How to build a parts cleaning system or hot tank set up?

I'm not sure exactly what type of system they use there. The automotive machine shop I worked at used a spray wash system that functioned sort of like a cross between a dishwasher and a steam cleaner - big space with a turntable you'd put the parts in and a fixed pipe with several pressure washer type nozzles pointing into the space. whole thing had a tank that was heated and used a water/detergent solution at about 180*. Worked well to removed grease and gunk.

Solvent dip tanks might work better for some things, but you'd need quite a bit of solvent and have the fire/fume hazard. Here in CA I don't think you can really used them anymore, not sure if that's true where you're at.

I would look at what used commercial equipment costs before I tried to build a system - I think the cost of parts and effort involved in building something would make it easier/cheaper to buy a real setup, and I'd bet making a homemade system really work right would take quite a bit of effort and possibly rebuilding it several times. With a solvent tank you also have pollution/fume/fire hazard if it leaks, heater sticks on, incompatible materials, etc.

The heaters also take quite a bit of power - IIRC the cleaner at the shop I was at took something like 50A 220 3 phase, and it was that large of a unit.

I'm familiar with the jet washers that you are talking about that use solvent and hot water. I don't think they remove paint and rust though. I heard of people building systems with 55 gallon barrels, plastic containers, using tank heaters for heat, hot water heater elements, using molasses, vinegar, electrolysis, using battery chargers for current, citric acid, lye, caustic solution, attax, sodium hydroxide, Drano and much more. I heard of people using shot and blasting things, but shot can get into areas like oil passages and get loose and harm parts when ran. I don't think it will take much to come up with a container or build something, just would like to know what works great for cleaning up parts and getting rid of rust without causing damage to things. I can use it in a well ventilated area. I heard some methods are dangerous and toxic and some methods are pretty safe.

The old reliable "hot tank" is long gone and banned by the EPA.
Nasty fumes, highly corrosive, ate aluminum, plastic and other non-ferrous metals. Required many rinses to rid the residue from parts, chambers, passages etc. Either an electric or steam heated coil in a tank with high concentration of Sodium Hydroxide solution (lye). What got spilled ate through concrete and poisoned the ground, and dissolved your shoes. No telling what damage the fumes did to buildings and operators. Even bigger problem was getting rid of the sludge residue. Good ol days!!! I don't think so but it did do a heck of job of cleaning.

the best I have found is a 50/50 mix molasses and water leave in for two weeks pull it out rinse it off put back in for another two weeks if needed I have been told this only works on steel and will eat cast iron

Paul

I bought a kit about 15 years ago. It was a 55 gallon drum, with a 220V heating element through the bottom bung, and a container of this caustic powdered soap. You would mix X amount of the soap with water, and turn on the heat for a few days. I thought the parts were going to come out squeaky clean the way they look when you buy remanufactured auto parts. Far from it, the parts came out with some of the paint still on, some of the grime, and the rust was still there. It was a waste of money...

I also used to work at a transmission shop that had one of those dishwasher type units. It did not remove paint or rust.

My machinist buddy had a hot tank that would take a D9 block...ended up GIVING it to an oil field shop when he closed down. What they finally did with it, I have no idea, probably don't want to know...The stuff in it was called Oakite, which is a brand name for the caustic soda/lye OM was talking about. You can still buy it here, but you have to sign a manifest with the EPA, & you are responsible for it forever, until it is disposed of at a hazmat facility...not worth the hassle. But it did clean stuff...aluminum would completely disappear.
The machine shop I use sometimes now has one of the bake oven type cleaners, but I really don't like them. They do nasty things to threaded holes, you have to chase all the threads in a block or head to get them to take a bolt. Plus they don't get all the rust & gunk out of the water jackets.