Chevy Blazer Goes Left Then Goes Right Then Repeats

My wife bought a 2003 Chevy Blazer LS 4WD recently and it’s nearly perfect except for one quirk. While driving on straight and level roads it will suddenly go left a little and then back to the right. I bought 4 new tires for her and had an alignment done at the same time. The technician allowed me to watch the alignment while in progress. All 4 wheels were connected to a computer and the screen showed the rear was in perfect alignment. The driver’s side front was also in perfect alignment but the passenger side was out. That side was aligned and the technician assured me there was no other problems.

On the drive home…it still wandered right then left then repeated every few seconds. I took the Blazer back this morning and they repeated the alignment but it still has the same problem. I have an appointment for Monday morning at a different alignment shop. Does anyone have any idea what might be going on? Everything seems to be tight on the suspension. The vehicle looks brand new inside and out and runs great. It only has 117K on the clock and looks totally original underneath.

Have ball joints, inner and outer tie rods checked and the steering gear.

Are the wheels, tires and suspension stock? Over sized wheels and tires and/or lifting the vehicle totally changes the geometry of the suspension.

@Bing…the ball joints, inner and outer tie rods all checked out. Some play in the steering box.

@RodKnox…the wheels and suspension are stock but the tires were over-size. I had new stock size tires installed. The old tires were 245/70R15 and I put stock 235/75R15 new tires on.

I talked to a brother of mine (40 year mechanic) in California earlier today and he said it’s probably a bad steering box based on my explanation. The old tires had no unusual wear and had been on the vehicle for about 20K before I had them removed. I just priced a new steering gear box (less than $200) so I’m ready for that hit if necessary. Thanks guys.


“looks totally original underneath”

I take that to mean the steering components might be showing some wear by now. The reason I’m saying this is that we have those Blazers at work. And the ones with your kind of mileage have considerable wear on the steering components.

Has anyone checked the idler arm and pitman arm for wear?

Even though the steering box may need to be adjusted (I have the factory service manual, and it’s supposed to be adjusted on the bench) . . . I would check out the pitman and idler first

If they are showing ANY play, replace them. The good news is that you shouldn’t need an alignment after replacing them.

Good luck!

@db4690…the idler arm is good. The Pitman arm does move but it’s tight at the tie rod end. The play seems to be in the steering box. I will have it removed and adjusted on the bench since the repair manual calls for it. They can do that at the alignment shop in the morning. Thanks for your input. I did not know the steering box needed to be adjusted on the bench. The last Chevy steering box that I had adjusted went bad soon after the adjustment. It was adjusted while still attached to the truck.


Here’s how I check the idler and pitman . . . you probably use the same method, anyways

Jack up the front end

Crawl underneath

Push the idler and pitman up . . . is there a lot of movement?

Have someone start the engine and slowly rock the steering left and right

Watch the pitman and idler while the assistant is doing his thing

You might be surprised how much slop you see

BTW . . . perhaps you should ask the alignment shop if they’re willing to adjust that box

I’d hate for you to remove it, only to have them say they won’t touch it

Could we be talking about “groove wander” - where the tires are following the cut grooves in the pavement?

Also, could we be talking about the car following the ruts where the previous 10 billion vehicles depressed the pavement - and the vehicle is trying to stay within those ruts.

A simple test: Take the vehicle to different roads and see if it does the same thing on each. If it doesn’t then which surfaces does it do it on? What is common about those surfaces?

Oh and before you do this, make sure you have the proper pressure in the tires.

Thanks @CapriRacer…I had already been on a few different roads and it wandered on all of them. I took the Blazer in early this morning and the owner did a road test. He came back in and told his technicians…“It’s bad.” It spent about 90 minutes in the alignment bay and now…all is well. I asked the 2 alignment technicians what the problem was and they just said “Everything.” That’s as specific as they got so that’s good enough for me.

I took the new alignment receipt into the original shop and they instantly refunded my money for the first alignment. They did this almost robotically (no fuss…no argument) so that leads me to believe that the technician who did the alignment may have a history of problems. That or their equipment needs to be calibrated…or both.



Although I must say that the explanation you were given was not very detailed


And I’m glad to hear you got the money back for the first alignment

Thanks @db4690…the reason that the repair was not detailed was the fact that they knew an alignment had just been done. They stated that the new alignment procedures were not documented was because of “professional courtesy.” I took them at their word because they did do a competent repair and that’s good enough for me. FYI…the shops are in different towns about 20 miles apart.