Honda Car Forum

I have a 1990 Honda Accord. It usually runs with the temperature
guage in the middle range. Frequently the guage will quicky go up
to close to, but not at the high end red mark. This happens even
when its 50 degrees out and I am going 45 mph. If I turn on the
heater the temperature usually goes back to middle. It goes down
very quicky, within 10 seconds of turning on the heater. I dont
believe the heater could cool things off that quickly.

I have a new radiator and antifreeze. I am not loosing coolant.

Could it be a hose or chamber that is blocked/pinched, and turning
on the heater is allowing the coolant to byupass the blockage ?

Any helpful comments appreciated.

G

On Wed, 04 Nov 2009 10:32:29 -0800, Gene Wagenbreth <genewxxx@isi-OS4>
wrote:

>I have a 1990 Honda Accord. It usually runs with the temperature
>guage in the middle range. Frequently the guage will quicky go up
>to close to, but not at the high end red mark. This happens even
>when its 50 degrees out and I am going 45 mph. If I turn on the
>heater the temperature usually goes back to middle. It goes down
>very quicky, within 10 seconds of turning on the heater. I dont
>believe the heater could cool things off that quickly.
>
>I have a new radiator and antifreeze. I am not loosing coolant.
>
>Could it be a hose or chamber that is blocked/pinched, and turning
>on the heater is allowing the coolant to byupass the blockage ?
>
>Any helpful comments appreciated.
>
>G

Head Gasket ?

"Clete" <lecllaij@halifax.ca> wrote in message
news:3ik3f59dersk7089c7l0jg95lig1ig22pk@4ax.com...
> On Wed, 04 Nov 2009 10:32:29 -0800, Gene Wagenbreth <genewxxx@isi-OS4>
> wrote:
>
>>I have a 1990 Honda Accord. It usually runs with the temperature
>>guage in the middle range. Frequently the guage will quicky go up
>>to close to, but not at the high end red mark. This happens even
>>when its 50 degrees out and I am going 45 mph. If I turn on the
>>heater the temperature usually goes back to middle. It goes down
>>very quicky, within 10 seconds of turning on the heater. I dont
>>believe the heater could cool things off that quickly.
>>
>>I have a new radiator and antifreeze. I am not loosing coolant.
>>
>>Could it be a hose or chamber that is blocked/pinched, and turning
>>on the heater is allowing the coolant to byupass the blockage ?
>>
>>Any helpful comments appreciated.
>
> Head Gasket ?


I'm thinking thermostat.

On Wed, 4 Nov 2009 14:24:16 -0500, "Seth"
<seth_lermanNOSPAM@hotmail.com> wrote:

>"Clete" <lecllaij@halifax.ca> wrote in message
>news:3ik3f59dersk7089c7l0jg95lig1ig22pk@4ax.com.. .
>> On Wed, 04 Nov 2009 10:32:29 -0800, Gene Wagenbreth <genewxxx@isi-OS4>
>> wrote:
>>
>>>I have a 1990 Honda Accord. It usually runs with the temperature
>>>guage in the middle range. Frequently the guage will quicky go up
>>>to close to, but not at the high end red mark. This happens even
>>>when its 50 degrees out and I am going 45 mph. If I turn on the
>>>heater the temperature usually goes back to middle. It goes down
>>>very quicky, within 10 seconds of turning on the heater. I dont
>>>believe the heater could cool things off that quickly.
>>>
>>>I have a new radiator and antifreeze. I am not loosing coolant.
>>>
>>>Could it be a hose or chamber that is blocked/pinched, and turning
>>>on the heater is allowing the coolant to byupass the blockage ?
>>>
>>>Any helpful comments appreciated.
>>
>> Head Gasket ?
>
>
>I'm thinking thermostat.


I hope u are right.

I doubt its the head gasket. It never gets too hot. Most of the time it
runs fine and doesnt get hot. Why would turning on the heater make the
temperature go down immediately if it were headgasket.

Thermostat sounds interesting. Does the heater somehow bypass the the
thermostat ? How difficult is it to replace the thermostat ? How much
should it cost to have someone do it (ballpark) ?

Thanks

G

"Gene Wagenbreth" <genewxxx@isi-OS4> wrote in message
news:hcskr2$4ak@venera.isi.edu...
>I doubt its the head gasket. It never gets too hot. Most of the time it
> runs fine and doesnt get hot. Why would turning on the heater make the
> temperature go down immediately if it were headgasket.
>
> Thermostat sounds interesting. Does the heater somehow bypass the the
> thermostat ? How difficult is it to replace the thermostat ? How much
> should it cost to have someone do it (ballpark) ?


The heater doesn't bypass but redirects heat. Those coolant lines go
through the heater core. With the heat on, a fan blows across it sending the
heat into the cabin.

For how to change it...
http://wiki.answers.com/Q/How_do_you...onda_Accord_LX

On 11/4/09 3:41 PM, in article hcsseu$bih$1@news.eternal-september.org,
"Seth" <seth_lermanNOSPAM@hotmail.com> wrote:

> "Gene Wagenbreth" <genewxxx@isi-OS4> wrote in message
> news:hcskr2$4ak@venera.isi.edu...
>> I doubt its the head gasket. It never gets too hot. Most of the time it
>> runs fine and doesnt get hot. Why would turning on the heater make the
>> temperature go down immediately if it were headgasket.
>>
>> Thermostat sounds interesting. Does the heater somehow bypass the the
>> thermostat ? How difficult is it to replace the thermostat ? How much
>> should it cost to have someone do it (ballpark) ?
>
>
> The heater doesn't bypass but redirects heat. Those coolant lines go
> through the heater core. With the heat on, a fan blows across it sending the
> heat into the cabin.
>
> For how to change it...
> http://wiki.answers.com/Q/How_do_you..._1990_Honda_Ac
> cord_LX
>
>
New radiator sounds like a clue. Check for air bubble in the system. I
believe a '90 has a "burp" screw.

Gene Wagenbreth <genewxxx@isi-OS4> wrote in news:hcsheg$33m@venera.isi.edu:

> I have a 1990 Honda Accord. It usually runs with the temperature
> guage in the middle range. Frequently the guage will quicky go up
> to close to, but not at the high end red mark. This happens even
> when its 50 degrees out and I am going 45 mph. If I turn on the
> heater the temperature usually goes back to middle. It goes down
> very quicky, within 10 seconds of turning on the heater. I dont
> believe the heater could cool things off that quickly.


It can indeed! Considering there's only about 20F or so difference between
"normal" and "overheat", the heater doesn't have to do much to cool the
engine down sufficiently.


>
> I have a new radiator and antifreeze. I am not loosing coolant.


Why was the old rad replaced? And how old was the coolant that was in there
before?


>
> Could it be a hose or chamber that is blocked/pinched, and turning
> on the heater is allowing the coolant to byupass the blockage ?
>
> Any helpful comments appreciated.
>


Sure does sound like a sticking thermostat. I'll bet it's crappy
aftermarket, too.

The heater feed is independent of the thermostat, so it will work even when
the engine is cold and the thermostat is closed.

Try a new OEM Honda thermostat. About $40 or so and worth every penny.



--
Tegger

The Unofficial Honda/Acura FAQ
www.tegger.com/hondafaq/

Where is the burp screw ? How do you use it ?

G

On 11/5/09 11:27 AM, in article hcv1ss$lop@venera.isi.edu, "Gene Wagenbreth"
<genewxxx@isi-OS4> wrote:

> Where is the burp screw ? How do you use it ?
>
> G

Look in the vicinity of the top radiator hose connection on the engine for
either a small hex head bolt/screw. Set the heater to max, open it a couple
of turns until coolant comes out in a steady stream without bubbles. Close
the screw, top it off & idle the engine until the radiator fan comes on
twice (heater still at max) then open it again (VERY slowly) and let any
trapped air out.

For the next several days, check & top off the radiator & overflow tank
before the first start in the morning & it should get rid of all the air.