Ball pin torque - PeachParts Mercedes-Benz Forum

67fintail230s · #1 02-04-2004, 05:08 PM

A rocker noise led me to a ball pin that had loosened just a hair. It was enough to muck up the threads enough that it will not torque tight again. I am installing a recoil thread insert (M18 1.5). Would anyone know a the right (or reasonable) amount of torque to apply to the ball pin? Or if anyone has any experience with thread repair inserts where the amount of torque needed is more than a typical spark plug?

thanks

Anthony

300SDog · #2 02-04-2004, 07:18 PM

Wait a minute..... it sounds like you are talkin about the self-torquing valve adjust ball-pin nuts on the single cam 6 cyl from the 1960's.

What you gotta do is replace the case-hardened ball pin nut assembly and the threads will torque themselves - always providing resistance. I had to replace a couple of these that loosened up long time ago and the parts werent cheap...... its something that everybody should look out for.

Is there a rating for torque value? .....i dunno, but its probably somewhere in range of 32 - 18lbs (at least) based on amount of pressure it takes to turn healthy self-torquing valve adjust ball pin nuts that dont loosen up. Sorry i cant give you exact specs. from MB shop manual, but i dont have the book.

Use a torque wrench on self-torquing ball pins that dont come loose and you will get ball-park torque figure thats required. Possibly you want to replace assemblies that torque at/near low 20 lb range?

This is a very good question!!!

Tomguy · #3 02-04-2004, 10:28 PM

If you mean the thing that looks like this:

If the threads are stripped, you must buy a new one. I think it's like 20 Nm minimum torque. These are designed to adjust the height of the rockers in respect to the cams (as you need a bit of space in there for expansion - 0.003" intake and 0.008" exhaust, respectively, for a 4.5). They need to be adjusted as the valve seats and cams wear. Your valve clearances should be listed on the plate in front of your rad, to the left side (the emissions plate).

67fintail230s · #4 02-05-2004, 08:38 AM

The height adjusting nut on the ball pin assembly is fine. It requires somewhere around 30 or so foot/pounds to turn. My problem is where the whole ballpin assembly screws into the head. It is the 18mm diameter thread that requires a 24mm socket. It is essentially screwing a steel shaft into an aluminiun thread. Since the adjusting nut on the assembly takes 'no more than 50 foot/pounds' to adjust (as stated by my workshop manual) I am assuming that the whole assembly must be torqued down even more.

Tomguy · #5 02-05-2004, 12:30 PM

fintail: Yup, that's indeed true.
What happens if you hold that 24mm nut while turning the smaller nut (17mm? That's the size of mine)
Of course, I wouldn't want to keep it like that very long, if it's loose it may begin wobbling, and a wobbly rocker can't be a good thing!

I'd just say tighten it to about 80 ft. lbs. without knowing anything, it couldn't be too tight or too loose. I don't even have a torque wrench myself *sees outrage from many members* and just guess on most stuff (then again, I haven't done heads or anything that would require a torque wrench that I know of).

I might overtighten or undertighten stuff, sure, but... I just never got around to popping the cash for a torque wrench! I should do that sometime before I (possibly) put "new" cams on...