1997 EJ22....EJ25...all the same:

 

I googled and searched some forums and struck out - what's the hose size for the large diameter hose going into the engine block up the fittings for the PCV hoses?

 

Need to have the hose in hand for this job....anyone know for sure?

I just went out and measured a block that's kicking around my garage. 3/4"

awesome, thanks.  i asked it partly because i thought it also might be helpful for others to know too as i couldn't find it anywhere.  i was kind of surprised i couldn't find it with as many of these that i have broken. 

 

of course the 3/4" hose in the auto parts store wont' be anything like the thick, rigid, formed, OEM piece....

I think the OEM one starts as nice soft rubber hose, then goes hard over the years because it's constantly covered in oil and lots of heat.

Whatever you do, don't buy heater hose to replace it. You'll be replacing it again in like a month. (You probably know that but just in case someone else has the same problem and doesn't know.) Emissions hose only.