Stuck bolts between turbo and catalytic converter

[rodiram]

Hi all !
I am trying to remove the turbo on my XC90 D5 2006.
The 3 bolts that attach the catalytic converter to the turbo are stuck (two of them can be seen on the bottom of the pict attached). They are 10mm and I am reluctant to apply to much force. I soaked them with WD40 for 2 days but it did not work (probably because the thread are far from the head due to the catalytic flange). I try to gently hammered them to unstuck the threads and hammered the 10mm wrench but it is still stuck.
I guess this is a fairly common problem but I don't find anything on forums. The only solution I see is to heat the bolts with a torch. Or maybe the turbo around the threads. Someone had a similar problem ?
Thanks !

Screen Shot 2020-05-05 at 18.29.50.png (1.34 MiB) Viewed 2277 times

[MoVolvos]

Hi all !
The only solution I see is to heat the bolts with a torch. Or maybe the turbo around the threads. Someone had a similar problem ?
Thanks !Screen Shot 2020-05-05 at 18.29.50.png

Have you tried to snap tighten the bolts further to get it moving? Worse case scenarios is to break them off to get the thing removed and tap later.
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[MoVolvos]

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Do not use a standard socket but use the thicker impact socket if you have room.
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[rodiram]

Thank you, I'd rather not break them, I guess this operation is done thousands times a day by chops that replace exhausts, one it is probably stucks 50% of the time, there should be a solution.
For the impact socket, you mean using it with an impact wrench or a manual one ? I am not sure an impact wrench would work for a small 10mm, I have no experience with them.

[oragex]

As above don't put wrenches on these, it takes sockets. I'm also guessing it may require a deep 10mm socket if the short sized one doesn't fully grab the nut. But the lower nuts may be difficult to access. And use an extension over the ratchet handle. If it can make you more confident, I did this on my non turbo which surely deals with much less heat, but my nuts were really eaten by rust and I was relieved to seem them turn without being stripped. These are actually not that stuck (unlike on japanese cars). Don't worry about the studs, these are solid metal - and I also recommend you reuse these nuts. The WD40 is however apple juice. A real fluid is Liquid Wrench or PB Blaster, and let soak 1 week without driving

[rodiram]

Ok, so I basically should force more.
Here there is no nut nor stud, it is a bolt and the thread is in the turbo, I am not sure an penetrant like Liquid Wrench or PB Blaster or others can reach there (I mean it is not like you were pulverising a nut or close to the threads).

[oragex]

Never mind my post, I thought it was about the bolts on the engine side

[abscate]

Lots of heat,at least 60 seconds with propane on the head of the bolt.

Heat forces things to expand, and also breaks up the rust chemically. If you go through three heat and cool cycles a few minutes apart, then use a good penetrant like PBB, they will come off

[SuperHerman]

Two things 1) It is clear that Volvo elected bolts with the heat temp and cycle and cast iron in mind as they are highly polished. How that helps I don't know. Is there a grade stamp on the bolt head?

2) Why do you need to take that piece off? If you are servicing the cartridge you may be able to get by leaving it in place. We don't see the diesels here, but with a petrol it can be done.

[MoVolvos]

Ok, so I basically should force more.
Here there is no nut nor stud, it is a bolt and the thread is in the turbo, I am not sure an penetrant like Liquid Wrench or PB Blaster or others can reach there (I mean it is not like you were pulverising a nut or close to the threads).

DirectTorque Technology helps prevent rounding of fasteners.
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https://www.amazon.com/dp/B01N5C929F?ta ... th=1&psc=1
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Check out the socket design. An air or electric impact will take it off due to the rapid snap twist and impact on the flat surface of the bolt.
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