Coolant Vanishing: '95 Civic EX 1.6 - Attn Tegger and Techs

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When I had the oil changed in November, I was told they had to add "quite a bit" of coolant to the reservoir. Since the car came from NM,
with a spotty service record, I had hoped that it was simply not topped off ever. Now, three months later, with only moderate driving, I see the reservoir is virtually empty again. I don't see excessive white smoke in the exhaust, or smell antifreeze in it - although I haven't sniffed it specifically for that, yet. The oil looks fine. I don't smell coolant inside the car, either. It would be hard to spot a slow drip in this wet Winter weather. How common are internal head gasket leaks in this engine, as opposed to slow leaks in the reservoirs?
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mjc13<REMOVETHIS> wrote:

Hi, First I'd replace the rad. cap and see.
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Tony Hwang wrote:

Good idea. I didn't realize that pressure leaks were such a common problem. I may have the system pressure-tested if replacing the cap doesn't work. Thanks.
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mjc13<REMOVETHIS> wrote:

I took the car to a local shop today. They do free pressure tests (I gave them $20 anyway). No leaks, including the cap. Unless I'm missing something, it has to be the #@!@# head gasket, right? Assuming it's going straight to the exhaust and not burning much, how safe is it to leave it alone? Any suggestions?
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mjc13<REMOVETHIS> wrote:

go for at least a 20 minute run, then look at the coolant reservoir while the engine's still running. [make sure you can see in, but don't lift the hose above the coolant surface!!!] any bubbles? if so, it's gasket. also, check under the car and look at the bottom of the timing belt cover. any coolant? if so, it's the pump.
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head gasket, right? Assuming it's

The pressure test needs to be performed in two places. 1) the cooling system, and 2) the combusion chambers.
the first is done in conjuction with the introduction of UV dye to the coolant, this being detected on the outside with a black light. The second consists of shop air being blown into each combustion chamber, then the rad filler neck being then inspected for bubbles.
There is a third test that uses special paper test strips dipped into the rad filler neck. These change color in the presence of combustion gases in the coolant.
Your problem is NOT the rad cap. If it were, the reservoir would be FULL.
There is also the possibility of a worn water pump. In that case the coolant would drip down the block under the timing belt cover and may not be obvious. Findinig that leak means carefully inspecting the crank pulley area.
Do not put this off. You WILL damage your engine, possibly badly. You're supposed to check your coolant level every time you open the hood, or at least once a week.
--
Tegger

The Unofficial Honda/Acura FAQ
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Tegger wrote:

The procedure in the Honda manual online in the UK is to just use a hand pump-operated pressurizer with guage, and see if the pressure drops in the cooling system or cap. I don't know which they used at the shop...

Good point.

What I'm going to do, assuming I can even afford the cost of a new gasket done by the dealer, is to tell them to look for leaks, especially at the water pump. If they find none, I'll have them replace the head gasket. Shouldn't they install the new timing belt and water pump for no extra labor charge (they will be providing the parts, not me) when they do the gasket? I'm also having the front oil seals replaced as a preventive measure. Thanks for your response. If you could answer this post before this evening, when I drop it off, I'd appreciate it greatly.
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On 2/20/08 6:20 AM, in article gWUuj.16648$FK2.1405@trndny08,

Seems like you're jumping the gun a little bit here. How low was it in the reservoir? When you say reservoir do you just mean the overflow tank, or the radiator?
In normal use, the system will settle out to where the overflow tank sits at the "min" mark when the engine has cooled & the level will rise to around the "max" mark when the engine is hot & has been running for a while.
I certainly would not spend money replacing a head gasket that has not even been diagnosed. There is not enough info here to even say for sure that there is a problem.
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E Meyer wrote:

----------------------------
Where did you get this bit of misinformation? I've owned six Hondas and the level in the reservoir never changes more than about 1", hot or cold, summer or winter.
If yours changes that much, there's something radically wrong from what the Honda engineers designed.
'Curly'
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On 2/20/08 11:03 AM, in article snipped-for-privacy@corp.supernews.com,

I get my bit of "misinformation" from the behavior of 27 different cars over a period 38 years. Where do you get yours?
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E Meyer wrote:

---------------------
Sorry, misinformation is a strong word.
Volvos and Dodge products that I owned had pressurized reservoirs. The coolant level in them went up and down with temperature, but the HONDA isn't supposed to, since it's reservoir isn't under pressure at all. Boiling hot coolant isn't supposed to take up much more room than cold coolant, as long as the rad cap is keeping the pressure up.
Since about '92 most Hondas will self-bleed any trapped air because the rad cap is the highest point in the system. When any trapped air is forced out, the air is supposed to bubble through the reservoir and when the system next cools, the level in the reservoir drops as coolant it drawn back in. That's when the owner is supposed to add coolant up to the MAX mark on bottle. The owner's manuals and the Helms service manual all tell the same story.
However, none of this theory applies if there's a hole in a hose, the head, the heater core, the water pump seal, or if the rad cap is shot.
'Curly'
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motsco_ wrote:

sorry, that's fundamentally incorrect. coolant liquid most definitely expands as it heats - for both systems. pressure doesn't stop coolant expanding, it simply raises the boiling point.
http://en.wikipedia.org/wiki/Coefficient_of_thermal_expansion

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wrote:

I think we all agree that this motor should not be losing so much coolant so quickly. IMO,a coolant DYE test is in order. see if and where there's a coolant leak.
--
Jim Yanik
jyanik
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Jim Yanik wrote:

but most antifreeze already has dye in it already. and dye does nothing to diagnose a head gasket.
as said by someone else, the o.p. needs to take this vehicle to a shop that /wants/ to fix it - clearly the current one doesn't. time to hit the phones.
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Jim Yanik wrote:

I told them to look for signs of a leak. If they find none, they will call me. How much should a dye test cost, and is it better or worse than a cylinder pressure test? The car already had a system pressure test, and passed.
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mjc13<REMOVETHIS> wrote:

you don't usually do a separate dye test for antifreeze since it's already dyed. dye is more commonly used for differentiating different types of oil leak [engine oil and mtf are similarly colored and hard to tell apart sometimes] or for a/c systems.
the best thing at this time is to take the vehicle to someone that has an interest in fixing the problem, not trying to tell you the vehicle is too old to be worth bothering with. there are plenty of independent honda specialists out there. find one and check to see if they have a good reputation.
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The two tests are meant to check for different problems. They are NOT equivalent.
I'm assuming the "system test" means they checked the cooling system by pressurizing it. If that test did not use dye, then the test was incomplete. A dye test also will not pick up leaks that come from the water pump, since those leaks take lots of time fo be seen from under the timing belt cover.
If there is suspicion on a head gasket leak, you must do the cylinder pressure check.
--
Tegger

The Unofficial Honda/Acura FAQ
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But it does. ALL materials expand with heat.
The reservoir level naturally rises and falls as the coolant heats and cools. This is the purpose of the various seals in the rad cap, and for the very presence of the (unpressurized) reservoir in the first place.
You don't have to take my word for it. Check your own reservoir's level at dead-cold. Drive the car to full-hot, then have another look at the level. It will be at least a half-inch higher.
Coolant is constantly traveling in and out of the reservoir with every heat-cool cycle. It's a normal and necessary feature of a modern sealed cooling system's operation.
--
Tegger

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s.com:

my idle question is, how much negative pressure is required to suck the coolant in. obviously, the spring keeps the in valve shut at zero pressure, but when the coolant cools off, there's negative pressure in the block which sucks the coolant from the reservoir. we assume the pressure of the spring on the valve leading from the block to the reservoir is what it's labeled as, but i just wonder how much residual vacuum remains in the block when the spring shuts the input valve. for no reason other than idle curiosity.
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z wrote:
in

almost zero. there are two springs - one for high pressure exit, the other is practically zero return. unscrew the radiator cap when cold and see how much vacuum there is when you release.
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