Heikki Lindholm

Q: 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

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Q: Working on the G5 quad liquid cooling system

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  • by Ramón G Castañeda,

    Ramón G Castañeda Ramón G Castañeda May 31, 2013 6:01 PM in response to G5Lover
    Level 4 (1,468 points)
    Desktops
    May 31, 2013 6:01 PM in response to G5Lover

    Thank you for posting this.  Glad I never knew Apple had used rubber bands to assemble its most advanced computer at the time. 

  • by G5Lover,

    G5Lover G5Lover May 31, 2013 6:06 PM in response to Ramón G Castañeda
    Level 1 (0 points)
    May 31, 2013 6:06 PM in response to Ramón G Castañeda

    Yes Ramón it's true!

     

    And in the interest of keeping it as close to original as possible, I re-installed new ones!

  • by Patrick 01,

    Patrick 01 Patrick 01 May 31, 2013 7:57 PM in response to G5Lover
    Level 1 (80 points)
    May 31, 2013 7:57 PM in response to G5Lover

    My issues were solved ( cpu temps uneven) by replacing the thermal paste with MX-4

    Now they are all the same or off one or two off by 1 (fans & pumps are fine checked in istat pro)

     

    Anyways . . .

    What happens when our power supplies fail?

    Then what?

    My MDD's are all running ATX psu's, I'd think the quad won't be as easy

  • by Ramón G Castañeda,

    Ramón G Castañeda Ramón G Castañeda May 31, 2013 8:11 PM in response to Patrick 01
    Level 4 (1,468 points)
    Desktops
    May 31, 2013 8:11 PM in response to Patrick 01

    Patrick 01 wrote:

     

    …What happens when our power supplies fail?…

     

     

    Repair them or replace them.

     

    Or am I not understanding your question? 

  • by G5Lover,

    G5Lover G5Lover May 31, 2013 8:19 PM in response to Patrick 01
    Level 1 (0 points)
    May 31, 2013 8:19 PM in response to Patrick 01

    My issues were solved ( cpu temps uneven) by replacing the thermal paste with MX-4

     

    Patrick,

     

    You got lucky with that simple repair. Most people that have tried just replacing the thermal grease didn't get off that easy. They ended up finding they still had to flush and fill the system to get it to cool properly.

     

    Congrats! MX-4 is good stuff. That's what I used when I put mine back together. All is well now. The machine runs quiet and cool.

  • by Patrick 01,

    Patrick 01 Patrick 01 May 31, 2013 9:29 PM in response to Ramón G Castañeda
    Level 1 (80 points)
    May 31, 2013 9:29 PM in response to Ramón G Castañeda

    Ramón G Castañeda wrote:

     

     

     

    Repair them or replace them.

     

    Or am I not understanding your question? 

    repair would be nice, but as in my MDD's it would be nice to enable a new atx psu than replace it with another 10 year old aging psu.

     

    Just pointing out that there is not much info on the above unlike the LCS repairs.

  • by Patrick 01,

    Patrick 01 Patrick 01 May 31, 2013 9:31 PM in response to G5Lover
    Level 1 (80 points)
    May 31, 2013 9:31 PM in response to G5Lover

    G5Lover wrote:

     

    My issues were solved ( cpu temps uneven) by replacing the thermal paste with MX-4

     

    Patrick,

     

    You got lucky with that simple repair. Most people that have tried just replacing the thermal grease didn't get off that easy. They ended up finding they still had to flush and fill the system to get it to cool properly.

     

    Congrats! MX-4 is good stuff. That's what I used when I put mine back together. All is well now. The machine runs quiet and cool.

    The old stuff was dried out and gooped on.

  • by G5Lover,

    G5Lover G5Lover Jun 1, 2013 10:19 AM in response to Heikki Lindholm
    Level 1 (0 points)
    Jun 1, 2013 10:19 AM in response to Heikki Lindholm

    Replacing your G5 pump or pumps with a new N.O.S. Laing DDC-1T from BMaverick:

     

    For anyone wanting to know how to connect the wires from the connector of a new Laing DDC-1T pump, (purchased from BMaverick, AKA-BMav) to the factory G5 connector. Here is the pin-out mapping chart below showing both connectors. I got this from a fellow G5 owner that successfully replaced his pump with a new one from BMaverick.

    PinoutConversions.png

     

    Note: The BMaverick pump connector has a number "1" on one side of the connector as a reference of where to start the numbering it.

     

    Here's the link again to new BMaverick Laing pumps that will work on the G5 single and duel pump LCS Quad. http://bmaverickddcpumps.wordpress.com/buy-ddc-pumps-here/

     

    Remember to check to see if your original pump has VC (volume compensation) or not. If your pump has VC, you will need to modify the new pump for VC also. You can find those instructions here. http://www.saunalahti.fi/~holindho/g5-quad-v1-lcs-repair-pump.html

  • by G5Lover,

    G5Lover G5Lover Jun 2, 2013 7:25 PM in response to Heikki Lindholm
    Level 1 (0 points)
    Jun 2, 2013 7:25 PM in response to Heikki Lindholm

    I'm putting this list of rebuild products on this forum in one place to save other's the time I spent researching specs. Below is a listing of the products I believe to be the best choices for rebuilding my G5 duel pump LCS. I used all these products on the list below except for the Laing pumps. My pumps are still working fine so I did not install the new pumps. Though I did buy two pumps from BMaverick in case mine go out in the future.  I talked with a guy that used one of Bmaverick's pumps to replace the pump on his G5 and said he had great success.

     

    There are many other opinions for different products out there on the web but after doing the research and talking with others that had successful rebuilds, the products in the list below were the ones I ended up using. I used them because of their good track record and specifications not because of their price. All of them worked fantastic for me, and I'm now enjoying my cool running G5 2.5 GHz Quad duel pump LCS.

     

    ITEM LIST WITH LINKS:

     

    Thermal Compound: Arctic MX-4 advanced formula with an 8 year durability service life.

    LINK: http://tinyurl.com/k588vxo

     

    Thermal Compound Cleaner & Prep: ArctiClean 60ml Kit (includes 30ml ArctiClean 1 and 30ml ArctiClean 2)

    LINK: http://tinyurl.com/ltg7f53

     

    Radiator Flush: Zerex Super Radiator Flush (kind to aluminum radiators, multi-metals and plastics) USE SPARINGLY. remember, the 22oz container was meant to be used in an automobile radiator with 4qts of water! The LCS only holds about 250 to 275ml of fluid total! I mixed about 25ml of it to boiling water to do the flush.

    LINK: http://tinyurl.com/os2t3bv

     

    Replacement Pumps: New Old Stock Pump, Laing DDC-1T (NOS) from BMaverick:  For G5 duel pump system. This pump will work on the G5. (Some modifications will be necessary)

    LINK: http://tinyurl.com/ma43zkj

     

    Replacement Coolant Used: Koolance LIQ-702 Liquid Coolant Bottle, High-Performance, 700mL (UV Blue) good for 3 years before refreshing.

    LINK: http://tinyurl.com/k6gnthh

     

    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 duel pump version.

    LINK: http://tinyurl.com/leo5o44

     

    1/4" ID Tubing: Clear Tygon brand tubing for the addition of a shut-off filling valve on the radiator.

    LINK: http://tinyurl.com/mpvha2l

     

    Epoxy Waterproof Putty: JB WaterWeld, Used for sealing the ends of the hoses similar to what Apple did on the duel pumps. Note: "This step was done at the factory only on the duel pump G5's It's not absolutely necessary but a good insurance against leaking."

    LINK: http://tinyurl.com/n7zeak4

     

    Shut-off service valve: Brigg's & Stratton brand for fuel line in lawnmower. (install on radiator stub off ports to assist filling the system-two required for Duel pump LCS.

    LINK: http://tinyurl.com/kzskqpn

  • by nospoonzz,

    nospoonzz nospoonzz Jun 9, 2013 7:13 AM in response to Heikki Lindholm
    Level 1 (0 points)
    Jun 9, 2013 7:13 AM in response to Heikki Lindholm

    Just wanted to say Hi !  Also would like to take the time to thank every one whom had anything to say on this post. The information was so great.  My Powermac G5 Quad <Late 2005 > was overheating. At idle it would see over 65 celcius accorss all the provessor cores sometimes they would reach over 70 degress celcius. This was at idle. During heavy use my mac would freeze, hard lock. So last night I took apart the G5 Quad and inspected the LCS and CPU's. I took most of the original metal Pipes Apple used and replaced them with preformed coolant hose from my local parts house. Before that though I should add, I flushed the whole radiator and LCS with a 50/50 mix of viniger and very hot water. I did not stop the flush process untill all was clear and clean. I must say my sstem was kinda dirty. The Apple coolant that came out was pink and I did note that there was an abusive amount of silicon used when the original metal pipes were put on , so much so that threre were clogs through out the pipes. I tried using some wire and pipe cleaners to clean them out it helped. However i did not have a lot of paitence so I just took out my die-grinder and cust the pipes off, replacing them with preformed hoses for automotive use. Then I filled my system with distilled water only. I used a new Turkey baster. I kept injecting water through one hose <inlet > until water from the other  hose on the opposite side <outlet came out. The first time I did this there was a lot of air. A lot. I repeated this sterp on both pumps <mine is a dual > until all the air was gone. I am confident my bleeding worked. As I sit here typing this my G5 is idling at 39 degrees celcius on all processors. I am so happy. Oh,IMG_0044.JPGIMG_0043.JPGIMG_0046.JPG I did use Antec Diamond Compund as a thermal paste on the CPU's Everything has turned out fantastic. Wonderful people here on this board. Thanks again. All of you !

  • by G5Lover,

    G5Lover G5Lover Jun 9, 2013 10:06 AM in response to nospoonzz
    Level 1 (0 points)
    Jun 9, 2013 10:06 AM in response to nospoonzz

    Congratulations on your success! By your description, it sounds like you had some serious electrolysis and radiator dye residue build-up going on in your LCS.

     

    My G5 Quad duel pump had similar overheating symptoms, (one processor always warmer by 30º) but not quite as high temp diffs. as yours. Over 70ºC is very bad and will usually burn out a processor. You got lucky that you didn't loose the processor. Glad you were able to stop this with your repair but IMHO, I think you should have used a good 3 year multi-metal compatible pre-mix LCS coolant like Koolance 702 rather than just distilled water. Simply using distilled water will allow the different metals in your LCS to go into full galvanic corrosion. For example the (copper and aluminum). This will start causing more problems sooner.

     

    However, it's not too late. I would recommend re-flushing the LCS with Zerex Super Radiator Flush, then replacing the distilled water with Koolance 702 or something comparable and do this within 6 months. I've posted links to these products earlier in this thread. BTW, the Koolance has a 3 year service life so you don't have to flush the system every year, as is the case with other coolants. It's also pre-mixed so you don't have to mix anything.

     

    Cheers,

     

    -Art

  • by Ramón G Castañeda,

    Ramón G Castañeda Ramón G Castañeda Jun 9, 2013 3:04 PM in response to nospoonzz
    Level 4 (1,468 points)
    Desktops
    Jun 9, 2013 3:04 PM in response to nospoonzz

    I'm simply in awe of all of you who have posted actually doing all this work on your G5 Quads.

     

    Thank you for posting, each and every one of you. 

  • by G5Lover,

    G5Lover G5Lover Jun 9, 2013 3:41 PM in response to Ramón G Castañeda
    Level 1 (0 points)
    Jun 9, 2013 3:41 PM in response to Ramón G Castañeda

    Ramón G Castañeda wrote:

     

    I'm simply in awe of all of you who have posted actually doing all this work on your G5 Quads.

     

    Thank you for posting, each and every one of you. 

    Hey, your very welcome Ramón.

     

    It was only because of the generous earlier posts by other's, that I was able to gleen enough info to repair mine. I thought the least I could do is contribute here like others did to help. I would especially like to thank the OP that started this thread-(Heikki Lindholm) and BMaverick for their input. They were my biggest help. I could not have done it without their posts.

     

    So how's your G5 running these days? Any heat or fan issues yet?

     

    - G5Lover

  • by nospoonzz,

    nospoonzz nospoonzz Jun 9, 2013 6:28 PM in response to G5Lover
    Level 1 (0 points)
    Jun 9, 2013 6:28 PM in response to G5Lover

    Thanks for the tip. I might do that several months down the road. It depends. I  have been around radiators all my life and certain coolants just seem like snake oil compared to regular maintenance. However, if I can keep from opening the system again for at least 3 years. I will have to decide. I left the G5 on all night and day. Just got home and it is at 42 degrees celcius. Such a good feeling. This board was my motivation. Had I not come across it I would never had learned so much.

  • by G5Lover,

    G5Lover G5Lover Jun 9, 2013 7:59 PM in response to nospoonzz
    Level 1 (0 points)
    Jun 9, 2013 7:59 PM in response to nospoonzz

    nospoonzz,

     

    It is a great feeling when you tackle some unfamiliar problem and are successful in fixing it!

     

    Allow me to encourage you to ad a good coolant besides straight water. Ultimately of course, it's purely your choice.

     

    I spent a bunch of time talking to people that know their stuff regarding the products I used in my LCS flush and fill. I researched each product and several forum discussions deeply before turning one screw on my machine. It's mine and other's understanding, that Koolance 702 LCS coolant, ( http://tinyurl.com/k6gnthh ) has a very good track record and is far from being a "Snake-Oil." Go to the link and read the specs on it.

     

    If you are familiar automotive radiators, you also know, they don't just contain water. It's a coolant/water mix. Even so, the manufacturer recommends flushing once a year to remove corrosion build up. Otherwise, they start to plug with gunk. The Koolance 702 is specifically designed for computer LCS systems and has special additive metal conditioners that slow the corrosion process, thus allowing a longer maintenance cycle. There are also lubricant additives in it that help the pumps last longer. It would behoove you or anyone else with a G5 to use this coolant or one comparable. Obviously, Apple had a reason to use a coolant additive, not just straight water when they designed the LCS system. If they had used straight water, our G5's LCS's would have died long ago.

     

    BMaverick, (the guy in this thread, who sell's the original NOS pumps, and who's dad worked for Apple helping design the LCS, checked out the Koolance 702 and recommended it's use. He recommends it mainly for it's ability to inhibit galvanic corrosion when used with mixed metals. Plain water will work for a while, but galvanic corrosion build-up and consequent heating problems WILL reappear without an adequate corrosion inhibitor additive.

     

    Hope this info helps.

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