Lower rad hose still cool after 20 minutes

[makriluc]

Ok guys, this was my previous thread:
Hi Guys.
97 Talon Tsi. I replaced a ruptured coolant line that goes from the head to oil filter housing. Then found out the thermostat was sized close. I replaced the thermostat. But now, even after 15 minutes of idling and/or driving, the thermostat does not seem to open. I do get good hot air through the heater core, so to me I don't have an air pocket problem in the system.

I’m a former mechanic and I’ve worked on American and Japanese cars.
First I know that when a T-Stat is open you can clearly see the coolant flowing when the “radiator cap” is off. I can understand that one of the two rad hoses may be cooler (but not cold) than the other one depending on which side the coolant flows. One thing thought, is I’ve never seen a double spring T-Stat. So by all means shed some lights here, how does this T-Stat works on these cars? Another thing is, when the engine is at normal temp (as per dash gauge or thermometer in the engine) and the E-fan starts, it is drawing cold air through the rad, this is telling me that the coolant in the rad is not hot or warm. But with all this the engine does seem to overheat??????

 

[ArticNemesis]

What kind of tstat did you go with?

I recently replaced a 3month old thermostat from NAPA with an OEM from Mitsu because I realized the tstat wasn't opening.

 

[makriluc]

Same thing, bought it from NAPA, the brand is Stant.
So, I probably will have to go OEM...
But why the double spring on these?

 

[ArticNemesis]

Not sure what you mean by double spring, the two i had looked identical, minus the size of the opening.

Also, I didn't mention because of the background you have in cars, but you are installing the tstat with the weephole facing upwards right?

 

[1gcrazy]

I've bought a bad stat before. I took it home, tested it in boiling hot water. The first one ended up being bad. I got it replaced, retested and worked like a charm.

 

[makriluc]

Ok here's a pic of the Stant T-Stat I installed.
What I mean about the double spring is the portion under the line. What I was used to in T-Stat, is what the top half usually looked like. So the buttom part with the flat disk seems to obstruct the opening in the head. But, mind you, the previous T-Stat was indentical and worked fine for several years. Also, You have a point there with the weephole, I don't recall. So I'll have to look at that after work.