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Old 08-02-2017, 03:50 PM   #24 (permalink)
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Originally Posted by Xist View Post
I am not excited about the crack in my radiator. It only released a fine mist.

For now.
Hello Xist,

Can't offer much help on your wiring issue, not being equipped with any Honda knowledge. Only suspect would be a bad wire to clip connection inside the plastic connector that plugs into the thermoswitch.

As for the split in the radiator, welcome to the "Gee, I fixed problem X, only to find the next weak point in the system" club. My condolences. My situation was a leaking thermostat housing. Replaced that, got a split in the radiator. Replaced that, blew the lower intake manifold gasket (that was old and leaking anyway). You can "buy some time" (not a lot of time) by depressurizing your cooling system. I have tried two ways, and can think of a third and fourth.

First way is to loosen the radiator cap to the first notch - the point where it releases the internal pressure seal and allows pressure to get to the overflow tank. Messy, as the outer seal above the inner seal also comes loose, so you get some overflow out the radiator neck, too. I've tried this for a commute or two, and lost a lot of coolant to slosh.

Second way is to get one of those "lever-release" type radiator caps, and either wire the lever up (if there is room for it with the hood shut, I did not have room when I tried it) or shim the lever base up so it depressurizes the system. This is what I did, it sort of worked. Kept spitting the shims out, though, so I probably only somewhat reduced the pressure. The radiator still dribbled from the crack, but it wasn't bulging at least, and did not "blow out".

Third way is to get or make a "blank cap" that has no inner seal, just an outer one to the radiator neck. You might be able to just drill out the itty-bitty "return valve" in the middle of the radiator cap's lower seal. This return valve is what opens when the cooling system pulls a slight vacuum upon cooling down and allows drawing coolant back in from the overflow tank. A small hole is all you really need to dump pressure.

Fourth way is to get a super-low-pressure radiator cap. This isn't as good as no pressure, but it is likely more available and requires no other mods. 6 PSI seems relatively available, which is ~10 psi less than most factory caps.

The idea is to run your cooling system open to the atmosphere via the overflow tank. This will reduce the stress on the split in the radiator, causing it to bow out less, grow slower, and not spit as much coolant. You'll lose the boiling point raising effect of a pressurized system, so this won't work for high load or extreme heat situations. It should limit the leak rate enough that you can "limp along" to a point where you can replace or repair the radiator. Do keep an eye on coolant level and temp, though. Don't want to turn a simple radiator leak into a cooked engine.

Note: make sure your overflow tank does not have a tightly sealing cap, else it might blow off. If you cannot find where it vents to atmosphere, check it a few times during driving to make sure the cap hasn't blown off. If it does, you may need to make a larger vent hole in the overflow cap, that you can later plug with a screw after you replace the radiator and go back to running a pressurized system.
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Xist (08-02-2017)