Water Leaking Past Thermostat??

[65mechanic]

Hey guys. I'm attempting to fix a "no heat"/cold engine temp issue on my 95 2.3 XLT, 5 spd Ranger. I've repaired vacuum lines and fixed a jam on the blend door so all that should be working fine. The temp gauge just stays suuper low. I've grounded the gauge and checked it, so that's not my issue. I got bored this morning and drained all the coolant to flush the coolant. So I go to flush the motor through the top rad hose. I said to myself "water shouldn't go past the thermostat right?". I sprayed down through it, and sure enough water came through the motor past the thermostat. So I thought I had a bad thermostat, until I took the gooseneck off and the thermostat just plopped out. I found that I can put the thermostat in the thermostat housing, twist/push, and the thermostat will stay in the housing by itself. I then filled the top of the gooseneck with water and water comes seeping past the thermostat. I can't exactly tell if the thermostat itself is leaking or if the water is seeping around the rubber o-ring. Should the thermostat hold water while just pushed into the housing or will it need to be bolted to the block to stop it? No water should get past it correct? Thanks guys

 

[adsm08]

The thermostat seal is not going to be complete without the pressure of having the neck bolted down. I would not expect a complete seal from it though, as it is a piece that is internal to the system, and isn't meant to keep things inside the system.

 

[65mechanic]

The thermostat seal is not going to be complete without the pressure of having the neck bolted down. I would not expect a complete seal from it though, as it is a piece that is internal to the system, and isn't meant to keep things inside the system.

A friend mentioned the same thing. I've just come back home with a Motorcraft thermostat, a new gasket, and some new coolant. I just bolted the gooseneck down with the new thermostat, gasket, rtv, etc. Torqued to 120 IN Lbs. Gonna let it dry and pour some water down the neck to see what happens. Thanks.

 

[65mechanic]

Filled the neck up with coolant. It stayed all the way full for a while and dropped juuuust barely (I assume just filling in cracks and crevices), I'm gonna fire it up tomorrow morning and see what she does!