hey guys, a couple days ago, i noticed that my temperature gauge is way low, specifically if i sit an idle it will go almost up to half, but while driving 50mph it drops to near the C (btw its about 30 outside)

odd thing is that the heat is still pretty warm, at least warm enough to warm me up, so i was wondering if this was a thermostat problem or temperature sensor problem

thanks
chris

 

It doesn't sound like a problem to me, very normal for the temp gauge to lower while doing hwy speeds and the ambient temp in the lower digits

 

Not sure which sensor is actually responsible for the temp guage. The "coolant Temperature sensor" near the distributor on my 89 and right where upper hose connects to engine block went bad, causing my fans not to run. I unplugged it and it had no effect on temp guage. If you have heat, then its either a short or the sensor that controls the guage, but Im not sure which one that is. Or like the other fellow said may be normal. Good luck.

 

It's the thermostat. You could get a new for around $15-$20. And it's really easy to replace if you have a Hayne's manual around. PM me if you need some specific instructions.

 

wow, that was a ...errr compounding my confusion

i will see if i can play withthe temperature sender, they are cheap and easy to replace

then if not, is there anyway i can replace the thermostat without draining my radiator

lastly, is there a problem???

thanks

Chris

 

Yes, you have to drain the radiator

The Hayne's said to drain the block too, but I ended up just draining the radiator and everything worked out fine.

 

are u guys kidding me?
during cold day crusing on the hwy..it's quite normal for the coolant temp to drop.

-he has heat, also car warms up properly when not on hwy..so i HIGHLY doubt it's the thermostat.
-the gauge works, moves with change in temp...so i doubt it's the gauge sensor.
-his fan works (no overheating i assume)..the coolant temp sensor works.

you guys want him to rip open the coolant system for something that's normal.

chrispy - LEAVE IT ALONE!

 

ahh I thought he said his temp gauage wasn't working. Mine seems to just have 3 settings; Hot, Cold, and normal. It doesn't really fluctuate any based on outside temps.

I kinda thought this was a fun install to be truthful, not expensive at all

 

Even driving at high speeds the temp guage should not drop. It would only drop if the thermostate was leaking slightly (or totally).

If you have the abilities to do the job, I say do it.

 

if the thermostat was not working right..then he should be on cold all the time since it's stuck open. but he gets heat..warm enough heat, and he is able to bring the car up to normal temp.

why do u think in 30 degrees or lower temp the coolant temp should not drop when the car is cruising on hwy?

i guess it wouldn't hurt to do it..but IMO it's not needed..at least wait until it's warmer to do it.

 

That's what I said. From reading his post is sounded logical to me, but when it started going down this route I left it alone.

 

haha, i never realized i could bring about an argument,

i will keep you informed of how things are going, i have some in city driving to do tonight, so that will help me figure it out


Chris

 

Sorry, I wasnt advocating you do a bunch of work for nothing. I agree if you are getting heat and the car does not overheat then it is not your thermostat. The switch I was talking about, called the "coolant Temp sensor" did not control my temp guage as far as I could tell, it only switched on or off the electric fans. It was around $20. I also changed it without having to drain the radiator. It could be that your fans are on all the time or kicking in while driving and giving you more airflow and causing the temp to lower some, but I doubt it. I had an old Volvo and my temp guage kept going up and pegging at hot, I was on a road trip and ended up taking the thermostat out as to let the coolant circulate constantly. When I drove across the parking lot to a payphone it was hot again. It turned out to be that the main wire harness that ran near the engine block had rubbed and worn through the insulation causing the temp gauge to go wacko. Anyway, hope that wasnt too confusing, just trying to help.

 

The temp by me is in the 20's and at crusing speed the needle doesnt budge. Plus I'm using the colder thermostate (170F). It means his thermostate has a slight leak. But I agree, the job can probably wait till summer since it sounds like a slow leak.

 

The temp guage should NOT drop at any speed...highway or city...i had the dropping temp guage problem too at highway speeds but that was also effecting my heating. i just changed the stat and its fixed.

last night i just drove through Michigan, Minnesota and down to Iowa (12 hours)...the outside temperature was 0 to -5 all the way (wind chill made it like -17) and sure enough...the temp guage stayed in the center....

but i did notice my heating got really weak at 75mph and above...the temp guage was still in the center...i stopped at a rest area and the heating came back ....checking out my heating system today

 

oops...i missed Wisconsin in the list

 

I think the temp guage sensor is opposite the ECU temp senor.

Stephen

 

so yesterday i drove about an hour to bloomington mostly 60mph er so, about 10-20 outside, and i was able to feel a heat difference, still warm enough to keep me warm but much cooler than normal

but last night driving around town was very warm kept at 50% er so

my theory is that the thermostat is stuck just partially open, and that the fans are able to come on when necessary

so, the temp doesnt go but so high, cause the fans kick on, and the thermostat doesnt have an ability to raise the temperature

does anyone know if there is a method to change the thermostat without drainin the coolant?


Thanks
Chris

 

drain 1/2 the coolant and go to town.

 

Hmmm that sounds familiar

 

you can also check for thermostat leakage by checking the temperature of the pipes going into the heater core, coming out of the heater core and the main pipe goign into the radiator...

the differences in temperature or lack of it may give u a better picture.