Proper Radiator Cap Pressure Rating for 1994 Honda Accord EX?

"TeGGeR®" > wrote in message
...
> "Gary Kaucher" > wrote in
> :
>
> >
>
> >
> > I did find out from my mechanic that he installed the 90C thermostat,
> > and not the
> > OEM 78C one.
>
>
>
> Oh, that changes everything!
>
> I did mention to check that, a few posts ago.
>
>
>
>
> > I wonder if that might have some effect on this
> > condition. When I shut the engine off and it cools down, the
> > thermostat closes at 90C instead of
> > 78C.
>
>
>
> You have it sort of backwards. It *begins to open* at 90C, which is WELL
> above the proper temperature for that motor.
>
> A 90C thermostat will cause the car to overheat. Your mechanic has
> committed a serious mistake here.
>
>
>
> > If I changed the thermostat to the OEM 78C one, would the engine
> > somehow
> > have an improved opportunity to draw coolant from the reservoir? Would
> > the thermostat being open for that additional 12C differential create
> > more suction from the
> > reservoir as opposed to through the head gasket? Does that make any
> > sense or is it just
> > "wishful thinking"?
>
>
>
> Replacing the thermostat is certainly worth a try.
>
> If the fluid boils so as to cause the top of the rad to be filled with gas
> and not fluid, the engine will be unable to pull fluid from the reservoir
> back into the rad.
>
> Put the proper **DEALER** thermostat in and see what happens.
>
> --
> TeGGeR®


I picked up a thermostat at a Honda dealer and installed it last night.
So far, it does not seem to have made any difference in my symptoms.
Maybe the damage is already done. I will continue to monitor things
just to make sure that all the air has been purged from the system.

I am also wondering what part the sensors for the radiator fans
play in keeping the coolant from boiling. I have noticed that
after starting the car, it seems to take about 20 minutes before the fans
come on, and when they do, both fans come on at once, never just one.
When they turn off, they both turn off simultaneously. This happens even
when the AC is completely off in the car. Is it possible that a sensor is
not
"telling" one of the fans to come on at a lower temperature? Also, are these
fans set up for one speed or two speeds?

Thanks for the help.

Gary Kaucher wrote:
> "TeGGeR®" > wrote in message
> ...
>> "Gary Kaucher" > wrote in
>> :
>>
>>> I did find out from my mechanic that he installed the 90C thermostat,
>>> and not the
>>> OEM 78C one.
>>
>>
>> Oh, that changes everything!
>>
>> I did mention to check that, a few posts ago.
>>
>>
>>
>>
>>> I wonder if that might have some effect on this
>>> condition. When I shut the engine off and it cools down, the
>>> thermostat closes at 90C instead of
>>> 78C.
>>
>>
>> You have it sort of backwards. It *begins to open* at 90C, which is WELL
>> above the proper temperature for that motor.
>>
>> A 90C thermostat will cause the car to overheat. Your mechanic has
>> committed a serious mistake here.
>>
>>
>>
>>> If I changed the thermostat to the OEM 78C one, would the engine
>>> somehow
>>> have an improved opportunity to draw coolant from the reservoir? Would
>>> the thermostat being open for that additional 12C differential create
>>> more suction from the
>>> reservoir as opposed to through the head gasket? Does that make any
>>> sense or is it just
>>> "wishful thinking"?
>>
>>
>> Replacing the thermostat is certainly worth a try.
>>
>> If the fluid boils so as to cause the top of the rad to be filled with gas
>> and not fluid, the engine will be unable to pull fluid from the reservoir
>> back into the rad.
>>
>> Put the proper **DEALER** thermostat in and see what happens.
>>
>> --
>> TeGGeR®
>
>
> I picked up a thermostat at a Honda dealer and installed it last night.
> So far, it does not seem to have made any difference in my symptoms.

monitor that coolant level.

> Maybe the damage is already done. I will continue to monitor things
> just to make sure that all the air has been purged from the system.

the wrong temp thermostat won't "damage" the engine, but it'll change
normal operations. it'll revert beck to normal with the correct one.

>
> I am also wondering what part the sensors for the radiator fans
> play in keeping the coolant from boiling. I have noticed that
> after starting the car, it seems to take about 20 minutes before the fans
> come on, and when they do, both fans come on at once, never just one.
> When they turn off, they both turn off simultaneously. This happens even
> when the AC is completely off in the car. Is it possible that a sensor is
> not
> "telling" one of the fans to come on at a lower temperature? Also, are these
> fans set up for one speed or two speeds?

there's only one fan temp sensor, so unless one is triggered by a
separate circuit like the a/c, they'll both come on together.

>
> Thanks for the help.
>
>

jim beam > wrote in
t:

> Gary Kaucher wrote:

>>
>> I picked up a thermostat at a Honda dealer and installed it last
>> night. So far, it does not seem to have made any difference in my
>> symptoms.
>
> monitor that coolant level.
>
>> Maybe the damage is already done. I will continue to monitor things
>> just to make sure that all the air has been purged from the system.
>
> the wrong temp thermostat won't "damage" the engine, but it'll change
> normal operations. it'll revert beck to normal with the correct one.



It CAN damage the engine, and that's Gary's threat right now. If the
cooling fluid boils for long enough during the engine's operation,
localized overheating may warp the head and cause gasket failure. He's been
driving around with the wrong 'stat for a quite a while now.

Honda blocks are quite strong and do not often distort unless severely
abused. It's normally the head that gets damaged.

Gary's next step (to be performed **ASAP** and by a more competent mechanic
than the one that put the 90C unit in) is to get a pressure check done, or
a combustion gas analysis performed. Either will confirm or deny the
presence of head gasket failure. Usually failure is dramatic enough to
create bubbles under air pressure.

--
TeGGeR®

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

"jim beam" > wrote in message
t...
> Gary Kaucher wrote:
> > "TeGGeR®" > wrote in message
> > ...
> >> "Gary Kaucher" > wrote in
> >> :
> >>
> >>> I did find out from my mechanic that he installed the 90C thermostat,
> >>> and not the
> >>> OEM 78C one.
> >>
> >>
> >> Oh, that changes everything!
> >>
> >> I did mention to check that, a few posts ago.
> >>
> >>
> >>
> >>
> >>> I wonder if that might have some effect on this
> >>> condition. When I shut the engine off and it cools down, the
> >>> thermostat closes at 90C instead of
> >>> 78C.
> >>
> >>
> >> You have it sort of backwards. It *begins to open* at 90C, which is
WELL
> >> above the proper temperature for that motor.
> >>
> >> A 90C thermostat will cause the car to overheat. Your mechanic has
> >> committed a serious mistake here.
> >>
> >>
> >>
> >>> If I changed the thermostat to the OEM 78C one, would the engine
> >>> somehow
> >>> have an improved opportunity to draw coolant from the reservoir? Would
> >>> the thermostat being open for that additional 12C differential create
> >>> more suction from the
> >>> reservoir as opposed to through the head gasket? Does that make any
> >>> sense or is it just
> >>> "wishful thinking"?
> >>
> >>
> >> Replacing the thermostat is certainly worth a try.
> >>
> >> If the fluid boils so as to cause the top of the rad to be filled with
gas
> >> and not fluid, the engine will be unable to pull fluid from the
reservoir
> >> back into the rad.
> >>
> >> Put the proper **DEALER** thermostat in and see what happens.
> >>
> >> --
> >> TeGGeR®
> >
> >
> > I picked up a thermostat at a Honda dealer and installed it last night.
> > So far, it does not seem to have made any difference in my symptoms.
>
> monitor that coolant level.
>
> > Maybe the damage is already done. I will continue to monitor things
> > just to make sure that all the air has been purged from the system.
>
> the wrong temp thermostat won't "damage" the engine, but it'll change
> normal operations. it'll revert beck to normal with the correct one.
>
> >
> > I am also wondering what part the sensors for the radiator fans
> > play in keeping the coolant from boiling. I have noticed that
> > after starting the car, it seems to take about 20 minutes before the
fans
> > come on, and when they do, both fans come on at once, never just one.
> > When they turn off, they both turn off simultaneously. This happens even
> > when the AC is completely off in the car. Is it possible that a sensor
is
> > not
> > "telling" one of the fans to come on at a lower temperature? Also, are
these
> > fans set up for one speed or two speeds?
>
> there's only one fan temp sensor, so unless one is triggered by a
> separate circuit like the a/c, they'll both come on together.


Does anyone know what temperatures the sensor turns the fans
on and off?

TeGGeR® wrote:
> jim beam > wrote in
> t:
>
>> Gary Kaucher wrote:
>
>>> I picked up a thermostat at a Honda dealer and installed it last
>>> night. So far, it does not seem to have made any difference in my
>>> symptoms.
>> monitor that coolant level.
>>
>>> Maybe the damage is already done. I will continue to monitor things
>>> just to make sure that all the air has been purged from the system.
>> the wrong temp thermostat won't "damage" the engine, but it'll change
>> normal operations. it'll revert beck to normal with the correct one.
>
>
>
> It CAN damage the engine, and that's Gary's threat right now. If the
> cooling fluid boils for long enough during the engine's operation,

but a 'stat that opens at 90 simply means the motor runs too hot - it's
still well below boiling, especially on a pressurized system.

> localized overheating may warp the head and cause gasket failure

correct, but localized overheating is where it's boiled dry.

>. He's been
> driving around with the wrong 'stat for a quite a while now.
>
> Honda blocks are quite strong and do not often distort unless severely
> abused. It's normally the head that gets damaged.

yes, because that bit boils dry before the block does.

>
> Gary's next step (to be performed **ASAP** and by a more competent mechanic
> than the one that put the 90C unit in) is to get a pressure check done, or
> a combustion gas analysis performed. Either will confirm or deny the
> presence of head gasket failure. Usually failure is dramatic enough to
> create bubbles under air pressure.
>

mine would only bubble under extended full throttle. the only clue was
that there was gas in the system so it wouldn't suck back properly.
purged, it would suck back fine under normal driving, and would behave
itself for some time until the car got given its next good workout.
only with extended repetition of this process over many months [i.e.
nearly 2 years] did this finally start getting bad enough to be
"noticeable", and even then, it was only because i was gunning grapevine
every couple of weeks. if i were not a picky kind of person and/or a
more gentle driver, doubtless it would have survived many more months
before degrading to the point where it got to be a problem.

"TeGGeR®" > wrote in message
...
> "Gary Kaucher" > wrote in
> :
>
>
> >
> >
> > Does anyone know what temperatures the sensor turns the fans
> > on and off?
> >
> >
> >
>
>
> Above 88.5C to 91.5C (it's a range, not an absolute figure).
>
>
>
> --
> TeGGeR®
>
> The Unofficial Honda/Acura FAQ
> www.tegger.com/hondafaq/


OK. I did some experimenting. I was suspicious that the new 16 lb radiator
cap that I put on the radiator in replacement of the old 13 lb cap was not
working
correctly either. So I spoke to the previous owner, and found out that the
current radiator
is an aftermarket radiator. So I installed another similar 16 lb cap, and
things seem to be
working slightly differently:

Starting with a "cold" engine in the morning on a warm summer day, it takes
about 17 minutes
of parked idling (w/ occasional 2000 RPM) before the AC fan and radiator
fans come on.
When they do come on, they only come on for about 13 seconds, and they seem
to only be coming
on every 4 minutes. Even though the temperature gauge is only 1/4 of the
way above the C, the
engine "seems" hot. There is bubbling in the reservoir. However, the level
of the coolant in the reservoir
does not rise as long as the car is sitting still. If I take the car out on
the open road and allow the natural
flow of air over the radiator, I find that the reservoir level rises about
1-1/2 inches. And when I stop
the engine and things cool down, it drops back down 1-1/2 inches. This new
cap seems
to be making that possible. Also, I had taken your advice awhile back and
removed about 1" of possibly
ill-fitting hose between the radiator cap and expansion tank. The success of
this possible improvement
may have been masked by the previous faulty cap.

I am thinking (hoping) that the bubbling is not combustion gas, but rather
coolant that is boiling because the fans are
not coming on when they should. Both fans work, and they have new brushes.
No intermittent problems involving
the fans themselves. I suspect that the fans are coming on at a temperature
that is in excess of the boiling point
of 50/50 coolant at 16 psi, which is probably well over the 88.5C to 91.5C
range that you cited. When I drive
down the highway, I'm thinking that the natural air flow does what the fans
fail to do, and makes it possible for liquid
to transfer to the reservior instead of bubbles.

I see references to ECT & TW sensors, and Auxiliary Fan Switch. Are they all
the same thing? What is the sensor that
turns on the fans on 94 Honda Accord EX (4 cyl, 4door)? I suspect I could
remove the sensor and check for
contnuity by placing the sensing part in boiling water, just to see if it
responds.

This car has only been used for short trips over country roads, with very
little stop and go. It has almost 300K, and I suspect that
the sensor (whatever it's called) is original.

Thanks,

Gary

Gary Kaucher wrote:
> "TeGGeR®" > wrote in message
> ...
>> "Gary Kaucher" > wrote in
>> :
>>
>>
>>>
>>> Does anyone know what temperatures the sensor turns the fans
>>> on and off?
>>>
>>>
>>>
>>
>> Above 88.5C to 91.5C (it's a range, not an absolute figure).
>>
>>
>>
>> --
>> TeGGeR®
>>
>> The Unofficial Honda/Acura FAQ
>> www.tegger.com/hondafaq/
>
>
> OK. I did some experimenting. I was suspicious that the new 16 lb radiator
> cap that I put on the radiator in replacement of the old 13 lb cap was not
> working
> correctly either. So I spoke to the previous owner, and found out that the
> current radiator
> is an aftermarket radiator. So I installed another similar 16 lb cap, and
> things seem to be
> working slightly differently:
>
> Starting with a "cold" engine in the morning on a warm summer day, it takes
> about 17 minutes
> of parked idling (w/ occasional 2000 RPM) before the AC fan and radiator
> fans come on.
> When they do come on, they only come on for about 13 seconds, and they seem
> to only be coming
> on every 4 minutes. Even though the temperature gauge is only 1/4 of the
> way above the C, the
> engine "seems" hot. There is bubbling in the reservoir.
<snip>

ok, if you're getting bubbling /after/ you've purged the system, it's
head gasket. sorry to be the bearer of bad news. the higher pressure
cap may delay onset a little, but it won't fix it. the good news is
that the parts are relatively cheap. if you want to do the job
yourself, it takes about a day if you want to do the job cleanly and
well. if not, the local shop will charge about one months worth of new
car payment. if the gasket's done cleanly [*NO* sandpaper or other
abrasive used to clean anything up], you should be able to get another
50k to 100k out of this car.

"jim beam" > wrote
> ok, if you're getting bubbling /after/ you've purged the
> system, it's head gasket. sorry to be the bearer of bad
> news. the higher pressure cap may delay onset a little,
> but it won't fix it. the good news is that the parts are
> relatively cheap. if you want to do the job yourself, it
> takes about a day if you want to do the job cleanly and
> well.

Seems to me this assumes the head will not need machining.
That's a mighty big gamble to take.

> if not, the local shop will charge about one months worth
> of new car payment.

But more than likely will check the head surface and send it
out for machining as necessary.

Elle wrote:
> "jim beam" > wrote
>> ok, if you're getting bubbling /after/ you've purged the
>> system, it's head gasket. sorry to be the bearer of bad
>> news. the higher pressure cap may delay onset a little,
>> but it won't fix it. the good news is that the parts are
>> relatively cheap. if you want to do the job yourself, it
>> takes about a day if you want to do the job cleanly and
>> well.
>
> Seems to me this assumes the head will not need machining.
> That's a mighty big gamble to take.

no it's not. honda heads don't warp unless they've been badly
overheated, like what happens if you lose coolant on the freeway and
don't bother to check the gauges. a little bubbling won't cause warping.

>
>> if not, the local shop will charge about one months worth
>> of new car payment.
>
> But more than likely will check the head surface and send it
> out for machining as necessary.

don't assume the head is warped. yes, a lot of shops will send it in
even if it's perfectly flat because they make more money that way, but
it doesn't mean the work is necessary. you should know that by now elle
- that's why you do your own work - you want it done right and you want
it done without unwarranted expense.

"jim beam" > wrote
>> Seems to me this assumes the head will not need
>> machining. That's a mighty big gamble to take.
>
> no it's not. honda heads don't warp unless they've been
> badly overheated, like what happens if you lose coolant on
> the freeway and don't bother to check the gauges. a
> little bubbling won't cause warping.

We disagree. To back this up, a friend of mine kept her 99
Honda Civic out of the red zone for a month or so while
there was evidence of a head gasket leak (overheating; loss
of coolant).

The shop said the head was warped and had to be machined.
(But keep reading.)

It's a gamble.

Toss in that it might not be a head gasket breach but a
breach elsewhere in the block, and it's an even bigger
gamble.

>>> if not, the local shop will charge about one months
>>> worth of new car payment.
>>
>> But more than likely will check the head surface and send
>> it out for machining as necessary.
>
> don't assume the head is warped. yes, a lot of shops will
> send it in even if it's perfectly flat because they make
> more money that way,

Sure, that's possible.

>but it doesn't mean the work is necessary. you should know
>that by now elle - that's why you do your own work - you
>want it done right and you want it done without unwarranted
>expense.

You should know by now that do-it-yourselfers have limited
tools which may preclude the checks--and certainly the
machining--of which we are speaking.

IMO too often you tell amateurs to take simple problems to
a shop, or spend money for this or that when it's not
well-warranted. So telling someone that they can do a head
gasket (and it might not even be the head gasket) is kinda
reckless.

Either way, the OP has some opinions on this at this point.
<shrug>