Bb had the exact solution for you, if you're willing to understand and follow it:


This approach will absolutely allow you to spin that nut off the threads, provided that the taper is not damaged.

If you don't fully understand it, post again for clarification.

Let me see if I can find a picture of what I was describing. Not sure if it will help. I'm at work until after midnight so nothing I can do from here. Maybe when I get home I can draw a diagram ... heaven knows I have nothing else to do, and insomnia.

Believe me, I know the feeling. Sometimes it seems like every project I do is one nightmare after another. My UCA bolt was a nightmare to get out of the frame. There's a thread on that drama somewhere here. But I got past it. Now I'm a new frustration ... I finally got the glow plugs and idle control all fixed, was so excited, and then like an idiot I overtorqued one of the motor mount bolts and it broke off. I can't get the other end of the bolt out. Frustrating. So I feel your pain. But deep down inside I enjoy the adventure.

__________________
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

Thanks, all. Brian, I understood BB's solution, but as I was working on it today, I thought I was effectively doing the same thing using the pipe (i.e., forcing the UCA down into the spindle). I can give it a shot with the wood next weekend. I think I understand the process. Basically I would be blocking the upward motion of the UCA using the wood thereby forcing the joint and the spindle together. Is that right? If so, would I need to make some measurements and figure out what piece of wood would work or are BB's measurements exact? ....

Bodhi, thanks for all your help. No worries if you can't get the diagram to me. I don't want to be a burden. I read the thread about your UCA bolt. Sounded like a pain. I played with the bolt in my car today. When I unscrewed the nut, the bolt came right out. But I screwed it back in because I didn't want to open a can of worms. Does that mean that the bolt will come right out? I assume that since the bolt would unscrew at all, I won't have a problem getting it out. Sorry to hear about your motor mount bolts. I haven't even looked at my mounts. What was wrong with your idle control? And the glow plugs were just old and needed replacing?

The problem with the pipe is that you need a tremendous about of force to get it done............and a very long extension bar.

Far better to use a hydraulic jack per the instructions of Bb. You understand the process perfectly.

I'd probably use his measurements.............he's done this many times...........you simply want to prevent the upper control arm from continuing upward............any wood that will accomplish that will be perfect.

I feel your pain, BTW. I struggled with the reinstallation of the LCA and ball joint for the exact same reason.

This sounds suspiciously of a hardware mix-up from previous service. After problems I ran into, found that the UCA ball joint uses a special fine thread nut (dealer only, even Fastenal doesn't carry it!) IIRC, 10mm x 1.25mm comes to mind. If someone forced the wrong nut on there, you may indeed have a minor battle on your hands. My final resort was very careful cutting of the nut with a dremel tool, taking care to not damage the ball joint threads.

__________________
Sam

84 300SD 350K+ miles ( Blue Belle )

OK, this may not be of much use ... I couldn't find a pic with the clamp on (I guess I never took one), but here's a pic with arrows showing where I put the C-clamp ... it has to be a pretty large clamp. The one I used had sort of oscillating washers on each end, if that makes any sense, so it gripped onto the top of the arm well.

As for my recent work, the first thing I did was replace the old loop-style plugs with pencil-style plugs and also a fast-glow relay that I wired in. It made a HUGE starting difference (your car has pencil-style plugs to being with, but older ones have not-very-effective series-wired plugs). The next issue was that my idle control cable was totally non-functional ... turned out it was basically seized up. I put in a new cable and it works great. Just tightened the motor mount bolts to be thorough before I took it on the road, and I was overly thorough. Now in the process of getting the other part of the bolt out and can't find the right tools.

Attached Thumbnails

 

__________________
1987 300D, arctic white/palomino--314,000 miles
1978 240D 4-speed, Euro Delivery, light ivory/bamboo--370,000 miles
2005 Jeep Liberty CRD Limited, light khaki/slate--140,000 miles
2018 Chevy Cruze diesel, 6-speed manual, satin steel metallic/kalahari--19,000 miles
1982 Peugeot 505 diesel, 4-speed manual, blue/blue, 130,000 miles
1995 S320, black/parchment--34,000 miles (Dad's car)

Spinning ball joint studs are a common problem, especially when copious amounts of penetrating oil have been used.

I'm going to try BB's method this coming weekend (jacking the car at the jack-points and pushing up the spindle while blocking the upward movement of the UCA). Brian/BB: should I remove the spring before trying this? I'm thinking that I can put more pressure on the UCA if the spring is out. I didn't remove the spring during any of my previous attempts.

If that doesn't work, I'm cutting the nut off. I sized the nut that was on my passenger side UCA ball joint (which ironically came off super easy, without any blaster or torching) and it's a 10mm x 1. If the driver side is the same nut (it looks like it is), I can't imagine it being the wrong size since the passenger side cam off so easy. Someone may have threaded the nut improperly though, in which case cutting the nut is my only hope.

Bodhi, thanks for the picture. I don't think the clamp will work for me since the nut is pressed snug against the spindle. If I put the clamp on the spindle, it effectively blocks the movement of the nut. I've heard about the old loop-style plugs. Great to hear you got that and the cable taken care of. Good luck with the mounts.

No, removal of the spring is not necessary. You'll be using a hydraulic jack that can easily offset the force of the spring.

The only way this scenario fails is if the taper is loaded with some type of penetrant/lubricant.

Thanks, Brian. I've been dousing this thing with blaster so lubricant may be an issue. Should I even try the jack next weekend or just cut the nut off and simplify my life? Thanks, again.

__________________
Alex
1984 300CD - Silver/Blue - 326,000 miles (sold)
1979 240D - Canary/Brown - 221,222 miles (I love this car)

I'd certainly try the jack. If you cut the nut off and damage the threads of the ball joint, you might be right back where you started with no way to get the new nut on the stud.

I don't know of any way to chase the threads of a ball joint stud......................

From the sound of things, new UCA's might be an outstanding idea.
If they are original, there is no chance that they are not due for renewal. And, given the inefficiencies associated with piecemeal front end work, there might be no time like the present.

Agreed...........but, isn't the ball joint replaceable on the W-123?

Not the upper one.

OK, thanks..........that's the same as the W-126.