mweiner Report post Posted August 8, 2017 Hello, had a CEL yesterday, and brought my Mercedes Benz to the dealership for a scan.. turns out that it was bad glow plugs at only 28,000 miles. I acquired this vehicle at 26,000 and the dealership said it was the first time they ever saw a vehicle with such few miles and this problem. Glow plug # 4 went bad, but I figured that it would not be long before the others failed as well, so, for an extra hour of labor, they replaced all six .. one would have been a minimum of two hours labor, so 3 hours for all six seemed reasonable. My question is whether it's possible if the original owners didn't follow the two step starting procedure, could this have prematurely worn out the glow plugs. What's the average time or mileage for these item? Also, with a modern diesel engine like the Mercedes Benz 3 litre V6, having a failed glow plugs would affect engine performance and fuel economy? Share this post Link to post Share on other sites
jleamont Report post Posted August 10, 2017 No, it would have little effect on their life expectancy. Those are prone to failure on those engines, along with the glow plug controller. Be thankful its not the inline MB 2.7L engine, those seize/weld them selves into the head. According to the dealer the cylinder head has to be pulled 90% of the time to drill them out . I got lucky on the ones I replaced....well if you call 12 hours of fighting it so I didn't have to pull the cylinder head lucky . When you take it in for service, ask them to pull the wheel covers inspect the wheels for cracks, common to see them fail, especially when its heavy in an RV application. Everything else will illuminate the engine light and give you a warning, wheels do not. Share this post Link to post Share on other sites
jleamont Report post Posted August 10, 2017 Not many coaches have glow plugs so I'm guessing you wont get much feedback on this post. Most inline diesels especially the big bore's do not utilize glow plugs for start assist. They have enough compression coupled with an air intake heater to fire the cylinders on a cold start. Onan Diesel generators have them, not much on the coach power side. Perhaps some FRED owners with the Maxxforce 7 might chime in or a Class C with a Diesel, off the top of my head I cant think of any others that would have glow plugs. Those usually go 100,000 miles before one might develop a problem. Share this post Link to post Share on other sites
mweiner Report post Posted August 10, 2017 3 hours ago, jleamont said: Not many coaches have glow plugs so I'm guessing you wont get much feedback on this post. Most inline diesels especially the big bore's do not utilize glow plugs for start assist. They have enough compression coupled with an air intake heater to fire the cylinders on a cold start. Onan Diesel generators have them, not much on the coach power side. Perhaps some FRED owners with the Maxxforce 7 might chime in or a Class C with a Diesel, off the top of my head I cant think of any others that would have glow plugs. Those usually go 100,000 miles before one might develop a problem. Thank you... I've recently read elsewhere that 100,000 miles is pretty normal... Thank you for your time to confirm this. Share this post Link to post Share on other sites
desertdeals69 Report post Posted August 10, 2017 On a GM 6.2L diesel the glow plugs went out on a regular basis. One of the causes was using starting fluid in cold weather. Sometimes they would go out for no apparent reason. I used to stock a number of them for my customers. Share this post Link to post Share on other sites
wolfe10 Report post Posted August 10, 2017 Ya, the 5.7 and 6.2 GM diesels earned a lot of techs and parts people a lot of money. I was General Manager of an Olds, Cadillac Honda dealership in the late 1970's/early 1980's. Next door neighbor asked what Cadillac for his wife. Engine choices at that time were: 1. the Cadillac 8-6-4 (we called it the 8-6-3 because that was how it ran-- not enough computing expertise to handle cylinder cut out, particularly for Cadillac buyers). 2. GM 5.7 diesel. 3. In the lowest end the Buick V6 gas which was, sadly, the best choice. Too bad they almost single handedly soured the American public on diesels for many decades. Well over half of all vehicles in Europe are diesel. Many are the same models as we have here, but get over 50 MPG. Share this post Link to post Share on other sites
kaypsmith Report post Posted August 11, 2017 I was in Victoria Canada in 2007, saw my first Daimler (Italian made) Smart car, it was a 3 cylinder diesel, 70+ mpg, boy did I want one. So in 2008 MB started the Smart car was coming to the US. I put my name in the pot to be one of the first. Then MB sent me an email that the SC was to be 6 inches longer than Canadian version with a Mitsubishi 3 cyl gas, with expected 42 mpg "thank you EPA". I withdrew my name from the wanted list. I did also own a 1980 VW pickup with 4 cyl diesel, 50 mpg, problem with it was an aluminum head, new head every ten thousand miles, oh yes, no glow plugs on that model, probably a good thing, they probably would have melted the head every time they were used. LOL Share this post Link to post Share on other sites
jleamont Report post Posted August 11, 2017 Brett, I had a 1980 Eldorado diesel in the early 90's, it went for maybe three weeks, came unglued under the hood. Nice car great on fuel, not dependable! Share this post Link to post Share on other sites
manholt Report post Posted August 11, 2017 Have had one diesel car in my life...MB, POS after 12K miles! 3 Silverado Duramax and one Ford F 350 diesel...all great ! Share this post Link to post Share on other sites
mweiner Report post Posted August 11, 2017 2 hours ago, manholt said: Have had one diesel car in my life...MB, POS after 12K miles! 3 Silverado Duramax and one Ford F 350 diesel...all great ! Carl, Question, how many miles did your Mercedes Benz have on it when you acquired it? And how old was the vehicle? I hope you're not saying that you purchased it new and had a problem at 12,000 miles? ---Mark Share this post Link to post Share on other sites
five Report post Posted August 11, 2017 I've had four diesels...3 cylinder Yanmar in a sailboat, Duramax in a Chevy 3500 dually, Cummins ISL 400, and the current 12.8L DD 500. No problems with any of them. Share this post Link to post Share on other sites
