steering and suspension Yellow Paint

['76mintgrün'02]

I am sure this is a silly question, but what is the yellow paint applied to suspension connections and such? I assumed it meant that a mechanic had been in there to replace something, but have seen it on too many cars. Did a search, but to no avail. Just curious, Tom

[lilcphoto]

you can get a paint pen to mark what youve done or what your going to do or where to cut... we use it at work all the time.

 

It also is applied when you pick up a part from pick-n-pull for their records... could be anything.

[nbcbird]

I always thought it was a reference mark for final factory assemblies that were properly torqued. 

[FB73tii]

I always thought it was a reference mark for final factory assemblies that were properly torqued. 

Agreed, yellow paint applied at the junction of a fastener to its mating surface indicates the fastener has been torqued to final spec. It is normally lacquer, which is very brittle when dry and cracks easily under load. Any cracks in the paint that show upon later inspection indicate the fastener has begun to to loosen, a good quick check when doing a "nut-and-bolt" inspection on a track car.

 

I use yellow nail polish on critical fasteners, in particular the CV joint bolts. A more expensive option is official "anti-tamper" paint or "anti-sabotage lacquer" as used in the aircraft industry.

 

--Fred '69 & '74tii

Edited October 31, 2013 by FB73tii

[M3M3]

i use cheap china markers aka grease pencils for the same function.

['76mintgrün'02]

Good to know, thank you for the information.

[TobyB]

If you're talking about the factory marks,

 

the ones I've seen aren't  lacquer, it's more of a quick swipe with enamel on a cheap brush.

 

I always figured that it was proof that an inspector had checked fitment and attachment-

it's like a dog peeing on a hydrant more than anything- 'I was here.'

 

And it seems to be kind of random, although I never cleaned up parts cars before shredding them.

 

t

[02Nut]

As a few others have posted, the yellow paint mark is often used during the assembly process. For Fasteners requiring critical torquing, assembler would torque per spec and immediately mark fastener with paint as proof fastener was correctly torqued.

I've worked in assembly operations where a paint brush or paint marker is attached to the torque wrench (often duct taped) to make the torque and mark process easier for the assembler.

BTW - type of paint usually isn't critical, just needed mark to last long enough for final inspection.