3S-GE Thermostat Diameter, Tracking down a replacement... Options

[incubus]

Hi guys,

I finally got my new baby, a 1994 GT in red, a few months ago and I've been slowly running through a full service. Engine temperature was always low (somewhere around 1/4 - 1/3 on the gauge) and it took at least 10 minutes to get to that level (maintains that level from that point onwards) so my guess was that the thermostat was stuck slightly open.

I looked at several different online parts companies and all recommended the same thermostat with a diameter of 64mm (even gives full dimensions here). I swapped the thermostat yesterday and, to my surprise, the old one was definitely bigger (~68mm) and the new one clearly doesn't fit snugly into the housing.

I did a trial fit, ran the engine for a while and, sure enough, there was a slow drip leak from the base of the housing (bolts were nice and tight).

My problem is that everywhere I look, they all say it's 64mm; I even tried searching for a later year in case they thought it was the rev 2, and for other car models with a rev 3 3S-GE, and every time they say it's 64mm.
Everyone seems to agree on the OEM part number being 90916-03100 (also given here and here).

Any ideas why everyone is trying to sell me the wrong part, and where I might find the right part? Thanks in advance.

This post has been edited by incubus: Jul 21, 2013 - 8:53 AM

[malpaso]

...
Everyone seems to agree on the OEM part number being 90916-03100 (also given here and here).
...

I have this thermostat for sale if you want it:



Of course in working condition. I have changed it for TRD sports one when I bought a car.