fine, so it must have been left off by accident at some point.

Thinking that the combination of the bad drive shaft, missing engine mount bolt were probably also big culprits.

The engine runs great!! In the spring it was re-sleeved, new fuel pump, new coil and new capacitor all make big differences.

I'll entertain offers or trades for the old engine.

Kevin
 

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Kevin,

Well I checked the TM1590 and CTM2 and the B48G and P220G engines are supposed to use 85 octane gas. The compression ratio is 7.0 to 1 with a 75 psi minimum. I could not find a normal or maximum psi for the cylinders.

I would be interested to see exactly what the compression is in BOTH cylinders. There should be only a 10 psi difference. I would run the highest octane gas for awhile to break it in just to be safe.

George of Buford

Well it's Miller time!!


PS I do not like Hon Deeres.
 

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Discussion Starter · #7 ·
Don't remember what the exact number was. Just remember the Deere dealer saying that the cylinders consistently ran at equal or within a psi of each other.

I can understand not liking a Hon Deere, but it sure beats the O Deeres.

Kevin
 

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Hello all,

I tried the LMGTFY that Terry showed us over in the corner store and nothing seemed to pop up. I dont have a lot of books on this model. Although I did locate one and picked it up. It does not run, but I think a carb cleaning will take care of that since it does have spark and I did get it to sputter when I put some gas in the throat. My question is does anyone have any good detailed photos of the engine compartment? Mine is not electric start and I was curious if it should be?
Thanks in advnace to anyone that can help,
Blake
 

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Stock was pull start with either Tecumseh (I think) or Briggs (68) power. Electric start could have been added by the dealer but there was no charging system so you had to recharge the battery from time to time. Basically the same cheaper version of a Model 68 with a 30 inch deck standard. Good mowers but not much else. Roger
 

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Roger,

Thanks first of all. That is what I thought by my tech manual. It covers the 66 and 68, but more pics of the 68 than the 66. Mine seems to be all there, but not sure. Have never seen one of these before. Are there very many of these out there?

Thanks,
Blake
 

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The 66 had a 6 hp Tecumseh, and the 65 had a 5 hp Tecumseh. The 68 had a 8 hp Briggs. I had both a 66 and a 68 a few years back. There are a lot more 68s than 66s. Most 66s had the engine replaced with a 8 hp Briggs in it's lifetime. There was an article in the L&G News when that magazine came out about a Missouri 66 owner putting in a 8 hp Briggs in his 66.

BTW, I have the Operator's Manual on a pdf.
 

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I bought a brand new 66 in 1976 (?). It came with a 6HP Tecumseh. The engine burned out twice, once under warranty and once within a year after being replaced. May have had something to do with the pure nitrogen I was putting on my lawn. They had a "neighbor friendly" shroud on them that probably kept them running hot. The 66 has two bolt patterns stamped into the frame, one for the 6HP Tecumseh and one for the 8HP Briggs. That makes it a very easy swap. In my case, I went to a 10HP Briggs which worked great. I sold it many years ago. Last I heard was that somebody managed to put a 13HP engine in it. These are neat mowers with lots of room to get off and on.
 

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Well, update to all. did a very quick cleaning of the carb. Got it to run this past weekend, even when I manually pushed the throttle shaft to where it should be idle it runs at full rpm's. the throttle shaft hole is wollered(sp?) pretty badly which I cannot get a new carb body via deere. I was wondering if anyone knew what model this engine is? is it the VH60? I figure the same carb will work, but I do want it to be factory specs. OR if anyone knows where to locate a body like this?
Thanks in advance, any suggestions welcome!
Blake
 

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After a new throttle shaft, new throttle shutter, new float, new governor linkage, new throttle/choke plate, new carb kit including both jets, soaking it 3 times in our ultrasonic, new fuel lines, new fuel filter, and a few curse words... She lives again!!! Now that it runs I see smoke coming out around exhaust. There is a fairly large oil leak that Im assuming is both pan gasket and head gasket that i am sure is dripping down to the exhaust and causing it to smoke. While the pan is off I will most likely put a new crank seal on the bottom. I will say aside from the smoke, it ran very well with little adjustment to the tech manual settings for the jets. May be many months now, but will update when I get further along.



I know the pic isnt the best. And another word-- I just parked her on top of the drain after running her. NEVER work on top of a drain...

 
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