1957 Intake Manifold leaking after replacement

[Zoopie]

Just switched out the intake manifold and used stainless steel nuts and bolts. In so doing, the fasteners cannot be torqued to original specs, upon completion there was a noticeable water leak on the valley pan. The question arises, re-torque the bolts and restart the engine, or remove the manifold and rebuild. My concern is having water in the oil and creating an engine environment that produces much less lubrication and potential engine failure. Any thoughts on this would be appreciated.

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[SWinner]

Zoopie, Do NOT start the engine. With water leaks, you could hydrolock the engine and bend a rod.

Take everything apart. Are the new fasteners too long? Does the new manifold have straight flanges? What type of manifold did you put on? Did you clean the mating surfaces perfectly clean? Any gasket residue will prevent proper sealing. Try using a wire wheel to clean the mating surfaces. Be sure to put paper towels or rags in the head ports to keep debris out of the ports.

When reinstalling the manifold, use Felpro gaskets, Aviation sealer (bottle with a bush in the lid) around the intake ports and silicone sealer around the water ports. Make sure that the gaskets stay in place while installing and torquing the intake.

Good luck,
Steve

 

[Zoopie]

Fasteners are of proper length and the manifold was of the original type, replaced due to hacked choke tube install. Mating services were absolutely spotless and paper towels used to block all ports. You answered the question as I was afraid of doing some damage, thank you!
cam

 

[doug7740]

I have installed a large number of these over the years and never had any issues with leaks, vacuum or coolant. I install them dry. Make sure the gasket surfaces are super clean. In my experience, if a gasket is meant to be put on dry, using RTV can upset how the gasket lays and it may actually cause it to leak. If it leaks when it's installed properly, then the surfaces may be warped. Take a metal straight edge to the heads and intake.

The torque setting in the service manual is 23 - 28 ft lbs and I use a crisscross pattern, starting with the 4 studs in the middle.

7 3 1 5 9
Front--->
8 4 2 6 10

This is the pattern I use, but it's by no means the only way, just the logical way to do it. I start with one of the front studs and work my way out. Torque it incrementally, in other words torque them all in that order to 10 ft/lbs, then 18, then the final 28. That will make sure everything seats evenly.

doug7740
1955 Thunderbird Blue

 

[doug7740]

I just found an article about installing the intake manifold gaskets. In the article he recommends using a copper spray sealant on the intake gaskets. I have never had any issues installing the intake gaskets dry.

doug7740
1955 Thunderbird Blue

 

[CSPIDY]

You said in your original post that you could not torque The fasteners to the required torque, did you determine why? Are the fasteners stripping out? Some stainless steel is softer than a grade 5 or 8 bolt. Perhaps you should use the original hardware (new can be purchased)

 

[Zoopie]

The fasteners were a grade 2, now going with grade 12, should do the trick. Ah but all that work and have to redo, oh the fun!