'90 Accord post-repair coolant leak

In the past two and a half years I've replaced my '90 Accord's radiator, water pump, thermostat twice, and just had the cooling fan motor and temp sensor replaced after the car started getting hot even
while moving fast (without boil-over). Following that last repair, I had to drive the car 150 miles home, following which I smelled coolant and found a fair amount dripping from the radiator area while parked.
The temp gauge reads low-to-mid-level, as it should, and the receipt says they did a pressure test (plus the mechanic said they'd idled it for 45 minutes to be sure the fan was working). So why the coolant spill? Any ideas? I don't know how pressure test and idle compare to real highway travel. I plan to call the mechanic when they open tomorrow, but any ideas from the crowd would be appreciated.
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Pete from Boston wrote:

Is the cap and reserve bottle ok? Sorta sounds like the radiator cap, but I'm just guessing off the top of my head.. Normally , any overflow should be routed to that bottle. The caps have two seals kinda stacked. Maybe the seal for the overflow function is getting funky. ?? MK
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snipped-for-privacy@wt.net wrote:

I'll have to check on these later (sucks that the repairing shop is prohibitively far away), but in the meantime, I think I've lost all or most of the coolant. Have to check more closely later.
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Pete from Boston wrote:

    Lotsa times it's just a loose hose clamp. Pressure test will help find it. bob
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Pete from Boston wrote:

Could it be a head gasket leak? If combustion gases are leaking into the cooling system it could be causing an over pressure condition and forcing coolant out of the system. Just a thought.
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Don R wrote:

I picked up a pressure tester (gotta love Auto Zone's free loaners) and I'm going to run it tomorrow to see what I see. Any tips on what to look out for? I'm hoping I actually see a coolant leak. If it's a more complex situation (like the head gasket) I'm not entirely sure how it will pan out.
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I'm not sure the pressure tester will show a head gasket leak. A better test would be a compression test. If one of the cylinders is low that would be a pretty strong indicator of a leak. There is also a chemical test that will show when exhaust gases are present in the coolant. Not sure how much this test costs, but I think it's on the expensive side ($90). Try the compression test, it's cheap and fast. I suspect you will find a low cylinder during the compression test.
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