Ok the car is a 1995 CX hatch with a 1990 sohc ZC non vtec (d16a6) converted to obd1, running off a po5 ecu.
50/50 prestone coolant
Half size Automatic radiator plugged at cooler
All stock

My problem is the car while driving does not warm up to operating temperature but if idling it will reach it after awhile..

Now i know thermostat right!?!

Well this is my third OEM thermostat from the dealership. 1st a 95 cx thermo (d15b8) 2nd a 90 crx si thermo (d16a6) and 3rd 95 cx (d15b8) as of yesterday.

No way i got 3 faulty thermostats in a row. So has any1 experience this? Any advice? Whats my next step on troubleshooting this?

Thanks!

I let it warm up for 10-15min then drove 15-20min to work parked snapped a pic..

 

Id like to add that something is over cooling it.
My needle operates as it should.
Fans NOT on.
Any suggestions or questions
Thanks again

 

I'd try to get a concrete number by measuring the coolant with a gauge.

Either an actual temperature gauge plumbed in somewhere or an infared gun measuring the coolant inside of the radiator with the cap off.

 

Get a new radiator cap. Iirc, if the coolining system does not build pressure, it will not go to full operating temp.

 

After some more research, The thermostats i have been putting in my car are 78 C°. Which is the thermostat for the engine but my 'hunch' is its causing the thermo to open up prematurely, Cooling it down.
I am going to try a thermostat that opens up 'hotter' in a sense.
But that still doesnt make sense, the thermostat should operate to the temp of the coolant. Unless the 78C° thermostat has i guess a limit of opening and closing only allowing a certain temp range, keeping it cooler constantly.
Which would mean the wrong thermostat for that engine or something else is causing it to over cool... idk

When i get home i will look at my radiator cap and check to see its pressure. I may have a thermo gun aswell to observe the temp at the thermo housing, radiator, and upper lower hoses. Thanks for the input! And if anyone else has a suggestion other than cardboard infront of the radiator

 

OEM is 172 degrees
My car stays too cool with that
180 degree is an optional OE temp


Have you bled your coolant

 

I didnt have a chance to read the temp with the temp gun.
I have a murray 16psi radiator cap on. i purchased it about 4months ago so its fairly new.

Yes i burped my coolant correctly when i replaced the thermostat.

When i get some free time i will be testing the engine coolant temperature sensor and i soppose the engine coolant sending unit before debating on buying a higher temp thermostat

 

I had an overcooling issue once too.
It was a defective sensor, all the autozone/kragen units send wrong overheating signal.

ONly OEM works

 

Thanks for all the help and acmoc hit the nail in the head.

I tested the ECT and it is faulty and hopefully the problem with my overcooling.
Will be ordering a new thermistor soon.
Now my test wasnt 100% accurate but accurate enough i believe. [I was going off my dash guage]
It was reading k-ohms about 0.33 and the temp gauge was just above C on the dash. It even went as high as 0.2!
Cold it was reading between 0.5 - 1.

Heres the chart i was using[from my haynes for a integra surely the same]-




This is from my haynes manual-

Heres how to CHECK/TEST the ECT :

1. The engine coolant temperature (ECT) is a thermistor (a resistor whuch varies its resistance in accordance with temperature changes). The change in the resistance values will directly affect the voltage signal from the ECT to the PCM. As the sensor temperature DECREASES the resistance values will INCREASE. As the sensor temperature INCREASES the resistance values will DECREASES. A trouble code for this sensor indicates a failure in the thermo sensor circuit so in most cases the appropriate solution to the problem will be either repair of a wire or replacement of the sensor.

2. To check the sensor disconnect the electrical connector from the sensor. Using an ohmmeter measure the resistance between the two terminals of the ECT sensor with the engine (COLD) cool. Reconnect the electrical connector to the sensor start the engine and warm it up to normal operating temperature. Disconnect the connector and check the resistance again. Compare your measurements to the resistance chart (*see illustration above*). If the sensor test results are incorrect replace the sensor.

3. Check the supply voltage red/white wire with the ignition key ON (engine not running). It should be approximately 5.0 volts. If not check for an open circuit in the red/white wire from the sensor to the PCM.

REPLACEMENT :
*warning wait until the engine has cooled completely before beginning this procedure.

4. Before installing the new sensor wrap the threads with Teflon sealing tape to prevent leakage and thread corrosion.

5. To remove the censor depress the locking tab unplug the electrical connector then carefully unscrew the sensor. Coolant will leak out when the sensor is removed, so install the new sensor as quickly as possible.

*CAUTION : handle the coolant sensor with care. Damage to this sensor will affect the operation of the entire fuel injection system.

6. Installation is the reverse of removal. Check the coolant level adding as necessary. Don't forget to burp the system.

 

Adding a little tip, i found it easier to use a aligator clip (idk what its called) for the bottom prong of the sensor, then using the other prong for the top.

 

Are you replacing the part that threads into the block?

I just tossed one this weekend from a junkyard b1. No idea if it works but you can have it for free.

 

Yes the one below the distributor. Oh im ok man thank you tho very kind of you.
I have it on my list of parts im ordering from oemacuraparts its only $35. Thanks again tho