Cooling System Maintenance Questions

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.

 

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

 

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.

 

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.

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...

....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.

 

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.

 

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.

 

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.

 

Sounds eminently logical, and so I did this. I did discover that the path of
hose water flow is through the upper radiator hose (from top of radiator to
top of engine block), somewhat through the block, and out the engine block's
coolant drain bolt hole. I speculate that the thermostat housing approach is
more effective. It's also more trouble, or it would have been for me this
time around.

snip for brevity

I took careful measurements of all the old coolant drained today. Things
added up nicely and consistent with my 91 Civic LX (1.5 liter, D15B2 engine,
manual transmission) manual as follows:

7 and 15/16 pints came out the petcock on the radiator = 0.99 gallon
2 pints came out of the engine block = 1 quart (Tegger!) = 0.25 gallon
Reservoir design spec. 0.88 pint = 0.11 gallon
Total coolant = 1.35 gallon, exactly what's stated to be the total in my
manual!


The job itself went extremely well today. The car's front hung out of the
garage a little, so I had plenty of sunlight to see as well as possible the
engine block drain bolt. The only interference I removed was the air intake
duct (two bolts) and the O2 sensor wire from its bracket (just laid it aside
without disconnecting anything electrically). I used a 19 mm 8-faced long
socket and an 18-inch breaker bar on the drain bolt. It wasn't going to come
free easily with anything with a shorter handle; I tried my ratchet. I
applied force but not so much that I thought I needed to lay pillows on the
car, to break my fall, in an extreme case. Thought I felt it break loose.
Son of a gun, it had loosened. By my records, the last time I had it off was
12 years ago.

For other folks, I suggest maybe spraying down the drain bolt head with PB
Blaster and wipe before trying to loosen it. Even though it came off easily
this time, it was quite gunked up and greasy, and I think this, combined
with not having a 19 mm socket, was why the first time I did this it was was
hellacious. I really beat up one face of that bolt some 12 years ago.

About 1/8 teaspoon of sandy residue (both brown and white) came out of the
engine block with the old coolant, so I'm glad I took off the drain bolt and
"properly" drained the block.

The old coolant that came out of the petcock looked pretty clean. As
SoCalMike has mentioned in the past, I think it's worth considering going
longer than the 2 years, 30k miles normally prescribed for a 1991 Civic,
using the Dex cool (which advertises 5 years/150k miles).

I used (Permatex Ultra Grey) non-hardening sealant on the drain bolt
threads, per my manual's instructions. Permatex Ultra-Grey is advertised as
suitable for the water pump, so it made sense to me that it would be fine
for the drain bolt.

During the fill part of the procedure, I had to wait 36 minutes for the fan
to come on the first time; five minutes more to come on the second time. It
was 64 degrees F ambient temperature here today.

In conclusion, I now have about as perfect a mix as possible of 50% Dex and
50% distilled water this time. Environmentally speaking, I didn't have all
that flushed, coolant-contaminated water to dispose of; just the roughly
1.35 gallons of old coolant.

As always thanks folks for sharing your thoughts.

 

What? Prestone?

As for Honda coolants - I don't believe any Honda-branded coolant
has ever been phosphate free. When reading a dealer flyer, they
advertised that Honda coolant was silicate free and borate free.
Silicates gel out and can plug up passages. Borates are abrasive.

Honda coolant is supposedly high in phosphate corrosion inhibitors,
which work very well. The alleged problem with phosphates is that
they will precipitate out when mixed with hard water. So if you
mix phosphates with heavy mineral content water, you've got crud
floating around, and some of you corrosion inhibitor just got
instantly depleted. Another thing is that the Honda Type 2 coolant
only comes premixed with deionized water to make it idiot-proof.

The main reason why the Dex-Cool coolants are phosphate-free are
to appeal to European car owners and just in case some idiot uses
hard water instead of soft tap or distilled water.

 

Type 2 (premixed) seems to be the only coolant type readily available.
I understand the old green stuff can be found, but not easily.

I used a Craftsman 8" ratchet with an old mountain bike handlebar as
and extension. Of course the key was to pad the right fender so I
didn't dent it when the bolt broke loose.

 

OK - I found a pretty good summary of coolant ingredients. it was
for a VW Vanagon website, but good info.

<http://www.vanagon.com/info/articles/coolants.html>

"Phosphate is the most ubiquitous and most controversial inhibitor.
It is a well known inhibitor of ferrous metal corrosion, hence
trisodium phosphate is used to clean of sheet metal. American car
manufacturers have specified phosphate in coolants because it is
highly effective at preventing cavitation. Europeans specify
non-phosphate coolants because phosphates have a propensity to
precipitate in hard water. Also, phosphates have a negative effect
on the corrosion rate of aluminum. This beneficial effects peak at
concentrations of about 3 g/l and decreases at both lower and higher
concentrations. Typical concentrations in coolants range from 0 to
8 g/l."

 

WHY go the dealer when you don't have to?

I have a great mechanic who uses OEM parts and I save a bundle!

My guy oil change $25 - Honda $54
My guy timing belt/water pump $400 - Honda $675

You want to send the dealer's kids to Spring Break in Paris? Go Ahead.

--

"This notion that the United States is getting ready
to attack Iran is simply ridiculous. Having said that,
all options are on the table,"
George Bush, Feb 22 2005

http://www.quantumphilosophy.net/files/clips/TimRyan_Medium.mov

http://www.bushflash.com/thanks.html
http://www.worldmessenger.20m.com/weapons.html#wms
WHY IRAQ?: http://www.angelfire.com/creep/gwbush/remindus.html
http://www.toostupidtobepresident.com/shockwave/chickenhawks.htm

"Bubba got a BJ, BU$H screwed us all!" - Slim

 

In my 91 civic i've gone 3.5 years and 109k on Dexcool and I didn't change
change the water pump and all I did was fush with water until clear at that
time. Still no problems.

 

This is easy for me to say because I have the tools:

Do it yourself timing belt change:

Belt = $35
Water pump = $38

Total = $78 and 2.75 hours of your time.

 

Easy way around the precipitate problem, use distilled water. That's all I
use in my radiators and batteries. My cooling system on my '91 Civic has
309k on it...

 

TeGGer, I like your math. You sound like me when it come to numbers.

But people keep it simple. After flushing/draining we all know there is
SOME water left inside. So simply determine the amount of anti-freeze you
need for your 50/50 mix, pour that amount of straight anti-freeze into a
pyrex graduated measuring cup (1 quart size is nice)and keep transferring
the cups contents to the radiator until you reach your target amount. Then
top off the system with distilled water until full. I gurantee you will be
very close to your target 50/50 or whatever ratio you decided on.