Weeping elbows

[Dave66]

Installed new manifolds, risers and elbows this past June. The elbows and manifolds are merc and the 6" risers are osco. They are mounted on 454 MPI's. While winterizing the motors I noticed rust lines running down the risers on one engine. The line starts at the gasket between the elbow and riser on one side of the engine. On the other bank of the motor I have a similar leak plus a leak at the joint of the manifold and riser. The other engine has no signs of rust. All the iron I replaced in the spring after 4 years had no signs of rust. Bolts are tight. Used merc gaskets.
Has anybody experienced this or have an idea why this is happening?

 

[Air O'Nautical]

Sorry to hear that,
The thinking here is leaking outside is probably leaking inside too.
Change the osco risers with mercury parts and gaskets.
Torque the bolts to spec. and your done.
Good luck,
m

 

[johnsross3]

The rust lines should tell you where the leak is starting from. Perhaps pictures would help others diagnose your problem. As for the leak between the manifold and gasket, my guess would be that you're not getting a good seal in the gasket between those surfaces. If it were me, I'd replace the gaskets and make absolutely both surfaces are free from any residue from the old gaskets. A gasket scraper or straight razor blade can be used to clean those surfaces. When reassambled, I also torque the riser to manifold bolts according to specifications.

 

[northern]

Does any one have experiencewith over torquing the bolts to get a better seal?

 

[pKai]

Does any one have experiencewith over torquing the bolts to get a better seal?

Overtorquinng is never a good idea. It stresses everything and could even cause parts to warp and leak more -- although this last portion is doubtful on substantial parts like cast-iron exhaust.... either way, everything is stressed beyond their design tolerances.

If all the parts are made to mate and the proper gaskets are used then the specified torque will do the trick.

I noticed the OP was using two different brands of manifolds/risers.... Although everyone supposedly makes these parts to the same specs.... my 30 years of boating have taught me that this is not always the case.... I would run all Merc (my choice) or all Osco or all "whatever" but not mix.

 

[Dave66]

Thank you for your advice. I bought the osco risers because the supplier did not have 6" risers by merc in stock. I will remove the iron over the winter and also check for internal leaks. I used merc gaskets and all new studs and bolts. According to my supplier Merc does not recommend putting any gasket cement on merc gaskets. Does anyone use any type of sealer on their gaskets and if so what type?

 

[Bt Doctur]

First run a fine flat file over the surfaces to make sure there straight, this applies to NEW units also.
Permatex Aviation liquid on both sides of the gasket
torque to specs.

 

[Dave66]

Bt Doctor, thanks for the info. Will use the permatex when I put it together.

 

[flarepoman]

anybody have the torque specs handy?