do what the guy did on my project car, use rtv. in my case it is because after changing the t stat 3 times (im assuming over the cars lifetime) he never removed the old gasket, but kept putting new ones on the old ones until he needed a tube of rtv lol.

 

Use Permatex #2 on both sides of the gasket. Unless there's badly warped surfaces or porosity, it will not leak.

 

Use Permatex #2 on both sides of the gasket. Unless there's badly warped surfaces or porosity, it will not leak.

How could I check for porosity in the intake? Is there some kind of marking compound that I could put on there while the stat housing is off that would bring out any porosity and make it plainly visible? There sure isn't any flaws that I can see by the naked eye.

I forgot to add that I am working on a SBF.

I always seem to notice the leak by the lower mounting ear of the stat housing. Not sure if there is a leak there and nowhere else or if I see it there first because that is the lowest point yet the whole thing is leaky.

 

Take your intake someplace that does certified welding and ask them to brush some dye on the inside and developer on the outside. If the intake casting is a problem the outside of your manifold will have chicken pox by morning.

or if you want a DIY approach, make some caps for the water passages and give one of them an air fitting, fill the passage w/ 100 psi and sink it in a tub. If there is a porous section youll see bubbles rising

 

Take your intake someplace that does certified welding and ask them to brush some dye on the inside and developer on the outside. If the intake casting is a problem the outside of your manifold will have chicken pox by morning.

or if you want a DIY approach, make some caps for the water passages and give one of them an air fitting, fill the passage w/ 100 psi and sink it in a tub. If there is a porous section youll see bubbles rising

I am REALLY dreading the idea of removing the intake for various reasons. The main reason being that I would likely have to remove the engine to install the manifold with any amount of success due to the placement of the engine. Yeah, old vans are a pain.

I take it brushing die and developer are not DIY and can't be done by a non-welder? I am not familiar with the process, but if it's just a liquid/paste that is brushed on, couldn't any rodder do that?

 

I have machined the housings on a true lapping stone to guarentee a true flat surface. Any suggestions??

I had the same problem with leaking on my Edelbrock performer RPM manifold.
If you look at a stock therm. housing, there is a ridge all the way around the mating surface of the housing. If you sand it flat or gouge it with a scraper, it's done for.
I tried everything to include after market chrome that the recess for the therm. was so large, the therm. was flopping around inside it and coolant was going around the therm. inside the housing. It wasn't until I went to the wrecking yard and pulled a stock housing, cleaned it like a surgeon, and painted it that I finally got it to stop. If there is anything that looks ugly, it's a bunch of permatex squished out around a thermostat housing on a nice clean engine. Good luck. :mwink:

 

If the leak is truly between the 2 mating surfaces and they are flat I have had great luck with Permatex ANAEROBIC in both coolant or oil applications. The nice thing is that you use very little and any that does ooze out can be cleaned up due to it's inability to set up in the presence of oxygen. Maybe this is an option that will help, good luck.

 

i seen one, that one of the bolt holes was leaking, coming up the threads and that took a while to figure out.
dope up the bolts and see if that fixes it.

 

I take it brushing die and developer are not DIY and can't be done by a non-welder? I am not familiar with the process, but if it's just a liquid/paste that is brushed on, couldn't any rodder do that?

It can be done by anyone wearing rubber gloves, but usually it comes in gallon jugs, and you only need like 3 oz of each to do the job, so get a pair of chemical resistant containers and buy a bit from a fab shop.Then you can prob do the job in place as long as you can get the brush in the water passage