Coolant flow direction through Thermostat ?

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I had Mercury tracer's thermostat replaced a month ago. I don't know if I install it correctly or not, it may be upside down.

From this picture, coolant should flow from bottom up or top down from engine to radiator ?

Which side should be facing the engine ? bottom or top ?

Currently the bottom is facing the engine, and coolant temperature is colder than usual and no heat, the coolant temperature gauge is very low even after 8-10 miles drive. Ambient temperature in So Cal is about mid 60's to mid 70's the last 3-4 weeks, some day last week it was mid to high 80's.

The coolant was at normal range after the new thermostat, Stant 13829, was installed a month ago but only for 30-45 minutes, after that short period of time the coolant was always at minimum range.

Either I didn't install it correctly or the Stant failed in less than 1 hour of use.

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The pellet is in the bottom,and thats whats supposed to get hot,so yes the bottom is toward the engine.
 
Either carefully test that part, or get a new one. The best you can find.
Also, there may be an air pocket that has to be worked out. But after a month, this should have fixed itself.
 
Originally Posted By: mechtech2
Either carefully test that part, or get a new one. The best you can find.
Also, there may be an air pocket that has to be worked out. But after a month, this should have fixed itself.

So you think that I had the bottom of the stat facing the engine is correct ?

If that is the case I just go get a new "Super Stant".
 
If you installed it backwards, you'd likely be overheating, not over cooling.

Sounds like a bad one out of the box. I gave up with the last two super stants I had - both failed to close after opening. Went with an OEM stat, and its worked fine. (That was on my Jeep).
 
Chalk it up to a lesson learned... Go to the Ford dealer and buy a Motorcraft stat and be done.
 
The other cars had original OEM thermostat, except LS400 had Stant thermostat and upper radiator hose installed about couple years ago after 250k miles, that Stant thermostat in the LS400 works as well as OEM so far. The coolant is at normal operating temperature after less than 2 miles city drive in the morning, and the heat at maximum setting is extra hot.

When I changed the thermostat in the Tracer, because engine ran cold for about 2-3 weeks, the old one was (original OEM stat?) broken to 3 pieces. I plugged them out without looking at the orientation.

I think MNgopher is correct, if I installed it backwards, it likely be overheating, not overcooling.

I'll remove the Stant thermostat and take it back to Pep Boys to see if they will replace it or not, I still box and have receipt that I bought about a month ago. If they don't exchange it for a new one I'll stop by Ford dealer get the OEM.
 
Agree with getting an OEM stat. I have bought many, many stats over the 50 years I've worked on engines. OEM stats are good because dealers & mechanics don't like to do the same job over without pay.
 
Originally Posted By: The_Eric
Chalk it up to a lesson learned... Go to the Ford dealer and buy a Motorcraft stat and be done.

That's not always foolproof. I recently installed a Motorcraft thermostat in my Mercury and it is running colder than normal - especially downhill. Funny but the older superstant didn't do this. I only changed the thermostat because I was doing coolant system maintenance.
BTW - anyone know who makes the Motorcraft thermostat? It sure looks very close to the superstant plus I heard on another forum that it was Stant (but don't know it for a fact). This is about the third bad Motorcraft I've had in the last 10 years that was bad out of the box.
 
Last edited:
Originally Posted By: oldmaninsc
Originally Posted By: The_Eric
Chalk it up to a lesson learned... Go to the Ford dealer and buy a Motorcraft stat and be done.

That's not always foolproof. I recently installed a Motorcraft thermostat in my Mercury and it is running colder than normal - especially downhill. Funny but the older superstant didn't do this. I only changed the thermostat because I was doing coolant system maintenance.
BTW - anyone know who makes the Motorcraft thermostat? It sure looks very close to the superstant plus I heard on another forum that it was Stant (but don't know it for a fact). This is about the third bad Motorcraft I've had in the last 10 years that was bad out of the box.


Interesting observation. So far, my personal and professional experiences have been that OEM works best. Quicker warm-ups, more consistent at temps and correct temps. In some cases, the aftermarket part is not built anywhere near as "heavy duty" as OEM, most seen in Asian applications. The most glaring difference was on a Mitsubishi Montero.

Says my parts guy best friend, Motorcraft is made by a low bidding contractor, like AC Delco. I can neither confirm, nor deny it, but have no reason to doubt. I can say that low bidder or not, see my above statement.
 
On my car, the spring faces the engine. The coolant always enters the radiator through the upper radiator hose and exits the radiator through the lower radiator hose. With that on mind, you can kinda tell which way the coolant flows.
 
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