1996 1500 5.2L. My truck started overheating so I replaced the thermostat and thermostat housing, cleaned mating surface perfectly and put on new gasket with RTV on both sides and bolted it tight down. I took it for a test drive and it started shooting out right where the housing meets the block. Thermostat worked it was in the right way. No oil in the coolant or coolant in the oil. Tried to see if it was a bad water pump but nothing is leaking from it. Also once truck was up to temp it didn't seem like coolant was flowing since the water in the radiator was still cold. Also once at temp it started leaking out of the housing again quite quick. No clue what's wrong. Is it a bad water pump?

 

Bad housing. Probably not totally square.....

 

Probably is just me, I've never had good luck with RTV or other silicone gasket maker stuff .... I almost always ended up with a leak on a T-stat housing.

My favorite is Shellac gasket compound .... use to be called Indian Head before that was considered politically incorrect. My Father use to use it way back in the day when he was a professional mechanic in the 1960's .... been around forever.
Water pumps, T-stat housing, cover on my rear end .... pretty much all gasket surfaces and no problems with leaks.

 

The stock thermostat housings on the magnum motors aren't the most study housings ever made. See if you can find another one.

 

There is a specific RTV sealant for thermostats and water pumps. I've seen this happen when someone got the thermostat off just a wee bit. It will wedge the housing away from the block and leak as soon as flow starts.These blocks aren't as bad as the Ford small blocks with the thermostat going in sideways. Still, it's something I watch close every time I do one.

 

Did you clean where the t stats sits and the housing mating surface? I know it's tough getting the surface clean because you can't get to it. It's wise to drill a small hole in the t stat body if yours didn't come with the bleed valve. Air gets trapped and causes problems. Check out post #14.

 

I have a 95 ram 1500 and I've been having problems with coolant leaking. I had to replace the gasket where the thermostat housing is and there is a small hose called a bypass it was under the compressor mine was all tore up I fixed those and it stopped the leak.

 

Here is a video of what I'm talking about on the hose. I never would have thought about it until I found this video 😂

 

That bypass hose is designed to blow when the temperature is below 30 degrees, the wind is at least 15 mph and the humidity indicates it's raining. At least that's what it feels like. When I did a major tune up on my '96, I replaced all the hoses. All of them were still pretty good but the bypass was soft and swollen. It would have popped last winter had replaced it.