I had to replace my thermostat housing assembly on my s Type 4.2 na, after completed I can’t get the coolant inlet pipe to seal. It keeps leaking from where the o-ring is. I’ve pulled it apart and tried different new housing assemblies and still leaks.

Yes I did use a new o-ring with lubrication on it and torqued to correct spec. I even changed the inlet tube under the intake elbow just in case the one had a problem but still leaks.