Thermostat housings keep leaking

had the same problem with my small block , then my friend told me about permatex product called "right stuff" so i figured id try it since ive tried 4 thermostat housings anyways it worked no leaks!!!! and for only 8 bucks woohooo

Got a thin sheet of cork gasket material and made my own. Works much better than the paper gasket. Fixed the leaking.

Take that POS chrome housing & throw it as far away as you can...

I take a wide flat file to it on the WP housing and the thermo housing

file till nice and smooth then it seals

the chrome one will seal after removing the chrome from the sealing surface

done this on old used headers that would not seal also

I have done the cyl head at the exhast ports by hand file when I had the engine out,like said you can see the high spots when the file is a workin

have hit all the flats on a few carb bases on alum intakes to make sure they are flat while I am doing the thermo surface

just dont take to much off the thermo housing,it needs some of the recesed lip/groove to let the thermostat be pinched inbetween the two surfaces

2 gackets and indian head gasket shelac has work before also

One last thing you might check. If your bolts that hold the housing down are threaded all the way thru to the water passage, you need to put sealer on those bolt threads. Not all holes are threaded all the way thru. Some are just blind holes. I've had about 50/50 on most S/B intakes going all the way thru. YMMV.

This has been a sore subject with me in the past; have tried the chrome and stock housings and they leaked. Finally after ensuring the water pump housing was true I purchased a billet thermo housing from Mancini; no leaks so far. I know for a fact that the chrome thermo housings warp as I have trued them up many times. Just my 2 cents.

Von, w/ what most everybody here has already told you. I had a chrome one that leaked like crazy no matter what I did to it. I tried a few different stock ones I had here and they all eventually started leaking no matter how I sealed it. I tried it w/ and w/o gaskets, w/ and w/o silicone, etc. I finally bought the billet piece from Mancini and finally NO MORE LEAKS!!
CHIP

The chrome water necks warp and leak. I tried truing mine up on a belt sander and it sealed for a while and leaked again.

Use a iron or billet piece and check flatness of the water neck and WP first. The easy check is to put the two cleaned parts together and check for rocking and/or gaps. File or belt sand to correct as needed.

With a good billet or iron neck, flat surfaces and correct torque it should seal with a gasket. Some sealer is insurance - I used the old hardening Permatex #1 type. Too much torque will warp the water neck and cause a leak.

Another vote for the Mancini Billet unit...I had mine powdercoated engine color and its perfect so far..

http://www.440source.com/waternecks.htm

and,.......you just might be overtightening them and warping 'em.

I draw file the wp housing(intake if SB) & the stat housing even if new, stock gasket, permatex #2 in the tube. no leaks.