Where exactly does the leak occur on the PowerMac G5 Quad?

[Rikintosh]

Recently I finally managed to acquire my dreamed PMG5 Quad, I was aware of the leak problem that usually occurs, my computer seems NEVER to have leaked, but I don't want to start using it without first ensuring that this will not happen. I also know there was a second revision that looks like it was problem free, but how do I know mine is problem free?

The ones that leaked, leaked for what reason exactly? Hoses? Bomb? Badly tightened screws?

I intend to disassemble everything and change the system liquid, I believe that automotive radiator fluid is the liquid present inside the system, correct?

 

[NikolaPPC]

Hello @Rikintosh !
There are 2 versions of the LCS, single pump and dual pump. Single pump version can be "easily" dissasembled, cleaned and refitted, while the dual pump is much challenging (as far as i know, you can't dissasemble the copper CPU block and clean the cooling fins thoroughly and you can't dissasemble and clean the pump, only exchange it).
The leakage in single pump version usually occurs on the O-ring on the copper CPU block, while the dual pump version has the block practically welded so it's more durable.
Both versions can leak on the connection joints or from dried up cracked hoses, but that's not so common on the Quad.
Radiator is made from aluminium.
Mixing aluminium and copper in LCS creates galvanic corrosion on aluminium. They have indeed used automotive coolants, but a special one for both aluminum and copper (even coolants degrade over time and leave small films of debris) that usually prevent this, but can't do it perfectly. So over time that corrosion, debris etc.. clogs up the pump and the small fins on the copper CPU block.

While yes, the dual pump version is better and more durable, the problem lies when you need to dissasemble everything

There are two ways to test the LCS:
-Put your Quad through stress test and monitor your temps, fan rpm, pump rpm and see if everything is normal. CPU temp shouldn't go over 75-80°C on full load. Idle temps should be around 30-40 °C.
-Run Apple ASD and run the test, if it passes, everything is good.

Cheers, Nikola!

 

[Rikintosh]

Hello @Rikintosh !
There are 2 versions of the LCS, single pump and dual pump. Single pump version can be "easily" dissasembled, cleaned and refitted, while the dual pump is much challenging (as far as i know, you can't dissasemble the copper CPU block and clean the cooling fins thoroughly and you can't dissasemble and clean the pump, only exchange it).
The leakage in single pump version usually occurs on the O-ring on the copper CPU block, while the dual pump version has the block practically welded so it's more durable.
Both versions can leak on the connection joints or from dried up cracked hoses, but that's not so common on the Quad.
Radiator is made from aluminium.
Mixing aluminium and copper in LCS creates galvanic corrosion on aluminium. They have indeed used automotive coolants, but a special one for both aluminum and copper (even coolants degrade over time and leave small films of debris) that usually prevent this, but can't do it perfectly. So over time that corrosion, debris etc.. clogs up the pump and the small fins on the copper CPU block.

While yes, the dual pump version is better and more durable, the problem lies when you need to dissasemble everything

Cheers, Nikola!

Thank you very much for answering me. I researched images of both types of systems, and found that I have the single pump, I'm going to have to completely disassemble it anyway, because it's so dirty.

When I turned it on, after 1 or 2 minutes, I heard a noise that sounded like two big air bubbles rising inside a gallon of water, is this normal? I found it to be extremely quiet even with the fans running and all the dirt on it.

 

[NikolaPPC]

Thank you very much for answering me. I researched images of both types of systems, and found that I have the single pump, I'm going to have to completely disassemble it anyway, because it's so dirty.

When I turned it on, after 1 or 2 minutes, I heard a noise that sounded like two big air bubbles rising inside a gallon of water, is this normal? I found it to be extremely quiet even with the fans running and all the dirt on it.

No problem!
You have luck, i also have 2 Quads Single pump version, but i never have time to do the disassembly and cleaning. With the right tools, it can take 2-3 days to do everything properly. I advise you to tear everything down, repaste the north bridge and thermal pads on the back..even the PSU, open it and see if the main capacitors are all right.
I can guide you through all of this if you have any problems.
Every LCS loses coolant over time, so it's normal for the Quads age to be dry.

It's okay, but it means that there is a bit more air than expected (the radiator is at higher point, so that air can be accumulated there and not go into the houses, CPU block, pump...), but few bubbles sometimes aren't worth the disassembly, because it is so much hassle to do everything properly, like a factory

Run some stress test script/program and monitor the temps via istat or the Apple's ASD and tell me the report! Also be sure to select maximal performance in the power settings.
What are the idle temps? Can you provide me with a screenshot?

 

[eyoungren]

I used to have an unreasonable fear that I'd leave the house with my Quad G5 running, only to come home to find the fire department outside because the G5 spewed coolant everywhere and started an electrical fire.

After three years of quiet running and zero leaks before I replaced the Mac with a Mac Pro - that never happened.

My Quad still doesn't leak.

 

[Rikintosh]

I used to have an unreasonable fear that I'd leave the house with my Quad G5 running, only to come home to find the fire department outside because the G5 spewed coolant everywhere and started an electrical fire.

After three years of quiet running and zero leaks before I replaced the Mac with a Mac Pro - that never happened.

My Quad still doesn't leak.

I know it sounds a bit silly, but in my country they are very rare and hard to find, and they are also quite expensive, I have to be extra careful, because if I break something, it means I have to import from another country , and whatever it is, it will cost me a lot (dollar is more than 5 times more expensive than my currency).

I'm silly, I could love and collect silly things that are easily found in my country, but no, I just had to love computers, most of which are made in other countries, and which were sold on a small scale in my country! lol

 

[Rikintosh]

No problem!
You have luck, i also have 2 Quads Single pump version, but i never have time to do the disassembly and cleaning. With the right tools, it can take 2-3 days to do everything properly. I advise you to tear everything down, repaste the north bridge and thermal pads on the back..even the PSU, open it and see if the main capacitors are all right.
I can guide you through all of this if you have any problems.
Every LCS loses coolant over time, so it's normal for the Quads age to be dry.

It's okay, but it means that there is a bit more air than expected (the radiator is at higher point, so that air can be accumulated there and not go into the houses, CPU block, pump...), but few bubbles sometimes aren't worth the disassembly, because it is so much hassle to do everything properly, like a factory

Run some stress test script/program and monitor the temps via istat or the Apple's ASD and tell me the report! Also be sure to select maximal performance in the power settings.
What are the idle temps? Can you provide me with a screenshot?

Yes, I have some OCD with this, everything I buy I take it apart and clean it completely, I can't use it until I've gone over and cleaned everything. It came without an HD, and I intend to install an SSD for the system, and a 1TB HD for programs and games. I want to try porting some things using it to compile.

I found some cooler master products for water coolers, I'll see if they have o'rings that have the same measurements as the LCS powerMac I will try to use transparent hoses with a nice shiny liquid

 

[NikolaPPC]

Yes, I have some OCD with this, everything I buy I take it apart and clean it completely, I can't use it until I've gone over and cleaned everything. It came without an HD, and I intend to install an SSD for the system, and a 1TB HD for programs and games. I want to try porting some things using it to compile.

I found some cooler master products for water coolers, I'll see if they have o'rings that have the same measurements as the LCS powerMac I will try to use transparent hoses with a nice shiny liquid

I feel the same, that's why i didn't have time for the repair & that's why i use DC 2.3GHz as daily driver, until I have time to properly overhaul the Quad.
For the SSD i recommend Samsung EVO 840 / Samsung PRO 840 / Intel 330.

As for the O-ring size/measurements, it's not your typical one, Apple doesn't do that

Factory hoses are heat resistant/smooth EPDM rubber with a High synthetic textile reinforcement made to withstand heat, vibration, pressure, and cooling system chemicals.

You can use silicone rubber hoses. These hoses are usually blue in color (EPDM hoses are black). One drawback to silicone hoses is its permeability to water. That means that water inside the cooling system can evaporate through the walls of the silicone hose. This causes lower levels of coolant in your cooling system which will need to be replenished. Using silicone hoses require more frequent inspections of your cooling system.

Every other type/material for hoses is not recommended for the automotive coolant!

You must take notice that this LCS is a bit different to the commercial ones. I've added repair guides in PDF, read them before attempting anything. The person has done an amazing job and you just need to follow his example

Also, one question: Do you have Apple service repair manual for the G5 late 2005?

 

[Tratkazir_the_1st]

I intend to disassemble everything

"Welcome to Hell" .

 

[TitaniumFrog]

Hi @Rikintosh, just curious whether you had started the project already? I'm also facing the issue of having to rebuild a single quad pump (and I'm not even sure that will fix the issues with this thing, but hey...)
I'm looking for some tips/tricks next to the files @NikolaPPC shared. It doesn't seem anywhere near easy, but it does seem to be doable. Buying a new LCS seems impossible anyway, so it's this or nothing.

 

[micahgartman]

I used to have an unreasonable fear that I'd leave the house with my Quad G5 running, only to come home to find the fire department outside because the G5 spewed coolant everywhere and started an electrical fire.

After three years of quiet running and zero leaks before I replaced the Mac with a Mac Pro - that never happened.

My Quad still doesn't leak.

Mine leaked. Remember that scene in Aliens when the Marines first go into the air processing station and there are lots of giant holes in the floor from the xenomorph blood? Yep—that's what is looks like. Still POST'd, though. It's now a shelf in my garage. Acid burns and all.

 

[Rikintosh]

I haven't done it yet, but I intend to replace the entire hose system, and I intend to insulate the cooling system, so that, even if it eventually leaks, it won't cause problems. I was thinking of setting up a glass "aquarium" around the system, that way, if an accident occurs, the liquid will be trapped inside it, and won't make a mess of my bedroom carpet.