Thermostat flange size difference
 

Hi

Im in the process of replacing my thermostat in a 1992 4Runner 3.0L SR5. Have bought 2 different brands both have been 52mm across the flange, just measured my old one, seems to be different from the specs listed on the packaging and as advised by the salesman (x2) at 54mm. On testing both new ones have leaked because of what seems to be the 2mm difference.

The previous owner had the head gasket redone, the radiator looks old and crap without a perfect fit. Starting to think they had put in another radiator and now thinking water pump as well at some stage? so the specs might be out?

Is it safe to put a 54mm one in (same brand) as long as the temperature (82 degrees) is the same?

Did it come with the o-ring? and did you use it? Just my opinion, I'd just go to the dealer and get the right one. Especially with a 3.0. Just curious why are you replacing it? Is it running hot, not warming up properly? How about some pics of the misfit radiator.

Yeah used a new rubber o-ring.

However this o-ring isnt identical to the old one either, doesnt have flat side edges, so will try get it from Toyota Monday. The old o-ring fits noticeably loose around the new thermostat.

Was about to get a photo, but the Radiator is actually okay, it just had the housing crack off where a nut and bolt should be, so it looked like it didnt fit because it was loose.

What happened - Was coming back from a 4wd trip when the air con went warm, temp guage was max, so i pulled over, and noticed steam from the bonnet, gave it a few minutes. Opened the bonnet and the coolant reservoir cap with the entire tube had come out, dripping coolant everywhere. I had checked the reservoir that morning, so only had myself to blame that i hadnt put the cap back on right.

Wow! don't wanna jinx it, but I hope your head gasket didn't blow. Keep an eye on coolant level.

I'd be worried bout the head gasket right now. Just don't put the thermostat in right now and drive the car some. Check if you're loosing coolant, milky whitish oil, or bubbles coming out of radiator.

I bought my thermostat from O'Reillys Auto. Used the old rubber gasket that goes around it and was a little loose so i used some silicone to hold it in place.

There's only one part number for a 3VZ-E thermostat. And that's all there's ever been. The OEM thermostat, part # 90916-03079, is 52mm(~2 3/64"). There are some aftermarket t-stats being sold for the 3VZ-E that are 2 1/16"(52.39mm), which is probably close enough to work.

I don't know why you would need a 54mm(~2 1/8") t-stat for a 3VZ-E. That just doesn't make any sense.

Anyhow, if you're going to get a new t-stat from Toyota, it's going to be 52mm. Or, if you're thinking about buying just the o-ring for it, that's only going to fit an OEM 52mm t-stat(and/or an aftermarket 2 3/64"(51.99mm) t-stat, and/or possibly even a 2 1/16"(52.39mm) t-stat). The OEM o-ring will NOT fit a 54mm t-stat(as it should atleast, though you might be able to install it on one).

Yeah, thing is it was a 54mm that was in there the whole time (from when i bought it a year ago) and it fit perfectly. I have no idea why its 54mm whereas whatever i buy is 52mm.
Im in Australia not sure theres is any difference? probably not?
I havent noticed any of those things Johnny Boy and when i drove it around the block it felt good, just started leaking out of the new thermostat after 10 minutes. Soon as i get the thermo sorted will get it compression tested even if it 'seems' all good etc.