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82 300CD with a wiggle problem. Need some advice

974 views 12 replies 5 participants last post by  OBX 300CD 
#1 ·
I've had this Coupe for 2 years now and it's been a great everyday car. Lately I've been having a problem over the past two weeks and really need some advice. I have a side to side wiggle (best way I can describe it) in my 1982 300CD. It only presents itself in very specific conditions. I almost always have to be driving for at least 15 mins over 30 to 40 mph, then when I coast down in speed (no brake or accelerator) and dip below 30 mph down to 5 mph or so the entire car wiggles or shimmies side to side. As soon as I apply the brakes it stops and the slightest touch of the accelerator it stops. After driving 40 mins to work, it's wobbling good. In heavy traffic on the way home it seems to be worse and happen quicker, thus my thought to brakes.

At first I tried a few tricks (looking for movement in the wheel at 3 and 9 and 6 and 12 jacked off the ground. I read here and found the drivers side tie rod loose. Replaced it, and still have the problem. I did take some photos with my phone of potential issues ... bushing on the left side lower control arm is pretty worn, the boots on both rear axles are split and even if not related to this will be replaced. The car has 210k miles, and I'd say it looks like 40% of the front suspension components have been replaced and look good. I can only spring for one target area of repair right away, so I need some help narrowing things down.

Brakes ... are in need of replacement soon. Rotors, pads and maybe bearings. Rotors are worn and definitely need to be replaced but since the problem stops when I apply the brakes or even slightly touch the accelerator, I'm thinking maybe not. I feel no vibration through the steering wheel or brake petal at all during this wiggle.

I'm game for doing whatever and repairs to a point are in my wheelhouse, I was just wondering if someone had this situation happen to them. I can't really afford to replace all I listed above so some narrowing of options would be huge!

Thanks so much! This is the greatest source of information I've run into.

Here are shots of the control arm bushing and rear axles. I also noticed it looks like 2 different types of axles?? Is that possible?
 

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#3 ·
I'm thinking your axles are shot as the boots are pretty torn. Also the fact that the symptom worsens the more you drive helps confirm this. Still could be something else causing this, but I would say highly likely it is the cv joints failing. You could lubricate both joints and duct tape them back together temporarily and take the car out and see if the problem is still persistent. Your axles might be too far gone, so that might not work though..
 
#7 ·
#6 ·
Honestly at this point I'm leaning more toward engine/fuel issue. The symptoms have increased since new fuel filters and a bottle of fuel additive. HP has also dramatically improved. lol
It's a really rough idle at 800 rpm's. Slowing/coasting idle.
At a full stop and below 5mph it's fine, and above 800 rpms it's smooth as silk.
Damper Bolt? Valve Adjustment?? It's appeared and gotten worse over 2 1/2 weeks ... would a valve issue present itself that quickly??
 
#10 ·
I went to my (new) mechanic and we hooked up a pressure gauge to the hard line from the pump. It was barely putting anything on the needle. I tested the rest of the vac lines the day before with a Mityvac and everything surprisingly held pressure. I figured it was a leak somewhere. Even though it was barely putting out any vac, I actually got the brake booster back today for a second when I was doing about 70. Shocked me for a second, then it was gone.
Timing sucks, as he's putting it in and is on vaca next week so I have to drive with it like this to work for another week. It never made a sound or clank or catastrophic failure ... just lost compression. Not sure how that goes down but it did. Thinking back, I did lose power door locks about 6 months ago (not a huge thing and thought it was the actuators in the doors). I plugged and tested all the vac lines one by one before going to him to test the pump. The mityvac wasn't giving me a reading and wasn't sure if I had a good enough seal. Scotts been working on these since 85, so he's not a rookie.
 
#11 ·
You know, I once thought my vacuum pump failed because it did not output anything. I am still a newbie to Benz having owned it now for mere 5 months. So I wanted to buy a new vacuum pump, but the price of it made me stop, think for a second and try few things first. Anyway I took my pump off the vehicle and cleaned it thoroughly and put it back and it this time it worked perfectly outputting 23-25 steady. I think the problem was main check valve located between the metal vacuum pipe and vacuum pump body. I washed it in lighter fluid. There are 2 more smaller valves inside the pump. I too washed them in lighter fluid.

If I am to do vacuum pump service again I would probably not remove it from the engine. I'd try to carefully remove round cover on the front of the pump to gain access to the two valves inside. When I put everything together I reused old seals and it was fine.

Good luck!
 
#12 ·
BTW I believe you don't need to go to mechanic or use some expensive vacuum tester to test vacuum pump output. Your Mityvac should do jut fine. In fact I used this attachment (see photo) with my Mityvac. I detached metal pipe going to vacuum pump from brake booster line and pressed this attachment against the opening of the metal pipe. This way I was able to get vacuum reading. Hope this will help somewhat.

Haha I forgot I did video on this



 

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#13 ·
Thanks for the info Alec! After using my MityVac, I actually thought it wasn't working right or I was doing something wrong, thus I had my mechanic just throw his basic vac gauge on it.

I did clean out the main check valve, as well as clean and replace with the one from my parts car (1981 300CD). I am getting a little vac from it at speeds over 50mph but nothing on the low end. Since this is my one and only car, and I've read about the procedure you did ... I'd have to pass. I believe I could do it but I can't roll the dice if something goes south and I don't have it operational at all. It's worth the $400 gamble to just replace it. I'm a little over 210k miles anyway, and I'd rather not have to worry about it in the future. Thanks for the advice though!

As far as the wobble, unrelated to the vac issue. I'll do a valve adjustment, new damper bolt and check for a bad injector. I'm guessing injector. Maybe some of those fancy Italian ones I've been reading about. They're on sale. lol
 
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