Question on smoke at idle - Page 2 - PeachParts Mercedes-Benz Forum

diesel don · #16 03-07-2002, 11:49 PM

Ken:

A buddy of mine (dieseldaddy) won the rims on ebay at 31.00 for the set (4). They're in medium shape are are 14's (identical to my others on the 300's).

Regarding the hood pad, here is what dieseldaddy and I have done. We got some of that 3-M spray adhesive. I did notice after I was all preped that it indicated that there was a better 3-M product for hood pads.....too late. I went ahead with it anyhow and it worked great. I used brooms and rakes on the vertical hood to keep the pad held in place while the adhesive took. It was pretty good stuff however in that it got tacky in 1-3 minutes. Prior to spraying and placing the pad, I scraped the small remaining remnants of the old hood which fell on a tarp I had spread across the engine compartment. I just used a putty knife and the stuff came off very well. Most of the underside of the hood was already in perfect shape to take adhesive, so I didn't use any cleaner. The end result looks pretty secure. Fairly easy job.

Don

loubapache · #17 03-08-2002, 08:32 AM

A diesel engine does not produce much heat when in idle. You should just start the car, make sure the oil pressure is high, and slowly drive away. Take it easy on the first mile or so.

I have never tried to idle a diesel for 20 minutes after starting but I doubt the temp will reach operating temperature that way.

kweimer · #18 03-08-2002, 10:24 AM

I had to make a trip to Indiana one January and during overnight stay in a motel (no block heater) I left my 220D idling all night---temp was right where it stays when driving---never noted any problems from this experience. And had a nice warm car to drive off in.
Ken

loubapache · #19 03-08-2002, 10:35 AM

kweimer:

It probably only used 1 gal of fuel!

Idle should be able to maintain the temp. I was refering to start the cold car and let idling warm up the car. It will probably take a long time for the engine to reach operating temperature that way (unlike a gasoline engine).

diesel don · #20 03-21-2002, 06:06 PM

To Jim Smith & Others:

I'm narrowing down my "smoke at idle" problem. I took the injectors in and they tested fine. Notice the symptoms:

Car starts great in cold weather without block heater
Car has plenty of power
Car is only acheiving 23 mpg (240D manual)
Car does not use excessive oil
Smoke appears only at idle. If I sit and up the rpms, smoke disappears
Smoke disappears going down the highway

Jim.....can you elaborate on the vacuum pump diaphram in greater detail. A neighboring mechanic thinks this is my problem but my line going from vacuum pump to air filter housing looks clean.

Thanks for any advice

Don

tcane · #21 03-21-2002, 06:24 PM

Sounds more like the injection pump's start of delivery is too rich since you have black/gray smoke at idle. At idle you should see very little smoke if any. When running you could see the smoke if set too rich, but you would have to be in another car behind the 240 to see it. There are numerous posts about adjusting the start of delivery. I wrote one up in the thread about the $8 ram air on 2-13-02 in this forum.

Good Luck!
Tom

can-do · #22 03-21-2002, 08:36 PM

Greetings Don,

I've read everyone's posts and still think you have one of three problems that causes your smoking at idle. The first problem, which has been addressed is the vacuum pump diaphragm leaking. There are generally two ways to check this besides just looking at the line going to the air filter housing. If it's leaking air it's also pushing oil through this line and sometimes it's no detectable by looking at the line. Is there oil residue in your filter housing or down in the intake manifold? If there is then disconnect the vac line off the top of your filter housing and rubberband an old white sock to the end and take your car for a ten mile or so drive. When you get home, look at the sock. Is it saturated with oil now? If so, the diaphragm in your vacuum pump has a hole in it and requires replacement. The second problem could be your injection timing is off, (this is not the start of fuel delivery that is spoke of) In order to check the injection timing you must remove the injection pump and line up the slotted lines on the two gears inside. The injection pump seal will need to be replaced when doing this, $1.00 item. If you don't have this procedure in a book I can provide it for you with an email address. The last item would be your start of fuel delivey to your injectors. If you try this one first and find that you can't get the start of delivery to happen at 24 degrees then the injection timing is off and you are stuck removing the injection pump anyway. When all the fuel timings are correct, then the only smoke that should be blowing on a warm idling engine would be valve seals or a tired engine in need of new rings. I've done all of the above and it's definitely a Benz bonding moment or hours.

Hope this helps,

Charles

JimSmith · #23 03-21-2002, 08:48 PM

Don,

I lost track of this thread, and just noticed your question on the vacuum pump diaphragm. Sorry.

The vacuum pumps of old had a diaphragm type pump and the side with the mechanism on it to push the diaphragm in and out is exposed to engine oil. When the rubber diaphragm ruptured, the vacuum created by the pump drew suction on the engine internals as well as from the vacuum system. Since the engine is kind of vented to atmosphere, most of the actuall work done by the pump is to evacuate the engine and that causes oil mist and oil vapor to be pumped into the intake via the little line leading to the intake manifold.

This in turn made thick white smoke when I stopped on the highway to pick up a hitchhiker. It was so bad the hitchhiker got lost in the cloud of smoke.

When it happened to my car (actually my Mother's car at the time) it turned the plastic line that used to be translucent white, to black. So if you do not see any apparent leakage, I would suspect your vacuum pump is fine. Hope this helps. Jim

diesel don · #24 03-21-2002, 09:00 PM

t-cane & can-do:

Your words are greatly appreciated as this problem is driving me crazy. I'm OD'ing on trying to find a solution. In reading extensive posts dating back some two years I found one with identical symptoms as my car. In doing so I should add one symptom which I used to think was unrelated. My car surges when de-accelerating in gear. It gets very jumpy so that you either have to put the clutch in or step on the gas. According to an old post, an older 240D manual had the same problem. It was a 1975 (mine is a 1980). His fix turned out to be the "injection pump diaphram". Although his "vacuum pump diaphram" replacement helped somewhat, it wasn't until the "injection pump diaphram" was replaced that he ironed out the smoke issue.

My question is: are the injection pumps related or is his an older model? Does my car have a pneumatic governor?

In the event that my research is a dead end, I will do the sock deal (though I took off my air filter cover and everything looks showroom new....no oil anywhere) and then tear into the injection pump.

Thanks again,

Don

diesel don · #25 03-21-2002, 09:07 PM

Hey Jim:

Your post jumped up as I was replying to the other guys. Thanks for spending the time to explain it. Its going to be fun getting to the bottom of this one. I suspect I have a good car on hand with many miles and years left, but I'm still in search of the core problem. I'll look at all three options during the next couple of days.

Don

can-do · #26 03-21-2002, 09:16 PM

Greetings,

You shouldn't have a diaphragm in your injection pump unless your engine has been changed out with an older model. If you have an older model engine the injection pump will have a noticeable round item (air cleaner on the top of the injection pump with knurled grooves) If you don't have this, it's not a pneumatic governor style. If you get time tommorrow, email me your injection pump number off the injection pump. The number will start with a PES 4 m I can track it down and give you more details about your specific IP.

Start of fuel delivery or injection pump timing could be your culprit. Worse case senerial, worn engine, but doubtful if you aren't getting steady puffs of air/smoke coming out of your valve cover oil fill while engine is running.

Charles

diesel don · #27 03-21-2002, 10:41 PM

Charles:

Does this number mean anything to you? 1 427 231 001.

It was stamped on the top of the injection pump's round thing. The adjustment screw sits in the middle of this round thing.

Down on the side near the Bosch name was another stamp but I couldn't get down there to get the number on that plate.

Don

can-do · #28 03-22-2002, 08:56 PM

Greetings Don,

The I.P. model is on the little riveted plate you saw on the side of the pump, most likely a green plate. The part number you gave me is for the altitude compensator that sits on top of the I.P. with an adjustment screw in the center. Just looking at the year and model you should see injection pump model PES 4 M 55 C 320 RS 104 or RS 107 on the plate. I'd say for sure that your I.P. doesn't have a pneumatic governor.

Charles

diesel don · #29 03-22-2002, 10:17 PM

Charles:

As best as I can make it out, the Bosch plate is stamped with the following number:

RW375/2200MW27

A number or two might be wrong due to the difficulty in reading. Does this look close to anything you might recognize?

Thanks for the effort!

Don

diesel don · #30 03-23-2002, 01:46 PM

Tom, Jim & Charles:

Thanks for the advice along the way about my smoking problem:p

I did the white sock experiment on the hose above the air filter housing. It yielded nothing.....very white. The hose also looks clean. I therefore think the diaphram in the vacuum pump is fine.

It sounds like my next two experiments are Injection Pump timing and Start of Delivery. I read Tom's thread several times and wonder if I have the ability to do this (start of delivery). Is the Injection Pump timing any easier?

Charles, could you email me that procedure as I don't have a manual which describes it? (diesel@bhbconline.org)

Thanks again,

Don

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