I think my thermostat and/or coolant temp sensor aren't working right. On the dash, the temp needle rises to about 2/5 of the way up, so it's definitely below the halfway point. Is that right, or should it be a little farther up?

I'm also concerned because I think my radiator fans are acting strangely and I'm getting shitty gas mileage. Last summer and the summer before, the radiator fan would cycle on/off a couple of times every time I shut off the engine unless I'd been driving really gently. Now, with my car up on jacks, and with the engine warmed up (~800 rpm idle, temp needle at 2/5) the fan hasn't come on, even though I let it idle for 4-5 minutes after getting warm.

Also, shitty gas mileage. Is there a trend here? Is this normal, or does it indicate that my thermostat or coolant temp sensor are bad?

Update: I remembered something. My torque converter locks and unlocks at freeway speeds. Maybe other times too, but that's much harder to notice.


Modified by likeguymontag at 7:28 PM 12/26/2006

 

First thing you should do is look for the underhood sticker that will tell you WHAT YEAR your accord is.
The cooling fans should cycle when the coolant temp is in the range of 200 degrees, it might take longer than 4-5 minutes of idle.
The Torque Converter is SUPPOSED to lock and unlock at highway speeds.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by hondadude &raquo;</TD></TR><TR><TD CLASS="quote">First thing you should do is look for the underhood sticker that will tell you WHAT YEAR your accord is.</TD></TR></TABLE>

Oh, crapola. That's useful info, isn't it. 1995 Accord LX. Glad to know the torque converter doesn't indicate a prob.

 

thermostat may be getting stuck partially open. that will lead to your guage not getting to where it used to be. mileage can be affected by o2 sensor wearing out. if it is not warm outside, idling on jackstands, your fans will take a while to come on... mine only do in the summer. f22 is quite efficient that way: VE wise.

 

Well, the max for your needle shouldn't be changed by a funky thermostat, unless its really really open when cold. 2/5 seems about right.
The main thing is, how long does it take your needle to start rising above the line and how long does it take to get heat?
And yes likeguymontag is right in worrying about the torque converter spasms. I think what is happening is the temp is innapropriatly dropping below the desired temp for the sensor. When that happens the torque converter doesnt work right for a bit. It happened in my case and now I changed the thermostat and the torque converter stays locked up constantly on regular traffic on the highway.
It also killed my mileage because there are things more than just the torque converter that require the car to properly warm up. Whats odd though is despite the needle showing it as a regular operating temp, it seems as though the other sensor reads you as not being warmed up.
The best indicator is probably when the car takes more than 3 mins to warm up and spit out heat.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Homesickelian &raquo;</TD></TR><TR><TD CLASS="quote">Well, the max for your needle shouldn't be changed by a funky thermostat, unless its really really open when cold. 2/5 seems about right.
The main thing is, how long does it take your needle to start rising above the line and how long does it take to get heat?
</TD></TR></TABLE>
stuck open thermostat will keep the engine from reaching correct operating temperature also changing the optimal VE. this will yield low gas mileage etc. like cold starts in the winter. mmkay.

 

His max operating temp is fine.. mm kay? cause I had a thermostat that was stuck open recently and it was open pretty far. I have practically the same exact car as him. It would take forever to warm up but the max temp is the same now as when the dysfunctional thermostat was in. Don't get cocky with me
And yes i know the mileage will be lower etc.....


Modified by Homesickelian at 8:23 PM 12/26/2006

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Homesickelian &raquo;</TD></TR><TR><TD CLASS="quote">His max operating temp is fine.. mm kay? cause I had a thermostat that was stuck open recently and I have practically the same exact car as him. It would take forever to warm up but the max temp is the same now as when the dysfunctional thermostat was in. Don't get cocky with me
And yes i know the mileage will be lower etc.....</TD></TR></TABLE>congrats that you had the same problem.
the point is that he is not reaching the correct max temp.

Dollars for donuts it is his thermostat stuck open that causes his needle not to get up and thus his lousy mileage.. mmkay.

 

Hey, cut it with the "mkay," alright? I appreciate all the input, and I'll do my best to separate the good stuff from the crap.

The dash temp needle moves up after a couple of of minutes of normal driving. Probably no more than five minutes on even the coldest days. I think that's ok, or close to ok. When the car's warm, I get full heat from the heater core. I still wonder if I might have a lazy thermostat or ect. Unfortunately, my dad's multimeter died tonight, so I can't check the ECT and a lot of other stuff I'd like to check.

So y'all say that 2/5 is fine, and it's pretty clear I'm not running too hot.

Is there a procedure to test a thermostat besides replacing it? Is there a way to tell if I'm in open loop or closed loop mode?

 

not that I know of but if you warm up in those times and spit out heat fast, i would say its not the thermostat.

Dolars for donuts, wow.. keep in mind if its not his thermostat, he's possibly reaching the proper temp so cut the bullshit and help him and stop ******* with me.


Modified by Homesickelian at 8:39 PM 12/26/2006

 

My gf's 96 ex is a lil below the middle line if that helps.

 

as is mine, I'd say its close to 2/5 up or 1/3.
I really think its a sensor, cause your thermostat seems to be functioning fine. Warming up, to the right amount at a good rate.

 

Update: I did some tests.

I warmed it up this morning with the radiator cap off. As it warmed up, the fluid slowly overflowed. About 4-5 minutes after reaching 800 rpm idle, the fluid started to steam. About 15 minutes after reaching low idle, the bottom radiator hose started to get kinda warm. At about 20 it started to get kinda hot. Also at 20 minutes I started to see small bubbles appearing at the right side of the radiator fill hole. I never saw the fluid suddenly drop or suddenly start flowing, which I think you're supposed to see if the thermostat suddenly opens. The fan never came on. The lower radiator hose also never cooled down after getting warm. It just got warm, then hot, and stayed hot. I re-thought the heat thing, and I don't think the cabin heat is as hot as it should be.

This evening I did some spirited driving before parking, so the engine was as warm as it will ever be. Once again, the lower radiator hose was hot and stayed hot - too hot to hold onto. After about 10 min. at idle, both fans came on for ~10 seconds. The AC also turns on both fans. It's about 40 degrees outside, and about 50 in my garage. Global warming, ya know...

Thanks for any ideas. Also, does anyone know how to tell if the ECU is in closed or open loop mode?

 

I think it's fine that the tubes stayed hot, your pumping a lot of heat from the engine. If the coolant wasn't cycling you probably would have a hot engine instead of a cold one. The tube that has the thermostat is to the left of the engine. You'll see the big tube going right into the engine. To see a variation in coolant volume look in the overflow tank.
I don't have as good of expertise with the coolant system, so hopefully someone can help you more precisely.
In my opinion I think it's a sensor.
Also the fan things are no problem I'm pretty sure, and again if they weren't working right your car would overheat not underheat. One fan is AC specific so thats why they turned on when you put the AC on.
Also if this helps:
http://auto.howstuffworks.com/cooling-system1.htm


Modified by Homesickelian at 7:40 PM 12/27/2006