November 10

2014 Audi S4 Water Pump Leak



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 we're talking about a 2014 Audi S4 that had a water pump. The water pump was doing something or not doing something. What was going on with this vehicle?

Bernie: Yeah. So the vehicle came to the shop. One of the concerns was there's a cooling system warning light on the dash. And that was kind of the primary concern with it. 

Mark: Okay, so that's great that the customer brought that in when there's just a warning light. A lot of folks don't. They wait for more catastrophic issues. What kind of testing and diagnosis do you do after there's a warning light like that? 

Bernie: Well, first of all, inspect the coolant level and we found that to be full. And then next thing, we hooked a scan tool up to the vehicle and did a complete vehicle system scan for codes and found there's a code for a water pump mechanical fault, which is a very unusual code to find in a vehicle.

Well, I guess it's not entirely, you know, beyond the realm, but just first time notice that in an Audi. 

Mark: Why would there be a code? Isn't this just a belt driven like what, in my ancient years, what I'm used to is for water pumps. 

Bernie: Yeah, it is a belt driven water pump. That's why I kind of say it's kind of an odd one to have. But this is a belt driven water pump that has a little extra to it. It actually has a vacuum operated diaphragm that can control the flow of the water pump. And so there was a fault. In that system, and that's why the warning light was on and there was a code stored in the powertrain control module. BMWs have used electric water pumps for a long time, but Audis, you've still got your usual belt driven pump.

So, I'm thinking, well, why would you have something like that? But, of course, with a vacuum controlled system, now you've got some other factor involved, you know, something to monitor and an extra bit of complication. 

Mark: So how does that work? And what's the value of it? 

Bernie: It basically just the cooling system flow from the water pump because basically with a belt driven water pump, as soon as you start the engine, the pumps driving all the time. It's pumping coolant and maybe you don't need to be pumping coolant.

So it's a bit of a waste of energy or else, you know, it impedes the flow of the engine warming up quickly. So by controlling the water pump flow, you can actually warm the engine up faster. I think that's probably the primary reason for it. Basically, you know, if you're not flowing any coolant through the engine for the first minute, 30 seconds, depends on the outside temperature. Maybe it's really cold out. Maybe for the first couple of minutes, you're going to get the engine to warm up quicker. And you know, I should say not no flow, but just very minimized flow.

Mark: Is this a replacement, an expensive, fancy replacement for a thermostat? 

Bernie: No, it's not. Because there's still a thermostat as well. And we actually replaced the thermostat and a couple of other things while we were in there. But no, it's not actually a replacement for a thermostat. It'll actually allow the engine to warm up even faster because there's no flow from the cooling system. So it gives more control. BMWs have used electric water pumps for a long time.

And, you know, again, with that, they can just determine when to turn it on, when to turn it off. How fast to flow the coolant through. It's all completely independent from a mechanical motion. We'll have a look at a couple pictures. 

Mark: So was the only problem just the water pump dash warning light, or was there any other issues going on?

2014 Audi S4 Water Pump Leak

Bernie: Well, the actual water pump itself was worn too. And you know, I had a video of that, but I'm not gonna be able to show it on this podcast. But it'll be in the show notes. So when we started stripping things apart, we actually found that the water pump in fact, the bearing was worn and that's probably why the vacuum system quit working. 

Anyways, there's a top view of this. It's a supercharged 3 litre engine. Awesome power train for sure. Very nice piece of equipment. I love supercharged engines because they have just such a nice, immediate throttle response.

There's the old water pump right there. You can see this pipe coming off. This is a vacuum hose. It attaches to a rubber vacuum hose, which is, I don't know, 3 or 4 inches long. And then there's a solenoid right beside it, which is computer controlled.

2014 Audi S4 Water Pump Leak

Inside this thing, what's different about this is you have this big round, I moved my mouse pointer around, this big round chamber here. And that's where the vacuum stuff happens. Just before we get into that, you can see this sort of darkish color here. This is antifreeze that's seeped out of the water pump over time. Not, you know, there wasn't like active drips, but seepage. So it's leaked out over time. 

Here's a side view of the water pump. So you can see this chamber here and what there is, there's a a sleeve that moves in and out, where I'm moving my mouse pointer. So it actually covers over the veins of the water pump. When the vacuum's activated and that will control the flow. 

And then we have one last view. This is kinda looking down on the impeller. And again, that ring, it's like a, I say a sleeve, it's like a metal ring, sits right in this area here. I'm moving my mouse pointer around. It's kind of hard to differentiate it, but that's the item that works. So it basically wouldn't hold vacuum properly and operate. 

2014 Audi S4 Water Pump Leak

But I was thinking, this is interesting because you know, over the years, we have a variety of issues that we find on vehicles from say, engine smoking problems. Sometimes it can be blue smoke, black smoke, white smoke and white smoke is usually excess coolant getting into the engine. And that's usually a head gasket kind of issue. 

But you know, in this case, you could actually have this diaphragm torn and be sucking coolant out of the engine in through the vacuum system. So there's another place where coolant could enter the combustion chamber and cause white smoke.

Mark: So what sort of a repair job on the list of complicated is this? Is this taking the whole front of the car off to get to this part? 

Bernie: It's not as bad as Audi's used to be where you'd have to put the thing into service mode and you have to pull the whole front off. There's access, but the supercharger needed to be removed. So there's a number of coolant pipes and things in the way. 

We did the thermostat at the same time. Which is actually quite an additional amount of work, but figured it was a good time to do the thermostat as well. Because they do fail. So we did that. Water pump and I said, you know, the water pump, if you look in the show notes video, there's there's a video you can see play in the water pump. So it actually had quite a bit of movement to it as well. 

Mark: How did it all work after all the repairing? 

Bernie: Yeah, it's good. Worked perfectly. Warmed up. No warning lights. The interesting thing about this water pump too, is that it defaults to a normal water pump. Like, if the vacuum system fails, it doesn't stay stuck in the no flow area. It stays stuck in maximum flow. So it's a kind of a safety thing. Some thermostats on vehicles, if there's a fault, it'll actually fully open. Some don't some do, some don't. You kind of want the ones that open. 

Mark: So vacuum modulated water pump, how unique to this Audi or to Audis at all, is this system?

Bernie: Yeah, it's used on a variety of VW, Audi, Porsche products of these type of engines. This isn't the only engine. It's not really common, but it's not an entire rarity either. So you'll find it on other models of Audis and VWs and Porsches. 

Mark: And just on a more of a straying into engineering territory, if you were to compare this with the BMW solution of just using an electric pump, is that a better solution? It seems less complicated than this.

Bernie: I think the BMW one is actually probably more complicated in some ways, but I think because you have to redesign the whole cooling system the way it flows, you have to design the engine around or, you know, there's got to be factors. I think engineering wise, this is simpler, but I think the BMW one is better because you've got like way more control, overflow and when and how and, you can even control where to flow the coolant as well. So, you know, like to heater hoses, for instance, or just 1 little circuit. I know I'm not saying BMWs do that, but, you know, I think there's more control with the electric pump. And is it more efficient? I don't know. Energy wise, possibly.

Mark: So this is a pretty complicated, fancy sports car with a lot of power. I've driven them. How are Audi S4s for reliability? 

Bernie: They're pretty good overall. They're pretty good, reliable cars. Yeah, I would recommend it, but just know that you're going to be spending, you know, there's a lot of complication and extra fancy stuff to spend money on. Your repair bills will be higher. And maintain it well. Yes. Change your oil, change your fluids, have it looked at, you know, and do everything. But yeah, it's a very nice car for sure. And pretty decent. 

Mark: And maybe the traffic tickets you'll get too. 

Bernie: Yeah. Yeah. You gotta be careful of that. 

Mark: So, if you're looking for service for your Audi in Vancouver, the guys to see are Pawlik Automotive. You can reach them on the website to book your appointment,, or you can call and book your appointment, (604) 327-7112. You have to book ahead. They're always busy, always full. The parking lot's jammed with people, but they'll get you in. They'll get you repaired. They're experts. This is the place that other shops send the problems they can't fix, to Pawlik, to get them fixed because they know it'll get done, right. Thanks so much for watching and listening. Thanks Bernie.

Bernie: Thank you Mark. Thanks for watching.

About the author 

Bernie Pawlik

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