347 Water Neck leaks

[Brave Salmon]

My BPE 347 sfb has been a real pita to keep the thermostat housing from leaking. I've done all I can think of to make sure the mating surfaces are clean and flat. I use a flat 1/4" plate of glass with wet 400g sandpaper. Nothing but new felpro gaskets with minimal rtv sealer. Torque bolts using anti-seize as best I can using a crows foot on the bolt hidden by timing cover. Now I have actually stripped out one bolt hole which means I have to pull the damn thing off and fix or replace it. I need the advice of you experts who can point me in a new direction so when I reinstall the stupid thing, it will not leak. What am I missing, doing wrong, or what? Can the housing be pre-installed on the manifold before the manifold is installed. I could do a better torque that way.. also, what torque setting is correct for the 5/16" bolts? Thanks.

[FF33rod]

I'm not an expert but I feel your pain. My initial problems with sealing the water neck on my 347 was because the necks I used had a very hard rubber gasket in a groove. The gasket had no give and the necks bent before sealing properly. Finally got more of an OEM style and powder coated it and this one used the standard paper style. I did use the "right stuff" sealant on it and tightened by hand with a standard 3/8 socket wrench (not a torque wrench). Hasn't leaked since. Subsequently I have had to take the intake off a couple of times and left the water neck in place no problem.

Steve

[Railroad]

You can put a heli-coil in the stripped hole without pulling the intake. Your intake surface might be uneven, but more than likely you have a leak at the upper hose. Now if you can see the coolant escaping at the housing and intake union, you are going in the right direction.
I would inspect the housing for cracks, do not be afraid to use a heavier coat of Permatex Gray Ultra on both sides of the gasket. Make sure the thermostat is seated in the recess, or it will not let the housing seat. Over torquing will not cure a defect. Any pics?

A couple of other things, tighten down the housing evenly, make sure the bolts are not bottoming out. May not be a blind hole, cannot remember.
Scuff the housing neck with sandpaper in a circular motion. Whether this is the issue or not, it needs to be done.

[Brave Salmon]

[QUOTE=FF33rod;462768]I'm not an expert but I feel your pain. My initial problems with sealing the water neck on my 347 was because the necks I used had a very hard rubber gasket in a groove. The gasket had no give and the necks bent before sealing properly. Finally got more of an OEM style and powder coated it and this one used the standard paper style. I did use the "right stuff" sealant on it and tightened by hand with a standard 3/8 socket wrench (not a torque wrench). Hasn't leaked since. Subsequently I have had to take the intake off a couple of times and left the water neck in place no problem.

Steve, thanks but mine sounds completely different. The housing is a stock Dorman with no o-ring and the bolts are 5\16 not 3\8. Appreciate the simpathy, though..

[Brave Salmon]

A heli-coil is possible in the upper left hole but the lower hole on the right is hidden behind the timing cover and you cant get a straight shot at it. I would rather pull the manifold than the pump and timing cover for obvious reasons. I'm going to go ahead and replace the manifold as cheap insurance although I am not pleased about it. Damn Ford. I sure hope you coyote guys get better access on the modern engines than we do on these 60s vintage beasts.

[BEAR-AvHistory]

A heli-coil is possible in the upper left hole but the lower hole on the right is hidden behind the timing cover and you cant get a straight shot at it. I would rather pull the manifold than the pump and timing cover for obvious reasons. I'm going to go ahead and replace the manifold as cheap insurance although I am not pleased about it. Damn Ford. I sure hope you coyote guys get better access on the modern engines than we do on these 60s vintage beasts.

Good plan.....If the housing you are using is chrome get a plain one. The chrome units are very hard to seal.

[egchewy79]

I smeared "right stuff" RTV on both sides of a paper gasket and haven't had any issues w/ leaks from my waterneck or any of the gaskets in the timing cover/water pump. Also make sure your water neck has a bead/lip on the end or else you'll have to deal with the radiator hose popping off the end.

[rich grsc]

Don't know what you're doing, but there is NO reason to put that much torque on waterneck bolts. My guess is the bolts are too long and bottomed out? Is it a chrome neck?

[johnnybgoode]

I have had very good success with this water neck from BS. https://www.billetspecialties.com/Store/Wheels/engine-accessories/cooling-components/thermostat-housings/item/ford-small-block-thermostat-housing/

Very nice piece, completely billet with O-rings (real O-rings, not the funky "figure 8" plastic gasket). I actually just replaced both of the O-rings in my neck as PM after close to 10 years of leak-free use. Installation does not require any sealant. Torque to 120 in/lbs. I also used a bottom tap to clean up the manifold bolt holes and get me another thread or two. I cut down a couple of 1.25" SS bolts (use a vernier caliper to get the correct depth in the manifold) to ensure I got full bolt engagement without bottoming with the O-ring fully compressed and torqued to spec. If you are taking the manifold off you can mock this all up on the bench and make sure it's all going together properly. I also cleaned up the manifold mating surface with some 400 and a small flat steel block as you have done. I'd do that again and then clamp down the water neck with the o-ring installed dry and leave overnight for the o-ring to mold to the shape of the grove. Take the water neck back off and put a thin smear of grease on the mating surface and tighten the bolts making sure the o-ring stays in the grove and torque to 120 in/lbs

I find working with quality parts a lot more enjoyable so spending a few extra bucks on quality billet stuff just makes it more fun to put together. My 2 cents anyway. Good Luck. Scott

[Fman]

Had same issue at my first start up after three failed attempts went with this Ford oem and has been fine after first install. Also use a small dab of RTV on T-stat to keep it in place on the neck. If it moves at all you will have a leak.

https://www.cjponyparts.com/ford-racing-thermostat-housing-90-degree-302-351w-1979-1995/p/M8592M90/?year=1985&gclid=CjwKCAjw3MSHBhB3EiwAxcaEu9xEWieNOo4iDRI0blmI dvPkDokql36DU1fqMRdEQ9vCm6rZ0gc-axoCGPwQAvD_BwE

[Norm B]

Torque spec from my Ford manual is 12 to 18 ftlbs. Over torquing will warp the housing and cause leaks. I would say you over torqued them because you stripped one but, Rich's guess about bolts being too long is at even odds. Either way the manifold has to come off to facilitate a proper repair.


Good Luck
Norm