Instant Smoke Signals - PeachParts Mercedes-Benz Forum

jjalex · #1 06-06-2003, 08:54 AM

This morning my "new" 91 300D 2.5T started up nicely, but as I backed out of the driveway I had a shudder. Ok, its a diesel and that happens.

But then it was like someone flipped a switch and it started to smoke like crazy. I drove it about a block and it was still pouring out so I turned around and parked it in the garage. I popped the hood and found nothing leaking, driping or looking out of the ordinary.

I put over 300 miles on it this week since I bought it and the records look clean.

Could I have fuel contamination? This is the fist time since I've had it that the fuel tank has been below half full....

Help!

kerry · #2 06-06-2003, 09:00 AM

If it had a 616 or 617 engine I'd say the vacuum pump diaphragm was the likely suspect. I don't know if you have a vacuum pump or if it can fail like the 616's or 617's. If you do, I would check there first. It causes the engine to suck oil from the crankcase into the intake.

jjalex · #3 06-06-2003, 09:17 AM

I definately have a vacuum pump in the 602. According to the records it was replaced a few thousand miles ago...

Makes me wonder if it was rebuilt or replaced...

I will check into that as soon as I get home, thanks to my trusty W123.

Thanks a bunch

jjalex · #4 06-06-2003, 10:20 AM

One more thing - the smoke was fairly white and the smell was burnt. Head gasket maybe?

JimSmith · #5 06-06-2003, 12:25 PM

jjalex,

Did the white cloud smell like oil or water? When enough oil makes it into the combustion chamber, the exhaust color is white. The white cloud from oil is generally thicker and lasts or hangs around longer. The only thing I have experienced that caused a white cloud of oil smoke was a vacuum diaphragm failure. The engine continues to run without any outward sign, other than the belching of white clouds of oil smoke, of distress.

I would look at the vacuum pump first, unless there is no connection to the intake manifold. I think later cars did away with this and the vacuum pump exhaust is ported to the crankcase volume. In that case it might not be as likely to have a vacuum pump diaphragm failure result in heavy smoking.

Good luck, Jim

jjalex · #6 06-06-2003, 01:15 PM

Jim,

The cloud definately hung around, had a bit of blue in it and and smelled a bit like oil.

I will check out the vacuum pump situation on the CDs when I get home. I'm just not very familiar with the 602 engine yet, but I have a feeling I'm about to be....

I think the W123 I've owned since November spoiled me.

Thanks a million,
John

CJ · #7 06-06-2003, 11:30 PM

The 602.962 motor uses a non-rebuilable v-pump. They are easy to replace.

jjalex · #8 06-07-2003, 09:37 PM

I didn't see a connection to the intake from the vacuum pump. After further study and a few antiacids:

- Running badly
- Excessive smoke getting more blue
- Rapid oil loss - 2 qts on a 14 mile short freeway run
- Oil found in turbo, intake
- Excessive vlave noise
- Oil coming out the tailpipe

I plan to have it towed (roll back truck) into Milwaukee next week. I have an excellent reference on a Mercedes mechanic at European Auto House 414/358-3552.

psfred · #9 06-07-2003, 09:58 PM

Two options here, one bad, one good.

If the turbo ate a housing, you are pumping huge quantites of oil down the engine. This is likely, since you have large quantites of oil in bot the exhaust and intake. Don't drive it, if you get enough oil in there you will bend some rods, and this is EXPENSIVE.

You could also have bent rods, independent of turbo condition. All the 60x engines can bend rods, although this isn't usually a problem in the 602. Diganostic is the clank of the piston rattleing around in the now oval bore since it is cocked and high oil consumption, but 2 qts in 14 miles, I'd bet on the turbo. The bad thing is that enough oil in the cylinders and.... well, rebuld or replace time.

Check the turbo for play -- side to side you may have some movement since the bearings "fly" on an oil film, but anything more than barely perceptible or ANY axial play, the turbo is gone and blowing oil. Oil dripping out the tailpipe makes me think turbo, since it won't burn in a cold exhaust.

Peter

jjalex · #10 06-10-2003, 09:05 AM

The turbo appeared to be ok, but I certainly don't know enough at this level...

I am trying to get an appointment at the European Auto House in Milwaukee. They were referred to me by a trusted source but they are booked for at least a week and a half....

Does anyone know if the vacuum pump could actually cause this on a 602.962 motor? It was just replaced a year ago. The first post referred only to the 616 and 617 motors.

Good thing the trusty '84 300D rolls on.

Thanks

Mordecai · #11 06-10-2003, 03:45 PM

Quote:

Originally posted by psfred

Check the turbo for play -- side to side you may have some movement since the bearings "fly" on an oil film, but anything more than barely perceptible or ANY axial play, the turbo is gone and blowing oil. Oil dripping out the tailpipe makes me think turbo, since it won't burn in a cold exhaust.

Agreed, check if the oil is in the intake manifold before the turbo, or in the air filter housing, it could be massive blowby (broken rings, broken piston, or a sucked valve). After the turbo, I'd suspect the oil seals in the turbocharger bearings.

A compession check should reveal the state of the pistons, rings and valves. Pull the glowplugs and see if they are covered in oil. If one is oily then suspect that cylinder; if all are oily suspect the t-charger.

If you remove the t-charger it would be obvious if that was the problem. They are rebuildable and someone around here had a link to a place that does that kind of work.

OTOH--Mercedes tubocharges are fairly reliable. If money is an issue, a used one from a wreck would suffice for a while.

M.

jjalex · #12 06-10-2003, 05:37 PM

The air filter housing is dry, so its on to checking the glowplugs.

I'm glad there is something I can do...

Here is what I found on turbo rebuilds:

http://www.forcedperformance.net

They do basic rebuilds for $300.

Thanks for the ideas.

Mordecai · #13 06-10-2003, 06:33 PM

Quote:

Originally posted by jjalex
The air filter housing is dry, so its on to checking the glowplugs.

I'm glad there is something I can do...
Here is what I found on turbo rebuilds:
http://www.forcedperformance.net
They do basic rebuilds for $300.

$300 bucks is cheap if they do a good job. I'd hate to price out a new one.

You might also pull the injectors and see if you can look down in the precombusion chamber.

M.

jjalex · #14 06-26-2003, 12:05 PM

The mechanic looking at the car tells me the turbo is fine.

He thinks my problem is probably a cracked piston or head as he continues to troubleshoot.

If it comes to the worst case scenario, what should I expect to pay for a resonable used engine replacement?

Any Ideas on where to draw the line if the rest of the '91 300D is solid?

Thanks

Mordecai · #15 06-26-2003, 01:34 PM

Quote:

Originally posted by jjalex
The mechanic looking at the car tells me the turbo is fine.

He thinks my problem is probably a cracked piston or head as he continues to troubleshoot.

Based on what facts? Ask why he believes this. A lot of guys will just say "Cracked piston."

M.