what size flat head ? changing gear oil volvo penta duo

[al1026]

I want too change my gear oil and not sure of flat head size or socket size. too remove so I can drop gear oil ? . . DO NOT WANT TOO STRIP
​Removed duo props ( have tool ) Removed plastic cover with the 3 screws . .
I see the vent screw but did not attempt too open until I find right flat head for oil removal
​TWIN lower units on a 2003 DUO DRIVE Volvo Penta .
​Checked fluid levels full , dirty , no water on dip stick .
​. I am in Fl and use all season
​I have assorted flat heads but non fit , too big or just a hair too small , METRIC ?
​I had shop change last season and just got boat back from new engines installs
Figuring I will do gear oil change

​thanks as usual .
​

 

[alldodge]

Same issue with Merc and the flat tip screw slot. I just put the largest one which will fit fully in the slot and then turn using both hands. Most the time there is not an issue and will unscrew. If one will not budge, I use and impact screw drive, and none of those tips fit exact either but have not had an issue

 

[Dave-R]

Every used boat I get has the gear drain plug slot chewed up. I also use the largest screw driver that will fit, or better an electric drill/driver (for removal only) Then I swap that plug with the fill/vent plug that has a nice clean slot. Not sure why they get tightened so much, they have an o-ring. Dave-R

 

[gbeltran]

What you really need to find is called a 'hollow ground' screwdriver or bit. There's a wide variety of sizes, not sure what the Volvo uses. I bought a new drain plug and sized the bit with that. Can't remember where it came from. Gunsmiths use the same style of driver, They fit the slot more securely as they are not tapered like a normal driver, thing is though each screw head size takes it's own sized bit, not a one fit all like normal screwdrivers.......

 

[Scott Danforth]

simply use the bits in the impact driver set

on your 2003, you will need to remove the props to get to the drain. good time to grease the prop splines

 

[BRICH1260]

I use the bits that came in my Harbor Freight impact kit as they are a little wider than typical screwdriver bits. I would like to find a better fitting driver though that completely filled the slot, length and width wise.

 

[Thalasso]

It's called a drag link socket. This it what i use. If you use a impact hammer to remove the screw be careful because you could remove the threads. It shouldn't be on that tight

 

[Thalasso]

Get one that is as wide as the groove in the plug. They are usually in a set of impact driver kits

 

[al1026]

Found the correct tool that works perfect
craftsman 5 / 16 long handled Allen wrench
​Fit is perfect , no wiggle grabs and comes out easy. The longer shaft a bit more leverage but a smaller one will do with a hollow pipe for leverage

 

[Thalasso]

You asked about a flat head,not a allen wrench

 

[BRICH1260]

Found the correct tool that works perfect
craftsman 5 / 16 long handled Allen wrench
​Fit is perfect , no wiggle grabs and comes out easy. The longer shaft a bit more leverage but a smaller one will do with a hollow pipe for leverage

5/16 allen wrench? How`s that fit a slotted screw? I`m confused. Post a pic if you can.