Re: 87 Honda Thermostat
 

The new Honda Thermostat failed after only a year!
It's under a 12 month 12000 mile warranty, I think I'm going with a Stant t-stant- maybe use their heavy-duty one?
The rubber gasket may be a problem but will have to see when I get it. :confused:

What would cause this to fail so soon? (it's not allowing the car to fully warm up. I think it's closing, but after it starts warming up it only get partly warm
(before I would have to turn down the heater).

Re: 87 Honda Thermostat
 

Check the stamped date on the old thermostat. I bought one for my old crx that was stamped 1990 or something like that. Very old stock. I was finally able to find one that was 2010 mfg date.

Re: 87 Honda Thermostat
 

The only thing I see on it is 78C and 09 11

I put the new Stant and the OEM in the pot of water.
The OEM started opening quick ~ 183 and the Stant didn't really open til 188F
I took them both to 200F and let them cool slowly. The Stant closed at 180F and the OEM was still wide open, it didn't close until 170.

My theory is the OEM opened when it warmed up, and once the cold water from the radiator started flowing by it cooling it only slightly, and preventing it to fully warm / maintain 180F.

When I first put it in I'd get 8 miles and would be chocking down the heater. Now I can drive the full commute (31 miles) and only turn the fan down to low.

Temps are only in the low 30's.