coolant temperature woes. stock gauge. any advice?

[fivespeedsteed]

when i got my car 5 or 6 years ago, it had always run at about 1/4 of the way up the factory gauge. a couple years ago i decided to change the water temp sensor, and when i did, it started working again, and fluctuated. usually ran about halfway up the gauge.

this is a stock fox (motor wise) with the fan clutch still. ive had my coolant flushed 3 or 4 times since ive owned it, even added water wetter. its not leaking much coolant, i have to add about a half a resovior full every year or so if that, i dont see it leaking anywhere, so it must be burning it.

as of recently on the stock gauge, the car has been running close to the halfway point on the factory gauge, and when i get in stop and go traffic with the ac on it will get up to the halfway point, sometimes a little above it.

a few days ago my air conditioning stopped blowing cold, so tonight i fixed the leak (o ring in the retrofit valve to 134a) and recharged it and the ac was blowing cold. this was at night, with the sun down. when i drove home i noticed that it was running a little above the middle of the gauge, and when i was almost home it was 3/4s of the way up the gauge. i turned on the heat full stuff and got it back down a little.

i just replaced the fan clutch again a few weeks ago with an imperial brand one from work (advance auto), and seems to have good resistance to it. when the car is hot and the motor is off, i can spin it, and it will turn another 1/8th of a turn or so on its own.

i know its the factory gauge and all, but it must do something. somewhere it must be sensing that something is hot. summer is almost over and the car will sit all winter, but im trying to figure out what can cause this if the gauge is reading right. im going to try to find a shop tomorrow that has a point and shoot temp gun to try to see if its actually running hot or not.

any ideas?

if you coolant is clean and your fan clutch has decent resistance, what else can cause higher coolant temps? water pump not circulating fast enough? i would say sticking thermostat, but its pretty consistent so far.

 

[lxman]

Have you radiator cap pressure tested! People don't realize this but your cap plays a big a part in your cooling system. Then check your fluid levels, and check your mixer with a hydrometer. You can pick one up at an auto parts store for around $5 or less. If your still have problems after all that then your factory gauge is fualty. I would then recommend going with an aftermarket mechanical temperature gauge. That will give you a spot on reading of how your motor really is. I hope this helps you.

 

[fivespeedsteed]

very clogged up radiator.

we got the new thermostat in, the water outlet gasket was leaking a little bit, that might explain my super slow coolant leak ive had.

we put rad flush in it, and found that its barely getting from one side of the radiator to another. you can take the cap off the car with it hot and running, you can put your hand on the top of the radiator and its not hot, however its very hot where the upper hose goes into the radiator. when you fill the radiator (it was empty) we sprayed it full through the rad cap, then it slowly lowered back down, then added more water, then it slowly lowered down, and kept doing that for minutes on end before it finally filled up. its just taking that long to get across it. so this whole time my waterpump has been sloshing water back and forth from my upper to my lower radiator hoses through the block.

gonna look into getting mine cleaned out, my buddies dad does it. this car will one day get a 3 core aluminum rad and all, just going to try to get it cleaned out for now.

 

[lxman]

You can get a stock replacement at oreillys for around $90 until you get your 3 core. In my opinion it isn't worth trying to unclogg one. Its just a matter of time before it does it again.
Good job on figuring it out though!

 

[fivespeedsteed]

friends dad is cleaning it out for 30 bucks. he heats up the cap on the driver side, and pulls the cap off, then runs a dipstick through all the passages and then hoses it all out. its flowing much better.

the radiator itself isnt in bad shape, just gotta make sure i use distilled water this time, and im adding some of the rust protector stuff made by peak.

 

[fivespeedsteed]

got the freshened up radiator in tonight and it does much better. i had the rad cap off and let it idle while it got up to temp. it got to about halfway on the gauge then started climbing pretty quickly, i was reaching for the key getting ready to kill it, and then it just stopped at about 3/4s of the way up the gauge, and i looked at the radiator where the cap goes and it had opened the thermostat and taken all the water.

it has a brand new thermostat in there, so i know it opened right at 195 like it should. we then tracked down a friend who had a point and shoot temp gun, went and got it, and my water outlet (pointing right at the thermostat, but with the gun hitting the water housing) at full operating temp (right between the O and the R in normal on the temp gauge) its no hotter than 188 or so. was riding to get the temp gun in a 95 gt, and thats almost exactly what his was reading too in the same place on the water outlet.

so the gauge is just off. good to know.

 

[lxman]

Good to hear!