General Ford Ranger Discussion General discussion of the Ford Ranger that does not fit in any other sub-forum.

Thermostat oring leak? Something else?

Old 02-19-2013
Crunchy's Avatar
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Join Date: Oct 2007
Location: Hull, Quebec
Posts: 486
Thermostat oring leak? Something else?

I have been noticing small spots of coolant on my driveway. I couldn't find any leaks on my engine, so I got some UV flourescent dye, and put it in my radiator to try to find it.

I found where its coming from, need to know whats the exact source.

This is the top of my thermostat housing with a UV light shining on it. It seems to show up on the top of the flat part, and in this seam shown. Is this where the 2 pieces of the housing come together which holds the thermostat?

It might be the 2 sensors, but I don't think so, its never wet around them unless the whoe top is wet, and it dries up not too long after The only liquid coolant around there is where the liquid has collected in that little notch circled in green.

Specs: 2003 4.0 SOHC, 120k miles. Its not leaking bad enough to add coolant, but ts enough to leak a spot on my driveway.

Never changed the thermostat ever. I did do a coolant change last year.

Ohh, its worse when its really cold outside, like -20C or colder.
Attached Thumbnails Thermostat oring leak?  Something else?-dsc_2336.jpg   Thermostat oring leak?  Something else?-dsc_2343.jpg   Thermostat oring leak?  Something else?-dsc_2345.jpg   Thermostat oring leak?  Something else?-dsc_2344.jpg   Thermostat oring leak?  Something else?-dsc_2349.jpg  

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