One Method to Loosen and Remove Stubborn 717 PTO Flywheels

[Ed Clark]

So, I had occasion to remove the PTO flywheels from two 717 engines. Not having performed this job before, I had no idea what I was in for. I learned that it takes an incredible amount of ass to get these things loosened. At least in my case. Of course I first tried an air impact and it was like swatting at a fly. Then I went to successively larger and longer breaker bars. I was loathe to use the suggested method in the manual of using a pipe wrench when all else fails. But, the main problem was that as the force on the breaker bar went up, so did the tendency for the engine to just pick up off the floor and go with it. Been there? Done that?

So, I was all ready to take the engine out in the yard and bolt the support pan to an old railroad tie retaining wall that I had. Then I happened to spy something in the shop that I thought just might work. I had a motorcycle up on a worktable. Estimated weight of both around 1,000 pounds. In photo one below you can sort of see an overview of my set-up. Photo two is a closer view of how I anchored the engine.

By the way, you will also have to find some way to anchor the starter flywheel. I happened to have a tool like was shown in the service manual. Ridiculous. Doesn't stand a chance of working. I really think the best way might be to weld up a scrap starter driveshaft so as the flywheel is locked by the jury rigged starter. However, I didn't have a sacrificial lamb available so I finally managed to jam a piece of wood between the starter flywheel and the engine support pan.

Using the above method for anchoring the engine and with my 210 plus pounds standing on the breaker bar and bouncing a little as I held on for dear life I was able to loosen both the PTO flywheels in question. Once they broke loose, they both just readily unscrewed by hand and all threads were in good condition and well lubricated! I will conservatively estimate that using my method with a 1-1/2 ft. breaker bar that the flywheel absorbed between 400 and 500 foot-pounds of torque before it broke loose. In any case, it was enough that the side of the worktable that the engine was clamped too was beginning to lift off the floor.

Just thought "enquiring" minds might like to know.

 

[mikidymac]

I hate to say it but that crank is probably not good anymore. It is going to need to be measured to see if it is twisted with V-Blocks and a dial indicator.
You never remove a PTO or Flywheel by holding the other end as you will twist the crank since it is pressed together.

The correct way is to pull the head and insert a block of wood or hard plastic on top of the piston closest to the PTO or flywheel you are trying to remove and reinstall the head to lock the crank.

Heat the PTO really hot until the paint starts to smoke then kit your wrench really hard with a heavy hammer and it will pop right off. IF it doesn't come off in a few wacks then you need more heat. I prefer a chain wrench for the Rear PTO. For the front flywheel nut an impact wrench is the easiest.

I also do not recommend using the PTO splines to remove it as they can strip out before it is removed.

 

[burtshaver2021]

Correct me if I’m wrong but you can shove some rags in through the exhaust port over top of the piston as well to hold the crank from turning

 

[mikidymac]

Correct me if I’m wrong but you can shove some rags in through the exhaust port over top of the piston as well to hold the crank from turning

Too much of a chance getting the rags stuck in the ports or piston ring lands. I am not sure you could get enough in to lock the crank either.

I have done a few with rope threaded down the sparkplug holes but on really stubborn ones it just compresses the rope and takes some shock of the hammer hits. The best I have found is hard plastic or wood as it transmits more force to removing the PTO.

 

[Ed Clark]

I wish I had mikidymac's suggestions before I undertook this job. Thank you for your thoughtful comments anyway as I'm sure I'm going to encounter this situation again in future. So, future readers of this thread take note (and heed). I am going to check crank alignment just as a point of interest. However, the "good" news is that regardless of that outcome, both cranks are in need of a rebuild anyway because of worn out inner and outer main bearings. I suspected this which is why I was pulling two engines apart in the first place. I do want to correct one thing I said. Upon closer examination, the threads of both PTO flywheels had been coated with one of the Loctite variants. So, that goes a long way to explain why heat might ease the task a bit.

While we're on the subject of cranks, I'm including a photo of the two cranks that I removed. As you can see, the rotary valve drive pinion has shifted sideways on crank #3. I'm wondering if anybody has ever seen this before? I don't know how the pinion attaches to the crankshaft but I would not have expected to see something like that.

 

[mikidymac]

Yes, the rotary gear typically shifts when a rotary valve catches something and stops like a bolt down the intake. It is just pressed on if I remember correctly.

It will eat a new brass rotary gear if not centered.