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Cookie18

macrumors 6502a
Original poster
Sep 11, 2014
583
684
France
So my mid-2012 MacBook Pro has a kind of burning smell. I hesitate to say burning, if I had to guess I’d say it’s like a heated dust type of smell? I’m not sure exactly. I’ve taken it apart and cleaned it, I took off the keyboard and cleaned every individual key too.

My next guess is that it’s maybe the fan? I’m not sure because I did take the fan out and clean it pretty well. Does anybody have any ideas what it could be? It works perfectly, I want to use it as a Plex server but not if it’s going to be putting out weird fumes.
 

Fishrrman

macrumors Penryn
Feb 20, 2009
28,713
12,831
Does it feel overly hot when it runs?
When you had it apart, did the battery look ok? (not swollen)
 

Cookie18

macrumors 6502a
Original poster
Sep 11, 2014
583
684
France
Does it feel overly hot when it runs?
When you had it apart, did the battery look ok? (not swollen)

Not overly hot, the smell does seem to intensify under heavier usage when it gets hotter. My wife used it for about 3 hours this afternoon for work as a test. She was using Skype, chrome, safari with tabs etc. It was much hotter than our 2016 MacBook Pro but I wouldn’t describe it has out of the ordinary for the age.

I didn’t notice anything out of the ordinary with the battery. I’m going to take the back off now and take another look though.
 

Cookie18

macrumors 6502a
Original poster
Sep 11, 2014
583
684
France
I took it apart and even removed the logic board to clean under there, I never removed it before. There was obviously a fair amount of dust but on closer inspection it seems like the smell originates from the battery. I can’t take the battery out yet because I don’t have the screw bit. I have a new set with the right piece in arriving on Monday.
 

rawweb

macrumors 65816
Aug 7, 2015
1,126
941
We've got two Mid '12 15" Unibody mbp's in the house, for whatever reason they STINK! To me, they both smell of BO more than burning. Happens as they heat up, and boy does this generation heat up. I think the smell is the batteries. I recall this is common for some reason and gave up on trying to figure it out. o_O
 

sakagura

Suspended
Feb 29, 2020
86
131
Replace the PSU and lightly repaste the CPU. When paste evaporates or hardens then the CPU will make a stink as it heats up the components around it.

But if you like this excellent Mac from a year when Macs were excellent then you can buy a used one for like 300-400 bucks. Upgradable storage remember that.
 
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Cookie18

macrumors 6502a
Original poster
Sep 11, 2014
583
684
France
We've got two Mid '12 15" Unibody mbp's in the house, for whatever reason they STINK! To me, they both smell of BO more than burning. Happens as they heat up, and boy does this generation heat up. I think the smell is the batteries. I recall this is common for some reason and gave up on trying to figure it out. o_O

Actually that‘s maybe the exact same! I’d describe it as a burning body odor smell now that you mention it. Once I take the battery out I’m sure I’ll be able to diagnose it. It’ll be a relief because it‘s a perfect machine for a plex server but not with the damn smell.

Replace the PSU and lightly repaste the CPU. When paste evaporates or hardens then the CPU will make a stink as it heats up the components around it.

But if you like this excellent Mac from a year when Macs were excellent then you can buy a used one for like 300-400 bucks. Upgradable storage remember that.

Thank you, I noticed the paste had hardened and run off to the sides. I’m going to order some once I diagnose whether I need to order a new battery as well.
 
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rawweb

macrumors 65816
Aug 7, 2015
1,126
941
Actually that‘s maybe the exact same! I’d describe it as a burning body odor smell now that you mention it. Once I take the battery out I’m sure I’ll be able to diagnose it. It’ll be a relief because it‘s a perfect machine for a plex server but not with the damn smell.



Thank you, I noticed the paste had hardened and run off to the sides. I’m going to order some once I diagnose whether I need to order a new battery as well.

Please report back what you learn! I've dealt with about 4 machines from this generation and own two and all have had the same burning B.O. smell, lol!
 

Cookie18

macrumors 6502a
Original poster
Sep 11, 2014
583
684
France
Please report back what you learn! I've dealt with about 4 machines from this generation and own two and all have had the same burning B.O. smell, lol!

I was able to take the battery out today, that isn’t the issue.

New thermal paste should be here in a few days. I cleaned off the thermal paste that had spread and I am fairly confident that it is the source of the smell. I smelt it really close and it was strong. Also, what I didn’t realise before was how far it had spread. It had travelled way off the area where it should be so the processor heating up could definitely be causing it to get hot and smell. I’ve cleaned the processor the best I can but I’m not putting it all back together until the new paste arrives so fingers crossed.

I’ll update on whether or not the new paste works.
 

rawweb

macrumors 65816
Aug 7, 2015
1,126
941
I was able to take the battery out today, that isn’t the issue.

New thermal paste should be here in a few days. I cleaned off the thermal paste that had spread and I am fairly confident that it is the source of the smell. I smelt it really close and it was strong. Also, what I didn’t realise before was how far it had spread. It had travelled way off the area where it should be so the processor heating up could definitely be causing it to get hot and smell. I’ve cleaned the processor the best I can but I’m not putting it all back together until the new paste arrives so fingers crossed.

I’ll update on whether or not the new paste works.
Your updates are most appreciated! Looking forward to learning if new paste will eradicate this bizarre smell!
 
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Webster's Mac

macrumors 6502
Dec 18, 2016
327
282
So my mid-2012 MacBook Pro has a kind of burning smell. I hesitate to say burning, if I had to guess I’d say it’s like a heated dust type of smell? I’m not sure exactly. I’ve taken it apart and cleaned it, I took off the keyboard and cleaned every individual key too.

My next guess is that it’s maybe the fan? I’m not sure because I did take the fan out and clean it pretty well. Does anybody have any ideas what it could be? It works perfectly, I want to use it as a Plex server but not if it’s going to be putting out weird fumes.
I'd clean it and repase. It is most likely the hinge clutch cover (black plastic piece over hinge) or the speaker assembly that is next to the heatsink on the underside of the logic board. Cleaning and repasting is about all you can do. See if that helps. Be sure to thoroughly clean the die until it is shiny with as little dust as possible. Clean the heatsink contact surfaces thoroughly as well. These tend to just run hot. Very reliable macbooks but they generate a ton of heat.
 

Cookie18

macrumors 6502a
Original poster
Sep 11, 2014
583
684
France
I'd clean it and repase. It is most likely the hinge clutch cover (black plastic piece over hinge) or the speaker assembly that is next to the heatsink on the underside of the logic board. Cleaning and repasting is about all you can do. See if that helps. Be sure to thoroughly clean the die until it is shiny with as little dust as possible. Clean the heatsink contact surfaces thoroughly as well. These tend to just run hot. Very reliable macbooks but they generate a ton of heat.

I forgot to mention, the clutch cover was basically smothered in the stuff. I really hope it fixes it because it really is a great MacBook even when compared to the newer Macs that I have. It will be a great Plex server/writing machine if I can fix this problem.
 

Webster's Mac

macrumors 6502
Dec 18, 2016
327
282
I forgot to mention, the clutch cover was basically smothered in the stuff. I really hope it fixes it because it really is a great MacBook even when compared to the newer Macs that I have. It will be a great Plex server/writing machine if I can fix this problem.
What was the clutch cover smothered in? That part *is* replaceable, though it can be a bit difficult. I've swapped a few of them. You can get replacement clutch covers on ebay for like $10-15 USD.
 

Cookie18

macrumors 6502a
Original poster
Sep 11, 2014
583
684
France
What was the clutch cover smothered in? That part *is* replaceable, though it can be a bit difficult. I've swapped a few of them. You can get replacement clutch covers on ebay for like $10-15 USD.

The thermal paste, the centre was still paste like but the rest was hardened up to the edges of the gold plate. I’ve cleaned it off now and it looks fine but I’ve yet to test it until I can get more paste.
 

Webster's Mac

macrumors 6502
Dec 18, 2016
327
282
The thermal paste, the centre was still paste like but the rest was hardened up to the edges of the gold plate. I’ve cleaned it off now and it looks fine but I’ve yet to test it until I can get more paste.
How did thermal paste get on the clutch cover? How much are you applying on the CPU? It should be a small bead and should NOT be visible when the heatsink is installed.
 

Cookie18

macrumors 6502a
Original poster
Sep 11, 2014
583
684
France
How did thermal paste get on the clutch cover? How much are you applying on the CPU? It should be a small bead and should NOT be visible when the heatsink is installed.

The thermal paste has never been replaced on this machine. It isn’t visible when installed, it’s only on the underside where it should be but it’s very spread out.
 

Cookie18

macrumors 6502a
Original poster
Sep 11, 2014
583
684
France
Please report back what you learn! I've dealt with about 4 machines from this generation and own two and all have had the same burning B.O. smell, lol!

Good news!

The thermal paste seems to have fixed the smell. I haven’t been able to test it thoroughly yet because I just finished putting it back together but I ran cinebench to get it working and then left it on for around 30 minutes and there seems to be zero smell.

If I put my nose right up to the keyboard I can smell it very lightly but I’m fairly sure that’s leftover and not still being put out. I can’t smell it at all while using the computer. To put it in perspective I walked into my wife’s office while she was using it last week and the whole room smelled of MacBook Pro lol.
 

steffmueller

macrumors newbie
Feb 7, 2021
1
1
Hello people,
I’m hopping in.

I am battling with some bad smell / stink with my unibody 15inch MacBook Pro Mid 2012 since quite some time.

I’ve read the body odor smell problem, but not quite sure if that’s what is meant.

As of now I’ve changed the old battery. It was time and getting really hot in there. After changing the Temperatur dropped by 20*C

I‘ve changed the thermal paste, since I read it causes the smell. And it was old and time too.

Today I am changing the fans since bearings are making noise and can cause smell when wearing out.

Next I would like to clean keyboard/backlight since there’s all the gunk of 10years of usage which definitely would not smell like unicorns.

And I will replace the ddr3 memory modules since these smell too.
Which brings me to my question:

? Can anyone give me some guidance on what is shown in the pictures?

It is some piece of foam(?) and is located right on top and below the ram modules. Pressing firmly into the modules.
They smell pretty bad. (I’m wondering if they cause the smell or the memory modules cause the smell)
Also they seem to peel off.

My guess is, that they are some form of heat spreader and begin to smell when getting too hot.
I think that the system got too hot at some point in the past decade and the materials just wore of.

? Could they be the cause of the smell and can they be fixed, replaced or safely removed?

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