Hi all - I will describe a situation I am having with my 2000 Civic Si (B16, 5 speed), if you can assist me in tracking down some information, I would appreciate it. Radiator (I believe to be original) developed a crack in the upper plastic tank. It had 1 1/4" hose connections top and bottom (measured at minor diameter, not at the bell / bead at the aft part of connection). Got a new Denso radiator via NAPA, pn 221-3206, which has 1 1/8" hose connections, but otherwise appears to be identical replacement. NAPA cross referenced this Denso part number to Honda part number 19010-P2T-A01, which the Honda dealership also comes up with for the car. Think these will both have 1 1/8" hose connections, but don't have a new Honda radiator check at the moment.
A handy, experienced Honda mechanic I know indicated that the Si's with b16 engines all came with the 1.25 " hose connections, but the parts people at Honda that I talk to indicate the above Honda number is all they come up with for the car. Aftermarket radiators seem to commonly offer 1.25 connections for Civic Si replacement, seems also to be a topic on forums. If I get a set of Honda radiator hoses, will they be for 1.25 or 1.125 fittings? Does not seem like this should be this difficult.....
Ideas? Part numbers? Who makes high quality aftermarket coolant hose kits? Thanks - Cody

 

Correct the d series radiators had a smaller diameter. Napa is just selling you a generic replacement, give them the part bumber for the dseries radiator and its probably the same

I've never had a problem with silicon hose kits on eBay. Ive bought probably close to a dozen sets over the years and all of them fit great

Ive used eBay dual core radiators with the 1.25 upper outlet on d-series hoses with no problems you just have to stretch the hose out a little

My em1 has a stock looking metal radiator