Is there solvent to un-do thread lock? - PeachParts Mercedes-Benz Forum

240 Ed · #1 12-23-2002, 02:06 PM

Is there solvent to un-do thread lock?

I am trying to undo the large screws on hinges of my drivers seat to take it apart, but it won't budge.
They are apparently glued on!

leathermang · #2 12-23-2002, 05:23 PM

On some cars that hole they are in goes to the bottom of the car and thus rusts.... hope that is not the case here....if you have one of those old fashioned ( I know this is a long shot ) soldering irons... a handle with a solid copper element which is heated typically in a small gas oven.... you might could heat it enough to cause some movement...
what kind of head does it have ? If you can get a straight shot at it by moving the seat.. then a hand impact wrench would be my best guess.... good luck....
Many times the screw is stuck as a matter of the friction between the item it is holding and the screw threads... so just cutting the top off with a good cold chisel allows you to turn it out with vise grips after you get the seat out....

Mark V · #3 12-23-2002, 05:24 PM

Propane makes a good solvent for locktite, however you have to light it first. Of course that may get exciting near the horsehair pads. Heat is the only one I know of but that may not be practical there.

Mark

240 Ed · #4 12-24-2002, 12:32 AM

Thanks for the comeback guys, but I am trying to remove the HINGES of the seat. They are giant "phillips" screws that won't budge with a hand impact and a sledge hammer. Oiy.

Yeah, I don't want to use heat here.

I am transferring the cushion guts from a passenger side seat. they are the same cushions!

It is weird, but the seat I bought was out of a 72, and mine is a 68--The 72 screws came out with the impact, no problem. I examined the screws and there was a single dot of threadlock on the thread.

I think they used the whole bottle on the 68!!

They probably got grief from the aftermarket upholstery people and lightened up on the sealant. Sounds like a Mercedes thing to listen to customers of all types and adjust.

Lycoming-8 · #5 12-24-2002, 02:26 AM

It is possible that acetone will undo the thread lock. It is a pretty good solvent and can clean some paints right off of the metal they were used to finish. Also be careful, as acetone is a very flammable solvent.

leathermang · #6 12-24-2002, 08:51 AM

Ed, are you sure you have that hand impact set right before you hit it ? It should either come out or break with a hand impact and hammer... however, there is a very good chance that you should not use the sledge hammer on it... because you really can not get the head speed you need... only half of your blow is directed toward rotation in the best of circumstance with that tool.. and a fast blow is needed for that... a two lb blacksmith hammer should be good...

240 Ed · #7 12-25-2002, 04:35 AM

Quote:

a two lb blacksmith hammer should be good...

This is exactly the hammer I am using, but didn't know what to call it, nor how much it weighed...(read; too lazy to go out to garage and look...)

The driver I was using I purchased in London in 1969 when I bought a Triumph motorcycle. (I knew if I needed to do some work on that bike, I would need this driver) It was actually made in England, and had a reverse and forward. It still works, but the bits keep falling out of it, etc. so I decided to splurge with a new one from Sears. ( that, and I could not find my #4 phillips bit...). To my surprise, the new one does NOT have a forward on it!

I looked up Loctite web-site, and it says to use heat on it, soooo, I shall use a small propane torch on the head of the screw and try again tomorrow.

Amongst my current projects is repairing the power window on the drivers door. It has a rubber "universal joint" coupling between the motor and the gear box which has sheared in two.
I have decided to glue and tape it back together and hope for the best.

And I shall install a used door check while I am in there.
I grabbed one off a rear door of a donor car. I just need to transfer the "arm" bit from the old one, as the rear door uses a shorter arm and is painted a different color. It is a gorgeous thing this door check mechanism, with little rollers and little leaf spring, etc.
I love working on these old Benzzes!

leathermang · #8 12-25-2002, 08:54 AM

Ed, I did not start my motorcycle career until 1970 , being 'busy' in 1969....
Someone ought to be shot if they designed that tool without a way to go either direction with power....what about left hand threads one might need to work on ?
A hand impact is one the most magical tools ever invented .... so if that won't work all I can suggest is a grinder and drill...
Mr Phillips designed his fasterners so they would not be able to be over tightened.. the head is meant to spit out the screwdriver before overtorqueing can happen... and the hand impact is the only tool which does a good job of counteracting that stupid design...
On the other fastening problem you have.. how about pop rivets ? They do not get the respect they deserve... they can hold airplanes together when designed and installed properly....they make long reach pullers which might get to your window problem....
Do you have one of those propane/solder ends which will allow metal contact while heating the end with the propane tank ?

240 Ed · #9 12-25-2002, 04:56 PM

Gregg,

The phillips screws are #4 size and are countersunk type to be flush with the bracket. A nifty chrome trim goes flush over the hinge. So I cannot use a plier or any other method of grabbing it.

BTW, I took another look at my new impact and it shows an arrow for tightening. Hmmmm. The packaging only says loosening.
The tool has a "neutral" area, but does NOT have any ramp mechanism for changing direction like the British tool. On that tool you had to deliberately switch the direction by twisting the end up a "ramp-like" stage, and then it dropped down into the opposite direction. This one justs goes back and forth in a neutral area....

I am going to use a small propane torch with a jewellers torch. It puts out a small fine flame, just fits the head of the screw.
Will let you know.

leathermang · #10 12-25-2002, 05:53 PM

Boy, I hate those " nifty chrome trim deals "

After thinking about it... that also sounds exactly like a heat sink between the head and where you need to get the heat to....bummer

I looked at the sears site and the impact driver and also noted that it only mentioned loosening..amazing if that is true....

You mentioned " deliberately " ... I found that if I did not hold it properly it would change directions on me....so I got to where I checked it before each hit.. don't ask how I found that out... that screw head came off slick as a whistle...

Good Luck....

Jim H · #11 12-26-2002, 09:13 AM

240 Ed,

A quick thought; will an electric heat gun, like a hair drier only hotter, put out enough heat to loosen the goop without as much risk of setting fire to the seat? Heat guns work good for vinyl tile glue, so I would wonder if they would work for you.

Good luck

leathermang · #12 12-26-2002, 12:19 PM

About that one direction hand impact....

I called Sears and after making sure I was talking to someone that would understand the question.. he was old and owned a two directional impact like I do... he confirmed that they now make them which only loosen right hand thread items....

Amazing .

240 Ed · #13 12-27-2002, 09:10 AM

Greg et al,

Well, here it what happened.

I used the propane torch on the screws. The thin hot flame fit perfectly into the head of the screw and It heated the screw throughly!
But no go! Hard to believe, but there you are...

Solution? Hack the turkeys off! Used a "Sawz-all" with a metal blade and was through them all within 10-15 minutes. Ta-Da!

As I was using another seat base, this turned out to be a good solution.

The seat retrofit worked like a charm too. I have what amounts to a new seat. I sit up high and straight in a 34 year old Benz!

The impact tool actually works in bothe directions too! You just move the tool through its neutral to the other side and have at it. I used it to tighten the screws.

The only problem I have now is, one of the captive nuts used to bolt the seat down has come off. It is inside the sheet metal tunnel at the front/left corner of the seat. I retreived the nut with a magnet, but can't figure out how to slip it back in there, as there is only a small round hole...

leathermang · #14 12-27-2002, 10:52 AM

You will need to describe the situation a little more for us to be able to help...
First, are you saying that the round tube is what keeps the nut from turning ? The "captive" part of the equation ? Or just that it is located there ?
How far down the round tube are we talking ?
Is the captive part of the loose nut still partially attached... or wholly attached ? How/why did it lose its "captive".... Is that structure in the way for simply inserting a new captive nut combination ?

Have to ask about the two direction hand impact.... how did that happen ?

#15 12-29-2002, 02:42 PM

I've never tried it on a #4, but there are liquids you put in the cross on the Phillips head to keep the screwdriver from spinning out. First Try is one name brand, and I've also used another with success (but can't remember the name of the stuff).

The mechanism seems to be fine grit in the liquid - it's not an adhesive.

Without it, I couldn't get #1 screws (that hold the side window fuzzies) out of a thirty-plus year old Porsche door. Amazing stuff, even if it won't help on your current project, anybody working with old cars should get some.