Hey, everyone. I love the G5, not very rare or valuable, but one of my favorites. I bought a late-2005 quad a while ago and just got around to opening it up. I was wondering if anyone could identify the type of cooling I have and its reliability. I know it's a Delphi one :( but wanted to know if I had the epoxied version or not. In the pictures, you can see a substance around the edges of the (pumps)? I don't know if this is epoxy or the "O" ring. Also, is there a gold-standard type of guide that someone has made for changing out the Dexcool inside? Thanks in advance for the help!

P.S: The first thing it needs is a good cleaning, i'll be getting to that shortly..

To me, that looks like epoxy, not crystalized coolant. Way too smooth to be crystalized coolant. This is what mine looked like...



The only guides I have seen are for one of the other variants on a non-quad. I have both versions of the non-quad assemblies (dual pump - fat radiator, and single pump slim radiator), I have never seen this quad version before.


A guide to replace the coolant

@phunguss Awesome, thanks for the link and for the help! I'm sure that it's the same basic concept no matter which version you have.. so that guide should work great.

I just picked up a G5 Quad and I found this thread on cleaning it.

@epalama1 not sure how far you have gone... just a warning to not go too far on this LCS. If you do NOT have any visible signs of a leak, you may not want to open it. This was my only sign of corrosion, which may be from condensation.



My G5 quad does not boot all the way, I can get ASD to boot but it soon freezes... the top pump is warm to the touch. I was suspecting a pump or coolant blockage, so I delved into the flush and rebuild.

I simply cut the 4 top hoses coming out of the pumps and drained it into a bucket. Poured it into a drinking bottle to look at sediment. There is some cloudiness there.


Into the wash tub, and filled an one gallon bucket with hot water and vinegar, run the pumps with an old UPS battery.


Both pumps seemed strong and similar level of acoustics, so assumed they are both good. This power pinout is from another site:


There was more sediment from the vinegar flush.


The next rinse was just hot tap water. I know I should rinse with distilled water, but I have to check some other things first. I removed the cut off pieces of original tubing, to find the pumps have a 0.25" inside diameter. The radiator also has 0.25" ID. However, the long S-tube has what I consider a flow-restrictor or some type of noise reduction device? A long silicone string held in by two plugs.


The ID of the plug is 0.18", so close to a 50% reduction in orifice surface opening per inches-squared (0.1963 vs 0.1017). I had to remove the S-pipe from the CPU block, and found the accordion tube is covering a silicon sleeve. The opening on the CPU block is also 0.25".


Trying to figure out a way to refill this closed loop when there is no tap on it. I carved off the rubber on the black radiator pin (see above pic), but there is a hard white plastic pin underneath it. I didn't push further. I figured I could get something to work if I put a tee in somewhere. Looking at the S-pipe, it also has a black rubber pin (assuming it has a hard plastic pin underneath, seen in same photo above).

Engineered correctly or over-engineered to not leak as much, this is definitely a very tricky LCS: silicone sleeves, weird inserts, and useless epoxy that is not actually sicking to rubber or metal.

@phunguss Wow! Yeah I haven't even started taking it apart. Everything seems to be working fine, my G5 boots normally and, although still loud, fans get quieter after boot. I appreciate all of the pictures and really thorough description. Not for the faint of heart. It's like you risk destroying the thing in trying to save it... wonder if Apple ever had any official documentation on this process, although it's not like they'd release it.