Powermac G5 Quad LCS issue. Anyone knows the system by heart?

[marqus]

Hi there,

I just took my G5 late 2005 Quad from the attic due to corona boredom...

I remember, that it did not post last time I tried. 2 years ago everything went fine.

It is the lat 2005 version with a single Delphi pump (though lots of people claim, that there are no single Delphi pumps in the Quad)

The system ist not leaking whatsoever, no trails or jelly spots. I just wanted to give it a nice review.

After 1 long day and night, I am about to give up. I am concentrating on the LCS module itself. So it is disassembled on my desk. Had it tore apart and back together again. Checked the pump seperately, blew air and sucked water through the hoses. Opened the two coolers and cleaned them.

Everything is clean. No corrosion. Pump works fine and very strongly. The hoses are ok, but I would like to replace them in case I get it to work at all. The radiator is free of "resistance" (sorry, I am German). When I put the pump seperately on the radiator, the water keeps shooting out perfectly. As soon as I connect any of the two coolers or both (normal way of connection), there is only very, very litte water or NO water running out of the system, while the pump is operating like crazy and stops eventually.

When I suck or blow (sorry) through the hoses, it is not an easy thing to do but it works. But I cannot get the system to operate normally. Not to mention the not yet thought about process of bleeding it.

As for now, I would be happy if the bucket full of water which is my water reservoir and at the same time input and output station for the pump and the last hose.

Has anyone ever understood, why the water pressure is not coming out of the LCS in the same amount as it went in? Any ideas?

thx alot,
Markus

 

[fourbirds]

Take a look at my post from last year when I encountered the same issue as you:

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

Essentially, the cooling blocks have a flow limiter that tends to accumulate crap. Making sure this is flushed properly is 80% of the battle. Use an air compressor to really get it clean.

 

[marqus]

Thank you for that. But since I have the rubber hoses only LCS and the single pump quad, I think the coolers are not the same as yours. I opened them and they seem to be very clean.
Basically there’s a copper cover (which contact the dies), under those you see a round, red and soft gaskety thing that lays on a white plastic plate. The white plate has some kind of very thin flow lines carved in. Under this white part, there’s a black rubber thing with a honey comb structure.
Als this is very clean. I am desperate...

 

[fourbirds]

Ah - I see then. Is your equivalent to this one:

Page not found – DoogieLabs

If you connect the pump to the outlet of one of the blocks, do you get any flow? There could be a flow limiter in there that is clogged up.

 

[marqus]

Yes, this is my LCS. But unfortunately I just broke it! I could f*** my own a**. I am such an idiot. Found out that in both inled nossles of the coolers, there would be those little filter elements, fits the hose inner side and is one inch long. Looks like a tiny motor bike fuel filter.
These two were not dirty at the first look, but I cleandet them in vinegar water und with p-air. I decided to leave them out completely.
Then the flow was much better. Not as strong as I expected, but ok. Then I killed it! I took a heat gun and went too hard on one of the coolers. The earlier mentioned whit plastik thingy just melted and everything was ruined.

So. If I ever want to see the G5 runing again, I would have to get one of theses coolers or the little white plate. 2 O-rings would come in handy, too.
I am more than frustrated right now :-(

 

[fourbirds]

That's unfortunate.

However all is not lost as I think you can leave the second CPU out and run it as a dual 2.5.

 

[Project Alice]

That's unfortunate.

However all is not lost as I think you can leave the second CPU out and run it as a dual 2.5.

I vaguely remember a post where someone made an air-cooled quad, and it was keeping temp just fine? Or am I crazy

 

[marqus]

ASAIK it is not that easy because of the very largely built coolers of the e.g. 2.3 DualCore G5. Dunno if it is possible to modify a cooler like this to fit onto the Quad system. I would def. do it though...

 

[dextructor]

I vaguely remember a post where someone made an air-cooled quad, and it was keeping temp just fine? Or am I crazy

Yes you remembered right. @MrVitalic that has done the G5 Quad to Air cooling. His tutorial it's on this page.

QUAD G5 AIR COOLED (dxf included)

It first started when I bought a quad core logic board to fix my broken dual core g5. Then I said to myself: wait a minute, I could convert my dual to quad! Then soon, I bought a quad with a broken lcs. Then I said to myself: wait a minute, I coud convert my quad to air cooling !! So here ya...

forums.macrumors.com

 

[MrVitalic]

I vaguely remember a post where someone made an air-cooled quad, and it was keeping temp just fine? Or am I crazy

Yup. The conversion use almost as much heatsink real estate as a dc 2.3 converted to air cooling to 2.5ghz (edit: my mistake, I was thinking of a dc 2.3, converted to 2.5 ---> not enough coffee) , per processor. I’m also pretty sure that apple was using average thermal paste back then in 2005 (and obviously 2005 paste technology). I use artic mx-4, its a great compound. I had no issue with temps. My DP 2004 single core 2.5 converted to air, always get micro fan burst and fan can ramp up pretty high playing logic exs24, while the quad is quiet.

 

[MrVitalic]

Hi there,

I just took my G5 late 2005 Quad from the attic due to corona boredom...

I remember, that it did not post last time I tried. 2 years ago everything went fine.

Hola mine was unused for about 6 months and when I booted it up, it did not shime. After the second attemp it did and booted into osx. At first I had 2 missing ram stick. After reseating the ram, all was good. I think its the age of the machine that start to cause problem. Should I recap the entire board ? I dont know but its a possibility. The capacitor plague was between 1999 and 2007. I'm saying that because, the copper plate from the lcs should be enough to cool your cpus (from a cold start) to boot into osx and surely shutdown from overheating soon after. Your lcs could be absolulety functional.

 

[marqus]

Just an update: I was able to buy a set containing the original Quad LCS, 2 2.5GHz CPUs and the original mainboard for 40 EUR. Very nice. I will build the whole rig in the next days. Therefore please check my post on the "best os for PPC" thread.

Thank you all