Smoking 1984 300D... lots of clues? - Page 2 - PeachParts Mercedes-Benz Forum

barry12345 · #1 11-29-2015, 08:34 PM

No but if not closing off it could be over fuelling that cylinder seriously. Producing black smoke out of the tailpipe. What I would be more concerned about is the oil passage to the head that I believe is just ahead of the first cylinder.

That is where the head gasket may have failed. That's why is suggested rolling the engine over with the injector removed and see if oil is being spit out of that cylinder. Head gasket failure is not as common on your engine as on the newer versions but can still happen. A leaky head gasket might also add pressure to the engine driving oil out of it. Anyways I would do the test with the injector out first. Basically an engine should not have a blowby type symptom at that milage. This being the oil forced out past the filling cap.

At your milage all injectors should have looked the same. Also at your milage as you have some background on the car. Not too likely a serious issue exists. A head gasket can just rot with age though.

I am usually more sure of what posters problems might be. In your case the only solid clue so far is the oil being forced out of the engine and the appearance of the number one injector is different. I also do not think if the turbo seals where bad that the oil would be leaving the engine in the fashion it is at your milage. You could have more than one issue but I doubt it.

landev · #2 12-03-2015, 10:23 PM

As the weekend is coming up, I'll see if I can't do this test. I'm curious as to how this is done with regards to the fuel supply. I imagine the supply needs to be capped somehow as does the return to the next injector? How's that properly done?

Thanks much for your time on this!

-l-

barry12345 · #3 12-04-2015, 03:19 PM

Just rolling over the starter should be enough to see if some oil is spraying out. There should not be a trace. Tie the injection pump shutoff in the off position. Takes two people unless you use the fender crossover to energise the starter. Make sure that transmission is in park though.

landev · #4 12-05-2015, 01:16 PM

How about placing a clean paper towel over the injector hole and seeing if it gets covered with oil? I'm out here by myself and have no one to help with this.

Thanks!

-l-

Dan Stokes · #5 12-05-2015, 02:22 PM

On the smoking -
It's time to sit down and have a firm but loving talk about the dangers of smoking. Tell it how many cars find themselves in the salvage yard as a result of excess smoking. Even the best people will only put up with SO MUCH of it. Be sure to tell it that you understand that it's old enough to smoke legally but it's NOT good for you no matter how old you are.

If this doesn't fix the issue you may need to resort to surgery of one form or another. The guys have provided that info.

Dan

landev · #6 01-03-2016, 03:36 PM

Well, I finally had some time to dig into this further! New Year's Day afforded the chance to take take Barry's advice... I stuck a paper towel in the injector's hole and cranked the engine. No oil on the towel and a great sigh of relief. I then proceeded to install the new injectors and just for kicks, I checked the valves... they did indeed need an adjustment. Loosened them up a bit, triple checked everything.

Went for a test drive down to the local winery yesterday. The car started fine, yet smoked a bit... I'm going to attribute this to the fact that it was 10F. Warmed it up thoroughly, then did the 60 mile round trip. No smoke once things were warmed. The test was the return home as I've a 5 mile 7% grade. I hit the grade @ 50mph... accelerated to 70 half way up... lots of power, very smooth and NO SMOKE!

Epilogue: Certainly seems that a lousy injector on #1 cylinder was the culprit, though I'm sure the valve adjustment didn't hurt.

Thanks all for your time and help! I'm looking forward to retirement when I can be of more assistance here!

Best New Year!

-l-

vwnate1 · #7 01-03-2016, 07:41 PM

Thanx for the followup ! .

barry12345 · #8 01-04-2016, 11:53 AM

Yes follow ups are great.

I have one issue with injectors. They should be tested before being repaired or replaced.

The logic being at least in my mind. Perhaps the last owner did them not all that long ago. I never got any substantial information on any of my cars for example when purchased.

I think it is pretty cheap and easy to build a small bottle jack tester and you can always easily sell it to another member when you no longer want it. Probably for your cost of building it.

Your car was a little different as it was a low milage car with some history.