Corsair H60 refurbishment

Team,

My first post as I've been a forum parasite for years without ever contributing anything til now. cheers to all the highly knowledgeable gurus out there who post on these things.  

I recently experienced a failure/fault in my gen1 (old school) Corsair H60 CPU cooler.

System:
i7 920 o/clocked to 4.2ghz.
ASUS PT6 MB
Ambient temp about 25deg C

Initial Symptoms:
Low frame rates / performance during gaming.  
Perceptible hot smell from case exhaust fan.

Diagnosis:
Ran cinebench while watching realtemp. The Core (not CPU) Idle temps were approx 55deg C. During cinebench CPU test it reached 100 and I stopped the test.
Radiator fan and pump were still functioning and checked with Speedfan.
Feeling along the lines between the radiator and pump it was obvious that liquid was not being pumped through at the required rate. One pipe was extremely hot, the other cold and the radiator stayed cold despite extreme core temps.
Pulling the pump pwr supply lead out while watching temps showed a steady and swift increase in core temp.

Decision:
Assumed that there was a blockage in the system or the pump was porting below required efficiency. Elected to biff H60 out the window as its way out of warranty.
Was walking through a hardware store and came across some vehicle radiator flush and coolant.
Thought I'd have a go at flushing and refilling the H60.

Removed and disassembled the pump/heat sink. I went in through the heat sink. Just have to remove the Allen screws on none heat sink face and your into the heart of the sink. Removing the bracket and the top cover gives access to the screws holding the pump into the unit. Drained the shitty smelling coolant in there. Put the flush fluid in and remounted it.

Result:
Upon pwr up there was a noise as the pump cavetated a little then went smoothly quiet. Checked realtemp, core temps were good at 40 deg C idle with the overclock.

Removed the unit again, drained the flush, refilled with 100% concentration vehicle coolant.

Remounted after a few practices to get the thermal paste looking good.

Now it runs sweet as a nut.

I think the overall cause of the low cooling efficiency was a combination of blockage by sludge formed in the old coolant and evaporation of the coolant over the last couple/few years.

With no overclock I get average idle core temp of 32deg C and about 67 to 75 deg C under full load depending on the method. (prime 95 gets hot huh).

Note for those who have problems with Corsair Hydro pump noise:
The pump impeller is driven by a magnetic system on the outside of the impeller housing. There is no mechanical connection between the motor and the impeller. It is possible that air is trapped between the impeller and the housing. This will allow the impeller to bounce longitudinally along it spin axis. It is bouncing between the bubble and the magnetic pull of the pump motor and creating a buzz by hitting the housing.

The solution is to get the air bubble out. I did this two ways. First on the flush by mounting the heatsink/pump and turning the computer over so the pump was upside down below the CPU, The copper facing up and the brand label facing down. This allowed the air to get out between the Impeller and be pushed out through the lines. It was very noisy for a few minutes, buzzing, knocking, cavetating etc. Then it got steadily quieter.

Second method during the coolant fill is to very carefully fill the coolant so that there is no air bubble. I did this by taking out the impeller, cleaning it, then when I replaced it I put drips of coolant between the impeller and its housing. This filled the void that would allow the air bubble. Then I slowly filled the coolant through the heat sink side. Took my time and made sure I had as much coolant in there as possible. I think I got it pretty much completely full as I can't hear fluid sloshing on the inside of the radiator any more.

Cheers, hope this helps someone who is having troubles with their Corsair hydro units and doesn't mind spending a day on it.