Leaking water neck

[Fish Tale]

I recently went through the cooling system (radiator repair, new heater core, hoses, thermostat, etc) on my 71 Cuda 383.  First time test run, the water neck leaked.  I removed it and cleaned up both surfaces, applied sealer, re-installed and torqued bolts, etc.  Leaked less but still leaked.  I am wondering if I am installing the thermostat/water neck incorrectly or maybe one or both surfaces are warped?  I did notice that it wasn't easy to keep the thermostat centered on the water neck as I was installing.  Maybe that's my problem.

Anyone have similar issue or may know what could be causing the leak?

[cudabob496]

using a gasket?

[4Cruizn]

If you are using an original or cheap after market, they typically will leak.  Need to get a billet one or I believe I just saw somewhere there Dave from Roseville just a few days ago is now stocking them . .  New product!  I had the same issue and no matter how much sealer or how much I tightened it. . . Would still leak. 

[lulurocks]

Trick I've seen fitters use at work with crappy Chinese pump flanges ...

Use small dots of adhesive silicone to pre glue thermostat to neck where it sits in the machined edge . Let it set up for 30 then come back to assemble .



If you want to use the original look neck.   You might try  recleaning everything . Run a 1/8 bead of adhesive silicone on the  engine side  , an 1/8 bead on the neck.  Place the gasket on the neck and then assemble carefully so you don't smash out the silicone  by totally  tightening the bolts.    Just run the bolts so it brings the two surfaces  together and starts to squish out the silicone slightly

  Wait  10 min   then snug them up to speck.  Then once dry  cut the squished out bead  off with a razor .   Don't wipe it when wet it will smear everywhere . 


Just a  idea........

[blown motor]

If it's a chrome water neck it will leak. Throw it away. When I'm installing it I reach down through the top of the neck with a needle nose pliers and pick up the thermostat. That way you can make sure it's centred properly. Set it in place and tighten the bolts.

[BIGSHCLUNK]

My experience is the necks warp , the chrome one I had was terrible. One year I even filed it flat. Next year leaked again. I took a 47 year old Ma original and put it on..... NO LEAKS!     

[rUNCHARGER]

Most likely warped. I always surface them when changing the thermostat. You can carefully file them or put some sandpaper on a flat plate and surface them that way. Just check them with a straight edge. If chrome then remove the chrome when surfacing them.

Sheldon

[burdar]

Tony's Parts is the one who just started remaking the factory water knecks. Roseville might sell them too. There are two versions...one with casting flash and one without.

[anlauto]

Tony's Parts is the one who just started remaking the factory water knecks. Roseville might sell them too. There are two versions...one with casting flash and one without.

Yup, easier to buy from Roseville

[twalker]

I bought this one from 440 source, extra thick flange.  Hope it works :-)

121-1017


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[Fish Tale]

Thanks guys very helpful info.  The neck is original not a chrome piece.  I will try to file both surfaces and make sure they are flat and then use the needle nose pliers trick or perhaps secure the thermostat with adhesive.