Benny23

Ok on the 67 olds 330 we noticed coolant leak when we bought it so I redid the thermostat and gasket it's not leaking as bad but not coming from the gasket or hose can the intake be leaking somewhere any help

Fun71

Could b the weep hole in the water pump, but any fitting, hose, frost plug, etc can leak. Look for wet spots on the ground under the engine to help figure out where the leak is.

Benny23

It's on top behind the thermostat on the intake manifold

joe_padavano

I'd suspect that your t-stat housing isn't flat. I assume you have the die cast aluminum version, not the later cast iron version. Remove the housing and flatten the mating surface by sanding it with a sheet of sandpaper on a known flat surface. A piece of glass is ideal, but a metal table top will usually work. I typically use 150 grit wet-or-dry paper for this.

harleyrules

It could be the thermostat housing itself. It might have developed a tiny pin hole in the casting if it isn't coming from an unseated/tight hose clamp. If the intake manifold is aluminum I've seen them develop a weep leak as well.

Benny23

Can you get new thermostat housing and or intake

olds 307 and 403

Yes, you can, don't buy the cheap chrome water necks. What I have found that a second gasket and a RTV like Optimum Grey helps seal. I had to sand the heck out of the factory aluminum water neck and double gasket with RTV in between each to seal. You can also try the 3M sanding and polishing disc's on a drill if the intake is pitted. Good luck.

Horsepower

If you are going to pull the pump replace it don't waste time with just a gasket.