Honda Car Forum

> The car: 1991 Honda Accord LX
>
> The symptom: The dash temperature gauge starts to gradually climb to about
> halfway betwen C and H. Usually stays there, but will climb slightly if
> left idling.
>
> Previously it used to climb to just 1/3 the distance above C and stay there
> no matter how long I idled or how fast/slow I was going. Recently I've
> noticed that the temperature gauge will climb to about halfway between H
> and C while I'm idling. Once I start moving, or if I have the AC on, it
> will usually stay about 1/3 above C.
>
> I have also noticed that when I start the engine after it's been sitting
> (so it's cold), the temp gauge immediately climbs to the 1/3 level (the
> previous normal operating level). Before, the temp gauge used to slowly
> climb from C up to the 1/3 level as the engine warmed up.
>
> What I've done: Both of the fans work (tested by turning on the AC and also
> letting it idle until the fans turned on). Just had the coolant flushed
> and radiator cap replaced. Radiator was replaced a couple of years ago.
> Thermostat seems to be working (upper coolant hose becomes hot to touch).
> No unusual whining or roaring noises coming from the water pump area.
>
> Any suggestions as to where I might look for the problem? Originally I
> thought maybe the thermostat or water pump had gone bad on me. I'm
> thinking maybe there's a bad temperature sensor somewhere. Could still be
> the water pump I suppose.
>
> I appreciate the suggestions.
> Eugene

From your symptoms, I would guess that your dash temperature gauge system
has a problem. And actually, from reading your post, it doesn't sound like
you have any other data that suggests that your coolant temp isn't fine.

The behavior of the temp gauge rising to 1/3 immediately on start with a
known cold engine is especially suspicious...that is just not the right
behavior (unless it is about 110F outside, and even then I would expect it
to be closer to the "C")

From an old post here:
> A reading from the 1992 Honda Accord factory service manual, chapter
> 23, verses 106-110:
>
> there are two switches"
> coolant temp switch A, near the front and coolant temp switch
> B, at the back of the head
>
> the sender for the temp gauge is also on the side near switch B, but
> it's only a single-wire connector (it's between the two)

I would check the wiring to the sender for a loose connector or heavy
contamination. It's a red wire. You can check that the gauge responds
smoothly when you short the sender wire to the engine block, and when you
remove the short (gauge should swing toward hot/cold with no "sticking")

If the gauge and wiring checks out, you can measure the temp sender
resistance ("approximately 142 ohms at low engine temperature, and
approximately 13 ohms at high temperature").

Good luck,

--
----
Arthur
1991 Accord LX MT, 146k miles

well, i think i have at least isolated part of my problem.
The ECU blinks an error code 6, which according to my Haynes
book is the Coolant temperature sensor.

Poking around the innards of my engine, I managed to pull
the sensor connector off (without breaking anything) and
measured the resistance of the sensor with the engine cold
(at least mostly...it was 90F outside while I was doing this).
Measured 1270 ohms. Haynes book says it should be 2200-2700 ohms
between 50-80F. Didn't bother to measure the resistance with the
engine warm.

So now for my next question(s).
What size and length socket do I need to get this sensor out?
The stubby sockets I have aren't quite long enough for me to
get at the nut so I can't tell what size I need.

Is it better to drain the coolant before doing this? I don't
want to have coolant gushing out while I'm fumbling around
trying to get the new sensor in place.

Thanks
Eugene

Arthur Russell <atr@REMOVE-CAPS-AND-INVALIDbellatlantic.net.invalid>
wrote in news:ImQUa.6276$AO6.4835@nwrdny02.gnilink.net:

>> The car: 1991 Honda Accord LX
>>
>> The symptom: The dash temperature gauge starts to gradually climb to
>> about halfway betwen C and H. Usually stays there, but will climb
>> slightly if left idling.
>>
>> Previously it used to climb to just 1/3 the distance above C and stay
>> there no matter how long I idled or how fast/slow I was going.
>> Recently I've noticed that the temperature gauge will climb to about
>> halfway between H and C while I'm idling. Once I start moving, or if
>> I have the AC on, it will usually stay about 1/3 above C.
>>
>> I have also noticed that when I start the engine after it's been
>> sitting (so it's cold), the temp gauge immediately climbs to the 1/3
>> level (the previous normal operating level). Before, the temp gauge
>> used to slowly climb from C up to the 1/3 level as the engine warmed
>> up.
>>
[snip]

>> I appreciate the suggestions.
>> Eugene
>
> From your symptoms, I would guess that your dash temperature gauge
> system
> has a problem. And actually, from reading your post, it doesn't sound
> like you have any other data that suggests that your coolant temp
> isn't fine.
>
> The behavior of the temp gauge rising to 1/3 immediately on start with
> a known cold engine is especially suspicious...that is just not the
> right behavior (unless it is about 110F outside, and even then I would
> expect it to be closer to the "C")
>
> From an old post here:
> > A reading from the 1992 Honda Accord factory service manual,
> > chapter 23, verses 106-110:
> >
> > there are two switches"
> > coolant temp switch A, near the front and coolant temp switch
> > B, at the back of the head
> >
> > the sender for the temp gauge is also on the side near switch B, but
> > it's only a single-wire connector (it's between the two)
>
> I would check the wiring to the sender for a loose connector or heavy
> contamination. It's a red wire. You can check that the gauge responds
> smoothly when you short the sender wire to the engine block, and when
> you remove the short (gauge should swing toward hot/cold with no
> "sticking")
>
> If the gauge and wiring checks out, you can measure the temp sender
> resistance ("approximately 142 ohms at low engine temperature, and
> approximately 13 ohms at high temperature").
>
> Good luck,
>



--
---------------------------------------------------------------------
Eugene Mah, M.Sc., DABR eugenem@ix.netcom.com
Medical Physicist maheug@musc.edu
"For I am a Bear of Very Little
Brain, and long words Bother
http://radinfo.musc.edu/~eugenem/blog/ me." - Winnie the Pooh
http://www.netcom.com/~eugenem/ ICQ 3113529
PGP KeyID = 0x1F9779FD or 0xE37A1591 PGP key available on request O-
---------------------------------------------------------------------