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Discussion Starter #1
So here is what is happening. The car will run at normal temp for awhile and it may or may not(depending on the day) start to run hot. When it starts to run hot it jumps by little increments will get up to the red line and sometimes go over the redline at which time I shut it off. If it doesn't get to the redline it will jump around and I mean the temp jumps its not gradual. Once the engine starts to get hot like this it is worse at lower speeds and lower rpms and tends to approach the redline even at idle. If I rev the engine I can get it to cool back down. The car did this once over a week ago then went back to running normal for a week now just yesterday it started acting up again. My big question here is what does this sound like is going bad? I personally think the thermostat is sticking but not completely stuck so it is not opening up fully when it needs to and when I gas it the pump creates more pressure causing it to circulate more which cools it back down. What do you guys think?
 

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Could be the cylinder head temperature sensor. Have you noticed any leaks?
 

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Most likely T-stat. Nothing wrong with replacing T-stat first, and hope that nothing else needs to be done. Troubleshooting it first with a IR temperature gun is another idea.

When Hot, are your cooling fans kicking into High speed?
 

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Discussion Starter #4
The cooling fan is kicking on when the temp is up I had it at an idle and got out popped the hood and the fan was going.

As far as leaks I haven't noticed anything.
 

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You could start with the t-stat like Marde said, or have it check with the IR temp gun like he said as well. I would have it checked before putting parts in it that may not fix the problem, but thats just my opinion.
 

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Part of troubleshooting a cooling problem is to verify that the fans run in both modes; low speed and high speed.
 

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Discussion Starter #7
Well I am going to try the thermostat its only $7. I don't have an IR gun so out of luck there and I am trying to stay out of a shop because of $$$
 

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Marde, correct me if I'm wrong, but doesn't a/c turn on high speed.
 

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Hi JFrye. Yes. However, AC on, does not keep the fans on High nor does it always come on immediately or even soon after the AC is turned on. The delay or duration of High speed fans is variable and controlled by multiple sensors and the PCM. I think it also uses magic fairy dust and the position of the Moon.

Sorry guys, I have ZERO time to type, gotta roll, see ya tomorrow or maybe later today.
 

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Low speed fan controls the temps, and it'll come on before the gauge goes above normal. High speed doesn't come on until gauge is at the high end or A/C turned on.

Gauge temps fluctuating over normal without the fan on is a fan problem.
 

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Discussion Starter #12
So could the fan be causing the temp to make significant changes back and forth over a 5-10 second span? I mean unless the fan can instantly cool I don't see how that could be the problem. I will check the fan tonight when I get home.
 

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If you rev it to get the temp down in inclined to say the pump. Had the same issue on an old bimmer and a replaced pump fixed it.



However if a thermostat is only 7 bucks you can start there.
 

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Fan doesn't instantly cool, but the gauge isn't a gauge either.

It stays in the center through a wide range of actual temps, then jumps fast toward the top when the "center range" is exceeded. So a small change can make the needle move fast in that zone. (You'll note it gets into the center fast on start up as well)

Fan check is always mentioned because it's the most common cause of the gauge going to the red end - happens every time the low speed fan isn't functional.
 

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Discussion Starter #16
Great info guys I appreciate it now I have more to go on if the problem continues. I put in the new thermostat and I think the problem is now fixed. I will keep an eye on it over the next couple of days to be sure. the fans all seem to be functioning so I think we are ok there. When I removed the thermostat there were two springs and inside the larger spring on the thermostat there is a cylinder which had serious wear marks on one side where it looks like it was rubbing and likely getting stuck so I am pretty hopeful that was the problem. Thanks!
 

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Hey guys, sorry to bring this thread back up, but I don't really know how to do anything except post replies on here so far. I have a 2003 Focus SVT Hatch. Recently I have been having problems with it randomly overheating while the engine is under load. I thought it was maybe I was just low on oil (which I have a hard time checking because no matter what I have tried, oil always sprays up the dipstick an inch above the full line) but it overheated again last night so I came home and changed the oil after it cooled, and I measured the old oil I recovered and the oil level was where it ought to be. Coolant level is also fine. I am a little stumped on this! If someone could help me diagnose, I would greatly appreciate it! Also, someone told me that it might be that the thermostat is stuck, so I would like to check that, but I honestly don't even know enough to know where that specific thermostat would be and how to test/replace it. Thanks for your help!
 

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My bad.......................

Oil being low does not affect motor temp but excellent way to walk home by tearing engine up. That will be all the warning you get.

If so far out of the repair loop you don't even know where thermostat is then I strongly suggest buying like a Haynes manual to learn more, while not perfect they are great for new learners and pay for themselves within a half hour of your use of it. If not willing to read you are not competent enough to work on the cars. Not trying to be mean but the reality of it. Today's cars require more knowledge than simply putting oil and water in them.
 

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Thanks amc49! I actually have been doing a lot of reading and I do have a Haynes, so I now know where the thermostat is and how to take care of it. I am not incompetent when it comes to these things. I'm simply inexperienced and in search of helpful people who may have gone through similar things. Thank you so much for the recommendations!!

Also just a random thought... Everyone I have ever talked to have said that if your oil is low, not low enough to seize up the engine, but just low enough that parts start to wear on each other, then your oil temp would go up, thereby causing your motor temp to rise. What do you think of that? Is there actually any merit to what they have told me?
 

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No merit to that as written.

The SLIGHT loss of oil cooling from lower level isn't even measurable, once you loose oil pressure even for a moment the wear can be FAST.

Hints in old threads are a good start, once you exhaust that help posting a new thread by clicking on "new thread" at the top of the section helps get answers specific to your issue. (too often replies are to the OLD part of the thread if you tag onto an existing one)

Fan operation is the first check after simply making sure coolant is good & filled adequately.

Lack of low speed fan is the usual reason for temps popping up into the red. Virtually unavoidable if the low speed doesn't work, it'll go red before the high speed fan can bring it down again.
 
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