91 240 Front End Knock on Left Turn

brivo · Post by **brivo** » 15 Apr 2015, 13:31

Hi everyone, I've been chasing a problem in my 91 240 for a while, and I think I could use some advice. When I take a left hand turn, upon the return to center there is a loud single KNOCK coming from under the right side of the car. People riding shotgun say they can feel it under their feet. This only happens when I turn left (though the sound is coming from the right side), and only while the wheels are returning to center. The car needs to be moving (at any speed), and the turn needs to be fairly sharp. At first I changed the right outer and inner tie rods, which were somewhat worn. This didn't fix the problem, but while I was in there I found the steering rack (cam gear) was leaking fluid from the piston connected to the inner tie rod. I figured the steering rack should be replaced anyway, and hoped it was what was causing the knock. No luck though--new steering rack, all new tie rods, and a new lower steering u-joint, but the knock is still there. I'm guessing it could be a bushing or maybe the ball joint? I couldn't find much about this online, and most people I asked thought it was the lower steering u-joint, but that's already replaced. I'd appreciate any ideas and suggestions, thanks!

93Regina · Post by **93Regina** » 15 Apr 2015, 16:46

brivo wrote:I turn left

Then place steering wheel about where it happens...jack up right front-side of vehicle to just where tire lifts off ground...then grab tire with both hands (3/9) in horizontal plane, and push/pull it while someone looks at suspension. Push/pull tire when hands are in 12/6 position, is there freeplay in wheel bearing?

Lift vehicle a pinch more, and slide a longer crowbar/prybar under tire at 6 O'clock position....slowly try to lift/lower tire while someone looks at ball-joint.

Warning - While vehicle is lifted up, stay away from vehicle's underside.

brivo · Post by **brivo** » 18 Apr 2015, 14:10

Thanks 93Regina,
I tried the tests you described, and I couldn't find any excessive play or anything unusual. I have a hunch the problem is with the anti-sway bar.

lummert · Post by **lummert** » 18 Apr 2015, 16:16

Stabilizer bar bushing wear will be evident upon inspection.

brivo · Post by **brivo** » 19 May 2015, 13:56

For anyone who was wondering I finally found out what the knock was-- ball joint. This confuses me, because I jacked up the control arm and shook the wheel at 12 and 6 but didn't notice any unusual play. I've checked other ball joints this way, and they swam all over the place and made plenty of noise. But this one seemed tight, and the left and right sides both felt the same. Also, right around when this knock began, my car passed my state inspection, and the mechanic actually jacked the car up and checked the ball joints. So after this ball joint felt fine to me, and apparently this other mechanic (who has failed more than one person I know for bad ball joints), I was almost certain the problem wasn't with the ball joint.
After talking to a few mechanic friends we figured if it wasn't the ball joint, it must be the upper strut mount. I replaced these on both sides (both of which were in fact bad) and the struts (also very worn). But while I was waiting for these parts to come in, luckily I was going very slow on a side street, my right ball joint separated. That sure solved the mystery. I'm irritated at myself for not determining this through shaking the tire at 12 and 6 (my dad double checked this too), and that the other mechanic didn't catch it; I don't know if there was something peculiar in the way this ball joint was worn that prevented the test from showing it was bad?
At any rate, after new inner and outer tie rods, steering rack, lower steering u-joint, anti-sway bar links and bushings, ball joints, struts, and upper strut mounts, the 240 is steering great with a much smoother ride.
Although of course the day after getting a front end alignment and putting it back on the road white smoke starts pouring out of the exhaust pipe... At least I know what this problem is, but it will be my first time changing a head gasket.

93Regina · Post by **93Regina** » 19 May 2015, 21:02

brivo wrote:...ball joint...

Normally, I just replace them as a preventive measure, along with other parts I see as defective.

Having another eye ball to watch assists too.

Stuff happens....

Literature:

1. MacPherson Strut Ball Joint Inspection/Testing Procedure

2. Strut Your Knowledge of Ball Joints