2010 Volvo XC70, Drive Belt Pulley Replacement
Mark: 2010 Volvo XC70 Drive Belt Pulley Replacement.
Mark: So Bernie, today's victim is a 2010 Volvo XC70 with a drive belt replacement. What was going on with this vehicle?
Bernie: This vehicle actually, it was the second visit to our shop. In the previous week, there were some concerns with the vehicle, some vibrations and clunks when shifting from drive to reverse, and into park, and accelerating. And we'd determined that a couple of the engine mounts were worn out. So we replaced the mounts, which solved a lot of the issues, but there was still one leftover noise that was occurring. It was an interesting condition. Most noticeable when you put it in reverse, and if you put your foot on the brake and rev it up. Now, normally, a person wouldn't do that, but this is what we had to do at the shop to find the noise. But when you're accelerating slightly in reverse, there would be this strange noise coming from the engine. So this is what we were looking at on this Volvo.
Mark: And where was the noise coming from?
Bernie: Well, the noise was coming from the centre of the engine compartment area, and this engine, it's a 3.2L Volvo 6-cylinder. It has a very unique distinction of having all the accessory drives in the centre of the engine compartment. They actually drive the accessories off the back side of the engine, not the front, like is normally done on, I'd say, 99.9% of every other car on the road. They've chosen a very unique system of having the drive belt pulleys, the air conditioning compressor, the alternator, power steering pump, and water pump all on the back side of the engine. And that's where the noise was coming from.
Mark: Oh, those Swedes. So, what was causing the noise?
Bernie: Well, eventually, after a very lengthy diagnosis, and we wanted to be sure we knew what we were doing, because there's some extremely expensive ... I shouldn't say 'knew what we were doing.' Knew what we were going to replace. There's some extremely expensive parts in this vehicle, and complication, which we'll talk about later. What we found is that the accessory drive belt pulley, which it's got a one-way clutch type mechanism on it was worn out, and causing the noise.
Mark: And how did you figure out that the pulley was the cause of the noise?
Bernie: Well, there's a few methods, but one sure-fire way to determine, sometimes, whether a noise is inside an engine or whether it's an external noise, is to actually remove the belt from the system. Now, actually removing the belt on this vehicle is very complicated, as I say, by the location. We'll look at some pictures in a second. But once the belt was removed, the noise had disappeared, so it was really a matter of thinking, okay, is ... And even with the belt off, there could have still been something that was loading the pulley or the rear-end drive unit, called the READ unit, in a strange way, that could have been causing noise. But we pretty much determined that the noise was coming from a pulley-related item, and after some time and testing, we found that this pulley was, in fact, bad. We also found that ... there's a tensioner pulley and an idler pulley, and they were both worn out, as well, so we replaced all of them. But those other two pulleys were not actually the cause of the noise.
So let me just get into some pictures, here. So there's our 2010 Volvo XC70. Nice looking station wagon, all-wheel drive, lots of nice accessories, and useful to go wherever you want to be going. So this is the 3.2L engine. So again, traditional with any modern engine, plastic covers over top of everything. But if you remove this cover, you can see the spark plug, the ignition coil area, fuel injectors, that sort of thing. This is the intake manifold here, and underneath here is the location of the alternator. And over here, underneath all these covers, this is where the rear-end drive unit is, and over here are all the accessories. The air conditioning compressor is buried underneath here, power steering pump is back here, and the water pump is way over here, driven by the power steering pump. So the belt is hidden, as I said. It's several hours' worth of work just to change the belt, believe it or not, on this car, so it's kind of a crazy design. Normally, all the accessories would've been over here, but I guess they decided, "Hey, we can cram the engine over further." And it's actually kind of a smart use of space, but complicated to repair.
So we'll just get into our next photo. So this is the accessory drive pulley. Inside, you're basically looking at, this is the part that bolts onto the shaft on the READ unit. And I'll just get into another picture that's perhaps a little more ... We were looking to view in this direction, but here's the pulley where the belt sits. And inside this large area here, there's a clutch mechanism. The smooth-out operation of the belt, mostly, I would think, is the idea of this, but this is what wore out. You really can't feel anything when you turn it, but once it's running and under a certain load condition ... as I mentioned, we got the noise happening most often with the air conditioning compressor switched off, the vehicle in reverse, left foot on the brake, and right foot accelerating a little bit. So about 1,000 rpms, there's this quite horrific vibration. That's how we got the noise happening most commonly.
And then, the other two items I mentioned we replaced, this is the tensioner assembly. So there's a big, round spring inside here, and this forces the tensioner tight on the belt. So this is the kind of thing that, why modern belts don't tend to squeal like ... When we work on the older car with v-belts, half the time they come in, they're squealing. And I remember, that was a big service we used to do. Tightening belts, replacing belts. It just never lasted very long. But on modern cars ... And it's a good thing on this Volvo, because it's so hard to get to, but they tend to last a long time. You know, 100,000 kilometres without any problem, where you try to get a, I don't know, a 1965 Chevy, you'd be lucky to get 20,000 miles before your belt starts screeching and squealing, and then you've got to adjust them, and you know, it's kind of crazy.
The other pulley down below here, this is the idler pulley. And again, you know, when we spin these bearings, they're very noisy, so it indicates the bearings are worn out. And we replaced them all, and the vehicle was nice and quiet afterwards.
Mark: So, you mentioned something called a READ unit. What's that?
Bernie: So this is a unique feature on this 3.2L Volvo engine. It stands for "Rear end accessory drive," and in order to drive these belts, and to conveniently locate them at the back of the engine, they had to create a separate mechanism that they wouldn't normally create. So the timing chain on this engine, similar to many Volkswagen and Audi products, is actually on the back side of the engine. And the READ unit actually, if they didn't have to drive the accessories off the back of the engine, they could've just put the timing chain straight from the crankshaft to the camshafts. And they have to have another piece sticking out the front of the engine.
So the rear end drive unit is a bunch of extra complexity. There's a timing chain that goes from the crankshaft up to the READ unit, then there's another connecting gear from there that goes to the camshaft. So it's an integral part of the timing chain. And they do fail. Very expensive to fix. And in this READ unit, there's also a shaft that sticks out in two directions: one goes to the pulley we replaced, which drives all the accessories, the other one goes to the alternator. And there's a coupler unit on that, as well, that can fail, too. So lots of bits and pieces. But that's what the READ unit is. An extra-complicated mechanical piece on the engine to facilitate this nice, crammed-in tight engine compartment.
Mark: So, overly complicated. Is it really worth all the hassle?
Bernie: Well, sometimes, you wonder. But, I mean, from an engineering point of view, I think to myself, well, it's a very efficient use of space. But, you know, when it comes time to pay the repair bills, you're going to be paying a lot more money, because there's a lot more that goes wrong. So I don't know if it's right or ... You know, I've kind of tried to stop judging whether cars are right or wrong, or I kind of tend to look at how well were the materials used to make it, and how durable is it? Because inevitably, most things will need to be fixed sooner or later. But how they make it? I don't know. It'd be interesting to have conversations with automotive engineers about some of this stuff. But yeah, if you don't want a complex vehicle, don't buy this particular one.
Mark: So, then, speaking of complexity, perhaps, how are Volvo XC70s overall for reliability?
Bernie: They're not too bad, but there are a few things we fix, and this is one item that tends to fail. As I mentioned, the belts, while reliable, can be expensive to repair. These are the kind of vehicle that have the rear differential bearings that wear out, so there's a few common problems, but overall, they're a pretty good car. I mean, they're a nice car. You'll spend more money than you will on a Toyota, but you usually hear me say that on every podcast anyways, but ... There's more to go wrong, and they're a little more complex. But a nice car.
Mark: You can reach them at 604-327-7112 to book your appointment if you're in Vancouver. And of course, if you're somewhere else, we love you watching our videos. You can check out the website, pawlikautomotive.com, as we get a lot of visitors from the United States and around the world. As well, on YouTube, there's hundreds of videos on Pawlik Auto Repair channel. And of course, thank you for listening to the podcast, and thank you, Bernie.
Bernie: Thank you, Mark, and thank you for watching and listening.