stuck hydro drain plugs

[phill_mi]

Any thoughts on how to get the drain plugs on my 560 gas freed up? I want to get at the hydraulic and PS pumps and filters, and change the fluids. The one behind the clutch is a female square plug slightly smaller than a 3/8 socket drive but bigger than a 1/4 drive. I have not found the right tool to open this one yet.

The square plug facing forward on the transmission housing does not want to budge with a large wrench on it. I'm afraid I will twist it off. Should I go for broke or try something else. I have not tried the hex plug at the differential as I thought it best to drain the front cavities first.

All of this is related to tracking down a noise and engine oil pressure issue detailed in another thread. I now suspect the noise is from the hydraulics system.

[Dale Finch]

These are similar to what I use:
https://www.amazon.com/Sunex-3841-Standard-6-Point-16-Inch/dp/B002GTA2F6/ref=asc_df_B002GTA2F6/?tag=hyprod-20&linkCode=df0&hvadid=309807921328&hvpos=&hvnetw=g&hvrand=6816252595150906498&hvpone=&hvptwo=&hvqmt=&hvdev=m&hvdvcmdl=&hvlocint=&hvlocphy=9009672&hvtargid=pla-570237526242&psc=1

I have also taken a bolt larger than the female plug, and ground four flats down until it fits snuggly into the square hole, then I can use a regular socket on the bolt head.

[phill_mi]

Thank you. I got the front plug out by borrowing a pipe socket set similar to what you posted. The 5/16 on a breaker bar did the job. And I got the middle plug out by just being more persistent. I thought the square part would sheer of but it turned out. I have yet to tackle the rear plug.