2011 BMW 335iS – Electric Coolant Pump And Thermostat Replacement
Mark: Hi, it's Mark Bossert from Top Local. We're here with Bernie Pawlik of Pawlik Automotive in Vancouver, Vancouver's best auto service experience. 19 time winners of Best Auto Repair in Vancouver, or 20 time winners, I'm sorry, 20 time winners. I'm cutting you short, Bernie. We're talking cars. How you doing?
Bernie: Doing very well.
Mark: Today's victim is a 2011 BMW 335is. BMW has such long names. There was problems with the electric coolant pump and the thermostat. What was going on with this BMW?
Bernie: Yeah. The owner was driving the vehicle and an amber warning light for the coolant system came on the dash. Then, shortly after, a red warning light came on and the vehicle went into a limp mode. I'm not sure whether he had it towed in or whether it was driven in but, anyways, the vehicle was not running well. The other thing that was happening at the same time as the electric coolant, there was a loud noise coming from under the engine, which was actually the fan running at high speed. That's basically how the vehicle came in with cooling system problems.
Mark: What testing did you do and what did you find?
Bernie: First testing we always do on a cooling system is to verify is there coolant in the engine? Had a visual inspection, looked at the coolant, it was down a little bit. Added some coolant to it, but it only took about not even a cup of coolant, so really not low enough to cause any sort of issues. Pressure tested the cooling system, made sure there was no leaks, there weren't any. Then, we proceeded to the next step, which is to hook up a scan tool, essential item to do in this kind of vehicle, hook up a scan tool and see what was happening with the engine running temperature and the operating temperature.
We did that, found a couple of codes stored in the engine module and ran some tests and found that basically the electric water pump was not functioning as it was supposed to. Now, that loud noise under the hood was basically the radiator fan running at high speed. Again, that's an electric fan and it'll come on whenever the computer tells it to. It'll tell it to come on, if there's a problem found with the cooling system, it will tell it to come on. That'll create the coolest possible temperature in the radiator and help cool the engine down. Say, the water pump isn't actually circulating, it'll help keep the engine cool.
Mark: Is it possible to do diagnostic procedure, I guess, on this vehicle without a scan tool?
Bernie: Pretty much impossible. I mean everything nowadays on cars, this car included, it's highly electronic. You really do need a scan tool to do pretty much anything. As I said, I mean the visual tests and the pressure tests, those are important initial tests and that could be where the problems are found. You've got to use a scan tool. You've got to have one to do any work on this kind of car.
Mark: We have some pictures.
Bernie: I do, let's get right into it. There is our 325is, I apologize if the brake rotors look a little rusty. We just washed the car and it still has a bit of moisture on it and the brakes were sitting. That's what happens with brakes when they sit, the rotors get rusted. A drive around the block, all that rust disappears. This car doesn't look quite as nice as it could. Next photo, we've got ...
Mark: Scan tool.
Bernie: Scan tool. When we do the initial test, we test the system for codes. It's always best on a lot of modern vehicles to actually test the whole vehicle. We can actually do a full vehicle code scan, because sometimes there'll be a problem in a different module that actually relates to a module you don't think is... Is not related to the engine. It's helpful to get that information. In this case, there were four codes stored in the system, two of them not really relevant, oxygen sensors.
These aren't relevant to engine overheating issues, but these two are, engine coolant pump cutoff, engine coolant pump speed deviation. What's happening here is that the computer commands the electric coolant pump to turn at a certain speed. It expects a certain thing to happen and it's not happening. That's why this speed deviation code is here. It's a pretty clear diagnosis from this based on experience that the electric coolant pump is defective. There are tests we do to warm it up, make sure there isn't anything else going on and we verified that the coolant pump was in fact the problem.
The coolant pump, let's have a look at that. There is the electric coolant pump, pretty fancy looking unit. It's got a very large motor in it, very robust piece. Even though it's a very robust large motor, they don't last as long as you think they should because this is an exceptionally common failure on any BMW that has an electric coolant pump, which is a lot of models. The business end of it here, this is where the pump impeller is. There's an electrical connector here and then there's an inlet and outlet there and there. The coolant just... Simple otherwise. Couple of other items on this vehicle, there's an electrically controlled thermostat and this is bolted up to the water pump.
We replaced it at the same time because, again, this is a failure item on these vehicles. In this case, it wasn't the failure item, but it would not make a lot of sense to take all this stuff apart and not change the thermostat at the same time. This is an electrically controlled thermostat. You can see there's a connector here with a couple of pins sticking out where the wire goes. Now, why would they have an electrically controlled thermostat? The thermostat generally, this is actually inside of the thermostat taken apart. This is the actual thermostatic piece that opens and closes.
Normally, in the past, it's got a wax pellet inside that expands with the temperature of the coolant. As the wax expands, the thermostat opens and allows coolant to flow. If the temperature gets below the specified point, then the thermostat closes again. This keeps the engine at the operating temperature it's designed to keep at, but it's limited. It'll only do that specific temperature. With electrical control, it'll actually heat the thermostat. If the computer says, "Hey. We need to open this thing faster or let's get the engine cooler or let's keep the engine hotter," it can control that thermostat opening. It allows more control over the thermostat, and that's our picture show for the day.
Mark: The coolant pump was bad. Why would they use an electric pump?
Bernie: Again, it's control. As I talked about with a thermostat, there's control that can be had with having electric components. You can switch the pump on and off. You can't do that with a mechanically belt-driven pump. It just runs. When you're idling, it runs at a certain speed. When you rev it up, it runs faster and that's the limit of control. Whereas with an electric pump, they can pump it at a low speed, a high speed, whatever requirements are needed. If the engine is getting too hot, they can pump it faster. If they want the engine to warm up really fast, you can just leave the pump off and just let the engine warm up quicker. Those are some of the things you can do. That's why the electric pump.
Mark: Ultimately, it's causing better... That's part of the system. As well as with the electric thermostat, because you're controlling temperature more exactly, you can reduce emissions and increase fuel economy.
Bernie: Exactly, and performance too. Yeah. All three of those can all be controlled much better.
Mark: Is this an expensive repair?
Bernie: I always think of expensive as being kind of a judgment call. Yeah, it's not cheap. The electric pump itself, I can't remember the price off the top of my head, it's a pretty pricey part. If you own one of these cars, you will need to replace it. No ands, ifs or buts. I own a BMW X3 with the same type of engine, the electric coolant pump's gone on it already. They go on all of them and probably sooner than they should. Yeah, I consider this to be a pretty expensive repair, certainly more than it would cost to do a mechanical pump.
Mark: How are BMW 335s for reliability?
Bernie: They're good. I was thinking, I mean it's a good car, but there are certain issues that you're going to face with this car. I mean one of them is this electric coolant pump. I mean that's a guaranteed issue. Say you buy the car from new and keep it to 130,000 kilometres, you'll need to do this electric coolant pump. You'll need to do the thermostat. You'll probably have some ignition coil problems. This car actually had one after we fixed it. Went out for a road test, the engine was misfiring, one of the coils had crapped out. I don't know whether it was brought to us like that. It was no code in the system.
It may be that as the engine got hot, it caused the coil to fail or they just do on these things. You can pretty well count on ignition coil replacement, coolant pump replacement. There will probably be some front end bushings that wear out and some brake work, which those kind of things are sort of normal and expected on pretty well any car. I mean the nice thing is these are predictable, but they are... Some of them are expensive being a BMW. Also, there's some fuel injection issues with some of them as well, injector issues with some of them as well, but that's basically it. Otherwise, it's a really nice car. This is a sporty car, fun, lots of power. It's a fun ride.
Mark: Of course, in the future, as more and more of the European specs kick in, actually at the start of 2020, almost every vehicle is going to be using an electric everything. Basically everything is going to be running... Any accessory type stuff is going to be running off electric, because they have to in order to meet the emission regulations.
Bernie: Yeah, yeah. Already, we have electric power steering in a lot of vehicles, which is fantastic because there's so much more flexibility. The neat thing about electric power steering as well, it has the potential to be super expensive to repair. We've never actually repaired one electric power steering unit in our shop ever, which is maybe disappointing because we do an awful lot of conventional power steering repairs. The good news about that is that there's a component there that's been electrified that's very reliable. Not to say it's 100%. I mean there's some that have had issues and I know that a lot of those have been covered by manufacturer's warranty.
There are things that have been kind of sorted out, but it's a really reliable system. I think they've had to do that. When you build something with a steering component, I mean if there's any problem with it, you don't want a failure where the car decides to steer its own way. I mean you're just asking for major lawsuits. I think the manufacturers of, this is my guess, but I think they've just taken it, gone, "Wait a minute. We can't F around this stuff. We got to make it like bullet proofly reliable."
Mark: There you go. If you're looking for service for your BMW 335 or any BMW, they're experts on it at Pawlik Automotive. You can reach them at 604-327-7112, you have to call and book ahead. They're busy, always busy, but they do excellent work. You can check out the reviews, really highly reviewed. Of course, 20 time winners of Best Auto Repair in Vancouver as voted by their customers. Of course, thank you so much for listening to the podcast and thanks Bernie.
Bernie: Thank you, Mark, and thank you for listening and watching.