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Post by brians2n on Jan 1, 2019 13:15:57 GMT -5
Does anyone have a good trick for removing the screws that secure the spark plug cover. I aquired an old 770G that was on the floor for the last 20 years or so and I want to see what is going on with it but can't get these darn screws out. I tried everything I know and still they won't budge. I really don't want to strip the slot out. I tried a wrench on a Snap-on screw driver. I hit it with an impact driver. Maybe a heat gun?...or a shotgun?
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Post by jerseyhighlander on Jan 1, 2019 13:42:10 GMT -5
Soak it from every direction with good penetrating oil. ATF & Acetone mix is popular, I also like Kroil soaking at least over night, a sharp rap with a bronze/brass hammer or drift , some gentle, focused heat (Don't ignite the magnesium) and most importantly of all, use the properly sized hollow ground driver tip. It should fit tight, with no slop in any direction. I use good gunsmithing drivers. Chapman is a great set still made here in the US and used ones are available at good prices on eBay.
Some of them just require coaxing over several days.
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Post by brians2n on Jan 1, 2019 14:04:24 GMT -5
Soak it from every direction with good penetrating oil. ATF & Acetone mix is popular, I also like Kroil soaking at least over night, a sharp rap with a bronze/brass hammer or drift , some gentle, focused heat (Don't ignite the magnesium) and most importantly of all, use the properly sized hollow ground driver tip. It should fit tight, with no slop in any direction. I use good gunsmithing drivers. Chapman is a great set still made here in the US and used ones are available at good prices on eBay.
Some of them just require coaxing over several days.
Thanks for the advice. I will keep at it and try to be patient...for now I will soak em up and walk away. Thanks again.
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Post by sweepleader on Jan 1, 2019 15:16:01 GMT -5
The suggestion to rap the top of the screw is a good one, it will crush corrosion under the screw head and reduce the clamp load on the screw. I use a flat ended punch in the middle of the screw or a solid steel driver that fits the screw recess. An interchangeable bit for a screw driver held in a pliers works well. Any little bit of corrosion under the screw head increases the load on the screw as the corrosion takes up more space than the metal did when the screw was tightened in place. Thus the screw can get tighter with age.
Another thing to keep in mind is everything gets bigger with heat, including the diameter of the hole the screw is in. If you heat cycle the assembly several times, say to 250 degrees F of so, then back to room temp or below, the screw will work in the hole. Often the tiny movement is enough to give you an edge getting it out.
I would also try the impact driver again (hammer driven not air driven) with a bit that really properly fits the screw. I have almost always had good luck with mine.
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Post by brians2n on Jan 1, 2019 15:41:38 GMT -5
The suggestion to rap the top of the screw is a good one, it will crush corrosion under the screw head and reduce the clamp load on the screw. I use a flat ended punch in the middle of the screw or a solid steel driver that fits the screw recess. An interchangeable bit for a screw driver held in a pliers works well. Any little bit of corrosion under the screw head increases the load on the screw as the corrosion takes up more space than the metal did when the screw was tightened in place. Thus the screw can get tighter with age. Another thing to keep in mind is everything gets bigger with heat, including the diameter of the hole the screw is in. If you heat cycle the assembly several times, say to 250 degrees F of so, then back to room temp or below, the screw will work in the hole. Often the tiny movement is enough to give you an edge getting it out. I would also try the impact driver again (hammer driven not air driven) with a bit that really properly fits the screw. I have almost always had good luck with mine. Thanks. I will give it another go and hopefully have success. Can't find my heat gun. I always had good luck with the impact too. Surprised it didn't work. Appreciate your help.
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Post by sweepleader on Jan 3, 2019 14:20:07 GMT -5
Here is a good video showing how to removed 4mm screws without damaging the base material. Adam, Abom79, is a machinist and is using a milling machine to do this but it can be done with a drill press or a hand drill too. He flattens the broken screw, drills it small, then uses a slightly larger left handed drill bit. This is not the same as removing stuck screws that still have a head on them but the head could be drilled off with the left handed bit. www.youtube.com/watch?v=RdD9sLk8eXg
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Post by blythkd on Jan 3, 2019 15:04:54 GMT -5
Yip, good process. Been spinning broken screws out with left handed drills for years. Doesn't work every time but when it does, it's a big win. Last time was on a 2007 GMC 6.0 exhaust manifold bolts, for which the LS engines are world famous!
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Post by brians2n on Jan 3, 2019 18:03:33 GMT -5
Here is a good video showing how to removed 4mm screws without damaging the base material. Adam, Abom79, is a machinist and is using a milling machine to do this but it can be done with a drill press or a hand drill too. He flattens the broken screw, drills it small, then uses a slightly larger left handed drill bit. This is not the same as removing stuck screws that still have a head on them but the head could be drilled off with the left handed bit. www.youtube.com/watch?v=RdD9sLk8eXgI love a success story. Thanks for that. Very helpful. Hope I have a success story to share with you. I am waiting for a can of Aero Kroil and I guess I'm going to have to buy a new heat gun...can't find it.
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Post by rowdy235 on Jan 5, 2019 0:19:09 GMT -5
Stubborn screws are the worst. I too am a fan of LH drill bits, have a couple around and have had some success with them, but I've also ended up drilling out a couple completely with the LH bit and no movement whatsoever lol.
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Post by sweepleader on Jan 5, 2019 9:23:23 GMT -5
As far as LH drills are concerned, no promises with screws that are rusted and cannot be heated. They do work nearly every time on bolts that have broken upon tightening and are not rusted. 50/50 on rusty stuff.
Heating to very hot a couple times gets another 50% of the rusty ones. Very hot is red in steel, not so much in alloy or iron, at least 2 hot-cold cycles. Too hot and iron will crack, alloy goes away in a puddle. Not quenched, just air cooled. I usually add some oil as the heat comes down. TIG welding a handle to the broken part is plenty of heat in any base metal, I oil these too as they cool.
I heat any broken screw that has been assembled for more that a year or so, put in all the cards on the first try to be better assured there will be not second try, which is always messier.
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Post by brians2n on Jan 8, 2019 18:10:38 GMT -5
The suggestion to rap the top of the screw is a good one, it will crush corrosion under the screw head and reduce the clamp load on the screw. I use a flat ended punch in the middle of the screw or a solid steel driver that fits the screw recess. An interchangeable bit for a screw driver held in a pliers works well. Any little bit of corrosion under the screw head increases the load on the screw as the corrosion takes up more space than the metal did when the screw was tightened in place. Thus the screw can get tighter with age. Another thing to keep in mind is everything gets bigger with heat, including the diameter of the hole the screw is in. If you heat cycle the assembly several times, say to 250 degrees F of so, then back to room temp or below, the screw will work in the hole. Often the tiny movement is enough to give you an edge getting it out. I would also try the impact driver again (hammer driven not air driven) with a bit that really properly fits the screw. I have almost always had good luck with mine. Got em out. What a GREAT feeling. Thanks to everyone for sharing all the helpful tips. I used a little from everyone. First I ordered the Aero Kroil. Soaked em good and waited a couple days. I heated em and soaked em some more. I struck them with a bit held with pliers. Finally I got the 3 pound sledge hammer and rapped it with the impact driver and at long last they loosened. Thank you all again. BTW my wife loves the smell of Aero Kroil... NOT.
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Post by blythkd on Jan 8, 2019 19:27:15 GMT -5
Couldn't find the 8# sledge? Just kidding, glad you got it apart with apparently no damage.
Reminded me of one of my favorite movie lines though, "think you used enough dynamite there, Butch?"
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Post by brians2n on Apr 23, 2019 19:54:00 GMT -5
So I am still working on the 770G and need so more advice. The Piston is siezed in this one. I tried soaking it with the Aero Kroil from all directions for days and days, tried heating it, tried taping the Piston with a brass drift pin but none of that worked. So I took it all apart. Now I can see the Piston and it is stuck below TDC but is covering the exhaust port completely. I removed the nuts and was then able to see the crank moves and I am able to separate the jug from the crankcase by about a half inch. It's encouraging but now I really want to get the Piston out but don't know any tricks. So I am putting this out there hoping to gleen some more wisdom from the experts. Thanks in advance.
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Post by edju1958 on Apr 23, 2019 20:04:34 GMT -5
I'm not exactly an expert on this,but an old timer told me to try to use reverse rotation when trying to get a seized piston unseized.I don't know if this works,but I thought I'd pass it along.You migt want to try the 50/50 mix of acetone & ATF too. Ed
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Post by rowdy235 on Apr 23, 2019 20:19:11 GMT -5
My go-to for stuck pistons is good ol' WD-40. I know its not a penetrating oil and blah blah blah but I've had good luck with it. I use the liquid rather than the aerosol and dump enough in to completely cover the top of the piston. Let it work for a while and add more. Doesn't hurt to give the cylinder a few side taps with a mallet either. I've never had one refuse to come loose doing this, but at times it has taken several days.
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Post by brians2n on Feb 19, 2020 19:16:52 GMT -5
My go-to for stuck pistons is good ol' WD-40. I know its not a penetrating oil and blah blah blah but I've had good luck with it. I use the liquid rather than the aerosol and dump enough in to completely cover the top of the piston. Let it work for a while and add more. Doesn't hurt to give the cylinder a few side taps with a mallet either. I've never had one refuse to come loose doing this, but at times it has taken several days. So I couldn't stand it anymore. I took a hacksaw to the jug and sawed it in half. I got the Piston unstuck finally. It feels good actually even though I totally ruined it. So now I'm looking for a new cylinder, piston and rings. I think it can still be salvaged.
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Post by sawnami on Feb 20, 2020 7:08:54 GMT -5
I realize that I'm too late here but I've used a grease gun and a pressure washer to break loose rotating assemblies. I used a grease gun on that Lombard that I posted a picture of. I rigged up a sparkplug shell with a grease zerk and pumped the combustion chamber full of grease. It made some nasty popping and cracking sounds as the bearings broke loose but freed it up. I used my pressure washer on a Disston DO-100 that was frozen up. I had a compression adapter that had the same quick coupler as my pressure wand and just hit the trigger and the piston broke free. I did the Barker in the pic the same way to break it free.
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Post by ken8831200 on Feb 20, 2020 7:35:09 GMT -5
I realize that I'm too late here but I've used a grease gun and a pressure washer to break loose rotating assemblies. I used a grease gun on that Lombard that I posted a picture of. I rigged up a sparkplug shell with a grease zerk and pumped the combustion chamber full of grease. It made some nasty popping and cracking sounds as the bearings broke loose but freed it up. I used my pressure washer on a Disston DO-100 that was frozen up. I had a compression adapter that had the same quick coupler as my pressure wand and just hit the trigger and the piston broke free. I did the Barker in the pic the same way to break it free. Well one more for a method I thought I invented something like 30 years ago! Mine was on a slightly bigger motor however, a six cylinder Mack Diesel! It had only been parked over the winter and would not crank over in spring. Tried towing it to start and only skidded the rear tires. Removed a couple injectors and made an adapter from spare junk injector and used air powered grease gun to get it to move. When first piston was at bottom of stroke move grease injector to another cylinder to move crank a bit more. Then removed the grease injector tool and pushed truck in gear to force grease out. Shot a stream of grease about 20 feet in the air! Reinstalled injectors and fired up the truck. Smoked quite a bit but did run after that for as long as I remembered always a bit of smoke!
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Post by sweepleader on Feb 20, 2020 9:43:47 GMT -5
The pressure washer can do 1000 to 3500 psi or so, depending on the model. The manual grease gun sometimes up to 5000 psi. I think the air powered grease gun might go as high as 10,000 psi. All will move something in a stuck engine. The high pressure has the advantage of expanding the cylinder as the pressure climbs, won't work of course if the piston is stuck below the ports.
Another thing to try is heat cycling the cylinder with a propane torch, hot, cold, hot, cold, a few times.
None of this helps much if the flywheel is jammed by a loose screw, don't ask how I know that one.
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Post by brians2n on Feb 22, 2020 11:16:20 GMT -5
Thanks for sharing. Very innovative. I love your creativeness. I don't think there was any saving this anyway. As you can see.
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