[RESOLVED] coolant gauge on dash fluctuates. Failed theromstat.

[16g-2ndgen]

well for about a month now my car has been running not as good as it should. One problem that i cant seem to figure out is that when i start the car and let it idle and warm up to operating temps, its fine on the gauge on the dash, but as soon as i start driving the guage will slowly drop from operating temp level to under completly cold after about 4 miles of 35 mph driving. My heat also gets colder after i start driving. What could this be? could this be related with my ect sensor and the reason im getting 10 mpg?

 

[buddahboost]

Maybe a bad temp sensor? Also.. make sure there are no bubbles in the system

 

[16g-2ndgen]

Maybe a bad temp sensor? Also.. make sure there are no bubbles in the system

if there was bubbles wouldnt that cause the car to run hotter and possibly overheat? i replaced the temp sensor with a working unit but i know im not getting a good connection from the sensor to the ecu because cold starts are horrible. i have a cel but idont have a code reader nor datalogger anymore.

 

[lowandsleekDSM]

I know on my old Ford F-250 when the coolant gauge started to spike every once in awhile it was due to a blown head gasket. The oil was getting into the coolant and making the temp gauge spike. I know its comparing apples to oranges, but it might be something to look at.

 

[16g-2ndgen]

I know on my old Ford F-250 when the coolant gauge started to spike every once in awhile it was due to a blown head gasket. The oil was getting into the coolant and making the temp gauge spike. I know its comparing apples to oranges, but it might be something to look at.

no, its not the headgasket. ive already did a leakdown/compression test and it was good.

 

[buddahboost]

You can check your codes by using a analog voltmeter with the sweeping needle.
Check it out in the tech section, they have a how to there

 

[16g-2ndgen]

You can check your codes by using a analog voltmeter with the sweeping needle.
Check it out in the tech section, they have a how to there

thanks! maybe one of these codes can tell me whats wrong.

 

[gsxtasy]

Replace your thermostat, see if that helps. Sounds like it gets stuck open.

 

[16g-2ndgen]

Replace your thermostat, see if that helps. Sounds like it gets stuck open.

i had that brought up to me, and im going to check it as soon as i can. But could this cause my horrid gas milage?

 

[Defiant]

Yes. Your ECU isn't letting you out of closed-loop. Use a 190° thermostat.

 

[16g-2ndgen]

Yes. Your ECU isn't letting you out of closed-loop. Use a 190° thermostat.

I will go pick one up as soon as possible then! thanks for your help!

 

[the_mork]

if there was bubbles wouldnt that cause the car to run hotter and possibly overheat?

Yes and no. The engine will run hotter but the temp sensor will show cooler (and your heat will run colder) because the temperature sensor is really bad at reading air temperature and your heater core is really bad at extracting enough heat to warm a continuous supply of air from an air pocket.

 

[ATLDSM96]

Can you get a 190 thermostat at car part store such as autozone and stuff? my car is doing the same thing exact thing.

 

[synthetek]

Can you get a 190 thermostat at car part store such as autozone and stuff? my car is doing the same thing exact thing.

You can, but I would highly recommend an OEM one from the dealer. If you compare an OEM one with one from an auto parts store you will see why.

 

[16g-2ndgen]

i got the 190 from autozone, thers no dealer local. but i see the whole air pocket thing and im going to change all the stuff out today.

 

[16g-2ndgen]

wow, soo i changed out the thermostat.. and as i remove the upper part of the thermostat housing, i see something odd.. i sideways spring sitting in there.. as i remove the rest of the upper part, I see that the thermostat has broken off into 7 different pieces! soo i get most of it out and then i have to go and get special tweezers and go inside the head and pull out pieces.. that god i found all the big big pieces.

moral: CHECK your thermostat when you do a coolant flush.

 

[16g-2ndgen]

You must be logged in to view this image or video.

oh snap.