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thermostat problem?

3277 Views 4 Replies 4 Participants Last post by  NVDiscovery
Confirm or dispel my suspicions. I just replaced the water pump on my 01 Discovery II. that all seemed to go just fine.

Now the thermostat does not seem to be opening up. the upper lines get good and hot but the lower line coming out of the bottom of the thermostat is cool to the touch. this is all when the car is at full warm/hot. the temp gage is getting up there but it has not over heated. the lower line coming out of the t-stat that goes into the lower radiator just isn't getting warm/hot like the upper ones.

my line of thinking is that the t-stat now needs to be replaced. Thoughts?

I've ordered a new thermostat and will put it on tomorrow.
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straight physics tells you that hot stuff rises and cold stuff drops

the hot water goes into the top of the radiator and cools and drops to the bottom of the radiator where it comes out and goes in through the bottom of the thermostat - you have the flow backwards.


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Sometimes it's really hard to get all of the air out of the cooling system and it gets air locked.

I don't have any guaranteed methods, but raising the expansion tank as high as you can get it with the cap off and the engine idling for a few minutes may work. There are lots of other tricks for bleeding the cooling system if you do a search. This has been a problem for me in the past. I bet your t-stat is OK.
T-stat is in, filled it back up from the highest points and its holding a normal temp. I thought the lower line would be the hot line, not the line returning cooled water to the block. I had it backward. The -tstat was the original and it has 155k on it. no harm in getting a new one to go along with the water pump. so far it seems to be operating normal. the tstat may have been just fine, i'll never know now. thanks.
Keep an eye on your coolant level as the air may continue to bleed out of the system and the overflow tank fluid level will drop. I have to top up mine 2-3 times and then it stays at the same level.
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