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Discussion Starter · #1 ·
I need to remove the cover on the hand crack shaft on our Yanmar 3gm30f.

The 2 screws on the cover are impossible to loosen (re the photo in which the upper screw in displayed)

Any tips on how the loosen them ?
 

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I need to remove the cover on the hand crack shaft on our Yanmar 3gm30f.

The 2 screws on the cover are impossible to loosen (re the photo in which the upper screw in displayed)

Any tips on how the loosen them ?
Unfortunately, the paint on many engines makes a penetrating oil solution for bound up screws/bolts ineffective. What I have found to work is a hand held impact driver that, usually, will not "bugger" up the screw head. For me, one blow with the twist in the tighten direction (clockwise) and a second in the loosen direction (counter-clockwise) has often done the trick.

FWIW...
 

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Same comments... make SURE you're using a screwdriver that fits the screw perfectly.. no wiggle room. If not, you'll end up stripping the already questionable grip that phillips head screws afford you. If you DO ruin the grooves in the screwhead, you can carefully cut a single long slot it in for a larger flat-head screwdriver, but be careful you don't cut too deep.

The tighten first then loosen trick can work... not a bad tip to break loose a stuck screw, provided it hasn't been over-torqued in the first place.

Breaking a screw or bolt loose required the OPPOSITE tactic of properly tightening it in the first place. When tightening or torquing, always apply increasingly steady pressure until you're at your desired tigthness... no yanking. When you're trying to free a bolt or screw, however, seat your driver as firmly has humanly possible... PUSH the sucker in with your entire body and weight (and then some if you can get extra purchase behind you) then really crank on it hard.. go for it. Try your best to imitate an impact driver.. impact!

Or, as one of the first responders said above, get an impact driver. DeWalt makes a battery-powered one that's saved my butt on rusty screws that would NEVER have come out any other way on my cars. Great tool, very small, and a surprising amount of power.

Good luck!

Barry
 

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Its nice you've got replies from professionals who know what they are talking about... Now you get mine :rolleyes:

I find swearing a lot often helps.

Next... Call the Yanmar mechanic because $90 may save a bucket load of drilling it out and all. This is serious advice from someone who isnt very good with a screw driver, or doesnt have the right tools.

The other bit is why are you removing it? Is there no other way to do the job? Is the job necessary? Like the other thread a few days ago where the forum wanted a guy to do a full rebuild on an engine with no problems. Do you really need to do it?

Good luck.

Mark
 

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You really need an impact driver for the already damaged screw. Almost all other approaches will just further damage the screw head. I can't imagine that on an installed engine in a sailboat that you can get I to a position to apply enough force into a screwdriver to loosen the screw without further damage to the head. If the head is damaged to the point it becomes useless I have found a better approach to the filing a slot for a flat blade is to use a dremel tool to create wrench flats for an open end wrench. Either way you risk sheering the head of the screw. Then you are on to a whole new level of work.
Good luck,
John
 

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Impact and torque should do it. Get some friends and a case of beer. One holds the large square shanked Phillips .One puts a twist on the wrench or visegrips and you smack the driver handle with a hammer. A bit of forth and back in the torque department will help. Swearing in unison sometimes helps. If not, you've still got the beers so the day is good.
 

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I just got the Dewalt cordless impact driver with 300lb/ft. It's brilliant for stuck screws, and changing wheels on the car.

I used it the other week to change the starter motor on the boat. I couldn't get enough purchase on the bolts from the side, so I wound up with the impact driver, and 5ft of extension, from the cabin. It worked like a treat.

You could also try one of these :

Ratchets, Sockets & Wrenches | Nut Drivers | Impact Driver, 3/8" Drive | B640736 - GlobalIndustrial.com

Every toolbox should have one. You hit the end with a lump hammer and it converts the impact into a twisting motion. Works great for stuck screws and it's cheap.
 

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Impact and torque should do it. Get some friends and a case of beer. One holds the large square shanked Phillips .One puts a twist on the wrench or visegrips and you smack the driver handle with a hammer. A bit of forth and back in the torque department will help. Swearing in unison sometimes helps. If not, you've still got the beers so the day is good.
or you could just buy a simple, inexpensive tool designed for the job.
 

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Here is the tool I would actually recommend for most peoples tool kit does screws as well as uses 1/2 drive sockets. Impact Screwdriver Set with Case I have used mine on many jobs even to break loose over tightened lugnuts on a car
And after you break it loose using the impact driver, you can use the bit and adapter with your ratchet to back it out.
 

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Discussion Starter · #14 ·
I drilled out both screws with a special drill and was lucky not to ruin the threads.

The oil seal on the hand cranck shaft was leaking and I needed to remove the cover to replace it.

I have now replace the seal with a new one and hope this will stop the leak (The old seal looked OK to me).
 

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I drilled out both screws with a special drill and was lucky not to ruin the threads.

The oil seal on the hand cranck shaft was leaking and I needed to remove the cover to replace it.

I have now replace the seal with a new one and hope this will stop the leak (The old seal looked OK to me).
Did you try the impact drive or just move directly to drilling out the screws?
 

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Discussion Starter · #17 ·
I bought a DeWalt impact driver (had to bring my tool box up to date any way :)

The phillips notches were destroyed on both screws when using the impact driver. Cut a new one - which also broke.

Then there was nothing else to do than drilling out the screws. It was remarkably easy (and no cursing :) )

Below is a photo of the drill and the screw with the destroyed notch
 

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I bought a DeWalt impact driver (had to bring my tool box up to date any way :)

The phillips notches were destroyed on both screws when using the impact driver. Cut a new one - which also broke.

Then there was nothing else to do than drilling out the screws. It was remarkably easy (and no cursing :) )

Below is a photo of the drill and the screw with the destroyed notch View attachment 34337
Ah... FWIW the impact drive I referred to is manual requiring only a good sharp blow from a heavy hammer which tends to press the screw bit into the screw as well as applying the twist, which cuts down on the chance of buggering up the screw. With electric impact drivers, its sometime difficult to apply enough pressure to a screw head to avoid the problem. They do work well on bolts, however. N'any case, I'm glad you were successful and hope that resolves your leakage problem.
 
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FWIW, I was also told (and have not enquired further) that a lot of Japanese equipment did not use Philips screws. Electronics and camera equipment from Japan often used Reed-Prince and other screws that are very similar to Philips--but just different enough to mangle them. This is supposedly because Philips refused to license patents to "the Japs".

Dunno if that's all bunk, but I've learned that there's a lot of variation in what is and isn't a genuine Philips head screw, and the quality of the drivers.

FWIW
 

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FWIW, I was also told (and have not enquired further) that a lot of Japanese equipment did not use Philips screws. Electronics and camera equipment from Japan often used Reed-Prince and other screws that are very similar to Philips--but just different enough to mangle them.
I can't speak to the patent issues. I can say that I have run into a lot of Frearson (also called Reed and Prince) screws on boats, particularly in good quality woodwork, including screws used to hold down the sole.

Frearson screws have a lot going for them: one bit fits all size screws and they are much less likely to cam out than a Phillips screw.

I'm a fan.

For more than you really want to know:
 
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