I have a 2003 Freelander that using a pressure tester has a small leak at the thermostat housing where it goes into the block and at the water pump end where the plastic pipe goes in.. There is a small amount of pitting on both parts.. everything is new. Is there a sealant that I can use that will make this problem go away. Other than that the engine runs strong. Just performed a total upper gasket job and all timing belts.

 

I have not had any luck with sealants, other than a short term fix. The o-rings for both must be a special size as the closest fit out of the standard sizes assortment is slightly larger and would break when installing. In all cases I've ended up getting the correct o-rings or simply replacing the t-stat and pipe to avoid a major leak.

 

The thermostat housing, pipe and elbow are all brand new..I even purchased the orings from Land rover.. the problem is the slight pitting of the aluminum in both the thermostat housing port and the exit port of the block from the water pump