A little off topic about Toshiba heatpipe

[rkoenn]

I am working on a friends older but rather high end Toshiba laptop. It starts fine and boots into windows but within 5 or so minutes it simply shuts off, not shuts down, just turns off instantly. I opened it up and found dust caked between the fan and heat sink fins. I cleaned it up and started it again and it does the same thing. So today I left it open, powered it up and inspected it while it was running. Well the CPU part of the heat pipe started getting warm and then hot and then quite hot. I felt further down the heat pipe and the pipe itself was just a bit warm. Also the cooling air coming off the fins was cool and barely even warm. So is it possible the heat pipe is not working, that certainly seems to be the case. However before I buy a replacement I was wondering if anyone has any experience with something like this. Obviously if the pipe had leaked that would be the case but I see nothing that indicates that. I don't know if the working fluid would show it it did or not. Any thoughts and experiences with something like this are welcome. Thanks.

 

[aigomorla]

heat pipes are virtually everlasting until it gets punctured or damaged somehow.

Ive even bent some heat pipes and they still worked, because they are based on a capillary principle where they ignore gravity.
If the section of heat pipe under the cpu is getting hot, there is no issue with contact.

The heat pipe itself should not have equalibirum in heat because there is no heat pipe which is 100% effective.
However the fan exhausting air, should be warm, in lue to the heat pipe getting rid of heat.

That is why that end section of your heat pipe is warm and not hot.

Have you had any shut down issues after you blew air though the heat sink fins?

 

[rkoenn]

heat pipes are virtually everlasting until it gets punctured or damaged somehow.

Ive even bent some heat pipes and they still worked, because they are based on a capillary principle where they ignore gravity.
If the section of heat pipe under the cpu is getting hot, there is no issue with contact.

The heat pipe itself should not have equalibirum in heat because there is no heat pipe which is 100% effective.
However the fan exhausting air, should be warm, in lue to the heat pipe getting rid of heat.

That is why that end section of your heat pipe is warm and not hot.

Have you had any shut down issues after you blew air though the heat sink fins?

I actually initially took the heat pipe and fin unit, it is a single unit, off the CPU and that was when I found the solid layer of dust between the fan exhaust and the fins. I had noticed when it was running that there was minimal airflow as well as no noticeable heat being ejected. So today I ran it with the bottom off the computer, on this Toshiba the MB is attached to the top of the case so that works pretty well. I have the bottom of the MB and heatpipe in clear view. It starts and I feel as the heat pipe and mount on top the CPU heat up. After about 5 minutes that part got to be uncomfortable to touch. However just downstream the heatpipe was barely warm and out at the fins, which I can touch as they are completely accessible in this configuration, they weren't even warm. The air exhausting from them was cool like it wasn't going over anything hot or much warm at all. I am fairly convinced that possibly the heat pipe fluid/gas has escaped or congealed or something. The laptop shuts down after about 5 minutes and won't start for a few minutes after. A replacement doesn't cost much but I hate to waste time and any money if that isn't it.

I've done quite a bit of work on computers over the years and this is my gut reaction. While I agree heatpipes rarely fail some googling seems to indicate they very infrequently do. One guy said his has gotten very hot, which it would have with that dust in the cooling system, and seemed to fail after that. Thanks and if you have any other thoughts they are welcome.

 

[heymrdj]

Running HWMonitor or something like that should tell you quickly, and scientifically, if you're overheating. Anything else is conjecture. It's very possible you have a hairline crack in the mainboard that's breaking a connection as the system gets warmer. But off had, it does sound like you could have a failed heat pipe.

 

[crashtech]

Just last year I did a repair where the heatpipe was bad for the first time in over 20 years of doing this stuff. Had me flummoxed for a while, but if the TIM is good, and the fan is running well, but it overheats, well, it might just be a bad heatpipe. You'll also see a failure to cool down quickly once the CPU goes to low load, that was what really convinced me.

You must have an app like CoreTemp to verify.

 

[rkoenn]

Thanks everyone. I ordered a replacement part off eBay for about $22 delivered and will install it with Arctic Silver compound when it arrives early next week. I did more testing and it is totally repeateable. The heat pipe section over the CPU gets very hot and the section with the cooling fins is at room temp. The fan is blowing away over the fins and the air coming off them is ambient as well. I know most laptops I've worked on before can get some fairly warm exhaust air. And the tube stays almost ambient down its length. The CPU is an Intel I7. The system is 3 or 4 years old but other than this problem seems to be fine. Another oddity was when she first brought it to me a month or so ago I ran it for quite a while and don't think it ever shut down while I was cleaning it up, software wise, and updating it. I think it must have been on and doing some extensive chugging and I don't think I ever had a problem. I do seem to recall I thought it odd that there wasn't much heat in the fan exhaust. So she calls me a couple of days later and says it's shutting down, I thought you said you fixed it. That was funny but when I got it back it is doing exactly that after about 5 minutes. That was when I did the troubleshooting and cleanup. So maybe the heat caused a leak in the heat pipe, anyway I'll find out next week.

 

[crashtech]

@rkoenn, please update the thread to let us know, heatpipe failures are exceedingly rare, but this may serve to show that they are possible as I found out myself.

 

[WhoBeDaPlaya]

Heatpipe failures happen. Had to replace the HSF assembly in 1 out of 3 of my old Thinkpad Z61t.
CPU would hit near Tjmax after booting into Windows, with the section of the HSF assembly over the CPU being nuclear and at the copper fin / exhaust portion cold.