when you have heads (block, etc.) "hot tanked" what chemicals are used to do this? are aluminum parts hot tanked the same way as cast iron?

 

 

my suspicions would be NO. I just took an Edelbrock SP2P Aluminum intake and a 1968 Cast Iron intake to the shop doing my block work. Asked them to clean them both up. He hot tanked the Cast manifold after removing the heat shield underneath. He media blasted the Edelbrock...he did these differently at no request from me...

 

My understanding is that the hot tank will involve "cooking" your part in a caustic solution; i.e. sodium hydroxide and water. I believe that the temperatures range from 140 to 170 degrees F. This will strip any grease or oil off of part hot tanked. Actually you can do this on your own, just buy caustic lye at hardware stores (it will be sold as a drain cleaner) , read the small print to make sure it's sodium hydroxide, and then soak your parts at room temperatures. You want sodium hydorxide as the active ingrediant. Some drain cleaners are muriatic acid; i.e. hydrogen chloride. If you use the muriatic acid drain cleaners, this will be a disaster. The muriatic acid will aggressively attack metal. The sodium hydoxide will not attack cast iron or steel.

Once again repeat, sodium hydroxide - OK for metals like cast iron; muriatic acid or hydrogen chloride acid is not OK. If you're buying drain cleaner at hardware stores, you have to read the small print to make sure what you're buying the correct chemical--sodium hydroxide also known as caustic lye.

If you want to stip rust from iron based metals, acid will work.Actually, the hardware muriatic acid will certainly work, but the problem is that it works too fast- like minutes. You can easily damage parts. A more gentle acid is better. Try vinegar, which is acetic acid, acetic acid is a very gentle acid. I soaked the spindle/axle hubs for my rear wheels in vinegar to get rid of the rust and it did a beautiful job. Actually on a warm day, I only soaked them for about 8 hours. The vinegar was actually doing a little bit more of an aggressive job job that I thought! I was surprised to see what I assume was hydrogen bubbles as the acetic acid attacked the spindle hubs iron surfaces. The nice thing about vinegar is that you can just dip your hands into the solution to check out progress. By being able to check out the progress of your etching process, you can just take things out and wash them with water to stop the process.
Some car parts are aluminum. I don't think its a good idea to subject them to sodium hydroxide (hot dip) or acid dip. I'm pretty sure that it's a good idea to keep aluminum away from hot dip and acid dip. Maybe some other readers have comments?

 

Definitely ----- NEVER soak aluminum in a caustic solution !!! It will ruin it. Steel and cast iron will work fine in a lye (caustic) dip, but it will eat aluminum up completely if left unattended ! Rick