I have a D4 7u and the radiator has a ton of rust. I’ve cleansed the top and bottom tank, but does anyone know who could clean the radiator in Northern or central California? 

any radiator service should be able to hot tank it for you. you can make your own anyway. all you need is a suitable size container, a immersion heater, some sodium hydroxide(caustic soda) and water, you could also make a agitator(air bubbler) out of some copper tube or a few plastic aquarium air stones note you want volume not pressure.

support the rad vertically on blocks blank any oil cooler ports, have the bubbler underneath the rad, have the temp set to around 45 to 50 degrees celcius and let it soak for a few hrs. you want it gently bubbling away so it loosens the crud it might take a couple of applications. blow out the core tubes between soakings with air.

remember to wear gloves and a face shield caustic is corrosive and will give chemical burns. this is also to be done in a well ventilated area.

Ok, Great. Thanks!

I would suggest you rod it out as well as the chemical cleaning. Most of Calif has hard water, so after 60 or 70 years there is a lot calcium build up on the tubes.

If you take your time not a hard job. Without soaking I have started a brass weld all welding rod and slowly tape it thru the tube. Then with the rod in the tube put another thru, until you had most of the width cleaned. In less plugged tubes I have used a piece of aluminum that was the right width and got it in one pass.

I used an ~3' long piece of Signoid pallet strapping 'tape' to rod out a Thirty radiator'.

Daron

i think you meant signet. they supply allsorts of packaging, marking and other warehousing supplies, quality at reasonable prices. but i would be careful rodding rad cores very easy to punch a hole in them especially if weakened by corrosion or cavitation