Hi, I have a 1974 XJ12 that has been sitting for over 20 years without any antifreeze. Can anyone help a good way to clean the water system out from rust sludge and badly scaled engine please.

 

Lots of beer, for you, not the car.

One of mine was in that state, oh boy.

Radiator out.Take it to the Guru's for sorting. I recored it, job done.
All hoses, and I mean ALL hoses off, so take pictures, do drawings, whatever rocks your world. Being Carbied, there will be hoses all over the place.
Thermostats OUT.
Water pump off, it will be SAD.
Flush the heater core, garden hose pressure only, and remember the Inlet is the bottom spigot.
Remov ethe steel header tank, take it with the radiator to be boiled out.

Then with a garden hose, and an opened out wire coat hanger, I got into it, hell there was some mud in that sucker. The coat hanger is to poke up the water channels with the pump off, and that loosens the crud around the liners, especially 4,5,6 area, where it WILL BE packed like concrete.

Do this where the muck will not harm lawn, shed floor, etc, and what comes out is really sad stuff. Good weed killer but.

Took a while, hence the beer, but it got there.

There is NO magic Brew for this, sadly. Lots of Snake Oil type promises, but they usually cause more issues than they solve.

 

Hi Grant.. oh man, i really was hoping for that magic trick, you know pop in same cleaner.... walla... all done. Ok thank you for the info, now I know where im at with this thing. Cheers Troy

 

Troy,

Any brew you puor in and circulate will dump all that goop into the radiator, heater core, header tank, IF you are lucky.
The risk of over heating it are HIGH, and I dont mean the gauge, I mean the lack of good circulation in the block, and heads. The #1 V12 killer.

Sooooo, you clean the radiator, heater, header, and a week or so later, SAME thing.

It gets boring and costly.

That one I did waaaaaaay back, now has 840K Kms on it and is just a happy Big Cat.