coolant leak source

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  #1  
Old 11-25-12, 12:53 PM
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coolant leak source

Have a bad coolant leak occuring with my 92 Accord. Not sure whether it's because of a leaking water pump or from a leaking o ring on the water pump end of the water pump inlet pipe which is connected from the thermostat housing to the water pump. Upon inspection from underneath, the coolant seems to leak from above the water pump weep hole from between the lower timing cover and the engine. With the car parked and the engine running there seems to be little if any noticeable leaking until the radiator cap is loosened, whereupon heavy leaking immediately occurs from the area I mentioned. Put the radiator cap back on tight, and the leaking pretty much stops. Assuming it might be the water pump leaking, I did take the upper timing cover off and started the car to see if maybe water might spray out from there, but it didn't. The engine surges on the car when it's cold, but as soon as the engine warms up the surging stops. I can fill the cooling system up with coolant and like I said there's no visible leaking occuring until I take release pressure by doing something like loosen the radiator cap, then it leaks badly out of the area I mentioned. Also, it must leak out pretty bad when driving, as if I fill the cooling system then drive to work one day or whatever then check it later it's really low or close to empty again. I really don't want to go to the trouble to change the water pump if the water pump isn't the problem, because that entails having to remove the timing belt. I was wondering about the possibility it is the o ring on the inlet pipe on the water pump end that might be bad and could the source of this leaking. Here's a diagram which shows the o ring I'm talking about, part number 19 in the diagram: Honda Automotive Parts
I removed the inlet pipe and inspected the o ring but it does not necessarily look bad to the naked eye, not obviously deterioated or cracked or torn. The o ring on the other end of the pipe, which is identical but which fits into the thermostat housing, looks slighty nicer, but actually not much different. On removal and close inspection of the o ring on the water pump end of the inlet pipe, its really hard to say for sure whether it might be have some wear or imperfection that is allowing the leakage I described.
This particular o ring is not one available at local auto parts stores, but instead really is a Honda part which I would need to acquire from Honda. I can get one and see if it helps, but before doing that I'd like to get some opinions on whether from what I describe it seems reasonable the o ring is the cause, or if in fact it seems likely this is indeed the water pump leaking.
 

Last edited by sgull; 11-25-12 at 03:52 PM.
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  #2  
Old 11-25-12, 03:34 PM
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PRESSURE WASH ENGINE.
Then add dye to coolant and pinpoint leak source.
Your 92 has timing chain?
Surge may be caused by dirty idle speed control valve, that has shared coolant supply. They get dirty and need to be cleaned once in a while.
Also, you may simply have inward leaking head gasket.
 
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Old 11-25-12, 03:51 PM
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timing BELT, not chain. Dang I always mis-type that. I went ahead and corrected it my initial post, thanks.
 
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Old 11-25-12, 04:01 PM
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Coolant will leak heavily from between the lower timing cover and the engine, just opposite the location of the water pump. I can plainly see it come from there without needing to add any dye to the coolant. Ukrbyk can you explain to me inward leaking head gasket, as opposed to outward leaking?
 
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Old 11-25-12, 04:34 PM
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I was reading also about the engine surging as I described, and came across info that when coolant is low, the "fast idle thermo valve" can act up and cause such surging, which seems to make sense, because that's when the surging occurs, when the coolant is excessively low. I believe this is what was referred by ukrbyk as the idle speed control valve.
 
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Old 11-25-12, 06:38 PM
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sounds like a water pump to me. with the leak being bad to not bad with the cap its a simple negative pressure thing. cap off allows it to bring in air as it goes out. cap on creates a vacuum not allowing high flow. drive down the road and you build pressure pushing it out. the o-ring you are talking about is on the other side of the water pump(no way to leak into the cover). could be the gasket on the water pump but if your that far in why not replace it(and the timing belt).
 
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Old 11-25-12, 06:59 PM
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Okay iceman. I was hoping to get some confirmation one way or another from someone about whether from my description of the leaking that it is indeed the water pump that needs replacing. My buddy (who pretends to be knowledgeable) said if it was the water pump shot/leaking that when we took off the upper timing cover we would've seen water spraying out all over, and since we didn't he said it wasn't the water pump leaking, and said it was probably that o ring. But as I mentioned we looked at the o ring and it looked fine, and, like you say thats on the other side of the water pump and no way to leak into the cover. I had just been confused about the leak not being bad with the cap on, but your explanation of the negative pressure thing clears that up for me. I'll go ahead and replace the water pump now and the timing belt along with it as suggested.
 
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Old 11-26-12, 07:00 PM
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outward leaking head gasket leaks outside, onto the engine block. Inward leaking leaks into the engine. like oil into coolant passages, or both into the cylinders.
 
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Old 11-26-12, 07:02 PM
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Personally, I replaced many leaking O-rings, and they all looked "fine". Tolerances are so minute, you can't really see it.
I'd join the rest. Coolant pump is bust.
 
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