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Hello gents;
upon reading rave it says that when engine is cold thermostat is closed,when it is hot thermostat will open and water will turn in the radiator to allow more cooling,now my question is the following:
when engine is started from cold and i remove the top radiator bleeding pipe going to the expansion tank,water is coming out from the nipple of the top rad where the small bleed pipe connects (had to do that to bleed the system from air while adding water in the tank continuously from my garden hose at the same rate of the water running out from the radiator nipple).so how water is running out fom the rad while engine is cold?and my engine warms up quickly not like as a stuck open thermostat?
i am asking to see if i have a faulty thermostat,coz my temperature gauge is slightly rising from the 12 o'clock position and coming back to 12 o'clock?it is not even reaching 1 o'clock.(between 12 and 1 with ac on in the traffic and 38 degrees c)
checked water pump ok
checked viscous fan the second speed is operating
checked belt ok
system presurising to normal
expansion tank cap not hissing
coolant is not lost
grounds checked in the engine bay ok
bottom rad hose hot and normaly presurized
temp gauge not getting under 12 o'clock even if driving the car on long descents for half an hour with no gas throttle applied (getting down the mountain)
ps: i did not add anti freeze yet so only water is used "will add" does it affect the gauge?
thanks alot
 

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Hi
I have a 95 4.6hse and mine also does not go above 12 o´clock in normal running. I have no leaks and my system seems to be operating correctly. Mine heats up quickly and then stays at 12.
I think that your thermostat is operating correctly and you should be thankful that it does not get too hot.

Just my thoughts . . .
 

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Hi Jorjiok,

What you describe is perfectly normal. The radiator has 2 big hoses connecting it to the engine and the rest of the cooling system (plus the small bleeding tube). The thermostat is located in the bottom hose, closing it off when cold to prevent full circulation. But the top hose is always open, so the flow generated by the water pump or you adding water will cause some pressure and thus flow through the radiator. As this is just a little bit, restricted by the size of the bleeding tube, and only through the top part of the radiator, the cooling effect is minimal and certainly doesn't hinder engine warm up.

A little movement in the needle is normal, especially in traffic or when towing. This indicates the thermostat opening/closing and/or the viscous fan kicking in when temperature rises a bit, resulting in the temperature lowering again. In some cars it is more pronounced then in others, probably due to differences in the components working together (tolerances, age, state...).

Anti-freeze could have a small effect on how the temperature evolves, because the temperature coëfficient differs from water, affecting the efficiency of the cooling system. But the effect should be minimal, and certainly nothing to worry about. A lot of people in warm area's run without anti-freeze. :wink:

Greetz,

Filip
 
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I just went thru a thermostat issue with the thermostat sticking open. Sounds to me like yours is working fine.

In the case of mine, it normally runs right around the 12:00 straight up position. But I traveled to a hotter area than I'm normally in, and the thermostat stuck in the open position. We were able to limp home without too much issue. A couple things I noticed... with the thermostat stuck open, the engine temperature, upon cresting a hill and starting down, would drop like a stone. In one case my engine temperature dropped clear to the bottom of the gauge.

But the thing that made me notice something was not right was that my climate control kept faulting on me, and giving the book icon on the control panel. I realized that when the engine temperature would drop to the bottom of the normal range, the climate control would just plain freak out. It would go all the way hot, then back cold, then hot, switch from the AC vents to the defroster vents... That was when I started watching the temperature closely. When I realized that the temperature was dropping way down when the climate control freaked out, I realized it must be stuck thermostat.

sure 'nuff... new thermostat and the climate control has been perfect. The temperature never drops below 12:00 except when it was stuck.
 

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Discussion Starter #5
hello gents;
glad to hear that everything is normal (knock on the wood).thanks for ur help
cheers jorjio
 

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coincidentally, I'm pretty sure my T-stat is stuck open. The 4.0 takes 15-20 min to get to the middle of the gauge.
 
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