April 13

2011 BMW 335D; Glow Plugs

BMW, Podcast2018


Mark: Hi  it’s Mark, producer of the Pawlik Automotive Podcast and Show. How’re you doing Bernie?

Bernie: Doing very well. 

Mark: So we’re talking with Mr. Bernie Pawlik, Pawlik Automotive in Vancouver, 38 years of repairing and maintaining vehicles in Vancouver and 18 time winners of Best Auto Repair in Vancouver as voted by their customers, and today we’re going to talk about a 2011 BMW 335D that had a glow plug problem. We don’t talk about these very often, a BMW diesel, what was going on with this vehicle?

Bernie: So the vehicle running fine, but a check engine light on and a code P0671 which is a glow plug fault, glow plug circuit fault, cylinder number one. So that’s what we were looking at on this vehicle.

Mark: And how did you diagnose this?

Bernie: Well, so they’re the code’s pretty specific. It says glow plug circuit fault and a lot of people would think oh yeah, it needs a new glow plug. Well actually the code’s a circuit fault. So the circuit is the glow plug, it’s the wire to the glow plug any related wiring and it’s also the control unit. Those are the items that could be at fault in this particular situation. So to diagnosis this particular vehicle, the glow plugs and the control module are all located underneath the intake manifold. So it actually required removing the intake manifold to do any further diagnosis on the vehicle.

Mark: Ok that sounds like a lot of work to figure out what was going wrong?

Bernie: Well it is actually a lot of work to at least get into what’s wrong and this is you know, where we like to do a little pre-planning with our client to say, you know to keep the cost down, if we were just to say, I just want you to diagnose this, it would be very expensive for us to take everything apart, test everything, put it all back together and tell you you know, this is what’s wrong with it. So it’s the kind of thing where we need to kind of pre plan what could actually be wrong with it. It could be the glow plug, it could be the control module, the most likely cause of the fault and with the vehicle being 7 years old, you might just need to replace, if one glow plug’s bad, you may as well replace them all. Or if it’s a lot of work to take the manifold off, why not just replace everything and then you’re done with it and it’s not going to leave anything to say 6 months from now, oh well plug 6 died or something to that effect. So this is the kind of pre planning we do in certain situations like this. Because it make more sense, if you’re going to take the manifold off to just fix everything at the same time. So once we remove the manifold, then we’re able to do some tests. We actually found the glow plug would actually heat up and light up and the module is faulty but as said, based on the mileage in the vehicle we ended up replacing all the glow plugs and the control unit at the same time while everything was apart. Let’s just have a look at a few pictures here.

This is the 2011 BMW 335D, your sort of standard BMW sedan but of course with a diesel under the hood. The engine again, covered in plastic with a nice, beautiful plastic, it’s hard to know what, you don’t really know what’s underneath until you take the plastic off. But this is the engine with the intake manifold removed and I’ve put some nice red arrows there indicating where the glow plugs are located. So the glow plugs were actually removed at this point, the intake manifold actually has two ports for each cylinder. So you have your lower set of ports, your upper set of ports. These are the fuel injector lines. The fuel injects are located up in this area here and the red arrows point to where the glow plug holes are. So we at this point removed the glow plugs and just for reference, the control unit sits down around this area under these hoses. What else have we got in the way of pictures here. We’ve got a view of the intake manifold removed. This has a swirl valve, well that’s a Mercedes term, but an intake manifold runner so you can vary the intake ports for different air flows and performance at different engine speeds. And here we have the EGR valve and throttle unit and in this area we did find some carbon deposits which we cleaned and we can talk about that a little later on. And finally the stars of the show, the glow plugs and the control unit. So here’s an example of two of the glow plugs. Your basic, standard type of glow plug and the control unit which looks like it says BMW on it, made by Bayer. These are, this type of control unit is very common. They look pretty much the same on a Mercedes, Volkswagen, a Isuzu diesel that we do a lot on, like in a medium truck. They’re basically all the same type of thing and they all tend to fail, same with the glow plugs and so once you get to a certain mileage, it’s best just to replace it all and be done with it.

2011 BMW 335D; Glow Plugs
2011 BMW 335D; Glow Plugs
2011 BMW 335D; Glow Plugs
2011 BMW 335D; Glow Plugs

Mark: So what did you find that was actually wrong? Was it the unit?

Bernie: It was actually the control unit that was bad in this case. As I mentioned we took all the glow plugs out and we were able to power them up and heat them and they all heated up fine. Now that still doesn’t mean the glow plug, even though it heated up fine didn’t have some resistance issue or something that the control unit found faulty. But in this case, the control unit was from what we could tell, the item at fault.

Mark: And you mentioned carbon deposits, I know that’s a huge issue on diesel intake systems. What did you find on this car?

Bernie: Well it wasn’t too bad as you could, I mean I know we’ve you know the pictures are gone now, but really there was actually a very minimal about of carbon deposit in the intake runners which is a good sign. This vehicle only has 78,000 kilometres, so it’s still pretty low mileage and it sounded, the owner I believe, has done a lot of highway driving with it so that all helps to, but we did find in the EGR valve and on the throttle plate, there was a lot of carbon deposit. We remove those and clean them out while we had everything apart. So that’ll definitely help airflow in the vehicle. 

Mark: Now something we’ve mentioned before about BMW’s, they use a lot of plastic parts, is this a plastic intake manifold?

Bernie: It sure is, yeah they use a lot of plastic wherever they can. Well a lot of other manufacturers do too, but yeah this is a plastic intake manifold. So nobody issues like that, you know I showed that swirl valve or you know, intake runner, whatever, every manufacturer has a different name, you know, those kind of things tend to wear after a while. I remember having a Ford years ago where that intake you know, after moving for years and year and years, it just wears the plastic away. So thats the kind of issue with plastic you know that you eventually get and the intake manifold will probably need to be replaced at some point. Who knows when. I mean at this point, it’s in very good shape.

Mark: And how are these BMW diesels for reliability?

Bernie: So far we’ve found them to be pretty good but you know, to be honest, we haven’t worked on a lot of BMW diesels. There’s not a lot of them out there. I think that’s mainly the reason, we’re starting to see more and more of them as they come off warranty and you know, there a few more on the market but when you compare it to Volkswagen or Mercedes, they really haven’t sold a lot of diesel vehicles or they’re pretty rare for BMW. Not so much for Volkswagen or Mercedes. 

Mark: And contrary to what people might think, this is a BMW high performance vehicle. In fact it might be the fastest 3-series and certainly in terms of torque, is that right?

Bernie: Yeah, it’s very peppy. After we did the repair I drove it, I go wow, it really moves well. So yeah, it’s a nice car, there’s really no compromise with a diesel. You know as I say, the thing about diesel’s that always worry me and we see it a lot, is they do cost a lot of money to fix when things go wrong and they tend to go wrong more than they use to. So you get a lot of good fuel mileage, you save a lot of money on fuel while you’re driving this vehicle that ’s for sure.

Mark: Absolutely. So if you need some service for your BMW diesel in Vancouver or your Mercedes or Volkswagen, the guys who are experts at it are Pawlik Automotive. You can reach them at 604-327-7112 or check out their website pawlikautomotive.com. We’ve got hundreds of videos on there and lots of them about all kinds of different diesels or our Youtube channel Pawlik Automotive or our new PodCast. Thanks Bernie.

Bernie: Thanks Mark.

About the author 

Bernie Pawlik

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