zx3focus

iTrader: (1)

I had some cooling problems with my car(ls1) this spring when I bought it. The car would overheat randomly so after trouble shooting a few things with no result I ended up pulling the thermostat and driving it all summer with problems. No that the weather has cooled I decided I had better put a t stat back in it becuase the engine was not getting much above 140 while I was moving. The engine will warm up to about 180 if I sit at a light. So I put a t stat in the car and the motor overheats idling but the upper and lower hoses are not even warm. The rad is full but the hoses are dead cold. Also there is no heat, the heater core hoses are dead cold as well. I have tried two t stats thinking that I may have gotten a bad one at first but the second t stat is behaving the same way. I have never heard of something like this happening and dont know where to begin. Any help would be appreciated.

LS6427

iTrader: (2)

try a 3rd t-stat. Thats the only thing that can cause that as long as your water pump is working.

zx3focus

iTrader: (1)

Yeah, the water pump has to be working. I have been dailying the car all summer. The only thing I can think of is that I bought cheap autozone and advance t stats. The gm, t stat is about 40 bucks more.

ae13291

iTrader: (8)

i bought a duralast t stat for my brothers car and we changed the t stat 3 times because all of them were defective and stayed open stuck. buy yourself a valucraft one from autozone and you will see that is the same one the dealer uses. its a Motorrad made in germany one. and another possibility to your problem is a clogged radiator, it will give the exact symptoms you are describing

intense3123

To rule out if it's the T-stat or not, put it in a pot of water and heat it to boiling and see if that thing opens

zx3focus

iTrader: (1)

Thanks for the advice guys.

1 FMF

iTrader: (1)

make sure you're radiator cap is good and that the system will hold pressure,

when the car is hot, with the cap on, have someone hold the engine around 2000-2500 rpm and then squeeze the upper radiator hose with your hand. You should feel a decent surge as coolant is flowing through it, if not your water pump may not be pumping or you may have air in the system.
with your current stat, it is a very good idea to check it in a pot of boiling water and verify it opens and closes without hanging up, other than that there's not much to cooling systems other than water pump, radiator cap, no air in system, and no clogs which i seriously doubt. you most likely have air in the system, keep checking the radiator level and top it off along with the overflow tank every time the car is cold. Also, when you fill the system via the radiator pull the throttle body coolant hose, that's a nice spot to let air escape as you pour into the radiator but you have to go slow and will take around 10 minutes. when coolant comes out the throttle body hose then reconnect and top off radiator and overflow tank.

zx3focus

iTrader: (1)

I bought a new water pump thinking that was the problem but it behaved the same way with the new pump so I swapped the old pump back on and left the t stat out and it runs the same as it did all summer: never getting over 180 degrees.


So, what would cause my cooling system to take a dump when i put a thermostat in? I pull the stat out and the system works just fine, but I cant drive it in the cold because it will run really cold, obviously.

FiredUpZ28

Sounds like a defective T stat. Also, make sure you burp the radiator. All air should be out, the car should always be running when you fill the radiator. Gently squeeze the upper and lower hoses until no air bubbles pop out.

zx3focus

iTrader: (1)

Thaks for the advice guys. I am going try another t stat and try it again. When I fill the system and start the car, it just overflows the radiator and the bottom hose gets alot of pressure in it if I put the cap on. The t stat isnt opening because I guess it isnt seeing hot enough temps. The top hose will be hot if there is anything coming out of the motor, while the bottom hose is cold because the t stat wont open. Why isnt it seeing hot enough temps to open?

LS6427

iTrader: (2)

The top hose is the one that should get HOT when the t-stat opens after the engine/heads get hot.

Its defective! A t-stat will open after about 10-15 minutes of idling. 160* t-stat like mine anyway.

zx3focus

iTrader: (1)

This is a 187 t stat and I have tried boiling it and it open like it should. I have tried 2 thermostat, both behave the same.