94 Civic: coolant drain/flush and thermostat

I recently had a stuck thermostat at an inopportune time, and had to get
whatever CarQuest supplied the mechanic instead of OEM as I had figured
to put in when I replaced the coolant later this summer. I still have to
replace the coolant and bleed the system, which wasn't done during
thermostat replacement.

I never had a problem with OEM thermostats in American cars. Any
particular reason to replace the new aftermarket with OEM here, when I
change the coolant? I wouldn't mind a thermostat that stuck open when it
failed instead of closed, actually, but since they don't fail all that
much I suppose it isn't really worth it.

Also, what's the best way to flush out the crud? There's some
nasty-looking green shit in there now and I have no idea what was put in
last--i.e., whether it was the right stuff for an aluminum block. On my
85 Pontiac (large engine, lots of room under the hood) I'd just use a
flush kit that allowed me to hook up a garden hose to the coolant
system. Would drain the old coolant, then refill, run the engine a few
minutes to get things circulating, then drain again. I suppose if I
wanted to get water contaminants out after that I could run distilled
water through after that and drain again. Thoughts?

 

I paid about $18 last year for an OEM thermostat for my 1991 Civic. My
recollection is folks here said the OEM was worth it. $18 seems cheap
enough, compared to IIRC something like $10-$12 for non-OEM.

I would dump this and flush the engine block and lines immediately. From
reports here and one of my own experiences, the conventional green stuff
will greatly shorten your Civic's water pump's life. The good news, though,
is that, if your 94 Civic is like my 91 Civic, it should be easy to give a
pretty thorough flush. (It's more of a fill and drain as opposed to flush.)
The reason it should be easy is that, by (1) opening the petcock on the
radiator; (2) removing the engine block coolant drain bolt; and (3) emptying
the reservoir, all coolant should come out of the system. I did careful
measurements of what came out of (1) and (2) and they matched exactly what
the manual stated should be the capacity for the system.

Here are my hints on the job. The hardest part will likely be removing the
engine drain bolt. But even that was very easy on my car this time. Others
have some horror stories on this, though.

-- Tips on Draining, Flushing, and Filling 91 Civic Radiator/Coolant
System ----
Engine block drain bolt:
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.

Flush:
Per Tegger's suggestion and experience, I removed the engine block drain
bolt, closed the radiator petcock, and put a garden hose into the radiator
filler neck. Run until clear. Then open the radiator petcock and drain. 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.

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.

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.

I have been using the Orange Dexcool for the last 2.5 years in my Civic's
engine. It's supposed to be good for aluminum engines. Some others here say
they are using it in their Hondas, without problems. Still others say do not
experiment; it's not worth the risk; just by the pre-mixed Honda coolant
from your dealer.

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.

 

Right--I'm not worried about the cost, just whether it might be
important, now that I've got a brand-new aftermarket in there (not by my
choice), to replace the brand-new aftermarket with OEM. I too have noted
that some folks here prefer OEM thermostats.

Thanks for this info and all the tips, Elle, exactly what I was looking
for. Alas, my socket sets don't include a 19 mm socket (if mine's the
same size)... Phooey. Well, I'll give a combo wrench a shot.

Is this the stuff (one option, anyway) that's meant by "liquid gasket"?
I assume that using it would obviate the need for a washer.

That's what I'll probably do, as I need to head down to the dealer to
pick up some manual tranny oil anyway, and don't want lots of extra
coolant lying around--no space. I had planned to use ordinary 10w-30 as
specified by the service manual till others here suggested that the
chemicals might not be right. Wonder what Honda uses... maybe ordinary
10w-30! ;-)

Yup, I'll probably do the same. Hopefully the local parts place will
take the old coolant. I've got a bunch of old brake fluid to dispose of
as well. Amazingly, my 1.6L engine holds only 1 gallon (plus the
reservoir, I presume). IIRC my old Pontiac held around 4!

 

Just a thought: Maybe the thing won't fail catastrophically any sooner than
the OEM, but it might not regulate temperatures optimally. I think the
biggest concern is different temperature setpoints for opening and closing
the thermostat valve.

So other engine components, particularly those that regulate engine
operation, may not operate optimally.

I'm sure some of the regulars here can add to this.

Have another car standing by so you can run to Autozone and buy a 19 mm
socket (six-faced, not eight-faced, doh, pardon my earlier post-o) as
needed.

Autozone IIRC will probably have the socket for under $6. I am pleased with
the sockets I've bought in the past from Autozone and found Autozone cheaper
than Pep Boys and Sears for sockets. Of course, one may get what one pays
for.

Yes. For example, the Permatex Ultra Grey's label includes the words "sensor
safe RTV silicone gasket maker."

But there are a few different grades of the stuff. The permatex.com site has
a good description of the different grades. Or just go to Autozone and read
what's on the packaging of the three or so grades it will likely have.

I just checked Majestic's online parts site to compare a 94 Civic LX's drain
bolt with my 91 Civic LX's. It appears under "Cylinder Block-Oil Pan." The
91's and the 94's are the same.

They use a 28 mm washer. I've never replaced it and probably should.

My Civic Owner's Manual directs that "non-hardening sealant" be applied to
the drain bolt threads. (Chilton's says nothing about this. But I trust the
Owner's manual more for this.)

True; you will only use about half of the gallon of DexCool.

Well, I have been quite happy with Pennzoil 5W-30 for my car's engine oil,
for all its life. I mean, I notice nothing bad happening from it, at 168k
miles and 14 years. (5W-30 is the weight my owner's manual recommends for my
climate.)

For stuff like this, I've had a lot of luck with either (1) local government
run recycling centers; or (2) hazardous material recycling drives a couple
times a year; and (3) places like Autozone and independent garages taking
the stuff off my hands. Maybe check your yellow pages for "recycling." Or
call your city hall. They've always been eager to help with matters like
this.

Some folks say where they live, the law allows them to dump anti-freeze down
the drain sewer.

This is similar to the capacity of my 1.5 Liter engine. Your owner's manual,
if you have one, has the exact specs. Or there are some sites online that
will have it, like the free repair guides at www.autozone.com .

Honda rocks.

 

That wouldn't kill me. I suspect it's close enough.

Oh, no need for that, there's an autoparts place (Strauss) just a few
blocks away, and anyway I'd try to loosen the plug first--the coolant
doesn't pour out just from cracking it loose, if I got lucky. I do
prefer Craftsman, however, given that I've had el cheapo sockets come
apart on me when I need 'em most...

I use only 6-point sockets myself for best grippage. My combo wrenches
are 12-point, having been purchased before I realized the value of
6-point. It's easier to fit 12-point combo wrenches in tight spaces, anyway.

Mine too; I was referring to tranny oil. All engine oils are created
equal, if they bear that grade stamp I forget the name of just now. For
the tranny, on the other hand, there was some discussion here about more
or less slippage adversely affecting the synchromesh gear system; hence
my caution.

The local autoparts place will take motor oil; have to check on the
other stuff. I thought I might have seen something about coolant in the
sewer here, have to check on that too.

That number (1.00) is from the Helm manual.

Yes indeed. My first one. I did enjoy the Pontiac, though, that monster
was nearly indestructable. I'm *really* sorry that my Honda bumpers are
just about useless and come apart at the slightest serious bump. On the
Pontiac, other bumpers were destroyed while merely a few chunks of rust
would fall out of mine (was rear-ended once on the highway).

 

not true abe. sorry. massively different additive packages. different
base stocks. all the grade stamp does is spec /minima/.

 

Really? I've read differently on several occasions, though I can't
recall where now. Could you point me to a good discussion of differences
between grades (excluding synthetics)?

 

There are several grade stamps. API, MB, ACEA, and ILSAC among them.

Not all oils carry all stamps, so there is considerable difference between
oils as far as compliance with engine makers' standards.

 

Oh okay.

I'll have to look this up. I've been using Pennzoil 10W-30 (or 40 in the
climate where I now live) in my 91 Civic's tranny. The owner's manual
doesn't say Honda oil is necessary.

I thought it was newer Hondas that had stricter specs on the manual
transmission fluid.

 

I'm talking about comparing apples with apples, however, not apples with
oranges. Is it not the case that oils bearing the same API grade stamp
(sans additives) provide at minimum the same engine protection
regardless of whether you buy the brand that's USD $2.50/qt. or the one
that's USD $1.00/qt.? Obviously, if you're buying an oil that bears
additional stamps that indicate adherence to higher standards or that
contains additives that increase protection, we'd be talking about a
different beast altogether.

Anyway, I suppose that is what Jim indicated: different additive
packages lead to different levels of protection. I'm not too worried
about it, however: Honda spec'd a minimum grade that you can't even buy
anymore the last I looked.

 

My manuals (owner's and Helm) specify ordinary 10w-30 as well; it was
only after following a discussion of the synchromesh stuff here that I
got the idea that Honda manual tranny fluid might be better. I suppose
the way to find out would be to try both and see if I'm able to detect
any difference in feel or response.

 

The additives ARE the standard. Base stocks between brands within
categories are similar or identical.

As far as I know, yes, you're correct.

Standards are upgraded over time. I think they're up to API standard SM at
this point. All the standards are backwards-compatible, so you can use an
SM in a 1970 car made for SD oil.

 

there was a whole long thread about this only a few months ago. there
was an additive present in the old engine oils [molybdenum?] that is now
absent for environmental reasons. this means you now need to use honda
mtf for your transmission becuase it contains that additive and it helps
your synchros last better.

 

abe, there's more about motor oils on the net than you could ever
reasonably shake a stick at. provided you google /excluding/ the word
"amsoil" you may even find useful info...

basically, oils are base + additives. bases are differing qualities,
compositions and purities. both bases & additives vary from company to
company - look for oil analysis results to see this for yourself. some
bases &/or additives are better than others. proportions vary greatly.
saying that an oil conforms to an api standard is like saying that
some beverage is qualified as "beer". sure, it may be qualified as
"beer" by the fda, and two beers may even have a very similar
composition, but that doesn't mean pbr is the same as a sam adams.

 

in that case, a "cheap" fleet oil like shell rotella T might fit the
bill. its formulated for diesels, but safe for cars. doesnt have the EC
"starburst" label. 15w40 is the regular grade, and they make a 5w40
synthetic. might be worth doing some research on.

 

Yes, I'm thinking about it... Unfortunately I just changed my manual tranny
fluid a month ago, and it likely won't be due again for two more years.

 

Point taken. Thanks. When I find some time to wade through the results
of that Google search... the problem is that most of the pages I'm
finding are from the oil manufacturers, which usually assert that the
API standards are stringent and that their oil is just great for your
engine, matches engine manufacturer standards, etc. etc.

 

which is why i say reject the word "amsoil"!

true. people like chevron publish some limited tech info, but i admit
you have to dig deep. there was this article posted a while back:

http://physicsweb.org/articles/world/15/2/7

from a thread on this group.

 

I see a thread begun by Tegger on April 26 on this. The only authoritative
citation on the subject appears to be from George M., who wrote that "the
Honda Australia site started to push Honda lubricants fairly recently and
now recommend Honda MTF for manual gearboxes; prior to that they used to
recommend a SAE 75W-80 API GL4 lubricant."

The only thing I found at the Australia site so far is at
http://www.honda.com.au/buying+a+honda/parts/ , which says: "Honda MTF Plus
Manual Transmission Fluid has been specifically formulated for use in all
Honda manual transmissions. MTF Plus is designed to provide smoother
shifting operation at all temperatures over the life of the fluid."

Googling yields comments like that at
http://www.inlinefour.com/honmantranfl.html . I am finding nothing
dispositive on the subject, so far.

Does anyone have a better citation (on the subject of using Honda's own
manual transmission fluid vs. the originally specified 10W-30)?

 

Uhhhhh.... I did, jim. Generally speaking, I try hard to catch what
people write. ;-)

Thanks, I'll check this out when I get back. Gotta run now.