2008 BMW 328xi – Front End Clunk
Mark: Hi, it's Mark Bossert, producer of the Pawlik Automotive Podcast and videos. We're here with Mr. Bernie Pawlik. Pawlik Automotive in Vancouver. Vancouver's best auto service experience. We're talking cars this morning. How you doing, Bernie?
Bernie: Doing very well.
Mark: So, BMW 328, XI 2008 vintage, had a front end clunk. What was going on with this vehicle?
Bernie: Last Friday, the vehicle came in for some service and among one of the items there's a tire pressure warning light on. It needed a flat repair on the front left wheel so we did the flat repair. We noticed after we drove the vehicle, so we just unbolted the wheel and put it back on. We hoisted the vehicle up and down, of course, which we needed to do, there seemed to be a really loud clunk in the front end. Course it was late Friday. The customer needed the vehicle and we did not have time to look at it. We weren't even sure if the clunk was possibly there beforehand. It turned out it hadn't been but for some reason this horrible clunk had developed in the front end. BMWs do have front end parts that wear out quite frequently. Things like ball joints or control arm bushings wear badly. We figured well maybe it just happened to have worn out, something like that had happened. That's what we figured was what was wrong with the vehicle. We proceeded to look. That's basically what led to the vehicle, so it came back for a look at. What we found was the engine mount bolts had broken on the right hand side. Basically the bracket that had held the engine mount in place had broken. That was what was causing the clunk.
Mark: So do you have some pictures?
Bernie: I do. Yeah, let's get into some pictures. There's our BMW 328. Nice, decent, all-wheel drive sedan. This is the engine mount bracket here that was loose. There's a bolt here. That's the yellow indicates the bracket. This is actually with the assembly redone but what we found when we did the inspection on the vehicle, no loose front end parts surprisingly. We found the heads of the bolts lying on the vehicle splash pans. These are three of the four bolts for the engine mount. You'll see they're actually all broken. The fourth bolt was no where to be found. It had worked its way loose at some point. These are all aluminum bolts. Obviously aluminum is not as strong as steel, which explains why they cracked. That's at least why they're broken, because a steel bolt would not break like this, but aluminum certainly will. That's what we found. The loose mount was causing it. When you'd hit a bump, the engine would be banging up and down on the frame of the vehicle.
Mark: Or I guess if you accelerated hard as well.
Bernie: Well, interestingly enough, it didn't because it was the right hand side so all the torque is on the left side so actually, fortunately for the owner of this vehicle, it was the right side that broke, because it was already sitting down on the frame of the vehicle. But it's surprising that we didn't feel more vibration in the vehicle when you accelerate, because you'd think that ... usually it transfers quite a vibration but for some reason, however it happened, it wasn't noticeable.
Mark: So how could it happen?
Bernie: How could it happen? Well, what we speculate happened was that these bolts had probably been loose for some time, and the fact that one of them was completely missing, I mean if someone had been in there previously and done a repair or-
Mark: And not tightened everything properly.
Bernie: Either not tightened the bolts or the bolt was loose, or somehow they just worked their way loose over time. Obviously, the bolts were all loose and at some point, and I'm assuming it happened Friday afternoon at some point on one of our road tests or just jacking the engine up or down, the rest of the bolts were loose and snapped, maybe two out of three were broken. And the last one finally snapped and just kind of went crazy. But that caused the clunk.
Mark: So why do they use aluminum bolts? That seems kinda crazy.
Bernie: Good question. Yeah, you're right. It does seem kind of crazy because aluminum is such a light-weight material compared to steel. But it's really light-weight is the reason that they do it. When you consider a car how many bolts there are in the engine and in various spots, there's got to be several hundred pounds worth of bolt, so if you can reduce half of them. An aluminum bolt is a featherweight. It's really interesting holding these bolts 'cause we bought a package of new bolts from BMW and there's four of them in a bag and they weigh ... It's weird when you hold them, because they weigh nothing. It's like holding up a piece of paper. It just doesn't seem right, because the steel bolts you get used to the weight of something like that. That's essentially why they use aluminum bolts to save weight. And they've obviously done their engineering and figured okay we can use aluminum bolts here. We can use them there. That's why they do it.
Mark: Are aluminum bolts reusable?
Bernie: No. Well, I'll say only at your peril. I would never reuse an aluminum bolt. The factory way of doing things is you replace them, so this is why a lot of these kind of things are ... as long as the car's not too old. Aluminum bolt technology is something that's only been ... This is like a ten-year-old car, so it hasn't been used for too long. The Germans seem to like it a lot. But a lot of times these bolts will be stocked or pretty easy to get. We never reuse them because they're designed for one time use and that's it.
Mark: Yeah. I remember Audi used to use these as well, right?
Bernie: They certainly do.
Mark: Could you substitute ... are there aftermarket steel bolts?
Bernie: Oh yeah, you could use a steel bolt. The threads are all standard types of metric threads. You could just get the right thread pattern and use them. We just in this case of this repair, just chose to get the bolts from BMW. They're easy to get. They've got the right socket heads and that's what the factory recommendation is but you could certainly hunt around and try to find aluminum bolts.
Mark: Steel bolts.
Bernie: Steel. I'm sorry, yeah. Thank you, Mark. You could certainly hunt around and find steel bolts and probably even get ones with similar heads on them, but that takes a lot of extra work. And a lot of times metric bolts and getting the right length and so on and the right type of head are difficult to find. So we went with the factory bolts and torqued them to spec, and all should be good.
Mark: With a completely loose right side of the engine basically, that sounds like a pretty bad thing. Did any further damage occur from this issue or could it have occurred in the future?
Bernie: Well, it certainly could have. Fortunately, as I mentioned earlier, it was a good thing it was the right side and not the left, because the left side as soon as you accelerate, the engine lifts because of the torque and the rotation of the engine. Usually at that point you get much worse damage of things like the radiator fence. Being a BMW, it may have a fan or some pulleys it will hit on things. But being the right hand side, I guess reverse is where it's a risk, because if you accelerate hard in reverse, the engine will jump up. In this case, fortunately nothing else got damaged. So that was a good thing. But it certainly can. A broken engine mount is a pretty serious thing. It can cause a lot of extra costly issues to occur.
Mark: So we're learning things. Cars' crank shafts turn clockwise, basically.
Bernie: They do. Yeah. Some engines actually turn counterclockwise. It depends on ... but I don't know of any rear wheel drive, this is essentially this is an all-wheel drive but BMWs are all basically rear wheel drive cars, so that they're longitudinal engine. I can't think of one that has a counterclockwise rotation. They all rotate clockwise. But some transverse mounted engines rotate the other way depending on which way they put the transmission and which way it's configured in the engine compartment.
Mark: So how did the vehicle drive after your repairs?
Bernie: It was good. Yeah, no problem no clunks. Just about perfect.
Mark: And how are 328 and 328xi all-wheel drives for reliability?
Bernie: Well, they usually need a few more repairs than your average vehicle. They're oil and coolant leaks develop on these after time. There's spark plugs and things, those type of things wear out as usual. Ignition coil failures are common. But overall, they're a pretty nice vehicle. But if you own one, expect that you're going to be spending more money on repairs and maintenance than you would on an equivalent type of Japanese vehicle.
Mark: So your elegant European hot rod is going to cost you a bit more for maintenance?
Bernie: Yeah, exactly. Exactly.
Mark: So there you go. If you're looking for repairs, maintenance on your BMW in Vancouver, the experts to call are Pawlik Automotive. You can reach them at 604-327-7112. You have to call and book because they're busy. Or check out their website pawlikautomotive.com. Our YouTube channel Pawlik Auto Repair. Hundreds of videos on there. And thanks for listening to the podcast. Remember for all you others across North America, they can't diagnose things over the phone. We are not experts over the phone. We have to see your product in order to be able to give you an accurate diagnosis, so if you're in Vancouver, we'd love to talk to you. Thanks, Bernie.
Bernie: Thanks, Mark. And thanks for mentioning that. It's much appreciated. Thanks for watching our podcast.