Hello all..I am new to the forums but not new to BMW's...I have a 2001, 325 XI with M3 18" rims all around...Lately I have been having some serious mechanical issues that not even the local shop recognized or fixed.

Basically what is happening is everytime I get the car going over 40 MPH, the steering wheel shakes like I have a wheel coming off the front of the car. I have checked the undercarriage, the wheels and tires, an alignment has been done, and a service tech has been over the car and says nothing is wrong. I beg to differ because I deal with it every day.

Has anyone experienced this before and if so, any thought on a resolution to the issue? I can't keep driving the car like this and the weird thing is that it doesn't do it all of the time. Mind you, it does do it the majority of the time but not always. I have started to log when it does it and what the PSI in each tire is, the amount of gas I have, weather, all of thost factors that could change things and there is no common denominator.

Along with this issue I have another question...Has anyone dealt with REALLY bad gas mileage on their 3 series BMW? I know that they are not exactly an economy car but currently I am pulling about 13 MPG and I am not even stomping on the gas at all. It seems as if the car in a mechanical sense is almost a lemon due to all of these issues since it only has 75,000 miles on it.

Any and all help is appreciated and I look forward to communicating more in the forums!

Newbie

Matt

Two possibilities: Worn out front halfshaft or a sticking caliper. After driving with the vibration for a few miles, stop and see if one of the front wheels seems to be emitting a lot more heat than the other, if it is, then you've found your problem. To check the halfshafts, you can just reach under the car and try to move the shaft up and down, anything more than the tiniest amount of play means your shaft may be on its way out. A tiny "click, click" is probably acceptable, but if you can feel it moving more than say, a millimeter, then there's trouble.

My money's on the caliper. And no, it wouldn't necessarily vibrate all the time if it's just starting to seize up. Rebuilding the calipers is an option, but replacing them is the easier (but more expensive) route.

Hey Critter7r, it's a rear wheel drive car - no front half-shafts! And a sticking caliper or warped disc would make itself more obvious under braking - however it might be a contributor to your poor fuel economy.
My suspicion would be the wishbone mounting bush (see http://www.realoem.com/bmw/showparts.do?model=AN37&mospid=47720&btnr=31_0600&hg=31&fg=05) or ball joints on the wishbone, or tie rod ball joints. Road camber or uneven surfaces will be a contributor in triggering the shimmy - as the wheel is pulled down the slope of the road, the alignment of the wishbone changes because the worn bush lets the back end of the wishbone move from side to side. I'm surprised the service tech didn't pick this up - or maybe I'm not ......

When was the last time your O2 sensor was replaced? Poor economy is often due to failed O2 sensor/s - although you should be throwing a code if this is the case. Possibly a blocked catalytic convertor - any issues with low power?

Wow, last time I checked an XI was all wheel drive. So the OP would have drive shafts up front. They are a very likely possibilty. Is the shake under a load or when coasting? Does it get worse when braking. Stuck calipers will shake when driving and will usualy get worse when braking. Ball joints and Control arm bushings will usualy get worse symptoms when cornering. Jack up your front end and check all moving parts for excessive movement.


Hey Critter7r, it's a rear wheel drive car - no front half-shafts! And a sticking caliper or warped disc would make itself more obvious under braking - however it might be a contributor to your poor fuel economy.
My suspicion would be the wishbone mounting bush (see http://www.realoem.com/bmw/showparts.do?model=AN37&mospid=47720&btnr=31_0600&hg=31&fg=05) or ball joints on the wishbone, or tie rod ball joints. Road camber or uneven surfaces will be a contributor in triggering the shimmy - as the wheel is pulled down the slope of the road, the alignment of the wishbone changes because the worn bush lets the back end of the wishbone move from side to side. I'm surprised the service tech didn't pick this up - or maybe I'm not ......

When was the last time your O2 sensor was replaced? Poor economy is often due to failed O2 sensor/s - although you should be throwing a code if this is the case. Possibly a blocked catalytic convertor - any issues with low power?

You guys are all awesome I just have to say up front!

Now down to the nitty gritty...To try and respond to everything already advised, the vibration does happen under braking HOWEVER, it happens at full accleration, coasting, and just about any other time of driving. It happens with a full tank of gas, 3 people in the car, just myself in the car...more or less it happens under any circumstance BUT it does not happen all of the time which is what baffles me.


The shaking is a straight vibration up through the steering column. I can take my hands off of the steering wheel and the car will drive straight at 40 MPH but the steering wheel will shake from side to side relentlessly. I have checked the tire pressure to ensure that all tires are properly inflated and are consistent and after I drive the car and it has an "episode", I check each wheel and brake area for excess heat but none is found.

On to the MPG issue...I have noticed that on the low end of things I don't have as much power as I would expect from the car and also that the Tranny shifts at a really weird pace. Again, sometimes it does this and sometimes it doesn't so I don't know what is causing the problem. I have noticed that even in colder weather, my temp gauge is a lot higher than I would expect it to be, usually well over the halfway point on the gauge but it has never overheated on me.

So that is about all of the info that I can provide right now however your feedback is very helpful! I am not exactly a genius with the wrench however i'm not an idiot either but this has just got me baffled.

Thanks everyone!

I'm not sure what the roads are like in Ut but in NH they SUCK. I bent 2 rims this year and had similar problems. My steering wheel would shake violently till about 45 or so, then stop. Usualy around 65 the vib. would come back though. At 80 it was intolerable. I just ordered new wheels and tires. As for the overheating, how many miles does it have? It could just need a tune-up and a Coolant change. My 325 xi temp gauge sits right in the middle all the time. I might sound stupid for asking but do you live in a higher elevation? That might explain a poor air-fuel ratio.

Wow, last time I checked an XI was all wheel drive. So the OP would have drive shafts up front. They are a very likely possibilty.
"Blush" not familar with the XI 4wd models here .... We only have X3/X5 - sorry critter7r!
However, now I know - drive shafts are highly unlikely to contribute to wheel shake unless the CV joints have failed and had developed enough play to allow the axle to slop around - which would be very obvious in other ways, clattering or grinding noises being one. Since the OP says he has had wheels, tyres and alignment checked, I now point to the thrust arm and lower control arm (wishbone) bushes and ball joints again. His description is of a "shimmy" rather than a balance (harmonic) problem - one or both wheels are flicking back and forth (or side to side) and I'd be surprised if you were not able to feel feathering on the tyre tread pointing towards the outside of the tyre, and/or the inside of the tread wearing excessively. Since wheel alignments are only done statically, once the vehicle is in motion and the worn thrust arm bushes are loaded up with dynamic forces, the wheel alignment will change - causing the shimmy.

Wow, I must've glossed right over the spot where you asid the MPG was down to 13 on the first read-through. Now I KNOW it's your caliper that's sticking. Mine did the same thing, it's ok for the first few miles or minutes of driving, then it starts vibrating... driving straight, turning, starting, full of people, no people.....

And for the record, a stuck caliper won't necessarily cause more vibration under braking - it's STUCK!! It won't let go of the rotor, it may also not squeeze it any tighter!! (Or conversely, it's already grabbing the rotor and causing vibration, gripping the rotor a little tighter - if it's not completely seized - won't necessarily cause more vibration. The rotor is only so warped).

To the OP: After driving for a while, see from which front wheel you can feel a ton of heat radiating, and that's your stuck caliper.

Been exactly there, done exactly that.

It's the caliper(s).

End of discussion.

"I check each wheel and brake area for excess heat but none is found."

OP said this, so more than likley its not a caliper. If its stuck it WILL generate heat rather quickly. Podmore is probably right on the money. Its likely a suspension issue. also you mentioned a service tec looked the car over. Was this a BMW tec? Did he jack up the suspension when he looked at it, or was it on its own weight? Suspension problems are eaiser to see when there is no weight on it. As for the mpg problem :confused I dunno?