Porosity sealant

[Mike R.]

When I bought my 65 FI car. it had some epoxy over a welded repair on one of the runner on the plenum. I inspected the interior of the runners and can see no cracks so I removed the epoxy. I have now reinstalled the engine and seem to have a vacuum leak. I don't know yet where the leak is but I suspect the repaired area. I know green locktite will wick into voids and seal casting but I was wondering if there are any others which would be suitable for DIY application. Ideally, it could be wiped off leaving only that which wicked into the casting.

[Dick W.]

Re: Porosity sealant

Green Loctite, and similar products, are anaerobic products. Anaerobic is "absence of air" in layman's terms. It would not set up in the crack. I guess you could clean the crack real good with something similar to brake cleaner and then attempt to force a two part expoy product into the crack, wiping the excess off. This would be a chancey repair at best. I believe you will be better off in the long run to go ahead and have the crack properly repaired.

[Jerry G.]

Re: Porosity sealant

I have some experience with this problem. Welding on these plenums is really difficult. Lots of dirt and crud down in the crevaces and porosity in the casting. I use JB weld on intakes and plenums regularly and it works great. As long as you are struturally sound with no cracks, try the JB weld. Jerry

[Mike R.]

Re: Porosity sealant

#290 Green loctite is for locking threads on fasteners that are already assembled. It wicks in and drys. Loctite says the stuff will work as a porosity sealant on castings. If it works as I think, then it would only dry in voids inside the casting and the rest should wipe off. The first step is to determine where the leak is and I will try to figure that out today. I was hoping someone else had tried this.

Green Loctite, and similar products, are anaerobic products. Anaerobic is "absence of air" in layman's terms. It would not set up in the crack. I guess you could clean the crack real good with something similar to brake cleaner and then attempt to force a two part expoy product into the crack, wiping the excess off. This would be a chancey repair at best. I believe you will be better off in the long run to go ahead and have the crack properly repaired.

[Ronald L.]

Re: Porosity sealant

Mike, conceptually, especially if it is really clean, when you run the engine, and it is pulling a vac, it should help to pull this into the problem area, then the issue becomes if it leaks too much to the inside. The carb rebuilders use an epoxy to seal the notoriously leaky inlet on these mid year Holley's, the same stuff should get pulled in and set up fine.