Re: Radiator Fan Not Coming On - Overheating --UPDATE
 

He says the temp gauge goes back down when the fans come on, so as far as
the car is concerned, its not overheated.

On 4/19/04 9:22 AM, in article
slrnc87ncl.2rm.The-Central-Scrutiniz...nt.comcast.net, "TCS"
<The-Central-Scrutinizer@p.o.b.o.x.com> wrote:

>
> To me that sounds more like a bad fan thermoswitch. If the engine is
> overheated, the fan should not turn off.
>
>
> On Mon, 19 Apr 2004 13:45:42 GMT, E. Meyer <e.meyer0SPAM@ieee.org> wrote:
>> That really sounds like a bad radiator cap. Most garages will have a
>> pressure tester to check if the cap will hold the specified pressure. Have
>> you tried testing it or simply replacing it (they are relatively
>> inexpensive)?
>
>
>> On 4/19/04 7:18 AM, in article
>> c60be9ea.0404190418.6f3ef3eb@posting.google.com, "John McConnell"
>> <design@narwhaldesign.com> wrote:
>
>>> Well, I did some extensive tests on my 94 vx on the weekend about the
>>> overheating. This is what happens on overheating -
>>> -radiator full and reserve at max line
>>> -start the car
>>> -idle for 25 mintues
>>> -at first only top hose is hot and then after a few minutes bottom
>>> hose from radiator is also hot
>>> -temp gauge is stable at mid-point
>>> -fan comes on goes off after about 30 seconds
>>> -fan comes on again a few minutes later and then turns off after about
>>> 30 seconds
>>> -reserve tank begins to fill and keeps filling until radiator fluid
>>> is spraying out from under the reserve tanks cap
>>> -temp gauge rises
>>> -fan comes on again
>>> -temp gauge goes back down
>>> -reserve tank fluid receeds
>>> -fan goes off
>>> -reserv tank starts to fill again and overflows
>>> -temp gauge rises
>>> -fan comes on
>>> -...and on and on it goes
>>>
>>> John McConnell
>>> Vermont
>>>
>>>>> I have a 1994 Civic VX, and it is slowly overheating. On cold days,
>>>>> city driving, I don't even notice it. But on a hotter day or longer
>>>>> drive after about 15 minutes of driving the car starts to overheat.
>>>>> If I turn on the car heater at it's lowest setting it cools the engine
>>>>> back down.
>

Re: Radiator Fan Not Coming On - Overheating --UPDATE
 

Excellent description! Many people have suggested a bad radiator cap,
but if I read your post right, the coolant is not leaking out from under
the radiator cap but from the reserve tank cap/fitting. Typically
radiator caps are made to open up above a certain pressure, that is the
safety release. The reserve tank cap should not open up. Remove the cap
and look for damage both at the neck of the reserve tank and at the cap
itself. Perhaps there is a gasket that is torn or has moved out of
position. I believe the reserve tank cap part number is 19110-P08-000,
perhaps you could go to the dealer and ask to compare your cap to a new
one. Should be less than $10 to buy a new one should it be needed.

John McConnell wrote:
>
> Well, I did some extensive tests on my 94 vx on the weekend about the
> overheating. This is what happens on overheating -
> -radiator full and reserve at max line
> -start the car
> -idle for 25 mintues
> -at first only top hose is hot and then after a few minutes bottom
> hose from radiator is also hot
> -temp gauge is stable at mid-point
> -fan comes on goes off after about 30 seconds
> -fan comes on again a few minutes later and then turns off after about
> 30 seconds
> -reserve tank begins to fill and keeps filling until radiator fluid
> is spraying out from under the reserve tanks cap
> -temp gauge rises
> -fan comes on again
> -temp gauge goes back down
> -reserve tank fluid receeds
> -fan goes off
> -reserv tank starts to fill again and overflows
> -temp gauge rises
> -fan comes on
> -...and on and on it goes
>
> John McConnell
> Vermont
>
> > > I have a 1994 Civic VX, and it is slowly overheating. On cold days,
> > > city driving, I don't even notice it. But on a hotter day or longer
> > > drive after about 15 minutes of driving the car starts to overheat.
> > > If I turn on the car heater at it's lowest setting it cools the engine
> > > back down.

Re: Radiator Fan Not Coming On - Overheating --UPDATE
 

Randolph wrote:
> Excellent description! Many people have suggested a bad radiator cap,
> but if I read your post right, the coolant is not leaking out from under
> the radiator cap but from the reserve tank cap/fitting. Typically
> radiator caps are made to open up above a certain pressure, that is the
> safety release. The reserve tank cap should not open up. Remove the cap
> and look for damage both at the neck of the reserve tank and at the cap
> itself. Perhaps there is a gasket that is torn or has moved out of
> position. I believe the reserve tank cap part number is 19110-P08-000,
> perhaps you could go to the dealer and ask to compare your cap to a new
> one. Should be less than $10 to buy a new one should it be needed.
>

===========================
Randolph,

I'm sure the reserve tank isn't (ever) pressurized on the Honda we're
discussing. The plastic lid is designed to not be air-tight, so it's
always at atmospheric pressure.

When the cooland boils, (because the rad cap isn't building pressure)
the overflow get forced thru the little hose and once the reservoir
fills, it blows out around the plastic cap.

When the coolant cools, the rad cap is supposed to allow the stuff in
the reservoir to be sucked back into the engine. Sometimes, on larger
engines they put coil springs inside the rad hoses, to prevent them
'sucking flat', which would prevent any coolant sucking back into the
rad after a hot run.


'Curly'

Re: Radiator Fan Not Coming On - Overheating --UPDATE
 

Sorry I didn't mention this, but I did buy a new radiator cap.
Actually, I was so excited it would work I left work early and bought
it after I saw your post Curly - no go. And, for those who haven't
followed the saga, a garage has already replaced the head gasket and
the thermostat.

Thanks for everybody's help.
John

>
> John, I explained on the 12th that it's probably your rad cap... Coolant
> will boil if not pressurized. When it boils, your thermostat and temp
> sensors won't work correctly (just like certain types of industrial
> thermometers have the words EMERSION ONLY printed on them) Steam won't
> trip a sensor / thermostat the same way a bath in boiling hot water
> will.
>
> A rad cap is so cheap to try.......... An internet search will surely
> find you a explanation of why they presurize cooling systems. Here's a
> hint: A pot of water boils at a lower temperature in Denver, than it
> does in Panama.
>
> 'Curly'

Re: Radiator Fan Not Coming On - Overheating --UPDATE
 

"'Curly Q. Links'" wrote:
> Randolph,
>
> I'm sure the reserve tank isn't (ever) pressurized on the Honda we're
> discussing. The plastic lid is designed to not be air-tight, so it's
> always at atmospheric pressure.

I stand corrected. On my grandmother's old Renault the reservoir was
pressurized like the rest of the system, and the reservoir was made from
glass. Working around a large glass bottle under the hood makes you pay
attention to where you throw your tools!