Hello,

About 3 months ago I got my first diesel, 1987 300D w124 turbo with the 6 cyl engine.
The car has 290K and the head was replaced 25K ago with a rebuilt, job done by the previous owner at a garage he had the car worked on. According to the records, it has been well maintained and it runs, I would say good when its hot.
When I start it in the morning, 60-75 degrees outside, it has a rough idle and it smokes a lot. I let is sit for a minute or so, rev slightly and it gets better as far as idle but it still smokes. Once it gets hot I can see at stop lights a little bit of smoke blown forward from the muffler. It accelerates good, the turbo seems to work fine. I bought a couple of cans of Diesel Purge and it made a huge difference on idle when hot but the cold idle is the same as before. It seems it smokes more since I have added a can of Motor Saver Oil additive with the last change of Rotella oil ( 1500 miles ago). I check the oil regularly and I had to add about a half a quart last week to bring it to top level like it was when the oil got changed ( 8.5 Qts).
Now, this rough idle and constant smoking are problems that should be addressed, right ?
I am used to gas cars and make a constant effort to adjust my driving for the diesel ( my other car is a BMW 740i). I am not pushing it hard. I see some smoke in the rearview mirror only when I kick it harder to pass and it is usually when the turbo kicks in 2700-3200 rpm's.
All I have gotten since I have this MB is 19.5-21 mpg with mixed local and highway driving with AC on. I switch the AC off when I start at a stop light, wait until the car gained speed than I turn it back on. I am adding a few ounces of Redline Diesel additive with every tank fill-up.
Can someone give me some advice of what to do about the rough idle, smoking and poor fuel economy ?
Thanks in advance.
Any recommendations for a good mechanic in the South Bend, Indiana area are more than welcome.

Marius

If you have not viewed the following link, check it out. It may help you to understand the problem.

'93 300D rough idle when cold

Switching the AC on and off too much may shorten the life of the compressor. I prefer system that does not recycle the compressor but use other methods to control ice build up.

David

Maruis,

When starting the car glow plug it for a 10 count. The plugs are still glowing after the light in the car goes out.... I just learned that with my diesel and it makes a great improvement on start up. Also have your glow plugs inspected. I would just replace them along with the injectors if they are original. 300K I think is enough life for your injectors. any how they are not hard to change out and not that expensive. Injectors $50 each and glow plugs are $10 on the fastlane. 360 dollars in parts is not that much in the wonderful world of mercedes benz. If you elect to change them out the offer yourself the piece of mind that you restored the two most important parts of the diesel engine. Diesels are dificult to start but once they do they will get you any where you want. They are also high compression fuel injected engines which require good fuel delivery to run at high efficiency. Now when I buy diesels I buy them to put at least 100000 miles on them so I dont mind putting in the effort to assure that they will. I owned seven diesels and would say that new glow plugs are a must...They are cheap and worth the reassurance come winter time. The injectors are more optional in my opinion considering your low mpg it would not hurt the cause.
Before you do the injectors change out the air and fuel filters.
Also have your timing chain inspected for slack.

Also get used to a little smoke it is half the fun of these cars.

good luck.

bob

Change the injectors. From what you descibed your injectors are worn. Not surprising with 300K.

__________________
Mark
82 300SD 110k
91 Caprice SS
92 Jetta TD
97 Cadillac Concours(300hp)
84 Celebrity 4.3L diesel