Ok, I bought the radiator today at AutoZone. It's a Spectra
Premium #CU1494, for $94.99. RockAuto sells it for less,
but I just didn't want to take a chance on shipping
damage or delay.
It looks like an exact copy of the original, at least along
the top. It's plastic/aluminum. I will have to install the
ATF fittings at the bottom. These are just flare connections,
which I hope won't leak.
The remaining issue is the coolant. I determined that the
shop which did the 60,000 mile service did not use Honda
coolant. They say they use top quality non-silicate,
non-borate coolant, but they consider all such products to
be essentially the same, and their source varies from time
to time. But they don't typically use Honda coolant because
of the price.
If I could match what they used, I would refill with the
same thing. But it could be Prestone or Xerex or whatever.
All I know is that it's green. I have about 1/2 gallon of
Honda coolant that's green, but it's quite old.
So the best I can do now is refill with new Honda HG coolant
- the blue stuff. If I though I could get to it and remove
the block drain plug, I would do that too, but I think it's
unlikely that plug has ever been removed, and I think any
attempt I would make would likely be unsuccessful, and
possibly damaging either to me or to the engine. Of the
three shops I talked to about doing the radiator for me,
none of them, including the dealer, said they typically
drain the block when doing this job.
So I'm going to end up with a mix - mostly new, but some
old - and just hope they don't react with each other in some
I appreciate everyone's help on this. I'll be into this for
about $140 versus at least $400 for the shop to do it. I
confirmed that I can with some difficulty get to the lower
hose clamp at the thermostat, which was the thing I was most
worried about, so I should be able to do this without major
complications. I hope.
Should be just fine.
Once you have it completely installed (top clamps in place), make 100%
certain that it's loose and wiggly in its grommets. The rad needs to have
lots of wiggle room, otherwise it will leak very quickly.
Use a wrench on both ends: the hose end and the rad end. You do NOT want to
torque the pipes and cause a split that will leak.
Most garages don't... unless you tell them to.
That's ancient! Do not use it. It is well-past its 5-year lifespan, and
will have little or no corrosion protection.
Use whatever new mix you wish that's non-borate/non-silicate, but replace
the entire coolant in 2-years. Mixing types may destroy the anti-corrosive
properties of long-life coolants, dropping their usable life to 2-years.
That is /not/ a good idea. At all.
The block holds about a quart. This means that they are diluting the new
mix about 75/25% new/old, which negates the long-life protection of the new
mix, dumbing it down to the 2-year baseline.
Plus, if they run clear water through the block (which /should/ be done),
then they are diluting the new mix, possibly below the minimum
corrosion/freeze protection points.
The factory did not install a block drain just for fun, you know.
Typically all you lose is the long-life protection, but you'll need to
replace the entire contents in 2-years anyway.
Remove the big black intake-air pipe. Using zip-ties, tie any hoses or
other items out of the way. These steps will /really/ ease access.
Basically, if there is no room, do what you can to /make/ room.
And whatever you do, DO NOT overtighten ANY fasteners! Overtightening is a
sign of inexperience and/or lack of mechanical aptitude. You overtightened
the bleed nipple, which is why it stripped. Learn something from that.
I easily removed the block drain plug from several of my Gen II Civics.
Unlike their Detroit counterparts, the Honda plug is a machined bolt
with gasket rather than a pipe (thread) plug.
I assume that Honda continues to use machined bolts in the later models.
All male screw-threads these days are rolled, not machined. This is true
whether they're tapered pipe-threads or staight-threads.
Block-drain-plug sticking is due to two factors:
1) thread diameter, and
The 19mm-head ones are the ones prone to sticking. The ones at the /rear/
of the block are much smaller than that, and are a LOT easier to get loose.
Not too sure about that. The Integra's 19mm bolt is torqued to 59 ft-lbs.
The Accord's to 43 ft-lbs. That hints at a smaller bolt.
However, I think the '88-'91 Civic's drain bolt is the same size as the
Integra, but is torqued only to 29 ft-lbs. What's going on? Thinner block?
OP might, in fact, have difficulty getting his block-drain loose unless he
has the car off the ground high enough to be able to use a cheater bar.
In any case, my original statement was the result of me mixing up Toyota
and Honda. Honda uses much larger drain bolts than Toyota. Sorry.
you can't rely on the color as an indicator of whether it's long life or
not. and besides, it's irrelevant if the shop used tap water as dilutant.
that may be true, but using tap water has a bigger negative impact than
worrying about used antifreeze. besides, the heater matrix inside the
car has both inlet and outlet at the top, so you will never drain that
thing. so, while you are indeed correct that draining the block is the
"right thing to do", it's also a pita and can be dispensed with if you
can handle the expense of changing the coolant again in a couple of years.
but it's also a pita to access. personally, despite the fact that i'm
super-anal about most car things, i just change the coolant a couple of
times. it's no worse than the dilution effect that works for
i don't either. and it's academic given that you can't drain the cabin
heater so that thing remains full of old coolant anyway. just change it
now, then change it again in a few weeks - even if the antifreeze
formulations are different, that'll take care of it.
use ready-diluted coolant or use distilled/de-ionized if you buy full
strength. don't use tap water or softened water, not even to flush the
Just out of curiosity, I'm trying to understand how the coolant
flow works. I assume the coolant has to flow into the radiator
through the top hose, and back to the engine through the bottom
hose. But the bottom hose is right at the thermostat housing, and
I would have expected the thermostat to be in the engine's outflow
path. The way it is, it seems that as soon as the thermostat heats
up enough to begin to open, cold water would flow through from the
lower hose and shut it off again. Could someone explain how it
if you have a garden hose, and you're interested in delivering water to
your lawn, it doesn't matter where you have the faucet - it can be at
one end of the hose or the other as far as water flow control is
concerned. with the thermostat, same principle applies.
regarding control, a thermostat sitting at the hot end of an
old-fashioned system doesn't allow flow until it's hot enough to open.
there can therefore be both hot spots and cold spots in an engine
because there's no through-flow. you can also have cycling between hot
and cold as this stuff circulates when hot enough to open, then stops
when cold enough to close, etc. this is an issue with fine-tuning
engine mixture, and thus emissions control.
both these are solved by having a bypass system where there is always
flow, and cooling is "added" by gradually diluting the stuff that's
flowing with coolant at the temperature you want. the honda thermostat,
and more specifically, the wax expansion bulb, sits in the bypass flow
at all times, so its operation is controlled by that. and flow through
the radiator is determined by the temperature of that bypass circuit.
water coming into the circuit from the radiator only has the smallest of
effect on the thermostat if at all, because the main flow the thermostat
sees is actually coming sideways from the cylinder head.
jim beam says...
> both these are solved by having a bypass system where
> there is always flow, and cooling is "added" by
> gradually diluting the stuff that's flowing with coolant
> at the temperature you want. the honda thermostat, and
> more specifically, the wax expansion bulb, sits in the
> bypass flow at all times, so its operation is controlled
> by that. and flow through the radiator is determined by
> the temperature of that bypass circuit. water coming
> into the circuit from the radiator only has the smallest
> of effect on the thermostat if at all, because the main
> flow the thermostat sees is actually coming sideways
> from the cylinder head.
Ok, that explains it. Thanks very much, Jim.
Used to be that way. But emissions laws demand more precision, so the
thermotat had to be moved.
There's a bypass mechanism that prevents the thermostat from closing.
Plus, the system is a high-flow, low heat-transfer design, so once at
operating temperature, the thermostat tends to stay open all the time.
Starting from the rad's upper tank, the coolant:
1) cools and drops down the rad until it reaches the bottom tank;
2) travels through the bottom rad hose to the thermostat housing;
3) passses through the thermostat, and moves through a tube at the rear of
the engine block until it reaches the water pump.
4) The water pump pushes it through the block, and up through the holes in
the head gasket into the head.
5) It then flows through the head until it reaches the upper rad hose stub.
6) It then flows into the rad's upper tank until it...<repeat from #1>
There are many more details, but this is the gist of it.
Ok, I got it done. And so far - no leaks. :-)
I'll need to check it later to make sure all the air is out. When
the dealer did the 30k mile service, which included changing the
coolant, they didn't get all the air out. I know that because the
transmission wouldn't go into lockup mode at speed, and one of the
experts in here said it was because the computer won't permit
lockup mode unless the engine is fully warmed up, and the temp
sensor used to decide that won't work correctly if it's in an air
bubble. That turned out to be exactly correct, and after bleeding
the air out, lockup worked fine. So that's my ultimate test for
air in the system.
It took exactly one gallon of coolant, including new stuff in the
overflow bottle. So there really is a good bit that doesn't drain
out unless you drain the block, as Tegger said.
Aside from it just being difficult to get to things, the only real
problem was getting the fans and hoses past the A/C hose. I tried
to do that very carefully, and think it went ok. But I do
understand why someone might prefer to jack up the car, remove the
splash guard, take things off the bottom of the radiator, and then
remove it. It might actually be easier that way overall.
One other small problem was making sure the rubber pads on the
bottom went into the wells in the frame. If one side went in, the
other side didn't want to. So I had to wrestle with that a bit,
but finally got them both in.
Well, I appreciate everyone's help with this. I saved $260 doing
it myself, and kinda enjoyed doing it. So thanks for all the
One other question. If removing the block drain plug isn't
feasible, would there be any way to siphon out the coolant
remaining in the block? If you removed the upper hose and inserted
plastic tubing, wouldn't it run into the water pump? If so, that
would presumably be a no-go. And the lower hose would be blocked
by the thermostat. That would leave only the place where the bleed
valve screws in - if that's on the block side of the thermostat.
Well, I was just curious if anyone had ever looked into that
not unless you used a real thin tube and got real lucky. otherwise
you're just going to poke it into the cylinder head cavity.
this is like people waiting for oil to drain for extended periods when
doing their own oil changes thinking they're getting the last drop out,
but not understanding that there's still a whole load of oil that'll
never drain because it's in oil galleries, pumps, cam pools, etc. all
that happens to that is dilution, not full change.
like oil, all you can reasonably do with your antifreeze, short of
stripping the engine down and rebuilding, is either remove the drain
plug, or just change the coolant again in a week or so. if you're doing
the latter yourself, it's not expensive and the dilution of old fluid
will be down to mere ounces, so it's simply not worth worrying about.
The water pump is at the back of the block, kitty-corner to the upper rad
hose. You won't be able to reach it with tubing stuck into the upper hose
I suppose it might work, at least to a degree. Provided you managed to get
the end of the siphon hose right to the bottom of the water jacket through
the upper rad hose outlet, you'd be able to remove /most/ of the quart
that's in the block.
But you'd still leave enough behind to compromise the new coolant and
reduce the corrosion protection to the baseline 2-years, just as though
you'd never tried that. Corrosion attacks the head-gasket first, and that's
a very bad thing.
What you can do in lieu of pulling the block drain is to drain and fill the
coolant as you just did, every two years. No need to remove the rad, just
open the rad drain and let whatever wants to drain out, drain out (turn
heater to full-hot first). That way most of the coolant will be fresh most
of the time, and corrosion protection should be mostly OK.
you'd need a /lot/ of air in the system to cause that. and this is a
frequently mis-diagnosed problem. yes, the coolant level can tell the
computer not to lock up the torque converter, but it can also be caused
by issues with the transmission selector switch - in my experience, that
can be more common on hondas. if the problem recurs, re-post and i'll
link you to a write-up of how to fix it.
like i said, you need to bend the hose a little - it's soft aluminum and
can accommodate that kind of thing if not done regularly.
but you can't get the radiator out that way - that suggestion was, let's
just say, "mistaken".
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