Scratching on lower control arms.

02V70 · Post by **02V70** » 13 Jul 2023, 20:34

Both of my lower control arms look like this, and have a weird scratching on the edges:

: IMG_3303.jpg (302.09 KiB) Viewed 456 times

I also sometimes hear a somewhat quiet clunking noise coming from both sides of the front wheels. I assume this is not normal. What is causing it, and what should I replace?

Post by **scot850** » 13 Jul 2023, 23:25

I'm trying to remember the back story on this car. Have you just recently purchased it or have you had it for a long time and been driving it?

Clunking from the front can be a number of things:

1) That rod in the picture near the middle with the ball joint on it is the anti-sway bar end link. If the ball joints either end wear out the ball joint becomes loose and will knock over bumps. Or 06 XC70 is noisy even with recent suspension over post holes or speed bumps.

2) Control arms - If either of the mount bushes on the sub-frame are worn they can knock. The outer ball joint at the knuckle can also knock but you would need to raise the wheel of the ground and try levering the control arm near the ball joint to see if it has movement.

3) Engine mount under the crankshaft pulley separating the rubber from the metal part. You can check by using a floor jack and a piece of 2" x 4" under the oil pan and gently lift it at the RH end and seeing if there rubber is still attacked to the metal bracket. Be gently and don't lift more than 1/2".

Then you are onto checking the struts for leaking oil and the anti-sway bar mounts for wear. They should be bonded to the anti-sway bar.

Final thing at the front end would be the sub-frame mounts. They can knock but start by groaning when they are loaded when turning left or right.

Almost forgot the scratches. If you have just bought the car, someone may have used a pry bar to try to find a knock............!

Neil.

02V70 · Post by **02V70** » 14 Jul 2023, 00:12

Back story:
My dad blew the head gasket because of a coolant leak in 2018. He had no idea it was overheating since the dash was broken. I took it upon myself to fix the head gasket, dash, and several other problems (I couldn’t have done it without your guys’ help) last year as I wanted a car for college and I thought it would be a fun project. Problem is that I couldn’t get a campus parking permit until this coming school year. Now I’m trying to get it in good shape since I won’t be able to fix much as I (and the car) will be far away from the garage.

About the scratches…
I replaced the right lower control arm and ball joint since it looked worn (it did not fix the clunking), and It did not have any scratches after I installed it. For some reason now it does. I think it may be the lower portion of the end link scratching the lower control arm on both sides, but I’m not sure why that’s happening.

Post by **abscate** » 14 Jul 2023, 04:45

Marks from install. If the link is getting that far out of whack there are much bigger problems

Post by **Krons** » 14 Jul 2023, 05:09

With high mileage Volvos I tend to throw everything at it with suspension noises: lower control arms, swaybar links, loaded struts, engine mounts. Not sure if your budget can tolerate a full refresh like that.

To diagnose you need to get under the car with a prybar and see what is loose. I’d guess the control arm bushings are shot and you have a lot of movement. Can’t you see fresh metal scratches on the other part rubbing against it?

Post by **Blacklab467** » 14 Jul 2023, 06:17

I would say those marks are from a prybar from someone checking for play in the lower control arms. you cannot get those marks from something rubbing in that spot. I would suggest looking for play in any and all front end components including engine mounts. Those are original Volvo LCA's, how many miles on the car?
Again, I don't know how much money you want to spend or what your plans are for this car long term. All the front end parts are pretty easy to change but can add up, and I would discourage using anything aftermarket or RockAuto in this application due to quality concerns and personal experience.
Get a friend to help you check for movement with a large prybar and make a list of things that are worn out, start at the strut bushings and spring seats and work your way down.

02V70 · Post by **02V70** » 15 Jul 2023, 22:19

Pry bar for the win! I didnt use it at first because I thought I would accidentally break something, but I carefully pried some components, and found it was the sway bar end links making noise. I also found that the lower transmission O--o mount had play, but im not sure if that was making noise.

Post by **jonesg** » 16 Jul 2023, 02:30

02V70 wrote: ↑15 Jul 2023, 22:19 Pry bar for the win! I didnt use it at first because I thought I would accidentally break something, but I carefully pried some components, and found it was the sway bar end links making noise. I also found that the lower transmission O--o mount had play, but im not sure if that was making noise.

thats a cheap fix, if the nuts dont want to come loose take a grinder/cut off disk to them.