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Replacing Thermostat in 1999 2.5L 4-cyl XLT


Carl

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My temperature gauge won't even peek above the coolest temp and my engine threw a code last week that said 'Low coolant temp for closed loop operation'. I want to replace my thermostat, but it doesn't reside where most authorities say it should...where the top hose enters the engine.

Can anyone tell me where to find the thermostat on my truck? The fix seems simple, so I think I can handle it...especially since the shop quoted me $170 to do it.

Thanks in advance for your help.

Carl
 


offroadranger

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It is in fact under the upper radiator hose. You have to remove the fitting that the hose attaches too from the engine.
 

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It is in fact under the upper radiator hose. You have to remove the fitting that the hose attaches too from the engine.
And all I'll have to do is remove the bolts to remove the housing, replace the thermostat and gasket, seal up and refit the housing with adhesive, and connect the hose back?

Seems easy enough. Thanks for the info.
 

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It shouldn't be necessary to glue the housing in, and if you do, the next guy to change that thermostat will curse your name and your descendents. Even if it's you.

Thermostats come either with a gasket, or usually with a slotted O-ring that fits around the thermostat body. Just replace that.

I recommend replacing thermostat (and water pump) bolts with stainless whenever they are removed. It sure makes subsequent removals nicer.
 

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So it really is that simple? Disconnect the hose form the radiator to the engine, under which I will find the thermostat housing, unscrew the bolts holding down the housing, remove the thermostat, replace it with the new one and then put it all back together?

Thanks for your help. The $170 really seems like a ripoff now.
 

MAKG

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To be honest, that pretty much describes a transmission replacement as well. As well as quite a lot of other things.

The devil is in the details. What do you need to remove to get at the thermostat housing bolts? Sometimes it's nothing. But not always. On my Prizm, I have to remove the airbox. On my 4.0L, the serpentine belt tensioner has to come off. Well, you get the idea. $170 does seem a bit steep, though.

FYI, you certainly are going to have to drain some of the coolant (not very much, though), or you're going to make a mess. However, now might be a good time for a flush. Be careful about spilling coolant; it tastes sweet and will attract small animals and small children. It's moderately toxic.
 

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Well, I just had the radiator replaced very recently, so I don't think it's time for a flush. I'll just let it cool down and drain enough to where the hose doesn't drain coolant everywhere.

As for the bolts, it seems like it should be pretty easy. The spot where the hose hits the engine is right in front, on top, so if I remove the hose, the housing should be right under there, correct?

Again, thanks for the help.
 
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offroadranger

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Well, I just had the radiator replaced very recently, so I don't think it's time for a flush. I'll just let it cool down and drain enough to where the hose doesn't drain coolant everywhere.

As for the bolts, it seems like it should be pretty easy. The spot where the hose hits the engine is right in front, on top, so if I remove the hose, the housing should be right under there, correct?

Again, thanks for the help.

Thats correct. Unplug the connectors for the temp sensors and unbolt the housing. It uses an o ring. No RTV, adhesive or anything is needed. You can only get that o ring(as far as I know) from ford. I re-used mine as it was in good shape and it was fine.

One thing I do remember from when I changed mine was the thermostat is oval. Autozone may try and sell you a round one becuase thats what thier computer says it uses, they are wrong. Its oval. You may save yourself some trouble by buying your replacement thermostat from a ford dealer.
 

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Thats correct. Unplug the connectors for the temp sensors and unbolt the housing. It uses an o ring. No RTV, adhesive or anything is needed. You can only get that o ring(as far as I know) from ford. I re-used mine as it was in good shape and it was fine.

One thing I do remember from when I changed mine was the thermostat is oval. Autozone may try and sell you a round one becuase thats what thier computer says it uses, they are wrong. Its oval. You may save yourself some trouble by buying your replacement thermostat from a ford dealer.
Odd. I got a rubber O ring from Autozone. They assured me that the round thermostat was the correct one, and that thye have sold many round thermostats that have not been returned.

Anyone esle?
 

offroadranger

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Odd. I got a rubber O ring from Autozone. They assured me that the round thermostat was the correct one, and that thye have sold many round thermostats that have not been returned.

Anyone esle?
I knew it!!!! haha. Well I suppose its POSSIBLE ford put two different thermos in but I HIGHLY doubt it. That would mean two different housings as well. My 1999 2.5 uses an oval thermo, I promise.
 

Carl

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I knew it!!!! haha. Well I suppose its POSSIBLE ford put two different thermos in but I HIGHLY doubt it. That would mean two different housings as well. My 1999 2.5 uses an oval thermo, I promise.
Well, I guess I should get one at the dealer instead fo getting into tt and being stuck. Thanks for speaking up!

How long did the repair take you?
 

offroadranger

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Well, I guess I should get one at the dealer instead fo getting into tt and being stuck. Thanks for speaking up!

How long did the repair take you?
No problem Carl. Been there done that, just trying to save you a trip/headache or two.

Its funny because there have been 3 times I've found autozones computer to be COMPLETLY incorrect. Ive pointed it out to them, they REFUSE to listen to me. Its really frustrating.

The install did'nt take long. Maybe an hour total.
 

Carl

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No problem Carl. Been there done that, just trying to save you a trip/headache or two.

Its funny because there have been 3 times I've found autozones computer to be COMPLETLY incorrect. Ive pointed it out to them, they REFUSE to listen to me. Its really frustrating.

The install did'nt take long. Maybe an hour total.
Even odder...just called the Ford dealership. The guy grabbed the part for my truck and said 'It's round for sure...not oval'.

Is yours a 1999?
 

offroadranger

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Even odder...just called the Ford dealership. The guy grabbed the part for my truck and said 'It's round for sure...not oval'.

Is yours a 1999?
yep. '99 2wd 2.5l. I dont know what to tell ya. Mine was oval - autozone sold me a round one, did'nt work, went to ford got the oval one for $10 or so, no questions asked, ford did not offer me a round one.

That IS odd.
 

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