Tips on loosening screw

[carlager]

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


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

Any tips on how to loosen them ?

 

[KrustyKrab]

PB Blaster or Kano Kroil. Last resort = screw extractor and new screws.

 

[justsomeguy]

Ever use a driver/drill with an adjustable torque clutch? They can bump a screw loose.

Start at a low torque, and increase.

Try not to let it "cam out".

 

[kloudie1]

An impact screwdriver will get them cleanly. Something like this:
http://www.harborfreight.com/hand-tools/screwdrivers/impact-screwdriver-set-with-case-37530.html

EDIT: Apply judiciously .. one hammer smack will do it. Have used these for years on motorcycles and outboard motors to remove stubborn screws without ruining the screw.

 

[Patrick S/V Shangra-La]

Use an impact driver as above but apply a little "valve grinding cream on the phillips end. It will prevent slip of the screw.

Actually i ale grinding cream works with any Phillips that is slipping it gives just a little more grip on the screw head.

 

[NYSail]

Be careful with the pb blaster or any other stuff like that..... Will destroy engine gaskets. Maybe a little heat with impact driver

 

[Ken13559]

I removed my hand crank shaft cover screw with impact driver. There's an oil seal behind the cover. If use heat, can replace the oil seal by plying it out with screw driver. Its easy. Just make sure the crankcase oil level be below the oil seal.
Curiously, why do you need to remove the cover?

 

[sailingseadragon]

As noted by others - a good impact driver & PB blaster.

 

[carlager]

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).

 

[KrustyKrab]

Carlager, thanks for posting a follow-up!