92 Civic 1.5 bubbles in radiator

I have a 92 Civic 1.5. If I open the hood (bonnet), leave the radiator
cap off and run the motor slowly, small bubbles appear in the radiator
cap aperture (Not in the expansion bottle). So, thinking this was a
sign of a blown CH gasket (and there was also some pressure buildup in
the hoses), I had the head skimmed. At the same time, I had all hoses,
radiator, rad cap and thermostat replaced. But after skimming, the
bubbles are still there. My mechanic seems to think this means I
should now have the engine block skimmed, I think because of the
danger of pressure building up in the hoses from said bubbles. But
another mechanic I spoke to for a second opinion said all Civics blow
bubbles (something to do with being a “high-pressure system”). Does
anybody know if all Civics blow bubbles under normal conditions?
There is absolutely no sign of oil in the water, or water in the oil,
or white gunge under the radiator cap (noted from another post to this
forum). Water usage is very small but I am not sure if it is
significant – about 1 cm on the expansion (overflow) bottle after a
400 kms hard (fairly high revs) drive. I am not sure how much water
such a system should use – the overflow bottle was correctly filled to
MAX but not beyond in order to leave enough space for expansion, so
presumably in theory the cooling system should not use any water at
all, as it is not open to the atmosphere, but does practice match the
theory? The temp gauge does not budge from normal. Any comments much
appreciated.

 

Has the thermostat on the dashboard ever gone well beyond
its usual position indicating overheating?

Some coolant leakage/evaporation is normal. Figure adding
maybe two cups a year.

If the level in the reservoir goes down suddenly, then one
should be worried.

You should check the reservoir level right after driving the
car for 30 minutes or longer. Top it off to max after this
period.

You may just have air in the system. A proper purge is
important. Notably, where the instructions for purging say
to idle the car until the fan comes on twice, it typically
takes over 40 minutes for the engine to get this hot.

Kinda extreme to have the head skimmed. You had a new head
gasket put on, too, right? And the car has never
overheated?? Just these bubbles were seen?

I have a 92 Civic 1.5. If I open the hood (bonnet), leave
the radiator
cap off and run the motor slowly, small bubbles appear in
the radiator
cap aperture (Not in the expansion bottle). So, thinking
this was a
sign of a blown CH gasket (and there was also some pressure
buildup in
the hoses), I had the head skimmed. At the same time, I had
all hoses,
radiator, rad cap and thermostat replaced. But after
skimming, the
bubbles are still there. My mechanic seems to think this
means I
should now have the engine block skimmed, I think because of
the
danger of pressure building up in the hoses from said
bubbles. But
another mechanic I spoke to for a second opinion said all
Civics blow
bubbles (something to do with being a “high-pressure
system”). Does
anybody know if all Civics blow bubbles under normal
conditions?
There is absolutely no sign of oil in the water, or water in
the oil,
or white gunge under the radiator cap (noted from another
post to this
forum). Water usage is very small but I am not sure if it is
significant – about 1 cm on the expansion (overflow) bottle
after a
400 kms hard (fairly high revs) drive. I am not sure how
much water
such a system should use – the overflow bottle was correctly
filled to
MAX but not beyond in order to leave enough space for
expansion, so
presumably in theory the cooling system should not use any
water at
all, as it is not open to the atmosphere, but does practice
match the
theory? The temp gauge does not budge from normal. Any
comments much
appreciated.

 

Thanks for the reply. Correct, a new head gasket was put on. The
thermostat stuck, and the engine did overheat, but never seriously (if
that is possible). The temp gauge was at the top of the thermometer
symbol when noticed instead of at the bottom of the symbol, i.o.w. the
gauge never went to the top of the range (not sure if this is "well
beyond" or significant). But after the thermostat stuck, it was
replaced but the head was not skimmed, the bubbles were only noticed
about 6 months later and the real reason the head was skimmed was
because the top of the (good condition) radiator sprang a leak which
prompted the mechanic to look for a cause. Mechanic said that the
pressure in the main hose was the cause of the leak as pressure was
too high and would land up bursting the hose while on the open road
one day.

As an aside, how does one predict a thermostat sticking, should one
pro-actively just change thermostats like cam timing belts and just
change them after X kms regardless of whether they are showing any
signs of packing up?

 

So from looking at my own 91 Civic's temp gage, I see yours
went about 3/4 of the way between "C" and "H." Your Civic
definitely overheated. The only thing I can say with
confidence is that the chances of a blown headgasket go up
with each overheating episode.

My thermostat seemed to be working fine when I pro-actively
changed it at 151k miles. First because it's very
inexpensive to put in an OEM one. Second because, from
general reading, I expect most cars go through at least one
thermostat in their lives. Third, from general reading, many
folks do pre-emptively change their thermostats.

There are tests one can do on a thermostat but given how
cheap it is, I'd just slap a new one in. Always go with an
OEM thermostat. The cost difference is small, and one will
then have the confidence that they have precisely the
correct design temp settings on the thermostat.

Also, FYI, c. early 1990s Hondas are usually on their second
radiator by now. So yours could be said to be par for the
course. IIRC leaks at the radiator top are a common cause
for replacement. Aftermarket radiators are fine.

I suggest you do a proper air purge (if you can handle a 10
mm wrench, you can do this) of the coolant system, monitor
the coolant levels, and report back. See autozone.com's free
online repair manual (or your owner's manual) for the
directions for purging. Have a magazine while you wait the
40 minutes or so for the fan to come on twice. Only use OEM
coolant (or maybe orange Havoline). Hopefully your mechanic
used OEM coolant.


Thanks for the reply. Correct, a new head gasket was put on.
The
thermostat stuck, and the engine did overheat, but never
seriously (if
that is possible). The temp gauge was at the top of the
thermometer
symbol when noticed instead of at the bottom of the symbol,
i.o.w. the
gauge never went to the top of the range (not sure if this
is "well
beyond" or significant). But after the thermostat stuck, it
was
replaced but the head was not skimmed, the bubbles were only
noticed
about 6 months later and the real reason the head was
skimmed was
because the top of the (good condition) radiator sprang a
leak which
prompted the mechanic to look for a cause. Mechanic said
that the
pressure in the main hose was the cause of the leak as
pressure was
too high and would land up bursting the hose while on the
open road
one day.

As an aside, how does one predict a thermostat sticking,
should one
pro-actively just change thermostats like cam timing belts
and just
change them after X kms regardless of whether they are
showing any
signs of packing up?

 

forget about the hoses - the radiator cap has a pressure relief valve.
avoid any "mechanic" that doesn't know that.

absolute bull!

yes, i know. they absolutely don't.

hardly ever happens with blown civic gaskets - they blow gas direct into
the coolant jacket.

sounds like you have a cracked head or block. at this stage, it's time
to stop wasting more time and money on this engine and just buy a "new"
one. low mileage used jdm engines are shipped all over the world -
you're bound to be able to get one for a reasonable price.

 

avoid this person. seriously. hoses bust when they're old, and if
they're chemically challenged as can happen with long term gasket
leakage, or if the radiator pressure relief system is somehow
malfunctioning, but gasket leakage alone cannot burst a hose if these
other problems don't exist.

yes. i think it should be a higher priority item than coolant pumps and
oil seals that so many shops replace preemptively.