Originally Posted by Crabid
Depends on how hardy the block is, something like an apogee XT, you'll kill it with a toothbrush, I would use a fairly fine tip paintbrush on anything with small metal pins that might bend.
And yes, I use soap and vinegar on mine.
Bah. I used a toothbrush on a Swiftech GTZ which has the same delicate pins as an Apogee XT and it didn't cause any harm at all.
Since your loop and parts are presumably somewhat newer and you know the loop has been pretty clean, it shouldn't be a big deal. I had what looked like calcium deposits in my pins, so I took the copper detached from the assembly and soaked it directly in cider vinegar (not great, but was the only vinegar I had on hand) and scrubbed it with a toothbrush for 15 minutes every 45 minutes.
You should be fine just rinsing your loop. If you're concerned, unhook a hose from your CPU block and take a look down into your heatsink block and see if you see any crap there. If it looks like there is crap there, then clean it out. If it looks clean, just give it a good rinse and you should be fine.