Civic Radiator Fan and Cooling System Problem.

Hi!
Can anyone tell me the disadvantages of having the fan turned on even
when the car is started?

Basically the radiator fan is supposed to turn on only when the engine
is hot already. I have a problem on the engine keeping its temperature
to the mid level. My radiator fan turns too late that it could not keep
the engine at normal operating temperature (at the mid range of the
temp gauge), hence it tends to overheat.

What is the problem with the fan turning on only a few seconds when the
machine is already hot. The overheat tends to happen when the car is
stalled or moving slowly but when during highway driving, it is not.

Please help.

Confused.

 

any bubbles in the coolant?

 

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You have air in your cooling system and your reservoir isn't full enough
(or there's an air leak) so it's not getting the air out. Fill the
reservoir to MAX and check it every morning. Top it up to MAX each time.
Once all the air is expelled the reservoir will be at the same level
each morning. Use premix coolant, not tap water.

'Curly'

 

I just recently got a solid 'Check Engine" light, and noticed that my
TEMP guage initally approaches mid-point, drops to C(old), and then
rises back to mid-point where it stays.
Odd.

I asked about the radiator fans and was told they ONLY should come on
if the car is over-temp, unless the A/C is engaged and then they come
on all the time. I can drive my car around town, stop and go, and the
fans will NEVER come on. The TEMP guage NEVER goes above 3:00 mid-point.

 

Thanks for all the reply.

There's no air bubble actually.
My concern is that, in order to prevent the overheating, I have to turn
on my fan (bypassed circuit) so that the engine will not overheat. So I
thought that my cooling system is not working properly that it tends to
overheat when it runs slowly or in a parking mode while the engine is
running. So to prevent overheating, i have to turn on the fan all the
time at the start of starting the engine.

So is there any disadvantages to this?

regards,
jeff d.

 

Yes. The primary disadvantage is that you are using the fan to mask a
problem in your cooling system. A secondary disadvantage is that you may
turn the fan on, forget about it, and run your battery down.

From your description I would suspect someone has installed a 194F (90C)
thermostat. It should be a 78C thermostat.

Without more details on the exact behavior of the engine and the
temperature gauge, I cannot rule out a plugged rad or rotted water pump.

Please give precise details on exactly when the car begins to overheat.
State how many minutes the car is running before the temp gauge begins to
climb abnormally. Tell if it overheats on the highway, in heavy traffic,
only AFTER coming off the highway and slowing down, you get the picture.

Also, what happens to the expansion reservoir level? Does it rise when the
car is hot and drop again once cool? Or does it raise then stay there
forevermore?

Basically, you have a problem with you cooling system. You need to sort
that, not cover it up. Covering it up will eventually cause damage to your
engine.

 

Answers below in Jeff:

Jeff: I agree, this is masking the problem and not identifying the real
root cause of it.
I have to make sure that my key is removed to make the fan turn-off.

Jeff: The car doesn't have a thermostat anymore. It was removed
previously when the engine overheated. We thought it was due to the
thermostat NOT functioning that caused the previous overheating. We
tried to install again with a functional thermostat with 78degC rating
but the same thing happens.

Jeff: The car overheats after 20 to 30 minutes of use without the fan.
It took a long time the fan to turn on so this is primary concern. And
when it turns on, it is just for a few seconds not even reaching a
minute, so the fan is bypassed. It OVERHEATS in HEAVY TRAFFIC, only
AFTER COMING OFF THE HIGHWAY and SLOWING DOWN. So your question is
perfectly attuned to my concern. So what seems to be the cars problem?

Jeff: I noticed the water has not decreased in level.

Does it rise when the

Jeff: It stays as is. So I have to add only a little water on the
radiator itself but NOT as often as I have to.

Jeff: I totally agree with you. Can you send more information to this
address: .

 

never ever run without the thermostat. there are two [three if you
include the cabin heater] coolant circuits on the honda. if you remove
the thermostat, you foul up the flow between the two main circuits.

ok, do the simple stuff first. check the rad for blockage internally
with goop, and externally with bugs. if it's ok, get a chemical test
done on the coolant for head gasket leakage. you may not be losing much
coolant, but it'll still bubble if it's leaking.

suspect #1 - head gasket. be careful about continuing to drive in this
condition - you can cause expensive damage.

 

Thanks Jim.

Are you talking about the cylinder head gasket which is the culprit of
this problem?

regards,
jeffrey

 

yes. you need to do testing to confirm diagnosis.

 

Dear Jim, All,

This will take a while for you to read but this somehow explains the
detail of the problem.

I already have replaced the head gasket (undergone top overhaul in a
shop) since it was noted that there is very high pressure along the
cooling system. So the head gasket was replaced. After a week, it was
again tightened in consideration to the expansion of the parts on the
machine..

However I can still observe minor bubbles but not exactly the same as
before. The mechanic mentioned it is just because of the water pump
blowing up the water. I can send a video of the bubbles if necessary.

I used the car but after two days in a 35km stretch, a sunny 1pm
afternoon, the gauge of the temperature started to climb to 3/4 when I
slowed down from a highway but i continued driving, slowed the aircon
to a minimum, and the gauge went back to midpoint.

For short travels, 20km stretch (i.e. from my home to the office) I do
not observed an increase of the gauge (to overheating) if in the
highway but when travelling for more than this, and after cruising from
a highway - in a slow-paced manner, this is when the gauge starts to
climb.

So the problem is still there even after the top overhaul so I have the
car checked back. I still observed that my fan circulates for a very
short time when turned on after the gauge reached the midpoint level.
So the mechanic have tried replacing the thermoswitch and we observed
today that the fan turns on a longer time than before, significantly.

While I have not yet tested the car travelling more than 20kms in a
sunny afternoon to check if the replacement of the thermo switch is
effective, I still have some doubts that the problem has already gone.

My further questions are:
1.0 What other factors may contribute to overheating aside from the
leak head gasket, and radiator?
2.0 Is the thermoswitch part of the problem?

Thank you for even reading this and in advance for all your
contribution.

regards,
jeff d.

 

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Most important things i know about Honda cooling system:

If there's air in the system, the fan won't respond correctly.
If the reservoir isn't full enough, the air can't be displaced when the
engine cools.
You should fill the reservoir to MAX a couple or three times (cold) to
be sure how much it's consuming.
On many Hondas, you can take further steps to bleed air, but you're
wasting your time if you don't keep the reservoir full enough, since it
will just suck more air in when the engine next cools down.
Most Honda manuals say to "fill to the MAX mark" if you've had any work
done on the cooling system.

'Curly'

 

this is not good. you probably have a cracked head or block. if the
system's been purged properly, you shouldn't be getting any more bubbles
with a new gasket. get a chemical test done to see if those bubbles are
exhaust gas. if so, time to buy a new [old] motor rather than waste any
more time with this one. go online and buy a jdm import motor for a few
hundred bucks and put that in. it's what i'd do with my own vehicle in
this situation.

blockage of failed coolant pump. the latter is most unlikely. the
former doesn't cause bubbling.

no, it just controls the fans. if the car's overheating up a hill at
freeway speed for example, the fans are irrelevant as forward air flow
exceeds fan air flow.

bottom line, check and eliminate the simple stuff - thermostat, radiator
clogged with bugs, coolant flow blockages, then do the head gasket
chemical test. you can buy the kit from napa auto parts for about $50
iirc. if it fails, since you've already done the gasket, you have to
assume the worst. cut your losses and replace the motor - labor to
replace the whole unit with imported jdm is way less than labor to prep
and repair something like a head.