Tegger's coolant leak

For the past year or more, I had an inconsistent and disturbing coolant leak in my '91 Integra. The engine would lose coolant at differing rates which appeared to coincide with warmer temperatures, but still exhibited
considerable variability within temperature ranges.
I went over the entire system with a strong flashlight, many many times, looking for the tell-tale blue crud that results when genuine-Honda coolant escapes the confines of the system.
There was no air in the system. The reservoir level dropped as the system sucked in its contents as loss occurred. All I could do was to monitor the reservoir and rad level every day, and top up as necessary.
Some online (in rec.autos.tech) suggested a cracked head. But that did not explain the lack of air.
Well, one day this past January, I got careless. I skipped a day checking the coolant, since it had been stable for several days prior. I drove about 3 miles, and wondered why there was no interior heat. An investigation revealed a dry rad and empty reservoir. I topped them up, then idled the engine to allow pressure to build. Coolant began pouring out from under the front bumper. Uh-oh.
Further investigation led me to strongly suspect the rad, so I ordered a new one. The new rad did not leak, but would not build pressure. I discovered a deep gouge in the plastic filler neck's sealing ring. The rad shop took back the rad and gave me a new one. This one worked fine, but the defect in the original meant that I ended up having to pull the rad twice, on a zero-Fahrenheit day! NOT fun!
Once I had the old rad out, it became clear what had happened: The gasket between the core and the bottom tank was leaking, right at the hose stub for the bottom rad hose. This area is virtually impossible to see on my car with the rad and hose installed. And since the car is treated against rust yearly and the coolant leak was inconsistent, the oily rustproofing residue prevented the coolant from crusting over and becoming visible. When the gasket finally allowed a Niagara-type leak, I could then see the streaks on the tank where the coolant flow washed the tank clean.
Engines's been fine since. Haven't had to top it up since February.
--
Tegger

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On 5/23/2012 4:20 PM, Tegger wrote:

There are gaskets on the rad besides the radiator cap and perhaps the drain plug? I thought the rad core and tank were soldered together. Too bad you don't have a picture of it.

Good feeling, eh?
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Go have a look at your own rad. The tanks are crimped onto the core with a whole bunch of little metal tabs. There's a rubber gasket in between. It's lighter and cheaper to make rads this way instead of the old all-metal, all-solder way.
Those tank/core gaskets provide about 8-feet worth of leakable join. Then you have the rad cap, the drain plug, and the hose stubs. Plus the two automatic-transmission cooler lines, if so equipped.
All told, there are probably about 50 possible leak points in the entire cooling system. Considering that, it's actually a bit amazing that the system is sealed as reliably as it is.

More of a relief than anything else. With 385,000 miles and 21-years on the engine and the rest of the car, I expect anything to happen anytime. Every day the car makes it from A to B and back again, I am grateful.
--
Tegger

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On 05/24/2012 05:40 PM, Tegger wrote:

that's not the reason. the reason is that h.o.a.t. antifreeze doesn't play well with solder. and frankly,t he more disparate metal systems the antifreeze has to protect, the more complex its task and shorter its life. aluminum radiators simplify the protection equation and lengthen antifreeze potential life considerably.

you haven't mentioned hose leakage at any point along a hose length - a not uncommon scenario. especially if it's one that's been having oil drip on it - as is a favorite with honda heater hoses under the distributor.

seals don't leak on their own - it's faults that leak. and a fault can be anywhere - cracked heads [which are not a joint], cracked radiator tanks [which are not a joint] stone punctured radiator [which is not a joint], salt corroded radiator [which is not a joint] and rubber degraded hoses [which are not a joint] being just some other scenarios you need to include in your checklist.

--
nomina rutrum rutrum

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On 5/24/2012 6:37 PM, jim beam wrote:

Well, the heater core being essentially a smaller version of the main radiator isn't built that way. Plenty of soldering there and no aluminum that I can see.
What is h.o.a.t. anyway? There are still some of us here who don't talk shop.

Oh boy! I've had a couple of those, too. Once in the upper rad hose and once on one of the two small hoses attached to the heater core. I don't remember if inlet or outlet. Luckily it happened close to my home.

There you have it. The list can be endless.
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On 05/24/2012 07:18 PM, cameo wrote:

http://www.eetcorp.com/antifreeze/antifreeze-faq.htm#q28 towards the bottom of that question.

it's the outlet of hot coolant from the head to the heater matrix - very common because the distributor o-ring always leaks and the oil rots the rubber of the hose. [i have a viton x-ring on my distributor and that stops it completely. but i would, wouldn't i.]

--
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On 5/24/2012 7:44 PM, jim beam wrote:

Oh, so it's Hybrid Organic Acid Technology. Is that what Honda coolant uses?

Thanks, that's good to know. Now I'll be checking that sucker more often. But that being a common problem, one would think that Honda could have come up with some special oil resistant covering for that hose, no?
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On 05/25/2012 11:15 AM, cameo wrote:

well, it's academic now they're on the k-series engines. but with the prior motors, they just presumed their o-ring spec was sufficient. and maybe it was with japanese o-rings. but the ones that got fitted to the u.s./canadian-made engines were hopeless.
but fitting a viton ring is not as easy as it should be. honda o-rings are metric, not standard, and it's pretty much impossible to buy economic quantities in metric over here, and certainly not in viton. the nearest standard size is a little over-sized, and the distributor thus retrofitted sometimes goes in ok, sometimes not, depending on the combined tolerances for the distributor and head. my accord worked ok, my crx ok, one of my civics runs with an x-ring ok, but the other civic is just too tight and no retrofit ring has yet fitted - it's running stock honda. fortunately a new japanese ring is doing ok so far.
--
nomina rutrum rutrum

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On 5/25/2012 10:48 PM, jim beam wrote:

My Accord was made in Japan.

Now that you're mentioned it, I remember that I used to have a pretty stubborn oil leak at the distributor. Wasn't leaking much but that was probably enough to weaken that outlet hose to eventually burst. The technician had to replace the o-ring twice but I don't know what brand he used.
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Tegger ( snipped-for-privacy@example.com) writes:

I have had coolant leaks seal on their own accord. I rebuilt an engine once and put in new frost plugs (OEM). When I started the engine up for the first time, some of the frost plugs started to weep a little coolant. The next day I drove the car for about an hour, the weeping stopped. The plugs were never weepy again.

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