'97 Accord overheating bizarrely

Last week, my 1997 Accord started running very hot. After just a few
minutes, the temperature gage fluctuates wildly between about half-way
and the red zone. It will usually stay in one place for a minute or
two, and then settle on a different setting.

Is this a known problem? Does anyone have a good idea of what might
cause the needle to shoot up to the red zone, stay there for 60
seconds, then float down (in 2 seconds) to about 3/4, stay there for a
while, and then keep floating around with the same pattern?

My thinking is that it's probably a stuck something, but what?

My dilemma is that the dealership that I trust is 45 minutes away by
highway. Should I drive to the dealership? (There's a dealership
much closer, but they already tried to cheat me once - I don't want to
go back there.)

I'll be grateful for any advice.

Thanks.

-Joel Hoffman
()

 

Sounds like it may be a thermostaic fan problem. The fan may not be
coming on at the desired trigger point.

Professor
Check out FlashAlert at www.telstar-electronics.com

 

Last week, my 1997 Accord started running very hot. After just a few

Sorry to follow up on my own article. Two more points:

1. I've already checked the oil and coolant levels. They're fine.

2. The cooling fan comes on, and stays on for a while after a stop
running the car.

Thanks.

-Joel Hoffman

 

Sounds like it may be a thermostaic fan problem. The fan may not be

I don't know for sure that the fan is on while the car is moving, but
I know that when I stop and turn the car off, the fan stays on for a
while.

-Joel

 

The point is... you really don't know if the fan is coming on too late.
Without getting into eleaborate diagnostics... you might just want to
consider replacing the sensor that triggers the fan. Repair shops
should be very familiar with that...

Professor
Check out FlashAlert at www.telstar-electronics.com

 

If it shoots up again, feel the top radiator hose to see if it is hot
or ambient. If ambient, your t-stat may be sticking.

 

when you checked coolant, did you look inside the rad or look at the
expansion bottle? if you have /any/ form of air leak in the coolant
system, it no longer sucks fluid back from the expansion bottle as it
cools so you /have/ to look inside the radiator by removing the cap.

fan & gauge use different sensors.

eratic behavior sounds like some kind of sensor or electrical problem.
check all the leads for security/conductivity and check the sensor. if
you ground the sensor lead, the gauge will go "hot". if it's open,
it'll stay "cold". if you do one of the above & it still fluctuates,
it's your gauge. buy used from a junk yard - they're /massively/
expensive new. testing the sender is simple. can't confirm values for
the accord, but for older civics, 56C = 142 ohms, 100C = 49-32 ohms.
test in hot water on the stove.

most junkyards require you buy a whole instrument cluster, not just the
one gauge. no biggie. the cluster comes apart easily & the temp unit
is easy to swap out. nice clean modular design.

if the above are not the problem, go through normal overheating
diagnostics. this includes thermostat, radiator, head gasket, etc. but
these usually give consistent readings, not erratic gauge behavior, so
check the gauge thing first.

 

If you have to use the car for any emergency, drive with the heater
fully on. I know it is Summer but better then destroying the engine.
If you don't get any heat, it's because there is no cooling fluid in
the heater radiator.
You probably are not over heating. It's only a gage problem.

Yes

 

If you have to use the car for any emergency, drive with the heater

I was driving home when the needle hit the red zone, and I did turn
the heater on full. I got a lot of hot air, but it didn't seem to
help much.

-Joel

 

| I got a lot of hot air, but it didn't seem to help much.

Remove the 2 shiny steel covers ( front & back ) of exhaust*manifold,
or even replace * with a long 4-2-1 aluminised mild steel *. Honda fits
only short branch ( 4 into 1 pipe ), cheap & heavy cast iron * for its
engines <2.2 litre : even a F22A's *'s twin pipes are short ( a bit cheapo
compared to Mercedes's ). Engine will be much cooler. Honda's
temperature gauges have no calibration ( like German cars' ), so users
cannot compare engines' temperatures.

Chk your radiator fans' motors : feed a pc's PSU's +12v to these motors.
If either fan feels stiff or cannot pull much air, then its motor needs oil
: remove fan & its blade, drip in the best lubricant you have ( synthetic
oil / fullerene / semi-paraffin, plain mineral oil is obsolete & inadequate
). @ just 70000 km, mine's Mitsuba motor could barely spin without oil
added ( not even listed in service schedule ).
Both my fans ( Mitsuba & NipponDenso ) have a ¼" x 14" = 3½ sq inch
gap between casing & radiator : I insert paper to close these 2 gaps, to
increase suction of air through radiator. Worse still, my SM4's Mitsuba
fan's plastic casing has 4 useless holes which I had to seal, to increase
suction.

Chk the relay which controls your fan(s) : windows' motors' relay is not
even necessary ( can be bypassed ), can be swapped into the slot for
radiator fan's relay.

Bonnet's rubber seals & felt, front wheels' hub caps too can be removed,
to help cool engine.

 

(Dr. Joel M. Hoffman) wrote in

That may be a sender or wiring problem.

You need to determine if the car is actually overheating or not. A laser
thermometer will tell instantly.

 

Oh yeah, that'll help.

 

or get those 80s era enkei wheels that look like fan blades! then the
faster you drive, the more air gets sucked into the engine bay via the
wheelwells.

 

I learned something further today. When the engine seems hot
(according the guage), the high-pitch fan only comes on when the car
is off. That is, when the car is running, there's no high-pitched
fan. When I turn the key to position I (or off), the fan goes on. Is
this normal?

Many thanks.

-Joel

 

(Dr. Joel M. Hoffman) wrote in

If your oil is over 226F, the fan will come on for up to 15 minutes on
shutdown. That part is normal.

What kind of goop is in the cooling system? Is there silt, gel, and crud?

Thermostats can get gummed up with crud; the return valve in the rad cap
can get fouled.

 

Warning: this guy is a whacko. Google him for his explanations on how
the fact that the clock and door lights draw power from the battery is
a design flaw. Also, a single coil ignition system cannot function
above 3000 rpm.

If your car is overheating, you have to find the problem and fix it.
If you follow Cheah's advice you will soon be disconnecting your clock
to fix the problem.

 

If your oil is over 226F, the fan will come on for up to 15 minutes on

What I meant is, is it normal for the fan NOT to come on while the
engine is running? I thought the fan STAYED on after the car was
turned off. What I noticed (and maybe this normal) is that the fan
only comes on AFTER I turn the car off.

So: is the fan supposed to run while the engine is running, or only
while the engine is off?

Thanks.

-Joel

 

(Dr. Joel M. Hoffman) wrote in

Yes. That's a fuel-saving measure as well as a way of getting the engine to
come up to speed sooner.

Engine-driven fans are inefficient.

Only if the oil temperature is over 225F. (I had originally said 210. That
was incorrect).

The fan comes on when the engine is running only if the coolant temperature
is over about 194F.

 

The fan comes on when the engine is running only if the coolant temperature

So in other words, if the temp. guage is in the red zone, and I'm
stopped with engine running, and the cooling fan is not on, something
is wrong?

-Joel

 

(Dr. Joel M. Hoffman) wrote in

Yes. Either you're not actually overheating, or you've got the usual
thermoswitch or relay problem:
http://www.tegger.com/hondafaq/overheating/index.html#nofan