imbest123

about a year ago i bought a 94 civic ex coupe that had/has all sorts of different problems. one thing i noticed was that the engine temp never reached normal operating temperature. the needle goes about 1/4 full and never any more regardless of how much/hard i drive. the fans are operating normally (they are not always on) or so i assume since it has never reached temperatures high enough for the fans to turn on, according to the gauge.

i somewhat believe that this may be the reason why my auto trans acts goofy and my gas mileage sucks. a gear hangs and when braking it auto downshifts around 10mph, just like a cold motor would, and i average around 22-25mpg, lower than what ive read other civics get which makes sense if the ecu thinks the motor is still cold an is running rich like a cold motor would.

the car has been running fine but i would like to get this issue corrected, if possible. could it be a faulty thermostat, if not what can it be? what tools can i purchase to troubleshoot this? a gauge to read the engine coolant temp?

BryanM.

iTrader: (1)

I would start by removing the T-stat (if it doesn't have one, problem solved) and inspect it to see if it's closed all the way, replace it if it is stuck open. If it's closed, test it by putting it in hot water, at about 180º it should start to open. If it opens at a much lower temp, replace it.



.

Fox14120

The cooling fan isn't suppost to stay on all the time. With that said if the fan does go on it's bacause the coolant is hot enough to trip the fan switch. The last 9 months have been a nightmare with the coolant system and other parts on my 97 civic Ex. If it takes along time to heat up the thermostat could be stuck in the open position but once it does if the fan comes on then the coolant is getting hot one thing you can do is drive it around alittle to warm it up and then pop the hood and touch the lower coolant hose if that's warm then you know coolant get getting through the thermostat back to the radiator. If the gauge only goes up 1/4 you might have a faulty engine coolant temp sensor. That sensor sends the info to the dash engine temp meter take a look at yous (should be on engine head on the side the thermostate is on. If looks original or looks like coolant has leaked out around it i'd change it. It's only about $20-$30 for a new one and not hard to replace just if you need to bleed the air out of the coolant system when you change a thermostate you should there also. 1/3 on the gauge is about normal it's not too far off but is low. Don't know much about trans so can't help there. I'd say try the coolant temp sensor first though it takes a few mins to replace and isn't as envasive as replacing a thermostat.

kulo

my engine temp goes down when i went up a hill
change the thermostat
fixed

imbest123

well this seems to most likely be the culprit. ill check that out. good thing they are cheap.
maybe it does go up to 1/3 of the gauge... idk im guesstimating lol. anyway, the trans issue isnt a big deal, just thought there may be a correlation. ill check the ect sensor as well. thanks

Former User

It does not seem to me that your engine is running cold because your temp gauge seems to be about 1/3 and the fan does occasionally turn on.

As for the auto trans, drain the current ATF and then refill with Honda or Honda-recommended ATF. Drive the car briefly and then do the ATF drain and refill again.

And auto trans Civics do get substantially lower gas mileage for city driving, so your mileage may be fine if it is city mileage. If your gas mileage is from highway/freeway driving, then do a basic tune up (plugs, wires, cap, and rotor). Is the CEL on?

imbest123

yeah i dont think the engine is running cold but im worried that the sensor may be telling the ecu that the motor is still cold. i may be completely wrong though, hence the thread posted. but im no sure if the fan turns on. i really dont recall it turning on at all and the temp does lower a litle after i run the ac fan

ill give the flush a shot easy enough to try out lol

no cel, mostly city driving and needs a tune up with spark plugs and fuel filter. thanks for the recommendations. i now realize that this car needs a bit more work lol

Duane_in_Japan

Yes, to do a good flush, you would remove the tstat, like the other mentioned, you may not have one or its stuck open.

Your computer may think that the engine is still cold so it is running in Open Loop Operation, it will get worse gas milage, the tranny shift points will be affected as the programming wants to heat up your engine as quickly as possible to stop producing emissions, which is what a cold, rich burning engine does.

I will make a guess that at highway speeds, your OD may not work also, thats a maybe, this is also an Open Loop Strategy but not a full on promise. All of these things could be seen with a scanner but checking the tstat will be your first step.

Linked

my needle stays at 1/3 temp and i get the average mpg (37 highway on 5spd), cooling fans do come on

what i've recently done though is replace the following:
fuel filter
air filter
checked pcv valve
o2 sensor
new mtf
new oil
decent spark plugs

make sure your regular tune up items are in good condition

i have the 94 ex coupe as well

Duane_in_Japan

Come on Bro, you spent money on an O2 sensor but say you put in decent plugs, the plugs do all the work, if they burn all the gas with proper timing there will be no O2 for the O2 sensor to report and no emissions for the Cat to clean up. I am messin' with you man, I am sure an expensive set of plugs will not get any more MPG if everything else is working well.

Now you may have a temp gauge that is off scale low, how does it look in the dead of heat August. It would be nice if your temp did go up some and put the gauge mid range that it actually meant you were getting hot. As you know, some gauges dont go red until its too late. Have you bumped yours against another ride just like yours. Are you running a lower than stock tstat.

Linked

lol

the gauge stays at that temp ever since i bought the car a year ago

whenever i run the full blast the temp goes down and one time i dc'ed the fan the temp went up (not dangerously tho)

the tstat is stock AFAIK, i've never took it out

coolant is still green too :D