DPittman
Ultra Member
Yes it would be nice to have one for that once in a blue moon occasion. Not everyone needs a EDM but I think everyone needs to have a friend with an EDM.
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How to remove a broken bolt extractor
- Thread starter Susquatch
- Start date
Yes. Mostly with his dad who learned from me - that is as it should be.
No idea what really happened yet. The engine stopped with a clunk (locked up) and wouldn't turn over afterward. I found nothing in the cylinder head to explain that other than a little dirt in the bearings that washed out easily. My son had hoped for a head problem and broke the bolt taking the cam drive off. He and my grandson will be looking at the block next.
It is out.
There was a little stud of the extractor still in there, but it came out with a punch.
I drilled out the remaining bolt stud. But the threads are not clean and the thread (wire coil) is not coming out normally. My jobber can get me a LH tap for tomorrow, so I ordered one. It will probably need extra care, but job is all but done now.
As for the rest of the motor, my son says the wrist pin is stuck solid. That can prolly be fixed but the big question is "How did that happen?" Low oil, low oil pressure, poor lubrication, varnishing, gunning it when it's too cold, etc etc
There was a little stud of the extractor still in there, but it came out with a punch.
I drilled out the remaining bolt stud. But the threads are not clean and the thread (wire coil) is not coming out normally. My jobber can get me a LH tap for tomorrow, so I ordered one. It will probably need extra care, but job is all but done now.
As for the rest of the motor, my son says the wrist pin is stuck solid. That can prolly be fixed but the big question is "How did that happen?" Low oil, low oil pressure, poor lubrication, varnishing, gunning it when it's too cold, etc etc
DPittman
Ultra Member
You mentioned that there was dirt on a bearing in the cylinder head....probably related to overall problems.
Possibly......
Then again, he brought me the head covered in dirt wrapped up in a dirty tee-shirt. Then showed me how the cam only rotated part way before jamming using dirty hands that were just holding the head. So it's also quite likely dirt fell in there then.
My assignment to get the stud out will be finished tomorrow.
So I may take a run to his house this weekend (an hour and a half away) and take a look at the piston, rod, and pin myself.
Chicken lights
Forum Pony Express Driver
I’m pretty sure that’s the cycle of life-
Kid gets dirt bike
Kid breaks dirt bike
Dad/grandpa fixes dirt bike
Kid gets dirt bike back
Kid breaks dirt bike
Until the kids old enough to fix it themselves. It’s much less fun breaking things when you have to fix it, I’ve noticed
Kid gets dirt bike
Kid breaks dirt bike
Dad/grandpa fixes dirt bike
Kid gets dirt bike back
Kid breaks dirt bike
Until the kids old enough to fix it themselves. It’s much less fun breaking things when you have to fix it, I’ve noticed
I’m pretty sure that’s the cycle of life-
Kid gets dirt bike
Kid breaks dirt bike
Dad/grandpa fixes dirt bike
Kid gets dirt bike back
Kid breaks dirt bike
Until the kids old enough to fix it themselves. It’s much less fun breaking things when you have to fix it, I’ve noticed
Sounds like the voice of significant experience.......
Wise words even if not.
Susquatch, whatever happened with the broken bolt extractor. I was following along intently while the suspense was building.
Ya, sorry. I dropped the ball on updates.
As expected, the broken stud part of the assignment ended with arrival of the proper left handed 8x1.25 tap. It worked perfectly.
I should add that I wasn't 100% sure of the thread pitch and couldn't put a thread gauge into the hole, so I made a small roll of putty 1/8" diameter, put it in the hole, and pressed it into the wall with a roll pin punch to pickup as much of an impression of the thread as possible, then confirmed that against a thread gauge.
The tap easily cleaned up the hole and even removed a small thread sleeve at the bottom of the hole that I didn't see.
After that I cleaned up the bearings with running solvent, then spun them with compressed air, rinsed, spun, rinsed, spun rinsed, spun. I could not eliminate an odd irregular resistance point. Because it's irregular and inconsistent, I believe one of the balls has a ding in it. I've told my son that I'd replace it if I were him. But apparently, they are not available separately. They come with the cam. I don't buy that, so I showed him how I, would find replacements.
More importantly, I looked at the engine when I was there. The wrist pin is quite firmly seized in the rod and piston. Neither one will move. He damaged the spring clip (sort of like a c-clip but made with wire) in the process of trying to separate the parts. We had nothing there to do any precise measurements with, but I plan to make a Puller for him to get the pin out without damaging anything more than it already is. Then we will clean it up and see if the rod can be rescued. Here is a photo of the piston and a rough drawing of the proposed Puller.
We will make epoxy pads for the Puller to sit on where the arrows are on the piston skirt.
A long fully threaded bolt will be inserted through the pin and Puller and a nut on top of the Puller will draw the pin out of the piston and rod. Freeze-it can also be used to shrink the pin a bit.
Then we can hope that the rod is not damaged.
I think the piston will need to be replaced. But that is my son's call.
TorontoBuilder
Ultra Member
I like seeing how people come up with solutions like this
Yes, and it rocks in the cylinder too so it's quite badly worn. That's prolly caused by the tight pin.
What is bothering me most is the question - What caused all this? It looks a lot like low oil. But my son says the oil level was fine. But we are also talking about a 14 year old boy here. I doubt he has the patience to wait for it to warm up. I'd bet he hits full rpm on a cold engine immediately after it fires up. That would do it too.
And why are the camshaft bearings damaged?
140mower
Don
If it was a chainsaw, I would say it was running lean...... I think oil starvation looks like a possibility, in the picture it looks like a little piece of pin boss is chipped out, I wonder if a little piece of needle bearing may have escaped it's cage so to speak, one trip through the cam bearing should be enough to leave it's mark.....
Inquiring minds need to know the forensic break down.
Inquiring minds need to know the forensic break down.
If it was a chainsaw, I would say it was running lean...... I think oil starvation looks like a possibility, in the picture it looks like a little piece of pin boss is chipped out, I wonder if a little piece of needle bearing may have escaped it's cage so to speak, one trip through the cam bearing should be enough to leave it's mark.....
Inquiring minds need to know the forensic break down.
My son did that trying to get the spring clip out. The clip was jammed because that's the end of the play that the pin froze at. I didn't need to give him poop for that - he learned his lesson already.
Ya, I looked at that while I was there. The filter looked good.
140mower
Don
In his defence, it would be pretty hard to do much more damage than has already been done.......
In his defence, it would be pretty hard to do much more damage than has already been done.......
At least he didn't hammer on the pin and frig up the connecting rod and crankshaft journal.
Both ends are the same size. I don't believe there is a bearing in there. But maybe I am wrong. Can you do a quick ugly pencil drawing?