Monsai52 asked about the power washing details so I thought I would include a couple of photos showing the products I use and like along with the equipment.
Today was warm so after I took the broken trailing arm to the welder, I started to clean the underside of the car. The rear end is out, the gas tank is out so there is plenty of access.
The products I use and like are:
Marine Clean, Aqua and Super Clean. I think these three have the same make up as they are industrial strength detergents. The only one available locally for me is the Super Clean (Advance Auto). I have tried Purple Cleaner and Green Cleaner and have not been impressed with their ability to cut through the grease. The $10 gallon of Super Clean was 10 times more effective than the $14/2gal of Purple cleaner. BTW, all of the products are biodegradable.
I mixed the Aqua cleaner, 5 parts very hot water to 1 part cleaner. Then I took a couple of scrub brushes and some scotch brite pads, long rubber gloves and crawled under the car. I scrubbed the existing dirty undercoating, etc with the brushes and scotch brite. Water ran down my sleeves and the whole process was not real effective.
I next used the Super Clean at full strength and applied with the small bottle pressure sprayer in the photo. This was essentially a prewash and it immediately started to drip dirty over the same areas I had just scrubbed by hand. I'm liking this action.!
I then took my power washer and hooked up the Super Clean to the siphon and applied another treatment to the entire underside including the back portion. I was amazed at the amount of dirt that started to drip off. I let that soak for several minutes and changed tips on the power washer to a more concentrated higher pressure. I then spayed the entire underside several times at close range to wash the Super Clean off. I cleaned until the water drops were no longer dirty.
I am hopeful that it will dry tonight and some time later tomorrow I can get underneath and start painting. I plan on using the Eastwood Rust Encapsulator paint. This is a flat black, it has great adhesion to almost any surface and can be sprayed over top with out prep. the POR15 would require a preparation of some kind for an overcoat. My painter will spray the underside with a black epoxy primer and that will apply overtop the Eastwood product. When I get the car back from the painter, I will apply some flexible undercoating.
Assuming the weather holds for us here in Atlanta (No rain), I should get the painting done tomorrow and the rear end suspension installed on Saturday.
I will take and post photos of the underside tomorrow to show how the cleaner worked.