Honda Car Forum

I am draining, refilling and possibly flushing my 164k miles, 1991 Civic
LX's cooling system tomorrow. I've done it myself at least three times over
the years, but not quite the same way each time. A few questions:

1.
My Chilton's manual says I can "back flush" the system by removing the
thermostat and sticking a "high pressure" hose in the housing, until clear
water runs out the radiator hose (presumably the one disconnected at the
housing). Is this really a "backflush," or is it more correctly a forward
flush but with higher pressure than the engine normally sees? If it's a
forward flush, I'm inclined to skip this, unless someone says they feel it's
worthwhile for a car this age.

2.
If I don't do 1. above, then I'm going to do my best to remove the engine
drain plug. I had it off once before, but as many here know, it's badly
located and tough to remove.

3.
If I do neither of the above, I'm going to fill and drain until the water is
clear. I have the capacity specs. on the engine coolant passages, etc. and
am confident about the dilution I will achieve. I've done this in the past.

No need to caution me about the coolant to use. I know people swear by Honda
coolant, but I've been using the orange Havoline Dex cool and am quite
satisfied (knock on wood).

"Elle" <elle_navorski@nospam.earthlink.net> wrote in message
news:seX6e.5012$yq6.374@newsread3.news.pas.earthli nk.net...
>I am draining, refilling and possibly flushing my 164k miles, 1991 Civic
> LX's cooling system tomorrow. I've done it myself at least three times
> over
> the years, but not quite the same way each time. A few questions:
>
> 1.
> My Chilton's manual says I can "back flush" the system by removing the
> thermostat and sticking a "high pressure" hose in the housing, until clear
> water runs out the radiator hose (presumably the one disconnected at the
> housing). Is this really a "backflush," or is it more correctly a forward
> flush but with higher pressure than the engine normally sees? If it's a
> forward flush, I'm inclined to skip this, unless someone says they feel
> it's
> worthwhile for a car this age.
>
> 2.
> If I don't do 1. above, then I'm going to do my best to remove the engine
> drain plug. I had it off once before, but as many here know, it's badly
> located and tough to remove.
>
> 3.
> If I do neither of the above, I'm going to fill and drain until the water
> is
> clear. I have the capacity specs. on the engine coolant passages, etc. and
> am confident about the dilution I will achieve. I've done this in the
> past.
>
> No need to caution me about the coolant to use. I know people swear by
> Honda
> coolant, but I've been using the orange Havoline Dex cool and am quite
> satisfied (knock on wood).
>
>
>

And thew orange stuff saves you how much??

I wouldn't flush anything. I think a drain and fill at recommended
intervals is just fine unless you have neglected the vehicle and deposits
are forming.

Be sure to use distilled water upon refilling 50/50 with your coolant.



"Elle" <elle_navorski@nospam.earthlink.net> wrote in message
news:seX6e.5012$yq6.374@newsread3.news.pas.earthli nk.net...
>I am draining, refilling and possibly flushing my 164k miles, 1991 Civic
> LX's cooling system tomorrow. I've done it myself at least three times
> over
> the years, but not quite the same way each time. A few questions:
>
> 1.
> My Chilton's manual says I can "back flush" the system by removing the
> thermostat and sticking a "high pressure" hose in the housing, until clear
> water runs out the radiator hose (presumably the one disconnected at the
> housing). Is this really a "backflush," or is it more correctly a forward
> flush but with higher pressure than the engine normally sees? If it's a
> forward flush, I'm inclined to skip this, unless someone says they feel
> it's
> worthwhile for a car this age.
>
> 2.
> If I don't do 1. above, then I'm going to do my best to remove the engine
> drain plug. I had it off once before, but as many here know, it's badly
> located and tough to remove.
>
> 3.
> If I do neither of the above, I'm going to fill and drain until the water
> is
> clear. I have the capacity specs. on the engine coolant passages, etc. and
> am confident about the dilution I will achieve. I've done this in the
> past.
>
> No need to caution me about the coolant to use. I know people swear by
> Honda
> coolant, but I've been using the orange Havoline Dex cool and am quite
> satisfied (knock on wood).
>
>

All right, thanks. I do have a jug of distilled water all ready for mixing,
etc.

"halo2 guy" <somewhereovethe@rainbow.com> wrote
> I wouldn't flush anything. I think a drain and fill at recommended
> intervals is just fine unless you have neglected the vehicle and deposits
> are forming.
>
> Be sure to use distilled water upon refilling 50/50 with your coolant.

"Ron" <rtd_2002@yahoo.com> wrote
> "Elle" <elle_navorski@nospam.earthlink.net> wrote
> > No need to caution me about the coolant to use. I know people swear by
> > Honda
> > coolant, but I've been using the orange Havoline Dex cool and am quite
> > satisfied (knock on wood).
>
> And thew orange stuff saves you how much??

Having to drive 70 miles to the dealer and back just to get wiseass comments
like the above from some likely misogynist idiot whose bottom line is to
rape customers for every dollar he can get and who isn't half as smart as I
am.

Newbies: What Ron so unpersuasively is trying to say is that, if you haven't
time to tarry, the Honda coolant is the safest bet.

I and others here with some experience in these matters (and able to change
our own water pumps) are experimenting with the orange Dex cool. I'm quite
satisfied after having had it in my engine for 2.5 years, but I did a very
thorough "flush" at my last coolant change.

Have a pleasant day, Ron.

"Elle" <elle_navorski@nospam.earthlink.net> wrote in
news:seX6e.5012$yq6.374@newsread3.news.pas.earthli nk.net:

> I am draining, refilling and possibly flushing my 164k miles, 1991
> Civic LX's cooling system tomorrow. I've done it myself at least three
> times over the years, but not quite the same way each time. A few
> questions:
>
> 1.
> My Chilton's manual says I can "back flush" the system by removing the
> thermostat and sticking a "high pressure" hose in the housing, until
> clear water runs out the radiator hose (presumably the one
> disconnected at the housing). Is this really a "backflush," or is it
> more correctly a forward flush but with higher pressure than the
> engine normally sees? If it's a forward flush, I'm inclined to skip
> this, unless someone says they feel it's worthwhile for a car this
> age.



All I ever do is remove the block drain, close off the rad petcock and
stick a garden hose into the rad filler neck. Let run till clear. Then I
open the rad petcock and let that drain.

I refill with Honda OEM. If I were to use aftermarket, I'd only ever use
distilled or de-ionized.


>
> 2.
> If I don't do 1. above, then I'm going to do my best to remove the
> engine drain plug. I had it off once before, but as many here know,
> it's badly located and tough to remove.


No kidding.

If you have somebody raise the hood all the way by hand and put a three-
foot cheater bar on your ratchet, it ought to budge. It'll probably let go
with a SNAP and give your hands a good thwack from the vibration.

If you choose not to remove the block drain, disconnect the lower rad hose
at the rad to make a nice big hole, then...


>
> 3.
> If I do neither of the above, I'm going to fill and drain until the
> water is clear. I have the capacity specs. on the engine coolant
> passages, etc. and am confident about the dilution I will achieve.
> I've done this in the past.


....the block holds about a quart. I suppose what you could do is find out
the total system capacity, then subtract a quart of water from your
dilution formula. That way you'd compensate for the water left in the block
from the garden hose.



--
TeGGeR®

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

Ron wrote:
>
> And thew orange stuff saves you how much??
>
>
>
bout $14 and a trip to the dealer. i use it on my 98, and it works
great. last time i changed it the old stuff looked new. its safe for
aluminum, phosphate, and silicate free. ive used it on japanese aluminum
engines for as long as ive known about it. numerous motorcycle, scooter,
and car engines, with no problems.

its generally agreed the green stuff sucks.

Elle wrote:
> I am draining, refilling and possibly flushing my 164k miles, 1991 Civic
> LX's cooling system tomorrow. I've done it myself at least three times over
> the years, but not quite the same way each time. A few questions:
>
> 1.
> My Chilton's manual says I can "back flush" the system by removing the
> thermostat and sticking a "high pressure" hose in the housing, until clear
> water runs out the radiator hose (presumably the one disconnected at the
> housing). Is this really a "backflush," or is it more correctly a forward
> flush but with higher pressure than the engine normally sees? If it's a
> forward flush, I'm inclined to skip this, unless someone says they feel it's
> worthwhile for a car this age.
>
> 2.
> If I don't do 1. above, then I'm going to do my best to remove the engine
> drain plug. I had it off once before, but as many here know, it's badly
> located and tough to remove.
>
> 3.
> If I do neither of the above, I'm going to fill and drain until the water is
> clear. I have the capacity specs. on the engine coolant passages, etc. and
> am confident about the dilution I will achieve. I've done this in the past.
>
> No need to caution me about the coolant to use. I know people swear by Honda
> coolant, but I've been using the orange Havoline Dex cool and am quite
> satisfied (knock on wood).
>
>
i'm on orange dex. seems fine to me.

i'd keep clear of the hose water & stick with swapping the fluid a
couple of times diluting the antifreeze with deionized water. the
mineral content of hose water really is an alloy block killer.

TeGGer® wrote:
> ...the block holds about a quart. I suppose what you could do is find out
> the total system capacity, then subtract a quart of water from your
> dilution formula. That way you'd compensate for the water left in the block
> from the garden hose.

in the whole scheme of things, if you do a 50/50 mix, a quart shouldnt
throw it off much. besides, IIRC, 50/50 is the *most* potent coolant
needs to be. 60water/40coolant should be acceptable.

SoCalMike <mikein562athotmail@hotmail.com> wrote in
news:_badnaLsjKA0McHfRVn-iw@comcast.com:

> TeGGer® wrote:
>> ...the block holds about a quart. I suppose what you could do is find
>> out the total system capacity, then subtract a quart of water from
>> your dilution formula. That way you'd compensate for the water left
>> in the block from the garden hose.
>
> in the whole scheme of things, if you do a 50/50 mix, a quart shouldnt
> throw it off much. besides, IIRC, 50/50 is the *most* potent coolant
> needs to be. 60water/40coolant should be acceptable.
>


Lets do a bit of arithmetic, using the B18A1's capacities as our reference:

Total capacity for the automatic: 6.9 US quarts.
A 50/50 mix would be 3.45/3.45 water/coolant.

If there is a quart of plain water in the block, and you put in a 50/50
mix, you're actually diluting it thusly:
4.45/2.45 water/coolant. That's a 64/36 mixture, which would be fatal up
here in the winter, as it would only protect down to about zero F. But even
then, the concentration of anti-corrosion additives would not be strong
enough, and you would suffer corrosion more quickly even if the temperature
did not get anywhere near -0F.

If we use the manual's capacities, it gets even worse.
6.4 US quarts total.
3.2/3.2 is 50/50
If a quart of plain water is present, and you fill with 50/50, mixture
would be
4.2/2.2, or 66/34, which is wholly unacceptable.

If you absolutely need to leave that quart of plain water in there, you'd
need to make your new mix 30/70 water/coolant. That would dilute to 50/50
when mixed with the quart of water.

--
TeGGeR®

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