Repairing/removing a corner marker light.

[Barn Owl]

I have a marker light that is not working and some rust to take care of. I tried to remove the Phillips head screws with one of those impact screwdrivers, wouldn't budge it. Has anyone had this problem and how did you take care of it? 

Thanks

[grantgoold]

When I had my 4517 fishbowl, I had the same problems. After several attempts with rust eater sprays to no avail, I decided to drill out the heads (carefully) so as to not eat up the aluminum casting. Once I got just the head gone, the entire assembly came off. Once that was out of the way, I then soaked the remaining bolt ends. Waiting several days and making sure that every once in a while, I would hit the bolt with a heat gun to get the rust buster solution inside the threads of the nut. Eventually, after several days, I took a set of vice grips and carefully began to work the bolt end back and forth. It worked great on all the bolts and the nutcerts

Lesson learned:  Be patient. 

Good luck!


Grant
Sacramento

[TomC]

I had to do the same thing on a couple of the clearance lights.  But, I don't have the same patience as Grantgoold does.  So basically just drill it out and use a larger screw in it's place.  Done in about an hour.  Or drill a new hole right next and silicone the old hole.
One bit of advice- on my AMGeneral, the skin is aluminum and the support ribs are steel.  AMGeneral used an obivous rubber or plastic insulator between the two and used stainless rivets so not to create electrolysis between the aluminum and steel.  As result, the bus skin is still in great shape after 30 years.  On the extra clearance lights I installed (being an old truck driver, have to have the extra clearance lights!) even though the lights are grounded through the frame of the light, I used silicone under the light to insulate as much as possible and ran a grounding wire from the light to the steel frame to keep the electrical current to a minimum through the aluminum.  You should watch when you have contrasting metals meeting.  On my first Kenworth truck, the cab was aluminum (like most all trucks now).  At the bottom of the cab was a rubber extender that had a steel backing plate-that caused the paint to bubble on the aluminum skin.  And on the aluminum intake stack behind the cab, the support bands were steel-I had to replace the bands about every 3 years.  One metal will take out the other depending on which has the superior electrical current.  Just thought you'd like to know.  Good Luck, TomC

[boogiethecat]

Heh... I remove those clearance lights all the time by just driving too close to a tree.  It's amazing how easily they come off!!!
I think it's up to #5 now for my rear right...
Maybe I need to trim some of my trees!!!!

Gary

[grantgoold]

You know, I never even thought of the tree trick!  I heard the curb trick is good for tires and sharp right hand turn tricks are good for luggage bays.  You guys are sooooo creative


Grant

[roadrunnertex]

GM PD4106 Corner Marker Light ?
The 2 screws on the corner marker lights are #3 Phillip's tip size a number #2 tip will round the Phillips slots out.
If I remember right the thread size is a 1/4 -20 on these countersink head screws.
GMC Coach used Rivnut's 1/4-20 size in the body of the coach.
Easy way to solve the problem is drill the head off of the screw using a 1/4 " drill bit.
Remove the lens assembly and using a small sharp chisel remove the shoulder from the Rivnut and the old Rivnut & screw will fall inside the body cavity of the roof.
Install a new Rivnut and reinstall the corner marker light.
Rivnuts and the Rivnut tool can be bought from any good rivet supply place.
Use good quality stainless steel screw and a small amount of never seeze on the screw to aid in removal the next time.
jlv