March 11

2010 Mercedes ML350 3L Diesel Engine Oil Leaks

Mercedes, Podcast


Mark: Hi, it's Mark Bossert here with Bernie Pawlik, Pawlik Automotive podcast and video series, and of course we're talking cars. How are you doing this morning, Bernie?

Bernie: Doing very well.

Mark: So we're excited. We just found out we were the number one automotive podcast in Canada and a few other countries around the world and we want to thank everyone for listening. Of course, today we're talking about a 2010 Mercedes ML350, 3L diesel, something we've certainly spoken about before. What was happening with this ML350, Bernie?

Bernie: So the owner of this vehicle brought it in for some oil leaks. She was only noticing some drips in her driveway of oil and was concerned about it.

Mark: What did you find?

Bernie: Well, we found some oil leaking. So our procedure with finding the oil leaks is to remove the, Mercedes, there's covers on the top, there's covers in the bottom. So we remove the covers on the top of the engine, remove the covers underneath the vehicle to assess where the oil was coming from. Most of the oil, actually fortunate for the customer this time, most of the oil leaks were coming from the front of the engine. These are usually less expensive leaks to repair than when they are coming from the rear of the engine, and I'll explain a little detail more in a minute, but let's just have a look at some pictures right now.

So there's our a 2010 ML350, and all that white stuff you see, I took this picture yesterday. We did the service yesterday. That's actually snow in March and Vancouver. So kind of unusual, but there it is.

Mark: People were freaking out everywhere.

2010 Mercedes ML350 3L Diesel Engine Oil Leaks
2010 Mercedes ML350 3L Diesel Engine Oil Leaks
2010 Mercedes ML350 3L Diesel Engine Oil Leaks
2010 Mercedes ML350 3L Diesel Engine Oil Leaks
2010 Mercedes ML350 3L Diesel Engine Oil Leaks

Bernie: Yeah, exactly. Well, we're getting used to it. It's been weird. February, it snowed a lot and I don't know, maybe we're getting used to it. Yeah, people do tend to freak out a bit. Anyway, let's get into some pictures. So we found the oil leaking from two spots. First spot. This is the oil filter housing and there's a seal in behind this area. You can see pulleys. This is looking down the front of the engine and there's oil leakage down in this area here.

This is one of the more common leaks from the front of the engine. The other leak that we found was from the power brake booster vacuum pump. So this is located on the right valve cover, the oil filter adapter's located on the left front of the engine. The yellow arrow points to the actual booster and the right arrow points to the oil leakage. Again, it's a little hard to see, it's not a huge leak in terms of tons of fresh oil coming down. But underneath it was definitely more obvious as to where the leaks were coming from. But that's basically where the leak was coming from.

So in terms of repairs, what's involved?

There's the oil filter adapter removed with the seal in place. This is the area where the leak occurs from. The seal basically gets hardened over time, and a good example of that. This is an example of the new gasket and this is the old gasket. You can usually tell when a gasket's old and bad. We have these special picks, they're very hardened, very sharp little hardened picks, like the thing a dentist would use to scale your teeth, only a little more rigid and a lot less expensive. But basically I had to basically pick this gasket out, and of course it came out in chunks as you can see, and the other one is much thinner. But over time it squishes out and flattens out and given 9 or 10 years, it'll probably look the same as this. But that's the new gasket.

The other area issue that we repaired was the vacuum pump. This is the brake booster vacuum pump removed. There is a gasket between the pump and the cylinder head, which was seeping a bit, but the actual pump itself was actually leaking a fair bit too. So we replaced the pump, replaced the gasket and that was it.

Mark: So you mentioned that these are, and we've done a few things about these 3L diesel engine with different problems. There's pretty common to have leaks on these engines, is that right?

Bernie: Yeah, oil leaks are one of the bigger issues that occur with these engines over time. There's probably, I'm thinking five, at least five common spots for oil leaks. We just covered two of them. The front of the engine, and these are the leaks you want to have, if you have any oil leaks on a Mercedes 3L diesel. The most expensive one to repair is the engine oil cooler seal, which is the oil cooler. We've done podcasts on this so you can find them somewhere, either on a Mercedes or Jeep 3L. They use the same engine. In the intake valley, the oil cooler is located right down in the bottom and there's seals that leak there. Also the turbo stand gaskets will leak, which is a bit less work than the oil cooler seal.

But when you do the oil cooler, you change the turbo stand at the same time. So usually you can kill two birds with one stone. But the other leak that does happen from time to time is the rear main crankshaft seal too. So again, that's a pretty involved leak. But the oil cooler seals and the turbo stand are probably the most common, and these are up there too. But fortunately for the owner of this vehicle, that's where the major oil was coming from, was from the front of the engine from these two leaks.

Mark: So as I mentioned a couple times, we've addressed these 3L Mercedes engines a few times. Is it because they're so problematic or is it a maintenance issue?

Bernie: Well, they are problematic. They're finicky. There's a lot of things that happen. We haven't talked about the intake actuator, or on Jeeps they're called a swirl valve motor. They have variable intake runners, there's an actuator system that causes problems. Anything and everything can go wrong in these things, and actually the other unfortunate issue with this particular engine is, when we started it up, on this particular car, the timing chain had a rattle for a few seconds. So it's going to need a timing chain replacement. It actually already does need it. It's just a matter whether the owner will choose to do it or not before something breaks. But there are a lot of problems that happen with these engines and I think I've said it before. A lot of times it's because people don't really get them warm enough.

They don't run them for long enough periods of time, and that's really where a diesel is best is for long hauls. Mark, I know you had a Volkswagen diesel. You're the perfect person. You live in Langley. If you actually had a job in Vancouver where you drove down the highway every day to work and back, that'd be the perfect use for that vehicle. But a lot of people don't. They just hop into the car, they drive the kids to school three kilometres, go home, park the car or they drive to work and the engine doesn't warm up properly. So it's really, really hard on it and really not the best use for diesel. But of course, you'll never be told that when you go to buy one. You'll just go, oh great, it's got the best gas mileage, it's economical. I want to buy that. So that, to me, is where most of the problems lie with diesels. You just really need to run them and you need to get them warm.

Mark: So diesel really isn't an around town, run about, little vehicle engine type.

Bernie: It's not really. But it's interesting because we do a lot of Volkswagen TDIs and they seem to be pretty reliable in that area. So I think somehow they built them a little better. These engines definitely have more problems for that kind of running. I've seen these with really high kilometres where people do a lot of highway trips and drives and they don't have the same problems. So the thing is, you're not going to drive another a hundred kilometres a day just for the hell of it.

Either it suits your lifestyle or it doesn't. So, I think the takeaway here is before you buy a car like this, check out what your usage is and if you're just going to be mostly a running around town thing, yeah, the thousand kilometres out of a tank is a really attractive feature. But if you just pay all that money back and repairs and breakdowns, it gets a little discouraging after a while.

Mark: Better to go for a hybrid then.

Bernie: Much better to go for hybrid, and I say a Japanese hybrid, because they've proven to be really reliable. There's Europeans that are coming out with hybrids. I don't know how reliable those are going to be. They're all still too new. But Toyota Prius has proven itself to be extremely reliable, and definitely a worthwhile car.

Mark: Or a Highlander or Venza.

Bernie: Highlander, Venza, yeah. There's whatever. The Toyota's, to me they're number one for reliability. When things do go wrong, they can be exceptionally expensive, but it's very rare, whereas on these engines, it's pretty predictable.

Mark: Of course, we've talked about replacing these engines as well, and that's a very expensive proposition.

Bernie: Engines, yeah, they'll go. The emission equipment, things will plug up. So sometimes it can be a real snowball effect of things going wrong. It's not hard to even be hit with a $10,000 repair bill, which is a lot of money. As I said, with the gas motors, you don't tend to have the same problem. You can buy a lot of gas for 10,000 bucks or even five, where some of the other ones come in for some repairs. So, just check it out before you buy it, see if it suits your lifestyle. It might. The numbers might add up and it might be worth your while.

Mark: So there you go. If you need service on your diesel, and you probably do, the guys to see in Vancouver are Pawlik Automotive. You can reach them at (604) 327-7112 to book your appointment. You have to call ahead to book, they're busy, or check out the website, There's many, many videos as well on YouTube, on our YouTube channel, Pawlik Auto Repair, and of course you're listening to the number one automotive podcast in Canada, and we thank you. We're also very proud to be number one in quite a few other countries as well. So thank you for listening and thank you, Bernie.

Bernie: Thank you, Mark, and thank you for watching. We really appreciate it.

About the author 

Bernie Pawlik

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