Replacing radiator fluid in 2001 Civic

I have a 2001 Honda Civic and need to drain and fill my radiator. I
have read some tutorials but have a few questions:

1) Some have advised draining the radiator, then filling with
distilled water and running for a while, then draining the water and
filling with coolant. However, if I put water in, won't that get
circulated into the engine block? If so, when I refill the radiator
with my pre-mixed 50/50 coolant (comes this way from Honda), then my
coolant in the system will be super diluted as it mixes with the water
I introduced into the engine block. Am I missing something here?

2) If the car has a bleeder valve (not sure if it does, I'll have to
check), how does it work? Do I simply open the valve while filling the
radiator while the car is off? Or do I fill the radiator, close the
radiator cap, then open the valve while the engine is running?

3) If I do the bleeding method where I open the cap and run the
engine, do I simply observe the fluid in the radiator while the engine
is heating up, and pour coolant in as the level drops, WHILE THE
ENGINE IS RUNNING? At what point do I need to worry that the coolant
will get so hot that steam blows my head off? Or does this not happen
since I'm running the engine with the cap off, preventing a pressure
buildup?

 

no, you're correct. i wouldn't call it "super diluted" but it's
definitely weaker than normal. you can top up with undiluted antifreeze
to get the right mix if this worries you.

the latter.

fill as much as you can with the engine off. squeezing the bottom hose
helps a lot. then run and bleed air with the valve - if you have one.
if not, simply overfill the expansion bottle, run, then let cool
overnight. contraction on cooling will suck the fluid you need back
into the radiator, provided you have no air leaks.

other tips on effective drain include unscrewing the plug on the block
to let all that fluid out too, and keeping the cabin heater valve open
so that drains as much as possible also.

 

Do you have an owner's manual? Follow its steps exactly and
you will be fine. Post back if you want a site that has free
online owner's manual.

Like Jim said, you are correct. With a lot of study of the
owner's manual coolant capacities commentary, one can figure
out how to mix the anti-freeze to make up for the diluted
water.

On the other hand, it is not a big deal to skip your
proposed flush, let a little old coolant stay in the engine
block, and add new coolant.

Coolant chemistry has come a long way. As long as you follow
the maintenance schedule for changing coolant, all will be
fine.

Your Civic does not have a bleeder valve. The procedure uses
the simple "burp" approach to purge air from the cooling
system via the top of the radiator (when filling) and via
the top of the radiator and out the reserve tank during
operations.

Caveats:
1.
Use Honda OEM coolant. Or you can try orange Havoline.
Orange Havoline comes both pre-mixed and undiluted. A few of
us here have been using the orange havoline for years and
are quite happy with it.

2.
Remember there is a difference between the radiator drain
plug and the engine drain bolt. Both are going to come off
to properly drain the system. Do get a new washer for the
engine drain bolt. Buy non-hardening sealant (per the
directions in the owner's manual). Permatex makes such a
sealant and it specifically says it is good for the cooling
system. You can get it at Autozone.

3.
One of the most important steps for ensuring a good purge of
air is making sure the radiator fan comes on twice. This may
take 40 minutes or more of the car idling, so have a
magazine and chair.

Correct, no pressure buildup with the cap off. Steam from an
open container is not going to exert any meaningful
pressure. Perhaps you are thinking of how some foolish
people take off the radiator cap /after/ the system is hot
and pressurized. Then a mixture of hot coolant and steam
will blow the cap off and create a dangerous momentary
gusher as the person removes it.

 

yes. make sure it's NOT the silicone sealant. most auto shops have
tons and tons of silicone sealants, and just one non-silicone. easy to
get confused.

 

You MUST drain the block as well as the rad. The block has its own drain
plug.

DO NOT just drain the rad. DO NOT fill the system with water and run it.

With block and rad drains open, run water from garden hose into rad
until drains run clear. Allow water to drain, then close drains.

If you need to capture /all/ flush water, open block drain only, place
large container on ground. Feed water in thru rad neck. When block drain
runs clear, allow it to empty, but leave open. Move catch container.
Open rad drain. More water thru rad neck until rad runs clear. Now close
both drains. Don't feed water thru rad too hard during this step, or
else it will come out thru block drain as well.

No bleeder valve. Fill system thru rad filler neck. Leave cap off. Start
engine. "Burp" upper rad hose to help free bubbles. Add as needed thru
rad neck until the level no longer drops but rises and begins to spill
out of neck. Put cap back. Make sure reservoir is filled to MAX. Allow
car to idle until rad fan comes on twice (WATCH DASHBOARD GAUGE!). Shut
engine off and allow to cool fully (two hrs or more) . Add coolant to
reservoir back to MAX mark. Check rad to make certain level is still up
to top with no air present. Watch reservoir level after next few drives.
Add as necessary until it stops dropping.

See above.