Working on the G5 quad liquid cooling system

I have a G5 quad with the one pump Delphi LCS ("version 1"). I'm guessing the LCS is clogged because when the machine sits idle (even in reduced CPU setting, which cuts the GHz in half), the fans and the pump slowly, over several hours, go to full speed. Temperatures of CPU B, particularly the second core, shoot to near 100C when loading the CPUs. ASD 2.6.3 usually passes, but sometimes ends in checkstop and overtemp. A local mac service center, which I had the machine checked at (in hopes of getting free repairs because of a leak), said it's fine.

As a simple first measure, I tried replacing the thermal paste on the CPUs, with little effect. The LCS didn't seem to be leaking or corroded anywhere, but when handling it, it sometimes made a bubbling noise, so, there's probably air in there. I thought I'd take the LCS apart next, but before that I have some questions which I hope someone can answer.

Which one, the upper or lower, is CPU A and which is B? I've read the machine runs on one CPU just fine, but which one?

If I switch the CPUs the other way around and later switch back, does something in the nvram reset so that thermal calibration needs to be run? I'd rather not run it as it seems to have mixed success.

What material/size are the CPU block O-rings on this system?

If I use a vacuum pump on the service valve (I gather it's of the "r134a high" type(?)), what would be a safe level of vacuum? Has anyone tried using the manual brake kits, or car cooling system refill kits that use compressed air and venturi valves, on the LCS?

I suppose I'm just going to try attaching a hose as a reservoir to the service valve and fill through that first, but if that doesn't bring satisfactory results, I'll level-up to some sort of vacuum method.

PowerMac

Posted on Sep 17, 2011 11:59 PM

252 replies

Jan 26, 2012 1:39 PM in response to Heikki Lindholm

Heikki Lindholm wrote:

Just to make sure the confusion doesn't arise again: these pictures are from a "version 2" of the Quad G5 LCS (mine was "version 1", which in turn is a 2nd generation Delphi unit).

Now I'm a bit confused again.

My particular G5 Quad was made late in June of 2006, shortly before the Quad was discontinued the first week of August of that year. Since it was manufactured during the last five or six weeks of its production, I would think it's safe to assume it has the last version of the LCS, presumably what you're referring to as "version 2".

Hardware monitor is reporting only one pump, not two.

So, is the "version 2" LCS the one with one or two pumps?

Frankly, this may be only an academic question, since the problematic pumps, whatever they are called, do not seem to have ever been used in any G5 Quad models, only in some of the G5 Dual Core models.

http://www.everymac.com/systems/apple/powermac_g5/faq/powermac-g5-liquid-cooling -info-leaks-issues.html

Which Power Mac G5 models use liquid cooling? Which Power Mac G5 models have been reported to have problems with the liquid cooling system?

Users with any liquid cooled systems -- but particularly users with Power Macintosh G5/2.5 DP (PCI-X) (June 2004) and Power Macintosh G5/2.7 DP (PCI-X) (Early 2005) systems -- in active service would be wise to carefully watch for internal and external leaks and if a leak or temperature anomaly is discovered immediately shut it off and notify Apple or an Apple Authorized Service Center.

Jan 26, 2012 2:23 PM in response to Ramón G Castañeda

Oh my... 😉 Yours is a version 1, with one pump. The "version 1" and "version 2" naming comes from Apple's service manuals. I think it could as well be "version X" and "version Y", or be the names of the manufacturers, meaning that you shouldn't consider "version 2" to be something improved or later than "version 1", just different.

I haven't seen reports on the Quad LCS actually leaking, either version. However, they do suffer from coolant clogging (corrosion inhibition package going out, dyes breaking down) and evaporation, and, sans the factory refurbished units, they are starting to be at the end of their designed lifetime. Another potential problem is the Laing DDC-2 pumps in some of the Quads (my version 1 LCS had one) which are, according to the PC water cooling people, fairly unreliable.

It was not the pumps that were troublesome with the Dual CPU units but more likely the corrosion inhibitor not working as well as expected and strong galvanic corrosion caused by aluminium and copper in the units. It looked like corrosion products clogged the copper fins in the heatsink which caused pressure leading to leakage through the O-rings. Some units also leaked through the pump's volume compensator, which I hear was a fault in some batch of the DDC-1VC pumps.

Jan 26, 2012 2:40 PM in response to Heikki Lindholm

Thanks, Heikki.

From what I can distill from your elaboration, there's no point in my worrying about the LCS in my Quad until something happens, which is about par for the course for most five-and-a-half-year-old machines.

On a related subject, an independent technician who worked on my G5 Quad to replace its damaged case and who represented himself to be both Apple Certified and a former Apple employee who actually worked in Apple manufacturing at the very same factory in Elk Grove (Sacramento), California, where my computer was made, claimed that Apple had gone to the Panasonics pump on the G5 Dual (not Quads) after early leaks were reported but eventually abandoned Panasonics and went back to Delphi because "the Panasonics pumps did not perform as they had hoped".

Jan 26, 2012 3:58 PM in response to Heikki Lindholm

Heikki Lindholm wrote:

…I haven't seen reports on the Quad LCS actually leaking, either version. However, they do suffer from coolant clogging (corrosion inhibition package going out, dyes breaking down) and evaporation, and, sans the factory refurbished units,… [emphasis added]

Would said "factory refurbished units" have been produced.assembled/sold after the production of the G5 was discontinued? Or is there any room for hoping that the technology involved in those would have been incorporated into the manufacture of my G5 Quad that was made towards the end of the G5 Quad production run?

A different but very important question, if my G5 Quad LCS actually fails, is there a source for a refurbished unit? Price would be irrelevant, as I need both the PPC architecture in OS X* and Classic, so I'd be willing to pay more than a new Mac Pro would cost.

* The PPC architecture is needed in OS X to run things like Grain Surgery 2, the unparallelled, unequaled set of film grain filters ever developed to this day on any platform and which Adobe bought from Visual Infinity only to kill it right away, without providing anything remotely resembling a decent alternative. http://www.plugsandpixels.com/grainsurgery.html

Jan 26, 2012 11:14 PM in response to Ramón G Castañeda

Ramón G Castañeda wrote:

Heikki Lindholm wrote:

…I haven't seen reports on the Quad LCS actually leaking, either version. However, they do suffer from coolant clogging (corrosion inhibition package going out, dyes breaking down) and evaporation, and, sans the factory refurbished units,… [emphasis added]

Would said "factory refurbished units" have been produced.assembled/sold after the production of the G5 was discontinued? Or is there any room for hoping that the technology involved in those would have been incorporated into the manufacture of my G5 Quad that was made towards the end of the G5 Quad production run?

This is just an assumption on my part, but I assume that units that had the "Processor" (meaning CPU cards + LCS) replaced due to either the CPUs or the LCS breaking down, got an LCS in pristine condition and thus ready to last the same amount of years as the original, except from the date of repair. So if a machine got such a repair done, say in 2010, it would last quite some years longer than machines in original condition. I also assume factory refurbished LCS Macs have had their LCS checked/flushed&refilled.

A local service tech here told that there are still parts available for the latest/last generation of G5 Power Macs. I haven't tested that claim, yet.

I was (un)lucky enough to stumble on pretty much every stone while overhauling my machine, so I had to find out various bits of information, and yes I had some truly gold sources. I'm also motivated to keep the thing going as long as the electronics don't fail. I have an early core2 macbook in addition to the ppc macs, but it, in practical user experience, actually delivers LESS than my old powerbook 667MHz DVI! And that's with 2.5 times the RAM of the powerbook. I think it can mostly be blamed on the intel GPU - theoretical "geekbench" scores and such don't always mean a squat.

And Ramón, I think preventive maintenance would have been the key here, say flush and refill the LCS every 3 years, but since no Apple service tech I know of implements such a service, you're pretty much stuck waiting for the thing to start showing signs of failure, or take matters in your own hands, which carries the obvious risks of DIY.

Jan 26, 2012 11:45 PM in response to Heikki Lindholm

Thank you for your further elaboration, Heikki. Now your previous posts are crystal clear.

Coincidentally, I have recently inherited a 2-GHz 13" "mb_late_06" MacBook2,1 made in May of 2007 and discarded by my wife after the idiots at the local genius bar told her it was damaged beyond repair, when in reality all it took was replacing the badly swollen battery that was pushing against the track pad with a $30 generic battery from Amazon.

So much for relying on Apple for repairs of legacy machines. 😝

Jan 27, 2012 4:16 PM in response to BDAqua

Funny you say that. Apple had to replace the logic board on my 2.2Ghz C2D MBP. Fortunately they did so 3 years after my purchase at no cost. Apparently I had Applecare. Maybe I just forgot but boy was I happy to not pay a cent at that time.

Jan 27, 2012 5:02 PM in response to japamac

Ah yes. I remember explaining that issue to them. A cousin of mine actually had flickering and whatnot so he had his card replaced by Apple. However, my MBP never had strange flickering or any obvious tell-tale signs of a failing GPU. My MBP would have trouble starting up occassionally. Then it progressively got worse to where the computer would only turn on when it was very cold. Then it reached a point where it would only chime, leaving me with a black screen. The service techs were never able to get the MBP to turn on so they just replaced the logic board. Problem solved.

Jan 28, 2012 1:00 AM in response to japamac

japamac wrote:

On the MacBook? 😮 Really?

http://www.tuaw.com/2011/03/08/have-a-macbook-pro-with-a-faulty-gpu-and-no-apple care-you-may-s/

Thanks, but that's not what I have. I have a plain vanilla MacBook, not Pro, and it has the Intel GMA 950 display… with a whopping 64 MB of shared system memory. 😀

Message was edited by: Ramón G Castañeda

Jan 28, 2012 1:23 AM in response to Ramón G Castañeda

Going OT here, but... These older macbooks had generous amounts of thermal paste applied. Really generous. Mine was overheating and producing an awful smell of burnt something. I opened it to find...generous amounts of thermal paste. Replaced the paste with a saner amount and cleaned out dust. Now it works nicely, and the temps went down 10 C or so iirc. I also had to throw out a bulging battery and now run the thing without one.

Feb 4, 2012 8:54 PM in response to Ramón G Castañeda

Just wanted to give you all an update. I was able to order all the new tubing, clamps, coolant, and thermal compound that Heikki recommended on his site from Sidewinder.

I have just finished draining the coolant and do not like what I see. In the pictures, you can see that the coolant was changed by Apple in the revision of the system. The fluid is still water-like in its viscocity and has the signature "fishy" anti-freeze smell. I drained almost 200mL. Unfortunately, as you can see, there was particulate matter that also removed from the system. The clear/yellowish bits are probably from the sealer/adhesive connection around the tubing but the red and black matter are from the inside of the system. I plan to use Prestone radiator flush clean the aluminum components and discarc the rubber plastic tubing.

I found it interesting that Apple used this very elastic tubing inside these flexible plastic hosing bits found on the underside of the radiator.

I also found it interesting that Apple essentially sealed off these aluminum ports found on the topside of the radiator but still used a heavy amount of sealant around them and capped them off with rubber caps.

Feb 4, 2012 11:13 PM in response to Chris323i

I'd expect the black bits to be corrosion products from the CPU blocks. In the version 2 LCS, the copper blocks are not plated as they are in the ver 1 LCS. The coolant is probably not the same also because of this. Vinegar should help with the CPU blocks, but since they can't be opened, it can take some time. For the aluminum rad, the most important factor seemed to be heat, e.g. boiled water, not chemicals. I'd apply heat with the Prestone as well.

The CPU blocks need to be able to move a bit to properly seat the cards (and the MB), hence the elastic tubing I suppose. A very short piece of the heavier hose might not give in much. You don't want the blocks to be so stiff that the CPUs either don't seat the MB anymore or rip the MB CPU connectors off when seated.

I'd replace the aluminum ports/stubs on the rad with valved ports for easier maintenance in the future and for much easier refill/bleeding.

Feb 10, 2012 9:50 PM in response to Heikki Lindholm

Finished attaching the hoses. 1/4" ID hoses are vinyl with the larger 3/8" ID hoses being Tygon. I went ahead and added RTV water pump sealant to all tubing connections similar to what Apple had done with the epoxy. I know it wasn't necessary but I'd like to have that extra bit of assurance in the back of my head. I still need small clamps for the copper blocks but that's really about it. I'm waiting the designated 24 hours for the sealant to cure before I fill it back up with fluid.

I went to my local Lowes and I was unable to find a bleeder valve similar to what you had Heikki. The closest thing I was able to find were some 3/8" ID fuel shut-off switches in the lawn mower department of all areas. I had to saw off the two ports at the top of the radiator to attach these switches with more vinyl tubing.

Also, if it hasn't been noted before, the radiator is closed off into two separate systems which explains why I had to use two switches. I guess this makes sense since the upper processor would overheat much quicker once the coolant level dropped (which seems to be the main culprit of the overheating issue since I wasn't able to extract much more sediment with several subsequent flushes with boiling water).

Feb 10, 2012 11:24 PM in response to Chris323i

Nice work and good info, Chris. As for the r134a valves and adapters the version 1 LCS uses, they are specialised equipment and only found from air conditioning service equipment suppliers. They are overpriced and overspecced for the job. I'm sure Apple/Delphi used them, because the A/C service stations have them and are a good fit for purging/filling the LCS. Lacking such service station, they are of no benefit for the DIYer.

Home improvement stores probably won't carry much good stuff for the LCS project. I shopped most items from hydraulics suppliers (like a local Parker Store). They usually have variety of connectors and valves as well as good quality hoses. The lawn mower fuel valves look like a good idea, and not costing an arm and leg as well.

Just for the record, I used black rubber hose because (1) opaque hose prevents algae growth and "seeing" the bubbles/coolant is of no benefit; the pump noise is a better indicator of air and (2) heated coolant makes plastic tubes leach plasticizers which form a film everywhere. The rubber hose also seemed to create much tighter seal with the barbs than PVC. PVC especially, once removed and reapplied to a connector, doesn't work very well as it deforms from the first application.

Feb 11, 2012 1:49 AM in response to Heikki Lindholm

Thank you for sharing your most valuable insights, Heikki.

Reading about your project(s), however, leaves me with the certainty that all that would be well beyond my capabilities, as I'm all thumbs when it comes to work like that, and my old-geezer hands not that steady. It would be great if you or anyone else could share some leads into where one might find a technician willing to do this kind of refurbishing of the LCS. Cost becomes secondary when you are as committed as I am to the G5 Quad on account of my absolute need for the Classic environment.

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Working on the G5 quad liquid cooling system