Quad G5 Liquid Cooling Pump Chugging, nasty thermal disparity between cpu's

Have completed the rebuild of the G5 LCS using a replacement Laing pump & seems to work well (note that even though the tag says Laing, it still has Delphi stamped on it !). Have 'bench' tested it to make sure there's no leaks & all seems tight. Have replaced some of the aluminum pipes with clear hoses so that I could ensure the system was filled properly & circulating. All seems ok. Used Feser One (blue) coolant, which is anti corrosion & also non-conductive, along with Feser hoses. These items are available on many over clocker websites.

Next task is to re-attach the CPU's & see if the Mac will start up (I hope the CPU's & board are ok !!).

Weblink shows the LCS testing....
http://gallery.me.com/andymac1966#100198

Cheers,
Andy

Yeah, was initially concerned about the small bubble, but having run the pump on the bench it's getting plenty of fluid head. The design isn't the most intuitive as the pump draws it's suction from the high point on the exchanger & delivers to a low point (the way it's positioned in the photos is how it'll sit in the PowerMac). As I said, the original design had no translucent pipes, so you'd never know if there was (enough) fluid in the system or not. At least I can check that easily now. Once the unit's had a chance to settle out over the next day I'll see if it'll take any more coolant (it's quite tricky as you know, given that there's no expansion tank in these systems !).

Cheers,
Andy

Hi,

I'm working on two of these right now my self. If you disassemble your old pump You"ll notice that the motor unit you'll notice it comes apart into 3 main sections; the top cover with the nipples, the bottom 3rd (springs and a couple pieces of plastic and such), and the motor third. If you look at the motor third there is a ruber gasket at the bottom, pull this out. Then take a good look at the motor third, you'll see a line, like it's made from two parts...this is half the truth. Give the thinner bottom part a good tap against a table, and it should just pop off (it's just a spacer). The original motor assembly should look similar to the Swiftech MCP350 at this point. Were not done, set the bottom black spacer aside, and push gently on the bottom of the motor section (there is a big round hole). The whole motor unit should pop free of it's housing now. Turn it over and you'll be able to see the contacts. If the Swiftech MCP350 motor is in fact the same motor, you should find the same contact setups inside of it as well. It should at that point just be a matter of soldering the wires from the original motor to the ones on the Swiftech MCP350.

If your pump as leaking, and you just want to try and fix it, go ahead and take apart the motor as explained (no need to separate the spacer though unless you really want to dry it out). At the top of the motor (under the nipple cover) you'll find a gasket running around the motor. Pull this out and head to the hardware store for a replacement (or RTV the crap out of it...totally up to you). You'll notice that the top cover is completly smooth...that's why they leak.

Thanks greasemonkey80,

I did pull the old pump apart as you've described. Looked like it had been leaking for some time as the 4 springs were well corroded & broken. I never though about using the old motor assembly in my new pump though. Too late now as it's all built & refilled. Just at the stage now of bolting the CPU's & heat-sink back onto the logic board (need to go out & get an extra long allen wrench to complete !).

Do you know why the original Delphi has the 4 wires ? As I said in an earlier post, my new pump has only 3, so I'm not quire sure how it'll pan out when I power things back up. I had hoped to get some further detail from the Apple Service Manuals for the G5 PowerMac, but it doesn't really give that much away.

Cheers,
Andy

Sorry about the spelling mistakes guys I wrote that in a hurry.

I really don't know why the original had the 4 wires. My guess would be temperature or RPM maybe? I managed to rebuild my pump with a slim 2" slip joint washer, RTV, and a lot of swearing. The pump it's self is not to bad, but getting the hoses back on it and filling it up was a major pain. Regardless I've got one of them back up and running...with no leaks! I'm going to wait a while before I try re-assembling the second one (already did the pump but inadvertently messed up my radiator...dropped it on the way down the stairs, also bent one of the water blocks). So if anyone happens to have a spare assembly their looking to sell (even if your pump is shot) I'm in the market 🙂

Thanks for all the help in this thread, you especially andymac, I wouldn't have figured out where the leak was if it weren't for those great pictures and the link to the Swiftech MCP350. Thanks much.

For anyone who comes across this thread trying to fix a leaking G4 Power Mac 2.4 Dual, I'll get the link for rebuilding the pump as soon as I can get it written, and photos taken.

Argh ! Looks like I'm back to the drawing board with the G5. Got it all back together again, but looks like the PSU isn't working. Machine is dead aside from a clicking sound (at rear of machine) it makes when I first turn it on at the wall socket.

Checked the power terminal from the PSU to the logic board (left hand one) and there's no voltage across pins 1 & 23, there should be 5v to trickle to the logic board. Disappointed as I wasn't expecting that one as the PSU was working ok when the machine locked up on overheat originally....

Not sure if I'll carry on from here as I can see this becoming a money pit !!

Cheers,
Andy

You are not clear if your machine is in fact leaking. If it is showing evidence of leaking, call Apple Care. They have been known to repair them, even out of warranty. You may need to get to the second level tech support and they usually have to check with someone, but I have heard that they do repair some, depending on the circumstances. It's worth a try anyway.

Hello,

I just made the transitional jump from the G4 MDD dual 1.25 to a Quad Core G5 machine. I just purchased it for a nice 1000.00 bucks and I am really looking forward to it. All this stuff I am now reading about liquid cooling leaks and stuff has me really concerned. I spoke with the seller today and they have on-site macintosh techs in the computer center and she told me that the quad core G5's have all been tested and NONE OF THEM HAVE LEAKING PROBLEMS.

Now, I did read somewhere on the net that cooling problems were mostly on the older G5s - someone correct me if I am wrong, but is it very rare that the last of the G5 quad cores rarely have leaking problems?

I am a little concerned.

And my plan was to keep this machine until I expand it to 16GB and then to trade it in, using the rest of the money to finally go into a Mac Pro, but low end.