Honda D16Y78/D16Y8 Thermostat Housing 19311-P2A-000

Genuine Honda Thermostat Housing (19311-P2A-000) - D16Y7 / D16Y8

If you've got a coolant drip that only shows up after the engine's heat-soaked, or your temps wander in traffic, the thermostat housing is a common culprit on these D-series engines. The cast aluminum housing corrodes and cracks over the years, and once it does, it weeps coolant and loses its seal. This is the genuine Honda replacement, a direct bolt-on that goes in like the factory part because it is the factory part. No fighting the fit, no hoping it seals, it just bolts up and holds.

The Leak That Shows Up When It's Hot

A failing thermostat housing has a recognizable set of symptoms. You'll see seepage around the flange, often worse after the engine's been up to temp and sitting, because heat and pressure find the weak spot in a corroded or cracked housing. You might get a random coolant smell, bubbles in the overflow tank, and coolant temps that wander or climb in traffic as the cooling system loses its integrity.

The housing is cast aluminum, and over decades of heat cycles it corrodes, especially around the sealing flange and the coolant passages. Once the metal degrades, the sealing surface is no longer flat and the housing no longer holds pressure. Swapping in a fresh one puts the sealing surface and the coolant path back where they belong, so the engine warms up cleanly and holds steady temps instead of leaking and wandering.

Cast Aluminum, Factory Fit

This is cast aluminum like the original, so it handles the heat cycles without warping or corroding into a crusty mess the way a cheap replacement might. The outlet matches the factory radiator hose size, so your stock hose slips on and seals without stretching, trimming, or guesswork.

It's a direct bolt-on with no modification, the housing, the sealing surface, and the hose connection all match factory, so it goes in exactly where the old one came off. Fit a fresh thermostat and gasket while you're in there, since you've got it apart, and you've refreshed the whole thermostat area in one go.

Do It While You're In There

Beyond fixing an active leak, this is worth replacing any time you're doing related work, a thermostat replacement, a coolant system refresh, or a timing job that has you in that area. A corroded housing that's starting to seep will only get worse, so if yours is showing its age and you're already working nearby, replacing it now saves you coming back to chase the leak later.

Fitment

1996-2000 Honda Civic DX, EX, HX, CX, and LX with the D16Y7 or D16Y8 engine

Part number 19311-P2A-000. Genuine Honda. Direct bolt-on replacement.

Who Should Grab This

This is for the D16-powered Civic owner chasing a coolant leak, a heat-soak drip, a coolant smell, or wandering temps, and for anyone doing thermostat or cooling work who wants to replace an aging housing while they're in there. Genuine Honda cast aluminum, a direct bolt-on that matches the factory hose fit, and the fix that puts the sealing surface back right. Bolt it on, fit a fresh thermostat, and stop the leak for good.

Fits: 1996-2000 Honda Civic DX/EX/HX/CX/LX with D16Y7 or D16Y8. Part number: 19311-P2A-000. Type: genuine Honda thermostat housing, cast aluminum. Fixes: coolant leak, flange seepage, wandering temps from a corroded or cracked housing. Fit: direct bolt-on, matches factory radiator hose. Tip: replace the thermostat and gasket while you're in there.