I can't find the answer on Google so I thought I'd ask here because there are a lot of good mechanics on here.

I'm replacing all the brake components on my 1980 Chevy K20 pickup and things were going pretty good until I got to replacing the original power brake booster. There's a few videos on YouTube but none that help. The main problem is that the booster is attached to the firewall with six studs that have 15mm lock nuts and all of them but the top 2 are sprayed with sealant. I was able to remove the top 2 nuts but I can't even get a socket on the other 4 that you can barely see. I'll probably have to remove the hood so I can see them better. I'm also removing the emergency brake assembly (it has 2 studs with lock nuts) to repair it and was able to break the break the nuts loose but was only able to remove the nuts about 1/4 of the way because the treads were sprayed with sealant.

I've tried paint thinner and gasoline with a wire brush on the nuts and threads but it didn't remove anything. I might try paint remover next. I've been working on cars since I was a teenager and this is the first time I've run into this problem.

Any suggestions will be appreciated!

Heat. Hit them with a torch to soften the sealant. Heat gun would also work.

that stuff is a bitch... i usually take a deep well socket with a universal joint & long extension and tap on the end with a hammer to knock some of the sealer off so the socket will go on... it's usually somewhat dry and brittle by this age... maybe try a long screw driver if you can get at it?...

How hot does an engine compartment get. That stuff was designed to withstand heat and solvents.

Not near as hot as a hand held bottle of MAPP gas would be on the nuts/bolts in question.

Go get a can of bug and tar remover from the auto parts store.

^^^^ & a wire wheel, plus safety glasses !

Hold them in vice grips.

** Sorry, missed that they are still on the vehicle !

6 point socket, ratchet and extension.
Soften the sealant with your torch and push/tap the socket on.

be careful with a torch... that stuff ignites pretty easily... keep a water hose at the ready...

DEET melted the tar sound deadener and paint in one of my Landcruisers. Lesson, don't leave a can of Bushman rolling around behind the seats.

Acetone % ATF is my current penetration mixture,, 50x50

.

Thanks but the booster is so close to firewall that a regular short socket will barely fit. There's no room to hammer anything. This stuff s so hard that a screwdriver doesn't faze it.

I've got a bottle of MAAP gas and good Makita heat gun there's no room for either one.

Pvc cleaner

That's why I use Picaridin insect repellent. It doesn't dissolve plastics like DEET does.

Thanks I'll give it a try but it evaporates so fast I don't think it will faze this stuff.

Thanks I forgot about acetone but I evaporates so fast I don't think it will help.

^ ^ ^ this ^ ^ ^

Might also try some Goo Gone
I think it's made for cleaning mung off of
shoes. I've used it to get chewing gum
off the soles of my shoes

I've got to get this stuff off the treads too or I'll never get the nuts off.

can you get a thread cutting die (or a cleaning die) on there and turn it with a wrench to clean the threads?... i usually put them on backwards to run them up against the nut...

Small brass or steel wire wheel and a dremel.
And they make verticle straight versions of wire brushes also for dremel,s to get in tight spots.

can you get at them with an open end wrench and wack the wrench on the end with a hammer to jam it on the nut and force the schit off?... i've sometimes used a prybar to force a socket or wrench onto the nuts...

"can you get a thread cutting die (or a cleaning die) on there and turn it with a wrench to clean the threads?... i usually put them on backwards to run them up against the nut..."

I thought about doing that and but I know I don't have the correct die. If I can find a die today I will give it a try. It will be very difficult but I don't think there's any other solution.

I've got a dremel and wire brushes but I can't reach the nuts or studs.

last resort... remove the left inner fender/wheelhouse for better access...

Cutting torch??

Are you sure it’s a stud instead of a bolt? Usually the master or the power booster was bolted on the firewall not studded. Bet you find a bolt head under the dash.

That gunk is not a normal condition for the mounting of a vacuum boost unit - someone took extra measures to apply it and you will need to counter that.

Those above have given some excellent suggestions. If you want to save the stud/bolt setup, take those measures and the needed time effort.

Melt gunk with strong solvent and, if needed, application of intense heat with a very focused torch flame. Then drive a 6 point socket on and carefully spin the nuts.

If you can't get good access to the gunk with solvent/torch, start removing body panels.

Nothing new in this post - simply a condensation of comments from others.

good post Cee Cee... but i can assure you that GM(and others) did apply that gunk to their brake booster studs/nuts... sometimes so much you couldn't even find the nut... i grew up in a salvage yard 70's-80's... pulled more of em than i can count...

I have better access on the fender side after I removed the windshield wiper/washer assembly. The big problems are on the engine side. I'll have to remove the hood so I can put one foot on the frame and sit on the the engine. Right now I can only use one hand because I have to use the other hand to hold up my body. I need a body harness, somebody to pick me with my motor hoist and suspend me over the brake booster. Then I will have better access and both hands will be free.

"Melt gunk with strong solvent"

I haven't found any solvent that has any effect on this stuff yet but I haven't tried paint remover yet. When I installed disc brakes on the rear end I couldn't the old gasket off of the differential cover. Somebody suggested suggested using paint remover so tried it and it worked.

We used to use pure MEK (MethylEthylKetone) but that was banned in the late 80’s early 90’s.

Loco - I don't doubt your comment/experience on GM using the gunk on those models. All of my experience removing/repairing booster units has been on older cars/trucks and am thinking I never encountered all of that mess. Maybe my memory is going to the same place as my arm torque.

Hey!, there's an idea!... the "Hover Harness"... needed one a few times... Hurry, get it patented... LOL

"All of my experience removing/repairing booster units has been on older cars/trucks and am thinking I never encountered all of that mess."

I've been working on old cars since 1958 (my first car was a 1950 Oldsmobile) and have never had this problem before. I'm thinking about using a cutoff wheel to remove most of the old booster (it's just thin sheet metal) so I'll have access to these nuts. I never give up! That way I can heat them up and use an impact wrench to remove them before they cool off. There's videos about converting the rear drum brakes to disc brakes on these old trucks but it's not near as easy as they try to make it look. They leave out a lot the problems you will run into.