Working on the G5 quad liquid cooling system

nospoonzz,

From what your saying, your system appears to be a Cooligy version. It SHOULD however have two separate chambers inside the radiator for "A" and "B" cores if it has two pumps. Identification of two separate chambers is not visible on the outside of the radiator. The only way to know, is by draining one of the pumps. If you get only 125 ml of fluid out, it's a dual chamber set up. The radiator should have a total fluid volume of around 250 ml of fluid. When I drained the "B" side only, I got only about 1/2 that, 120 to 125ml of fluid out. This is how I know mine has two radiator chambers.

How much fluid came out of yours when you initially drained it? The fact that you say your radiator has a single reservoir IS very interesting! I have never heard of a Cooligy dual pump having a single chamber radiator. 😮

Apple moved away from the single pump and single chamber radiator in late 2005 because of coolant leak problems. I do know that at some point they went back to a single pump design later. It makes more sense for it to be dual chamber. If the fluid was to evaporate slightly in your single chamber radiator set-up, I would think the "A" cores would overheat first since they are above the "B" cores. I believe that's why Apple designed the dual pump with dual radiator chambers. Each pump has "VC which compensates for higher or lower fluid in the cooling system.

It's possible Apple may have made an earlier, later or mid-version of the Cooligy cooler, with a single chamber radiator design and two pumps. That's why it may help if you could find out the build date of your machine. The date may explain better the reason for the single chamber dual pump design. Sounds like your's is some sort of hybrid interem design. 😎

I do not know how much water came out of it. When I flushed it, I did it in a large automotive drain pan. I connected a turkey baster to the inlet hose on right side of pump that I had already filled with distilled water.

Then I let a long piece of hose lay in the drain pan that was connected to the left side of the radiator. I flushed

this way for a while till the water was clean and clear. Then I switched sides and water was clean and clear. So I am confused. I did fill my radiator only with distilled water but then switched to a blended distilled water and GM coolant <orange stuff> mix. I did ad a "T" fitting that time around and I think that is the best way to make sure you have absolutely no air bubbles.

Hmm… strange indeed. Next time you flush it, ( if there is a "next time") you could replace just the upper (short) pump-to-radiator hoses with some clear type. Then you whould know for sure since your coolant is colored.

My guess is, that you it might have slipped by you somehow. Then again, maybe you own a hybrid Cooligy LCS!!! "Only your hair dresser knows for sure." 😝

Fantastic idea. I think I will do that. Replace my hoses with clear hoses. Any idea which are the best?

Sure,

This is what I used:

3/8 ID Tubing Replacement: Tygon brand (placticizer free) clear reinforced. (Note this hose may be too stiff for use on the single pump configuration but will work on the G5 dual pump version.

Here's the link below to where I got mine.

http://tinyurl.com/leo5o44

I have the Cooligy version. How do I get this core out? I removed 4 screws near the rear fans and 2 near the front fans but it remains firmly stuck. I found some instructions on ifixit that illustrate removing a different core that uses 8 screws. I can't seem to locate the additional screws.

I've also seen references to the ASD 2.6.3 disc needed for thermal recalibration. Where can I find this?

Thanks.

Update. I got the cooligy cooler/cpu core removed. I needed to get a ball-head hex for the remaining screws. The unit looks very clean. No leakage visible. No crystallization.

I opted to install a 2nd core with the single pump design, same quad processors & speed. Then I'll look over the first core more later. But I'm coming up with the same #2 & #7 diagnostic LEDs as before. CPU A overheat? The system might get to a grey screen, maybe the apple logo, but never further.

I also tried reseating the RAM, changing sticks, using a minimal configuration. PMU reset. Still after the boot tone, #2 followed by #7 and then freeze up.

Suggestions?

I've also seen references to the ASD 2.6.3 disc needed for thermal recalibration. Where can I find this?

Yes,that is what you need,but was not available to the public,so if anybody did have any clues, your eMail is marked private in your profile.

Thanks. I made some changes and appreciat any help with the ASD and my Quad core problems.

Is it possible to boot without the CPU-A board installed? Would that help determine if it's the CPU overheating or if it's a logic board issue?

No, it can boot without the 2nd CPU, but not without the 1st one.

If I can't get this Quad Core revived, which old intel PowerMac/OSX combo can still run PPC/UniversalBinary apps?

10.6.8 is the last OSX to use Rosetta for PPC emulation, I think the newest Mac Pro that can run 10.6.8 is Mid 2010.