Finding cooling system leaks

FORD RANGER
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MUSKSNIPE
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2000 Ford Ranger 3.0 engine 85,000 miles
After the engine warms up to normal heat, the temp. drops, cool air blows from the heater, then the temp. spikes hot for a short period (30secs), and then seems to run normal engine temps. Checking under the hood, I find the coolant overflow tank cap blown off.

I believe my cooling system has a small leak allowing air into it. I can find no coolant. How would I find a small leak?

I have replaced the thermostat and bled air out of the system but I continue to get these symptoms.
Feb 8, 2007 at 8:44 AM
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GARFIELD
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Small coolant leaks are hard to find. The quickest and easiest is to use a UV light with dye that was put into coolant and ran for a short time and use the UV light to find out where it is coming out. It will show as a glowing green color where it is leaking. You can get the kit from Napa and most other auto parts stores. Hope this helps.

Gary
Feb 8, 2007 at 8:56 AM