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Temperature Fluctuation


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#1
caseyweed

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Sorry to be asking so many questions but I just got my car and am noticing a few little quirks I would like to see if they are normal or not. First off my car is a '95 626 with a v6 and automatic transmission. I notice sometime my temperature gauge fluctuates. For the most part, it's rock solid right in the middle and then sometimes I notice it climbs up in temperature pretty quick and then back down almost a fast as it climbed. -_- Usually it goes about 3/4 of the way to red when it does it but earlier tonight after I had gotten off the highway and slowed down it got pretty close to the red and then when back to the middle within a half a minute. Is this normal? Does it sound like a serious problem or just a problem with the gauge?

#2
kksh

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I had sort of the same problem with my skyline before. If you are confident your car is not overheating then it could be a sensor problem. The temperature gauge gets its reading from the water temp sensor. It has a thermistor which changes resistance according to the temperature of the water. If somehow along the circuit, there is something that is making causing it to have less resistance. ie, short circuit between the two wires. You could get a high reading and then drop as soon as the short circuit goes away.

I think your car has something to do with the sensor cos water's temp can't go up or down that fast.

#3
caseyweed

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Is it possible it’s the thermostat? I was watching it a little more on my way into work this morning and I started my car about 10 minutes before I left and the gauge was right in the center when I started driving but I still wasn’t getting any hot air from the heat. When I pulled into work (which is only 5 minutes from my house) the temperature was up high again so I sat there to see if it would go down, and it didn’t so I revved the engine and the heat came on the gauge dipped down again pretty quickly.

#4
Trebuchet03

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I think your car has something to do with the sensor cos water's temp can't go up or down that fast.

yes it can ;) there is a lot of thermal energy coming off that block.... if you don't believe me, start your car, wait a few seconds and grab the exhaust header ;) couple this is low coolant and it can shot up quickly...

That being said. Top off your coolant. I had this same problem because I accidentally let some coolant escape (I forgot to put the cap on tight) and did not realize it. All it needed was a little more coolant and she was all better.

IF that does not work, try washing your radiator. Dirt and other debris on there acts as an insulator reducing its capacity to vent heat off ;)

--

You can always check the guage with a multimeter - check the repair manual for exact instructions B)

#5
NickR

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^Agreed. First check your coolant level. Notice that there is a coolant filler cap. on the passenger side of the engine, next to the oil dipstick. When the engine is cold, open it, and check it is full to the brim.

#6
CCStooge

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I had this same problem in my car, and all that it was was the temperature sensor. I would suggest trying that after making sure your coolant is topped off. I'm not sure about your car, but on my 98 the sensor was right beside the airbox on the block.

#7
hominid7

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Possible problems:

-temp sensor
-thermostat
-radiator clogged/dirty/empty
-electric cooling fan not operating correctly/broken
-weak/collapsing radiator hose
-serious ignition problem causing detonation problems/heat problems
-engine filled with sludge

One time i had an overheating problem with my Jetta. Turned out the problem was not so much mechanical, but a sheet of pollen and debris (looked kinda like packed dog hair) had formed covering the front of the radiator (behind the evaporator). I loosened the radiator, reached in and the whole sheet of nasty stuff just pulled right off. Problem solved.

#8
caseyweed

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Thanks for all the responses. I topped off the coolant and was able to get about a half gallon in there including in the overflow. Driving home today the heater started to warm up right away. So far so good. I will report back in a day or 2 if it is not fixed.

#9
Trebuchet03

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Thanks for all the responses. I topped off the coolant and was able to get about a half gallon in there including in the overflow. Driving home today the heater started to warm up right away. So far so good. I will report back in a day or 2 if it is not fixed.

if it took that much... I bet that was it :blink:

#10
kksh

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you guys are right.... it's most probably be because the coolant level was low and once he reved, the air pockets hit the sensor and they are much hotter than the water. Shooting the needle up. I think so anyway......

#11
flora macdonald

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Great!

But now you have to ask yourself why you were able to add half a gallon!
Something wrong somewhere!

Flora

#12
caseyweed

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I just bought the car so I hope nothing major is wrong with it! I haven't seen any leaks. Most of that 1/2 gollon went into the overflow. I'm hoping that maybe they just haven't filled it in a long time... :unsure:

#13
flora macdonald

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Hi!

yeah, it's possible that they never maintained it properly as the coolant will evaporate in hot weather, etc.
Just keep your eye on the level in your overflow tank, you might have to add a little since you just filled the system up...if you notice you're starting to add coolant every week, then start looking for other problems.
Good luck and happy motoring!

Flora

#14
caseyweed

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Thanks for the help everyone. Hey flora, I thought you were'nt going to help me anymore? :P I'm just kidding, thanks for the responce.

#15
caseyweed

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If one was to accidentally overfill the overflow container would the extra coolant drain out somewhere? The reason I ask is because when I filled it up yesterday I got it pretty full and when I went to check the coolant level this morning it’s not as full as it was yesterday. The overflow is at the full point on the dipstick, but the amount of missing coolant since yesterday kind of scares me. I checked the oil there is no sign of coolant in there. I haven’t noticed any puddles under my car but it’s been raining pretty hard for the last week, so it’s possible it’s getting washed away.




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