V12 intake manifold

Removed my intake manifold and found some corrosion on the top inside manifold, is this common? Also does someone know how to repair it, or can it be welded with aluminimum. Looks like it was caused by hot gases.

Thanks

very common, good aluminum welder can fix it

Thanks Doug; I will try to find someone in our area. Appreciate the reply.

Good you're fussy here - is very important. The manifold is made of two chambers in one. There is a heat chamber on the underside of the intake manifold, only about 8" wide below the carberator. There are (4) ports about 1/2" diameter (not the 12 ports about 1" dia feeding gas to the cylinders), and they provide heat to warm up the intake gases, and these (4) 1/2" ports often plug up with carbon, and corrode thru to the intake gas vapor chambers side going to all the cylinders. If someone used too much starting fluid, it burns hotter and will melt thru here as well. If this happens, your intake is pretty much a duster. Can't really reach inside to weld it. And if you try to run the engine with a hole corroded thru between the 2 chambers, you will loose vacuum, depending how big the hole is. You probalby want a minimum of 17" vacuum I think-check specs, 18"-20" better. A good way to check for leaks with the intake off, is to turn the intake manifold upside down, and pour water in the 4 ports and see if it stays in the heat chamber's (4) 1/2" ports, or leaks out into the intake gas vapor chamber side. Actually the intake manifold is not really pure aluminum and you can't get a good aluminum weld. If you pick up the manifold, it's heavier than alum, but not really pot metal, it is an old aluminum alloy not used any more. Vets in the club tell me you can weld intake cracks, etc on the manifold if your weld rods are of the same material- if you melt down an old junk manifold and make welding rods of the same material, then you can weld on places you can reach and it will stick and hold up well. But have not heard of anyone ever saving an old manifold with corrosion leaks inside the heat chamber, because you can not reach in or see to repair it. Hope that makes sense-good luck. Paul

Just a thought...anyone try using JB WELD? Heat shouldn't be factor. JB WELD has been used by some earlys V-8 owners to save flathead blocks.

John, I've used a product from Alvin called hi-temp metal. It's a metal putty that can be applied with a putty knife. After air drying it needs to be baked at 400 degrees for an hour. Luckily the manifold will just fit in the kitchen oven but open all the doors and windows when "baking".... very smelly. This stuff really did a nice job fixing a badly eroded heat-riser section after a though cleaning. When cured it looks and "rings" like the rest of the aluminum casting.

Thanks Dee. Gotta be a lot cheaper tha welding.

Excellent discription, I went back again to look at it and most of the corrosion is on the lower side, did notice some carbon in one of the half inch holes and now I will check for leakage between the two chambers. If all looks good I will probably wire brush the area and try the patch method as it is minor and may delay any further corrosion. Once that is done will probably be on the lookout for a standby manifold. I really appreciate all the assistance and would be lost without this forum.

Thanks to all