Originally Posted by xaliscomex

Own a 1979 300sd (w116).

The thermostat housing (6172002415) is pitted/corroded at the inlets/outlets.
Although the rubber hoses are properly secured and tightened using good clamps, coolant continues to leak out.

I drained the coolant and replaced all coolant hoses approximately 6 months ago and I was surprised to see encrusted buildup at joints between the hoses and the metal openings (inlets/outlets) to the thermostat housing. Obviously, the buildup throughout the years is responsible for such corrosion/pits.

I thought about using some type of epoxy to smooth out the pits and even out the corrosion so that the hoses can get a tight fit but I wanted to know if anyone out there has encountered this problem before and what is the best way to handle this.

Before I go out and by a brand new thermostat housing, is there a better way to smooth out the pits or a better way to secure the hoses so that future coolant leaks can be prevented.

Also was wondering if I should use a silicone piece of hose (42mm) instead of a rubber hose between the thermostat housing and the metal line located directly under. Thats the area where I'm getting most of the coolant leaks. Hope I'm describing the area correctly. A short rubber hose (42mm) secured with two clamps on each end allows the coolant to flow thru.

Any advice is greatly appreciated