Leaky water neck

Hey guys after my headgasket install my darn water neck is spraying antifreeze everywhere. I've tried taking it off and using rtv blue and black with and without gasket and with and without those rtv sealents. The other day I picked up a new water neck and this morning I put that on with the gasket and no rtv still spraying out of the bottom just in front of the bottom bolt and spraying upwards. So I thought I'd let it warm up and see if it cleaned up. It did until I bumped the throttle and it looked like a squirter. I did buy some rtv specifically designed for water pumps and thermostats but I don't think I should have to use it I hate using it.

Not saying you didn't, but torquing bolts to spec and letting rtv cure full 24 hrs is how I get good results. Other than that about all that can go wrong is thermostat in backwards or not seated all the way in the groove.

Well when I did use the rtv I let it sit overnight before starting it. And I may have overtorqed a bit my torque wrench doesn't go low enough so I just have been doing good n tight

-Check for old gasket/mineral crud on mating surface and tstat recess.
-Verify the head mating surface, and new water neck are flat (new ones are often garbage right out of the box, or crack when you torque them.
-Make sure your thermostat isnt 'falling', then blocking your tstat from sealing


I never wait 24h (thats a bad joke, imho), nor do i torque these. Havent had leaks since my 2nd or 3rd. See checklist above

I never wait 24hrs for rtv to dry. I use black hi temp rtv on both mating surfaces, and both sides of the gasket.

I dont tourqe them down either.

Its possible you did not clean the head well enough, and its possible the new part is not flat.

1. Clean old surfaces
2. apply Rtv and mate parts
3. only install bolts enough to allow skin to adhere on both sides
4. wait about an hour for RTV to cure some more, then snug down to spec.

waiting allows the RTV to partially setup, thereby making a thicker gasket that get compressed, vs oozing out the sides if you do it all at once

It can be hard to clean sugar (coolant) off of metal, especially metal that is porous. I've noticed many times the RTV comes off of the old pieces easier than it should, which leads me to believe it never bonded well in the first place. Really hot water and soap is best for cleaning off coolant, Window cleaner spray works in a pinch, brake cleaner and solvents not so well.

I lay a sheet of 400 sand paper on something flat and take a couple of swipes with the thermo housing on the sand paper. Low spots, high spots and missed chunks of old gasket show up quick.

Best guess is sometime in the past the thermo housing was over tightened and is now bowed or there is a hairline crack in either the housing or the block. And/or the housing had been way over tightened in the past has has raised/ridged the very edge of the bolt hole in the block. A quick cleaning with a counter sink will remove the ridge. I can usually feel that ridge ridge with my finger tip, where my eyes may not be good enough to see it.

If you can get the crack cleaned well enough, epoxy can get the crack sealed. But like I mentioned coolant specially coolant soaked into a porous metal can be hard to clean. Repeated cleaning with soap and near boiling water usually works best. I've used JB Weld, Permatex multi metal epoxy, or Loc Tite epoxy. The trick is to find an epoxy that bonds well but isn't overly brittle, so it survives heat and cool cycles.

Don't discount a casting flaw and/or a tiny pinhole as being the culprit. The pinhole can be a significant distance from where the stain appears as they tend to spray. Pinhole leaks are fairly common in cast aluminum parts.

The thermo housing bolt holes go all the way through the block into the water jacket (most times). Clean out the bolt holes and use a sealer on the bolt threads.

Ok ya I havnt used rtv on the new water neck yet but I plan on doing this tomorrow and I will let you know what happens saturday