April 10

2007 Mercedes Benz SL600 – Coolant Pump



Mark: Hi, it's Mark from Remarkable Speaking. I'm here with Bernie Pawlik, Pawlik Automotive in Vancouver, Vancouver's best auto service experience, and we're talking cars. How you doing Bernie? 

Bernie: Doing very well. 

Mark: So today's victim is a 2007 Mercedes-Benz SL600. What was going on with this vehicle?

Bernie: So the customer's complaint was a noise coming from the front of the engine. Thought it was maybe a belt noise or a bearing noise. It was like a kind of a high pitch, sort of screechy kind of noise. The description wasn't exactly perfect, but there was definitely a noise coming from the front of the engine. It was intermittent and mostly when the engine was hot. So that was what we were tasked to find. 

Mark: So where did you start? What testing and diagnosis did you start with? 

Bernie: Yeah. So we basically ran the engine to listen to it and we you know, got a stethoscope out and listened to all the bearing pulleys at the front of the engine cuz that's where it seemed like it might be an accessory belt issue of some sort. So, you know, we listened to that nothing found. Ran the engine for a very, very long time in the shop, never heard a peep out of it. The engine was very warm at the time. Never heard a noise out of it. Drove it outside, left it running for a couple of hours and never heard a noise from it either.

So after that we actually had the car for a few days. So I drove the car around a little bit, stopped somewhere, came out, started up, and then I could hear this little high pitched little whining noise. And that's when we kind of found the heart of it. Kind of came and went as the client had had described, but eventually traced it down to a noise coming from under the front left side of the bumper.

There's a water pump under there, a cooling system pump for the turbocharger. It's an auxiliary cooling system, it's an electric pump. And you know, this is where experience comes in, like the moment I heard the noise coming in and out, I started listening. I go, that sounds like an electric motor bearing going bad.

So, it kind of gave me an idea where the problem was. Did a little bit of research. Yep. There's a water pump down there. Hoisted the vehicle up, ran it again, for a very long time in the shop until the noise happened. Found the pump, listened to it with his stethoscope. Yep, that's it. 

That's a very long description but sometimes things don't happen fast. You know, you may be driving the car and going, oh, there's the noise. Well, sometimes it doesn't happen quite fast enough, and so it takes time to work things through and we don't guess at things. We wanna know for sure we're fixing the right thing cuz these cars are complicated. Labour intensive. Parts are expensive. You wanna make sure you fix the right thing. 

Mark: So you mentioned this coolant pump's for the turbocharger, is that what it's for? 

Bernie: Yeah, yeah. So it's an auxiliary cooling system for the turbocharger and it's like a low pressure cooling system. It has a very small radiator, almost looks like an AC condenser, located right in front of the radiator and the AC condenser. So it provides coolant for the turbocharging system. It's a separate system, so the turbocharger has different needs for coolant than just regular engine coolant flow. And so that's why they put that system in there. 

Mark: So you mentioned the pump was buried behind the bumper on the car. What was involved in replacing it?

Bernie: Yeah, so this is a lot of work getting this piece out. We'll just get into the picture show right now and we'll have a look at some things. 

So there's a car, beautiful red colour SL600. So it's a V12 engine, twin turbo. Lots of power. It's not an AMG model, but it still goes awfully fast. Smooth. Yeah beautiful car, hard top convertible. And it's a sunny day too, and this picture was taken, so it's a perfect day to remove the roof, although it's still kind of cool around Vancouver. 

2007 Mercedes Benz SL600 - Coolant Pump

So this is the pump. There's actually two auxiliary pumps in this vehicle. One is for the regular cooling system that just provides extra coolant flow for the heater when you have the engine off, if you want to, if you know, or whatever time they set that. But this again, is the separate coolant pump for the turbocharging system. So complexity.

2007 Mercedes Benz SL600 - Coolant Pump

So this is the front bumper off. So the front bumper has to be removed to access this piece. And you can see there's an awful lot of stuff under here. This is sort of the metal part of the bumper here and that nice red plastic cover goes over here and around here. There's a number of plastic covers underneath that need to be removed. The red arrow points to where the coolant pump is, is here. 

2007 Mercedes Benz SL600 - Coolant Pump

This is a closer view. Just a few other things we're looking at while we're here. 

2007 Mercedes Benz SL600 - Coolant Pump

You can see the front front left brake rotor. I'm my most pointer around, by the way. Front left brake rotor. All this stuff here. These components here are all for the hydraulic suspension system, and there are a variety of components located throughout the vehicle. But this is the valve block for the front suspension for the hydraulic suspension.

2007 Mercedes Benz SL600 - Coolant Pump

And we've done and replaced bits and pieces. This is accumulator. This is a common failure part for the hydraulic suspension. Anyways, that's where the pump is located. So the bumper has to be removed and this cover out of the way, and then the pump can be taken out through that area. 

Another view looking in on the pump and another view that we've already looked at a little closer view.

So the pump, the pump and bracket comes off. And other, you know, that's pretty straightforward once you get the bumper off, of course. And then of course it's a matter of putting everything back together and adding some coolant and the way it goes. 

Mark: Clearly, once the pump was replaced, everything was good?

Bernie: Yeah, yeah. No more noises and it's all good. Should be good for another I dunno, I tend to look at these things and go, how many years did it last? You know, we put a exact same Bosch pump in it, it should last the same amount of time or longer. You never know.

Mark: What would be the consequence of ignoring the noise?

Bernie: Well, eventually the pump is gonna fail and it will not provide coolant to the turbochargers. Now whether that'll set any codes or warnings, I'm not sure on the dash, there was nothing like that. But you know, I guess the consequence of course is the turbochargers could overheat.

There's obviously a coolant pump there for a reason. The turbochargers could overheat and resulting... 

Mark: Gets expensive. 

Bernie: Exceptionally expensive repair, exceptionally expensive, especially when you have two of them. I mean, one turbo is expensive, but two is double the cost. So it's definitely something you don't wanna mess with.

Mark: So these are clearly from the images that you've shown us, these are very complex vehicles. Wouldn't it be better for someone to just take it to the dealer? I mean, do you guys understand all the stuff that's in these vehicles? 

Bernie: So the first answer is no, it's not better take it to the dealer. I mean, unless you're going to a shop that's incompetent. But that's certainly not us. You know, we work in a lot of these cars and I've owned one myself a SL55 which is slightly different, but almost the same in many ways. We have all the repair information. We have the diagnostic equipment. We have access to resources to help us out with repairs for things that are complicated that we don't know.

So whatever we need to know, we figure out just like the dealer. I mean, we have a wider resource plus we have a wider availability of parts. So, I mean, one advantage of the dealers, you're always gonna get dealer parts. One disadvantage of that is that's the only thing they sell, and they're often very, very high priced.

We often have the same parts for less money or different options you know, that are available. It can save you a lot of money. So there's no advantage in my opinion. 

Mark: So you've owned, and you mentioned you've worked on quite a few SLs. How are they for reliability?

Bernie: They're pretty good considering how complex they are. But I mean, there are a lot of things that go wrong and you know, we've done a number of podcasts on these cars. I like to do 'em cause I find that they're interesting cars. There's a lot to them in a lot of things that do wear out and can go wrong, but they are generally a pretty reliable car. 

The 55 I had was, you know, quite good, it had about 170 Ks on it and I started thinking, well, you know, this thing's getting pretty old. I mean, a lot more stuff is gonna happen to it, but even up until that point it really was in pretty good shape and not a lot wrong with it.

I think they're good cars, but you need to budget a lot of money for maintenance and repairs. Cause there are many very, very expensive components on these cars that can go bad. 

Mark: The luxury, high performance car, therefore maintenance is more expensive. 

Bernie: Yeah. But that's not in the league of a Ferrari or anything, you know, insane like that. It's a mainstream car so that's good. 

Mark: If you're looking for service for your Mercedes in Vancouver, the guys to see you are Pawlik Automotive. You can book online on their website, pawlikautomotive.com. Or you can call them (604) 327-7112 to book your appointment. You have to book ahead, they're always busy, very popular place. The lot's full of cars, and they're moving them through quickly but with deep care. There's a reason why they've won best in Vancouver 24 times. Pawlik Automotive. Thanks for watching and listening. We appreciate it. Thanks, Bernie. 

Bernie: Thank you, Mark.

About the author 

Bernie Pawlik

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