I am going to do a job on a Jeep 3.1 diesel that the oil cooler has blown and oil gone into the coolant. Need some ideas how to get the oil residue out the water jacket, radiator,heater and so on. I am thinking of flushing the whole system out with some sort of detergent, when I have repaired the oil cooler of course. I will check the old oil cooler out to make sure that that was the problem.

I would say sodium hydroxide, but that will attack any ali in the system, very aggressively.
washing powder may work OK though......

I like the idea of liquid clothes detergent. Still open to ideas though.

I swear by Forte BioDegreaser

Only thing I've ever found that get's rid of oil in a cooing system. It might need treating twice if it's really bad but it would have to be almost solid emulsified cream for that. One dose and a good flush out usually does the trick.

Another vote for the Forte Bio Degreaser, I normally use 2 bottles in the cooling system when there's a lot of oil in the cooling system

wash powder works well used it in my mates 206 to clean out after oil ingress in water system

You want to use an non-foaming detergent. Don't use strong alkali or the aluminium components will corrode badly.

Dishwasher tablets have bee used by some with success but Shout laundry detergent is recommended by many.

In recently used Vanish liquid to clean alloy wheels and it was very effective.
Whatever you use to degrease do a final flush with weak citric acid solution then water flush Citric acid is cheap to buy off eBay.

As this is the 3.1 vm engine i'm guessing i would make sure it really is the oil cooler 1st....its not usually! And if the oil coolers gone and it gone and its got hot one or other if the heads will be leaking.....if its not yours dont get involved.been there its a never ending nightmare.