Is this truly a proper thermostat replacement

[Scott_]

Ok, so it's all over the internet that the late model year Toyota Corolla thermostat makes for a decent replacement.
It's even been posted here with the measurements of the stock stat compared to the Toyota replacement.

It's documented that there is a 5mm difference in the total length of the stat. Stock is 30mm from wide flange to the foot flange, and the Toyota one is 35mm.

I picked up one of the Toyota stats(7214-180) from AutoZone thinking that I would put it in the '95.
As I was looking at the differences and the cavity that it fits into, I decided to get out my extra radiator to fit them and take some pictures.....

Stock.


Toyota Stat.


Side by side.


Stock stat in the housing looking in from the bottom hose port. Notice the space between the bottom foot of the stat and the bypass port to the right.


I measured the depth of the housing from the flange lip mounting point to the back surface of the bypass opening.... 35mm...
Here's what the Toyota stat looks like in the housing. I don't seem much space for water to bypass and flow to the pump.
Yes the foot is spring loaded, but I would question if the water pump has enough pressure to overcome it.



In the end I didn't install the Toyota stat, not liking the lack of space for water to flow.....

I'm posting this for others to comment and question if this really is an adequate replacement or not.

[johnny]

greetings _ ...

ive naught ever replaced a motobrick thermostat... butts if i gotts to on down the road... it wont be the 35mm unit...

thanks for the pictorial...

j o

[drut]

Looking at your photos(thanks) I would pay the extra for the stock stat: " I don't seem much space for water to bypass and flow to the pump.
Yes the foot is spring loaded, but I would question if the water pump has enough pressure to overcome it." would echo my take on it.

[kioolt]

I really doubt that the spring is put there for the pump to overcome anyway.  I also would like to know in which direction is the flow.  I was going to buy one of the Toyota t-stats to replace mine.  Now that I see this I don't believe I will.  I have a spare radiator with a t-stat.  I hope it's a good one.

[Scott_]

I also would like to know in which direction is the flow.

The flow from the pump goes thru the engine, then up from the riser tube on the top of the block behind the radiator. The riser tube feeds water to the left side of the radiator and the bypass line that comes in the small 1" inlet behind the t-stat. So when the stat is cold, the water comes in the bypass(from the rear) and then down thru the larger line to the pump inlet.
As the stat opens up with heat, the foot pushes out to close off the bypass and allow water to flow thru(from) the radiator thru the front/top of the stat then down thru the larger line to the pump inlet.

I have seen an image/diagram of the water flow, I'll see if I can find it and post it here.......

[F14CRAZY]

I put one of those Toyota stats in this weekend...we'll see how tomorrow's commute goes

[rbm]

I have seen an image/diagram of the water flow, I'll see if I can find it and post it here.......

[Tuco]

Good info Scott, thanks! Had something similar happen with my Cummins 4BT powered Jeep Wrangler. Used something other than OE thermostat. The temp gauge needle swung back and forth once warmed up with the new 'stat, which it didn't do before. Went to Cummins, paid their absurd price, got new stat and installed it. Rig now runs at an even temp once warmed up. Wont run anything but OE stat in it from here on out.

[Scott_]

Thanks for the image RBM........

[The Mighty Gryphon]

It's the bypass closure valve that causes the problem with trying to use a different  thermostat.  Closing the bypass is probably more important to the cooling function than opening the flow to the radiator.  If that bypass isn't closed off, a lot of the coolant will take the low resistance path around the radiator.  Judging from the photos, the guys at BMW designed it to make using any alternatives impossible which seems to be part of the design culture there.

[F14CRAZY]

While it may not be relevant to the bypass closure, my Toyota thermostat now has my system running at almost 180f in 50f ambient temps. I'll post in my other thread later

[wmax351]

When I was running the megasquirt,  I was datalogging with a 192* toyota thermostat. On the freeway, it would stay dead on at 192. Traffic would see it rise then oscillate around the fan temp.

[wmax351]

I swapped to an OEM thermostat. In the cold weather, it seemed the engine was running a bit cold; lower mileage, occasionally running at low throttle like it does when warming up.