February 12

2010 Audi A4, Camshaft Timing Chain



Mark: Hi, it's Mark Bossert. I'm here with Bernie Pawlik, Pawlik Automotive in Vancouver, BC, Canada, and we're talking cars. How are you doing Bernie? 

Bernie: Doing very well. 

Mark: So today's victim is a 2010 Audi A4. Something was going on with the timing chain. What was happening? 

Bernie: Well, there was a lot more to it than that. The vehicle came to our shop. Wasn't running. It had been at the Audi dealership. They'd looked at a few things, had a thought that it might need a high pressure fuel pump, for whatever reason, the customer didn't want to deal with them anymore and brought it to us to look at. So to kind of make a long story short, we did some testing, diagnosis. We determined that the high pressure fuel pump was in fact bad. We replaced that vehicle. Would almost start, but still wouldn't start. 

Tested a few more items. I think at the end, and I can't remember the whole list, we ended up replacing all the fuel injectors, doing a number of tests and determined that the engine computer was bad as well, so we replaced that. We were able to get a used computer, which, you know, saved the customer some good amount of money over a new one. Had it programmed and the vehicle actually started at that point. But when it ran it was very noisy. The engine was very noisy. You hear the noise from the timing chain area.

So we figured, okay, the timing chain is bad. And you know, it was going to need to be replaced, but at that point it was running sort of adequately. And the other interesting thing is we weren't getting any timing chain type of codes when the engine was cranking. But once the engine started, then we started getting a number of codes.

So interesting about the diagnostic process on this vehicle is it seems like to get a timing code, that you would get from the engine computer, the engine had to be running as opposed to just cranking, which is kind of unusual. 

Mark: So what happened next? 

Bernie: After a fairly large amount of work we, you know, told the customer, Hey, the timing chain needs to be replaced. And they kind of hummed and hawed and said, okay, I'll go ahead and do it. Now, weird thing happened in the interim. You know, we'd driven the car in and out of the shop a couple of times. It was running, again it was loud and noisy, but running okay. And then sort of one of the last times we ended up running it out of the shop, it cranked over, but wouldn't start.

So we're like, Oh, that's kind of weird. Well, maybe the timing chain skipped a tooth because it was so noisy. So we thought, okay, you know, got to be the timing chain. So we proceeded to work on the timing chain from there. Pulled it apart, found the timing chain badly stretched, but hadn't actually skipped a tooth. And the other thing we found, there's an item on the front of the timing chain, it's called the bridge.

It basically pumps oil into the front of the intake camshaft for the valve timing functions. And there was pieces broken in there. So we replaced that. So again, the timing chain was quite an extensive repair, put it all back together. And the engine still wouldn't start, which is really frustrating. 

Mark: So can we see some pictures of what was going on? 

Bernie: Yeah. Before I show the pictures, I'll just cut right to the diagnostic. So at that point we figured, okay. Maybe some debris from this bridge that broke, it's got a little valve inside it, got stuck in the valve timing gear and just wouldn't allow the valve timing to be proper. So we figured maybe there's something wrong with the camshaft, pulled the covers back off, verified the valve timing was good, which it was. Pulled the valve cover off and found some interesting things.

And so I will share those right now. So there is the intake camshaft. We ended up replacing this piece. Now, these are the cam, I'm moving my mouse point over. These are the cam lobes. This is the piece that was bad. And what this is is a it's got little notches on it. I'll show some more closeups in a minute, but this sends the camshaft position signal to the engine computer.

2010 Audi A4, Camshaft Timing Chain

And this piece had actually broken off of the camshaft. It's supposed to sit against this lobe, right tight against that lobe. And it did actually come off. And of course, without that signal, the vehicle wouldn't start. But the strange thing is. It was all working fine, and somehow, for some reason, this basically broke off the camshaft in the time we had it running.

Why that happened, I don't know. There was also a valve lifter for this cam lobe here that had popped out, and so it's possible that that lifter was loose, maybe from bad oil pressure. It popped out and hit this piece and knocked it out of position. That's probably what happened. But it's sort of sometimes hard to know.

Here's a sort of another closer look again. These teeth and sort of cutouts here, there's a magnetic signal. It's generated as these pass. And so the computer can tell by the different lengths of these cuts here, what position the camshaft is in to fire the spark at the right time. 

2010 Audi A4, Camshaft Timing Chain

Again, here's another view of it.

2010 Audi A4, Camshaft Timing Chain

There's a timing chain tensioner, and this is basically the position we found it in. So the timing chain was stretched very badly and way out of position, but hadn't actually skipped a tooth, but that's how a timing chain tensioner looks for the main timing chain.

2010 Audi A4, Camshaft Timing Chain

There's a view of the camshaft. I'd mentioned this bridge piece that we replaced. It's basically a sort of cover plate that pumps oil into the front of this camshaft here. So this had broken apart and there's pieces missing. So this actually will move depending on oil pressure and adjust the cam timing.

2010 Audi A4, Camshaft Timing Chain

There's a view of everything put back together. So there's that piece I was showing you with the timer piece for the Cam shaft timing. There's a, there's the new lifter in place right here, but this had actually popped out of play. So somehow probably the lifter was worn, bad oil pressure, just knocked the thing out and it just sort of happened in the shop. You know, it's always hard to tell a customer things like that, but at least it's better that it happens here.

2010 Audi A4, Camshaft Timing Chain

Then they pick it up and drive it down the road and five minutes later, it happens, or a day later.

Again, sort of a top down view of the piece. Again, remember the other pictures, this piece here where I'm moving my mouse pointer was sitting in the middle. So I think that's kind of self explanatory, with a lot of pictures. 

2010 Audi A4, Camshaft Timing Chain

Mark: So how did it run after you repaired all these different pieces? 

Bernie: Yeah, it ran perfect. No more rattling timing chains, fired up right away. Yeah, it ran perfectly. 

Mark: So what do you think was the first event that caused all this cascade of failures to happen? 

Bernie: Well, I think the timing chain may have probably been worn pretty badly before the car even came to the shop and before it actually died for this customer. Like, this is what I'm assuming, but I hadn't seen the vehicle, so I don't know. But I'm assuming the timing chain was probably pretty badly worn at the time.

Perhaps the high pressure fuel pump failed, and that may have taken out the actual computer. It's hard to know, but you know, the fact that we had to replace the computer as well, and the injectors weren't being triggered properly either. I think there's a cascading effect from that high pressure pump in the computer.

And then as I said that it ran after that. It may be that also that it had a bad valve lifter, you know, from bad oil pressure. You know, this car had been sitting, you know, like the process took a while. So maybe the lifter had unpumped itself, like, cause they have oil pressure, you know, that holds the lifter tight.

Perhaps it had kind of lost its oil pressure and being old, it somehow popped apart. So I think that was kind of a secondary thing that happened after we got it running, you know, with the timing chain. Maybe with that bridge piece that was worn. Maybe there was an oil pressure problem with the engine as well, due to that part being broken and then cause that piece to break off.

It's a very, very weird issue, like very unusual and very unusual to have stuff that happens all these problems one after another. 

Mark: Yeah. So that's what I was going to ask is like, how often do you see this? Where one part failure leads to a cascade of a whole bunch of other stuff breaking? 

Bernie: Well, once in a while that happens and sometimes it'll happen inside an engine where you'll have a catastrophic failure where one part will come apart and it'll cause, you know, everything to bust apart. So that does happen. 

In this case, it wasn't a failure like that. It was kind of some fuel injection parts, some electronic pieces, and then some mechanical items. So not ever having seen the vehicle beforehand and knowing the history is a little difficult. But fortunately we don't see this very often cause you know, jobs like this, they're not money making jobs for us. The amount of time it takes. 

I know like a dealership will usually just go, well, we spent two hours, there's a two hour bill, you know. Needs this. There's the bill. We ended up actually doing the camshaft for free for the customer just as a goodwill gesture, even though it had really nothing to do with us. We do those kinds of things from time to time. Yeah. Don't count on it. Yeah. I don't count on it. It felt like it's a goodwill gesture after everything that had happened. So it was a very, very expensive part that someone had got for no charge. 

Mark: Right. 2010 Audi A4s. I mean, that that's 14 year old vehicle. How reliable are they? 

Bernie: They're not bad, but they do have their share of problems. And when things go wrong, they are expensive to fix. So you know, like I say with anything, make sure you change your oil often. Now, of course you say it's, it's a 14 year old car at this point, so you hope that if you're having to buy it used, that whoever owned it beforehand has done good maintenance on the car.

Still a very nice car. And you know, just being an Audi, it's expensive to fix and yeah, certain issues happen. Things like timing chains are not an uncommon wear item on them, so you may need to change it. You may not. It kind of depends. Sometimes it's a bit of a luck of the draw, roll of the dice.

Mark: So is it fair to say that if you started hearing funny noises in your car, you should take it in to get it checked? Because if you just ignore it, you're asking for big trouble? 

Bernie: Oh, absolutely, for sure. If you hear like, especially things like timing chains rattling, it's like the moment that happens, you really need to fix it right away because it's not going to improve itself.

Yeah. It won't get better. You know, and sometimes, sometimes there's early warnings like when an engine's cold, you'll hear like a little rattle of a timing chain. And so that's a good early warning to take action. 

Mark: So it's time to either put it up for sale or get it fixed.

Bernie: Yeah, exactly. And it's funny we say put it up for sale, but it's like, are you going to be honest and pass on something that's problematic? Or are you going to, you know, level with the person. You know, we're all honest people until it hits us in the pocket.

Mark: If you're looking for service for your Audi, you've got complex problems or simple stuff, or you just want to maintain it properly, the guys to see in Vancouver, BC are Pawlik Automotive. You can reach them at their website, pawlikautomotive.com. You can book right there online. They'll call you, they'll get ready for your appointment. Or you can phone them at (604) 327-7112 to book your appointment. Same thing, they'll go through the issues with you and find out what's going on. Of course, they can't diagnose it over the phone. Don't expect that. They have to take it apart and look at it. Pawlik Automotive in Vancouver. Thanks for watching and listening. Thanks, Bernie. 

Bernie: Thank you, Mark. Thanks for watching.

About the author 

Bernie Pawlik

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