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PM G5 2.5ghz Quad LCS removal

Amigaz

Amigaz

macrumors newbie
Original poster
Sep 28, 2009
27
0
Stockholm, Sweden
I'm in the process of removing my LCS unit from my Power Mac G5 Quad to inspect and rebuild it but am not 100% sure how to remove it because I haven't found any good guide on the net that matches my cooling system.
For example the cooling system in this guide doesn't match mine:
http://www.xlr8yourmac.com/systems/G5_CoolantLeak_Repair/G5_CoolantLeak_Repair_p1.html

Some of my screws seem to be hidden that you have to loosen to remove the LCS untit for the chassi.

Here's my LCS unit:

IMG_0130.JPG


Any help and tips on how I should proceed would be highly appreciated
 
O-ring size

I am currently repairing my LCS for a PowerMac G5 dual 2.5. The reference guide at the xcelr8 site is a great resource to help, however, you should measure the O-rings needed for your machine to make sure you order the correct size. I didn't and ordered what they recommended, which was for a dual 2.7 and they were too big.
You might want to check out this site http://home.earthlink.net/~strahm_s/manuals.html and see if you can find the manual for your machine.

I had to really search to find the coolant. I had to do a search for the product number to find a site that had it. The name of the company is Performance-PCS out of Florida. http://www.performance-pcs.com

Oh ya, when you get to the part when you are going to remove a tube to let out the coolant, it might be under pressure so have goggles on and protective clothing so you don't get covered.

Good Luck!

Norm
 
Thanks for all the tips/help so far, guys

Still waiting for my 3 and 4mm hex screwdrivers to arrive

I'm still unsure on how to fill the system with coolant when I've rebuilt it...it's not built up like a PC LCS exactly
 
LCS refill

Morning,
I found this site last night that might help you out regarding refilling the LCS.
http://kitspy.com/2009/10/leaky-powermac-g5/

I have found a couple of other posts elsewhere that also ran the pump or used a different method of running the coolant into and through the radiator to get out all the air or as much as possible.

I also read on a post that the LCS pump was making some noise after refilling. He said that it could have been from some air in the system or perhaps some 'crud' that attached to the impeller inside the pump.

I am going to see if I can open up my pump and see if there is any 'crud' in there and clean it out since I have the machine and LCS already in pieces.

Finally, I noticed in the link I listed in this site that the author was able to find the o-rings at a local, non-big box, hardware store. I am going to try my luck and do the same. I will keep you posted.

Norm
 
photonorm said:
Morning,
I found this site last night that might help you out regarding refilling the LCS.
http://kitspy.com/2009/10/leaky-powermac-g5/

I have found a couple of other posts elsewhere that also ran the pump or used a different method of running the coolant into and through the radiator to get out all the air or as much as possible.

I also read on a post that the LCS pump was making some noise after refilling. He said that it could have been from some air in the system or perhaps some 'crud' that attached to the impeller inside the pump.

I am going to see if I can open up my pump and see if there is any 'crud' in there and clean it out since I have the machine and LCS already in pieces.

Finally, I noticed in the link I listed in this site that the author was able to find the o-rings at a local, non-big box, hardware store. I am going to try my luck and do the same. I will keep you posted.

Norm
Click to expand...

Mornin'? it's 16:39 here (4:39PM) lolol :D

Gotta stock up on those o-rings...have a dealer here who I think has them in stock in the viton material
 
Extra O-rings!?!

If you happen to find some and they fit let me know where. I am now thinking that if my fix works I can rebuild some used machines :)

I am going on an expedition to find some locally. Let the hunt begin!
 
Guys, contact OrangeSVTguy. He's done LCS rebuild in his Quad and may have some info about parts suppliers.
 
666sheep said:
Guys, contact OrangeSVTguy. He's done LCS rebuild in his Quad and may have some info about parts suppliers.
Click to expand...

Thanks

Here and subscribed lol.

I replaced the stock tubing in mine with Tygon tubing and I reused the old clamps. I used Feser One fluid as that seemed to be the best solution since it is stated to be non-corrosive and non-conductive of electricity so if it were to ever leak it won't self-destruct the entire G5. I don't have a guide anywhere but I did have a thread somewhere with pictures. I only had the single pump version as I guess the dual pump was an updated version.
 
New O-rings on order

I have new o-rings on order and will arrive on Monday. They are one step smaller than the ones mentioned in the fix for the dual 2.7 at http://www.xlr8yourmac.com/systems/G5_coolant_leaks.html.

I spoke with a tech person at MCS Industrial Supply about the best o-ring for this application and he recommended the Viton, which is the same compound for the o-ring in the xlr8yourmac.com site.

I am going to start a new thread with a more detailed explanation of the steps in the repair on my machine.

I will update here as to the result of the new o-ring.

Norm
 
The hex tools has arrived so I started loosening the LCS unit step by step using the service manual from Apple.

Evening though I followed the manual and I'm no newbie when it comes to loosening screws, following service manual (use to work as an outboard engine mechanic) I can't remove the LCS unit..it's stuck! it feels like I'll break something if I use more force

According to the manual it's a matter of lifting the LCS unit straight up out of the case:

bajsx.jpg


Anyone got any idea's? :confused:
 
Sounds like you missed some of the screws. I don't know specific how many screws hold down the dual-pump assembly but I do know that there were 4 hex screws in the back(far right if looking at it from the side) that supplies the power to the CPUs, these attached to the visible part of the CPUs PCB board.

Then there were 4 more hex screws on holding the assembly down near the CPU power screws. 4 more in after the radiator, these don't come out, they "float" in the assembly and these are what keeps pressure from the CPUs to the logic board. 2 in front of the radiator.

I can't be certain as the dual-pump has more obstructions so be sure to look all around for the screws.
 

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OrangeSVTguy said:
Sounds like you missed some of the screws. I don't know specific how many screws hold down the dual-pump assembly but I do know that there were 4 hex screws in the back(far right if looking at it from the side) that supplies the power to the CPUs, these attached to the visible part of the CPUs PCB board.

Then there were 4 more hex screws on holding the assembly down near the CPU power screws. 4 more in after the radiator, these don't come out, they "float" in the assembly and these are what keeps pressure from the CPUs to the logic board. 2 in front of the radiator.

I can't be certain as the dual-pump has more obstructions so be sure to look all around for the screws.
Click to expand...

Have loosened all those screws you mention and according to the service manual, I've fololwed it to 110%
Can it be the expander "pins" that the bolts go into that are still holding the LCs unit somehow?
 
Ok, some progress here....managed to loosen the LCS beast...the blue, rubber thingie on the pic below was the thing that was still keeping it from coming loose...like trying to remove a cylinder head on an engine when the gasket sealing compound on the head gasket is keeping the head from coming loose



Next question is...what is the best way to proceed now to remove the cpu's?
 
Amigaz said:
Ok, some progress here....managed to loosen the LCS beast...the blue, rubber thingie on the pic below was the thing that was still keeping it from coming loose...like trying to remove a cylinder head on an engine when the gasket sealing compound on the head gasket is keeping the head from coming loose



Next question is...what is the best way to proceed now to remove the cpu's?
Click to expand...

Congrats on the completion of the easiest step :p lol

Just take out all the black hex screws. All the screws goes through the PCB into the bottom of the assembly bracket except for the one in the middle of the copper heatsink, that hold the heatsink to the CPU board. Once all the black hex screws are removed, slowly loosen the 4 screws holding the CPU to the waterblock in a clock-like fashion. Then lift off the CPU board from the LCS assembly. You have to swing it back as the heatsink on the back attaches to the top of the LCS.
 
Guys I’m removed the PCBs from the Heatsink. I have a Quad G5. While removing all the things I noticed some black rubber “wires” here and there. What could they be? I thought they could be broken O-rings.

Also I would like to know:
- where are O-rings placed in a Quad. (Please if you have photos share them)
- if I remove them, could the liquid leak?


Ps:
My LCS seems fine. But when my Quad powered on, all the fans run at max speed (very scary). I had to power it off the hard way. Also before quitting (by holding the power button) I attached my USB mouse but nothing moved.
 
mePy2 said:
Guys I’m removed the PCBs from the Heatsink. I have a Quad G5. While removing all the things I noticed some black rubber “wires” here and there. What could they be? I thought they could be broken O-rings.

Also I would like to know:
- where are O-rings placed in a Quad. (Please if you have photos share them)
- if I remove them, could the liquid leak?


Ps:
My LCS seems fine. But when my Quad powered on, all the fans run at max speed (very scary). I had to power it off the hard way. Also before quitting (by holding the power button) I attached my USB mouse but nothing moved.
Click to expand...


I recently rebuilt mine and documented my experience here:
forums.macrumors.com

Power Mac G5 Quad Overtemp and Checkstop

I've got a new (to me) Power Mac G5 Quad that was in supposedly working condition. When I got it, it would boot to OS X fine, but after a minute or so of running, would hang and the overtemp and checkstop LEDs on the logic board would come on. I suspected the liquid cooling system, so I took it...
forums.macrumors.com forums.macrumors.com

There are two different LCS on the quad. Mine had the Delphi dual pumps. The large o-rings on the Dephi system hold the cooling blocks against the CPU dies. They do not function as seals.
 
fourbirds said:
I recently rebuilt mine and documented my experience here:
forums.macrumors.com

Power Mac G5 Quad Overtemp and Checkstop

I've got a new (to me) Power Mac G5 Quad that was in supposedly working condition. When I got it, it would boot to OS X fine, but after a minute or so of running, would hang and the overtemp and checkstop LEDs on the logic board would come on. I suspected the liquid cooling system, so I took it...
forums.macrumors.com forums.macrumors.com

There are two different LCS on the quad. Mine had the Delphi dual pumps. The large o-rings on the Dephi system hold the cooling blocks against the CPU dies. They do not function as seals.
Click to expand...

Thank you. I’ll check it soon. I need the precise o-rings size.
 
Thanks (I thought I already replied :) )

Ps:
Would you check the other thread in the 68kmla forum and see if you can help me? About the pump and that bad situation with my PCBs.
 
Last edited:
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