Thermostat Housing Question...
- Thread starter huntin5L
- Start date
Buy some paper gasket material to trim out for the thermostat housing because the rubber gasket that goes around the thermostat itself is not enough!
thedave925 said:
It is enough. If it doesn't seal with only the o-ring, then the sealing surfaces on the housing or water neck are pitted/erroded, and need to be replaced.
That said, I have only an o-ring on my car, and it seals just fine.
Mines seals just fine with just the factory seal also.
Another common problem area on these cars, torque value is in the inch pound region, I think its 86in/lbs to be exact, and seeing as they are M6 bolts threading into toyota aluminum, they tend to strip out quite easily. When this happens, the bolt gets installed for the last time, seemingly looking like its fine nice and flush, but the next time you take it off, it will not pull the thermostat housing flush up against the water outlet housing. This is where a helicoil and a steady hand comes in handy. Helicoiling an M6 is a hell of alot easier than an M10 let me tell you.
Another common problem area on these cars, torque value is in the inch pound region, I think its 86in/lbs to be exact, and seeing as they are M6 bolts threading into toyota aluminum, they tend to strip out quite easily. When this happens, the bolt gets installed for the last time, seemingly looking like its fine nice and flush, but the next time you take it off, it will not pull the thermostat housing flush up against the water outlet housing. This is where a helicoil and a steady hand comes in handy. Helicoiling an M6 is a hell of alot easier than an M10 let me tell you.
The "O ring" is plenty adequate. Just be sure it's installed correctly ie; around the thermostat's perimeter. That last guy who brought a car to me after fighting with a leak kept putting the thermostat in first and the seal on top of it. Why he thought that'd work is beyond me.
And Frank makes a good point. Don't be reefing on those bolts. Either tighten only enough to compress the seal and bring the faces into contact then a tiny bit more or do as I did and add split locks there. Tighten only enough to compress them. Makes it a no brainer.
And Frank makes a good point. Don't be reefing on those bolts. Either tighten only enough to compress the seal and bring the faces into contact then a tiny bit more or do as I did and add split locks there. Tighten only enough to compress them. Makes it a no brainer.
I tend to put a thin layer of silicone on the 2 faces to smooth out any imperfections from pitting and corrosion. And yeah, don't crank on those bolts. Little bolts like that are really easy to break. It's also very easy to over torque them, and stretch or twist them, making them break easily the next time you put it together. I see that happen a lot on valve covers, oil pans, and trans. pans.
I just replaced mine a couple weeks ago and apparently put it in upside down(???). I bolted it all up, no leaks, started the car, and all the coolant just sorta drizzled out... Rotated the thermostat 180 turn, bolted it all back up and it's been fine.
So I guess if you can't get it to seal make sure you've got it in right (duh...)
So I guess if you can't get it to seal make sure you've got it in right (duh...)
The jiggle valve on the stat goes at the top...12 o'clock position.
Stat orientation has nothing to do with the seal.
Stat orientation has nothing to do with the seal.
jdub said:
Jdub, I'm not a mechanic by trade but I don't think I've ever seen a vehicle with a thermostat mounted like the Supras, basically on the side, requiring the jiggle valve to be oriented at 12 o’clock presumably to enable proper air removal from the water right? Has anyone out there taken a block of 6061 and made replacement housing so the thermostat sits in a normal orientation? I wondered if this 12 o’clock orientation requirement not being met is how so many get air trapped in their systems.
the t-stat I used would only go in one way with the jiggle valve at the top...
don't re-use the o-ring, as it's cheap, and if you re-use it, it can possibly leak like mine did...
use a torque wrench on the bolts, it's that simple... you DO have torque wrenches don't you?
don't re-use the o-ring, as it's cheap, and if you re-use it, it can possibly leak like mine did...
use a torque wrench on the bolts, it's that simple... you DO have torque wrenches don't you?
Geezer - yep, that's it. The jiggle valve is on top to allow air to be purged from the system. The only mod I know of to help is to use a pair of snips and remove the jiggle valve...the small hole will allow constant flow through the rad, preventing back pressure and is better at purging air. It will delay getting coolant up to ops temp only a very short time.
I would use a Stant SuperStat as well, no lower temp than 180 deg and that's for hot climates...allows the rad to "get ahead" of cooling with a hot OAT. Otherwise, the stock 190 deg temp is fine.
I would use a Stant SuperStat as well, no lower temp than 180 deg and that's for hot climates...allows the rad to "get ahead" of cooling with a hot OAT. Otherwise, the stock 190 deg temp is fine.
jdub said:
I tried the 180 degree thermo and found my car (believe it or not) ran below optimum operating temperature, even though both of my electric fans (dumped the original clutch fan in favor of two electric fans) are thermostacally controlled and adjustable.
It just wouldn't stay hot enough no matter where I set the electric thermostatic fan control. And this was during the summer in Socal.
I'm probably the only Supra owner who ever had that problem.
Yeah...that is the risk you take using a 180 deg stat. You must have a very healthy cooling system and a big rad 
Don't have that problem here in Phoenix! You want the coolant to get above 176 deg F to signal the ECU to switch from warm-up enrichment to normal mode. In most cases, a 190 deg stat is what you want to run.
Don't have that problem here in Phoenix! You want the coolant to get above 176 deg F to signal the ECU to switch from warm-up enrichment to normal mode. In most cases, a 190 deg stat is what you want to run.
I only have the stock gauge, but normal in town driving I barely get up to a quarter after the coolant system overhaul I did...
might have to switch back to the factory T-stat...
might have to switch back to the factory T-stat...