Gary Kaucher wrote:
> "jim beam" > wrote in message
> t...
>> Gary Kaucher wrote:
>>> "jim beam" > wrote in message
>>> t...
>>>> Gary Kaucher wrote:
>>>>> 1994 Honda Accord EX, 4 door
>>>>> 4 cylinder, Automatic Transmission
>>>>>
>>>>> I just recently replaced the Radiator fan motor, and now both my AC
> fan
>>>>> and Radiator fan seem to be capable of turning on and off. However,
>>>>> I don't think that they are turning on soon enough. With the recent
> hot
>>>>> weather here in PA, if I idle the car with the AC off, I've noticed
> that
>>>>> the temperature gauge needle will rise to just under the red zone
> (hot),
>>>>> and then both fans (AC and Radiator) will come on, cool things a
>>>>> little, turn off and then cycle on and off as they should, but at a
>>>>> generally
>>>>> higher temperature than I remember in the past. The radiator cap is
>>> rated at
>>>>> 13 psi. Is this the correct rating for the above vehicle? I am
> wondering
>>> if
>>>>> it
>>>>> may have been accidentally replaced last summer.
>>>>>
>>>>> Thanks,
>>>>>
>>>>> Gary
>>>>>
>>>>>
>>>> before worrying about the cap pressure, consider the following:
>>>>
>>>> when was the thermostat last replaced?
>>>>
>>>> in what condition is the radiator? is it clogged/sludged? filled with
>>>> bugs?
>>>>
>>>> what level is the coolant? are you losing any? any bubbles in it?
>>>> [check inside the radiator, not just look at the expansion bottle.]
>>>
>>> The thermostat was replaced last summer. When I looked into the
>>> radiator recently I did not see anything particulary unsightly, but I
>>> suspect that it may have been six years and 50K since the antifreeze
>>> has been changed.
>> hard to change the thermostat without changing the coolant.
>>
>>> I keep the coolant level between Cold and Hot, and
>>> I don't appear to be losing any. I thought that I saw bubbles once in
> the
>>> expansion bottle, so I fiddled with the radiator cap, and they seemed
>>> to go away.
>> hmm, that's suspect.
>>
>>> I imagine that I could be due for some kind of radiator
>>> flush and antifreeze replacement. The antifreeze doesn't look too bad,
>>> but I suspect I've seen cleaner.
>> can't hurt.
>>
>>> I called an auto parts place just to see what pressure rating was listed
> for
>>> my Honda Accord's radiator cap and they said 16 psi. Since the one that
>>> I have is 13 psi I wonder if it is the wrong radiator cap, and if it
> would
>>> make a
>>> significant difference in the ECT sensor's ability to turn the fans on
> at
>>> the correct
>>> temperature.
>> no, it won't affect that at all. a higher pressure cap just elevates
>> the boiling point a little.
>>
>>> Or, is six year old antifreeze more likely to be a factor?
>> not unless it's really dirty. check the thermal switch and the fan
>> relays for operation. if the switch checks out ok, to eliminate the
>> head gasket as a suspect, have a chemical test done on the coolant to
>> see if there's exhaust gas in there. then look at the radiator again.
>> they fill up with bugs and all kinds of other debris that impairs
>> airflow significantly. if replacement is in order, i've had good
>> experience with these folks:
>>
>>
> http://catalog.eautopartscatalog.com...pe=A utomatic
>> i'd go plastic tank.
>
>
> This car is mostly driven on short trips over country roads. It is only
> recently that we are
> having really hot weather here in PA, so I suspect that this problem may
> have existed
> for awhile, possibly since last summer. Yesterday was particularly hot, and
> I drove the
> car for about an hour before I noticed that the fans were cycling at a
> higher than
> expected temperature (around the 3/4 mark). Overnight things cooled off, and
> when
> I checked the antifreeze reservoir, it looked like the radiator may have
> sipped about
> a pint out of it. I removed the radiator cap, started up the engine and
> added antifreeze
> whenever I could. I would say that it may have taken another pint . Now the
> fans are back
> to cycling on and off at about the 1/4 mark as Nick indicated.

excellent. you'll see gas mileage improve now too!

> So I think
> that might be back
> in business. I did notice some things when I purged the radiator:
>
> 1) I would sometimes see bubbles coming from the coolant at the radiator
> fill.

that's normal when refilling. fill it as much as you can, then put the
cap back on and crack open the bleed nipple. let some air out, close,
rev the engine, and crack open the nipple one more time. bubbles you
see after a few minutes and at full working temperature are suspect.
keep the heater full on while doing this too.

> 2) The level of coolant would go up and sometimes overflow
> the radiator when I revved the engine up to about 2000 RPM.

that's normal - don't worry about it. the fluid expands as it gets warm
and will surge as the pump increases pressure.

>
> Do either of these things imply a bad head gasket?

no.

> If so, maybe that is the
> reason that I needed to
> add coolant. If not, maybe the radiator was never properly purged last
> summer when the thermostat
> was changed.

let's say the system was never purged. replenish accordingly, but stay
on top of this situation by checking daily. the early stages of a
gasket failure have very minor symptoms and may persist for a
considerable period before they get bad enough to warrant surgery.

>
> How can you tell when the thermostat opens? Does the big hose on top of the
> radiator become
> pressurized?

there will be pressure, but that's not a result of the thermostat
function - pressure is equal throughout the system. the thermostat's
open when the /bottom/ hose gets hot.

>
> Thanks everyone for all the help.
>
> Gary
>
>