The TEMP needle on my guages (94 Accord LX) has recently been going all the way up past red.

This would happen, when the engine isn't even warm...?

For example, before setting off on a 1 hour drive home (the car had been given a while to cool down) it imediatly would go straight up to past red. On the way home, it went back to regular...on it's own???

What would cause the needle to do that, and what does the Temp needle ACTUALLY get it's reading from (which sensor?)


Modified by DIYaccord at 6:27 PM 6/4/2006

 

Its a bad Coolant temperature sensor..

Its On the Block Right under the distributor

 

Are you talking about Number 15?




Modified by DIYaccord at 11:35 PM 6/4/2006

 

it is not the temp sensor... not even close .......... sounds like a stuck closed t-stat

http://www.hondaaccordforum.co...m.htm

 

but the engine ISN'T that hot...

The needle would go up, and after driving a while, it goes back to normal (under middle)


Modified by DIYaccord at 11:36 PM 6/4/2006

 

There could be a problem with the radiator cap. If the radiator cap does not hold pressure correctly then coolant could boil and therefore the engine would overheat. Another reason might be caused by thermostat failures. Also check the exhaust system which you can discover by checking vacuum readings, pipes and converter. You should also check the electric cooling fan by making sure that the fan motor, the relay and temperature are correct. Check the antifreeze concentration which should be 50/50

 

I don't believe the problem is over heating, I believe it's an electrical/sensor error.

 

Start out with the thermostat, that is the cheapest fix and it probably needs to be changed anyway.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Projekt &raquo;</TD></TR><TR><TD CLASS="quote">There could be a problem with the radiator cap. If the radiator cap does not hold pressure correctly then coolant could boil and therefore the engine would overheat. Another reason might be caused by thermostat failures. Also check the exhaust system which you can discover by checking vacuum readings, pipes and converter. You should also check the electric cooling fan by making sure that the fan motor, the relay and temperature are correct. Check the antifreeze concentration which should be 50/50
</TD></TR></TABLE>
50/50 isnt the ideal mixture for maximum heat wicking.

&gt; (Therm. cond, boiling point, freezing point)

&gt; Water: 1.42, 100 C, 0 C,

&gt; Ethylene Glycol: 0.624, 198 C, -11 C,

&gt; Where conductivity is in units of Cal/(sec)(cm)(degK)

&gt; Thus, water conducts heat 225% better than antifreeze. A 50/50 mix

&gt; would conduct about 72% as well as pure water, but would boil at about 150 C

&gt; vs. 100 C.

Borrowed from http://www.realbig.com/miata/1997-08/2814.html

But from the sound of it, it seems like a stuck thermostat. I've has similar problems happend intermittently with diffrent cars and have always just replaced the thermostat and that seems to always fix it.

 

this sounds like a stuck thermostat.

 

Here's what testing tonight has given me:

Thermostat (#4 on picture above):
-Tested Ok
-Replaced last year

Sensor B (Towards front, #18 on picture above)
-Could not test acuratly (can't get water above 215*F, tried torch near bottom) but did turn on
-When plug jumped:
=Car off: Turns 1 fan on
=Car on: Turns 0 fans on

Sensor A (On thermostat housing, #17 on picture above)
-Tested Ok
-When jumped
=Car off: Turns 0 fans on
=Car on: Turns 2 fans on

 

anyone?

 

HELP!

 

...last bump...need oppinions OTHER THAN check thermostat...

 

Well if your gonna try yourself i would try with the cheap stuff first....you already changed your thermostat so thats #1, go 2 autozone or 2 a shop and have your water pump tested also that could be the case too! if not that start testing your yours senors like your o2 sensor, your heat senor with is located at or near your cat converter, and even check your mass airflow senor too! the o2 senor should be located on your header thats only like 20-30 bucks 2 replace at autozone. and last but not least it sounds stupid but did u check your antifreeze levels yet?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Diplomat1929 &raquo;</TD></TR><TR><TD CLASS="quote">Well if your gonna try yourself i would try with the cheap stuff first....you already changed your thermostat so thats #1, go 2 autozone or 2 a shop and have your water pump tested also that could be the case too! if not that start testing your yours senors like your o2 sensor, your heat senor with is located at or near your cat converter, and even check your mass airflow senor too! the o2 senor should be located on your header thats only like 20-30 bucks 2 replace at autozone. and last but not least it sounds stupid but did u check your antifreeze levels yet?</TD></TR></TABLE>
dude I don't mean to be harsh but damn, half that **** has nothing to do with this problem!

- how is autozone going to test your water pump for you???
- what would an o2 sensor have to do with an intermittent temperature reading?
- what's a heat sensor?
- 94 honda accords do not have mass airflow sensors!!!!

to the OP: you're seeing intermittent very hot conditions reported by the coolant temp sensor, when the motor's not that hot - an air bubble in your cooling system could cause this - have you burped the cooling system recently? if not, try bleeding the system and see if that fixes the problem.

 

I'm new on this particular forum but I know alot about autos and how everything works within them and this sounds like the temperature sending unit has gone bad. Actually, I'd say it is definately the sending unit because that is the only thing that would make the needle jump around instantaneously like he is describing. The temp sensor is just a resistor if it is like most all I know of. And the way it works is the hotter the temp the more resistance across the unit and thus the less current it allows thru thus making the needle move. Replace the sending unit and see if that fixes it!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 19dabeast85 &raquo;</TD></TR><TR><TD CLASS="quote">I'd say it is definately the sending unit because that is the only thing that would make the needle jump around instantaneously like he is describing. </TD></TR></TABLE>
a hot pocket of air moving around in the cooling system can cause this behavior as well since the air can be hotter than the coolant around it.

 

I guess that is possible but it seems much more likely that a 12 year old sender would go bad than to have air pockets in the coolant. I don't think an air pocket would really have time to change the temp of the probe quick enough to make the needle jump that fast unless it somehow "sat" right on the probe. Hot water will heat up the probe much faster than a blast of hot air simply because of its heat capacity. And air has such a low heat capacity that even after the metal probe (aluminum or copper) absorbs the heat it really won't have much of an effect on the temp of the metal unless it is a HUGE pocket of air. That's my theory anyway.