krava

Are the reliability of diesel cars any better then their regular gas counterparts? I was looking at gas today and Diesel and Supreme is about the same price now. Diesel doesn't have ethanol in it to ruin the engine and also gets better gas mileage. Would that help these 2 cars be more reliable or is the problem elsewhere like electronics etc?

geko29

Let me preface by saying I'm a happy owner of a 335d for almost 3 years (bought a 2011 demo with 8700 miles, currently has 46k). It has the M57, which is the twin-turbo progenitor of the single-turbo N57 in the 535d/X5 35d/740d. With one exception (which I'll get to later), it's been a spectacularly reliable car. Just oil changes and the usual bushing squeaks that need grease, stuff like that. The engines themselves are pretty much bomb-proof--they have to be, just to withstand the violent combustion process.

That said, the one weak spot on most modern diesels is the emissions controls. Some of them are the same problems as gasoline models: Specifically, EGR (Exhaust Gas Recirculation) is EVIL in direct-injected engines, regardless of fuel. It brings filthy exhaust back into the intake track, which causes buildup of carbon for gasoline engines, and soot for diesels. Then, because the fuel is injected directly into the cylinder, none of the detergent it carries gets into the intake runners to clean this gunk off. Often times this means the intake manifold has to be removed and walnut blasted at higher mileage.

Then there are the unique ones: the urea system and the diesel particulate filter (DPF). The urea system is comprised of two primary parts: the tank and the SCR mixer. I haven't heard of many problems with the SCR mixer, but there are occasionally issues with the tank. Some are self-inflicted (filling improperly), while some are not (leaks, etc). Mine was replaced under warranty because of an issue with the vent that caused urea to crystallize around it and killed the temperature sensor. Some people have had issues with the DPF becoming obstructed, but that doesn't seem to be terribly common.

Don't let any of this scare you away--I love the hell out of my car despite all that. It's currently getting 30mpg in mixed driving, despite being chipped and ~500lbft of torque, and is an absolute hoot to drive. I'll probably try to get a walnut blasting done right before the extended warranty expires, then block off the EGR. Until the SS caught my eye, I was dead-set on replacing my wife's RX with a 535d or X5d. If Chevy doesn't import the 2016 (looks like they will), we'll probably add a second diesel to the stable.

tex2670

I'm not sure that you can make a blanket statement about diesel vs. it's gas counterpart that applies to all makes and models. I know some people hate Consumer Reports, but if you are in the market, I'd track down a copy of the April '15 Car issue, and check out all of the reliability ratings. They break down different aspects of each model (like transmission, electronics, HVAC, etc) across the past few model years--and they will have separate listings for gas and diesel models.

spwolf

generally speaking, diesel has a lot more complexity today than gasoline engine... especially if we are talking about NA gasoline engines.

MPG should be much, much better though.

All depends on how long you would be keeping the vehicle.

bitkahuna

iTrader: (20)

great feedback for krava guys...

TangoRed

I'm glad to hear you had a pleasant experience with your 335d. I got rid of my 2010 three years in and was having similar problems to many people online. Fuel pump, SCR issues, AC compressor, fuel tank replacement (!), waste gate issue resulting in turbo replacement, and oil leaks. Apparently the later models saw some of these issues addressed but it was not a pleasant experience.

Jacket

geko hit it pretty spot on. I traded in my Audi Q7 TDI last month for a GX, and we were kinda glad to see the Audi go. The gas mileage was great for a 5500 lb vehicle, and there is certainly a "cool factor" with driving a turbo diesel that is pretty rare, but growing in popularity in Colorado. The core engine was/is solid, but the electronics and emissions equipment is frustrating and prone to a lot of servicing. We had a high pressure fuel pump failure and an EGR valve failure, both of which stranded us on road trips where the vehicle had to be towed back home. We had a bunch of other "nickel and dime" issues, but that's to be expected with most European cars.

There is a reason diesels are so popular around the world - simple, efficient and economical engines that get the job done for 100's of thousands of miles. That said, the emissions issues are significant with diesel engines, and as a result the US laws require heavy duty equipment to compensate and these emissions systems are prone to maintenance and failure. Many of these systems are programmed into the computer as "critical", such that when something goes wrong, you're stuck (limp mode). That's the part that did it in for me.

spwolf

there is nothing simple about modern turbo diesel engine Jacket :-).

Maybe 30 years ago diesels were simple, today all things taken together, they are the most complicated powertrains with most points of failure.

Jacket

I should have prefaced my words with "At its core..." It's all the bolt on stuff that's made the diesel powerplant overly complicated.

spwolf

yeah, plus in the old days they used iron block for diesels... so iron block, low hp, no turbo, no high pressure fuel pump/injectors, no emission equipment.... no wonder they lasted forever!

geko29

The M57 in my 335d is still an iron block....they switched to aluminum alloy for the newer N57. Everything else you mention definitely applies though.

doge

The guy that runs a shop down the street from my shop has a 535D, he was driving around in a loaner for over a month. Not sure what the problems were but it was gone for a while.

nipponbird

This is fast escalating into an argument of Diesel versus gas power plants and in this regard I would say none of the two is perfect, we're stuck with them for the past century and all the engineers are doing is trying to sort of perfect something that is not perfect. The kind of guys who can invent a real alternative is either still on a journey from outer space or not understood like Victor Schauberger.
https://www.google.co.za/webhp?sourc...or+schauberger

But OK this is about the BMW and the Audi in the thread title. About a decade ago European turbo Diesels were notorious for blowing their turbo's (usually far from home), but to a large extent that is the past. In this country Diesels are immensely popular and although Diesels have become quite sophisticated there is no indication here that it has led to unreliability.

Aron9000

I know my uncle did not buy a new turbo-diesel pickup truck because of all the emissions stuff on them. He ended up having some work done on his 250,000 mile 2005ish Chevy Duramax(head gasket, EGR delete, and some other stuff). Says it runs better now than it did when it was brand new.

As for diesel's popularity in Europe, as somebody else mentioned European cars don't have all the emissions stuff on them that US cars have. So they're more reliable, less complex, and cheaper than a hybrid in Europe. Plus all the governments in Europe don't tax diesel as much as petrol, so diesel is cheaper in Europe.

As for all the emissions parts on US diesel cars, its kind of like the 1970's all over again. Manufacturers are scrambling to meet these air pollution regulations. Granted the technology is much better this time around, but once again car makers are still trying to sort out how to make these cars comply with regulations and be reliable at the same time. I'm thinking in the past couple of years the car companies have worked out a lot of the problems that plauged 08-10ish model years when the regulations were first enacted.

krava

Thanks for the info. I have test driven a 535D and it was nice. I created the thread to try to find a competitor to the new 4GS. I am trying to find a car before my 3GS starts eating engine oil again. I plan on keeping the next car 10 years or so I don't switch them out. The BMW 535 or any BMW I was told had bad reliability so what about their diesel counterparts I was thinking? It doesn't look like audi is too reliable either form what I see. I was thinking about what about the acura RLX. You can get a 2014 RLX advanced with 6K miles for around $37-$38K but consumer reports rates that thing horribly. I just posted on acurazine.com seeing if anyone has any good reviews on it. I have had a 2gs, 3gs (really pissed about the engine issue on that car and makes me not want it). I can't find any competitor at all to a 4gs out there. There are a few if you are talking 100K miles. Once you go over that, I don't see anything at all that can compete with that in its class. I know diesel engines are known for 500K to 1 million miles so that is why I brought it up in a topic.
My 3GS is 10 years old and I haven't replaced a strut, a CV joint, nothing at all. I know I have posted all over the place in a lot of groups trying to gather as much info as I can. Its a real pain and driving me nuts knowing that my car is on its last leg (I will be damn if I will pay $6K every 40K miles or so to fix that engine problem each time). I want atleast some kind of competition if possible. If I buy a 4gs and they find out 6 years later there is an engine issue again, I swear I might go postal for real. If there was competition and I picked the wrong one then it is my fault.
Emissions might be important since I plan to get out of here and get back to TEXAS.