am trying to figure out source of excessive white smoke out the tailpipe from new 91 300D. Here are some facts:

254K

no external oil leaks anywhere I can see.

lots of sludge/wet oil everywhere on intake plumbing, now cleaned up best I could do.

pulled rubber boot to inspect turbo impeller, no play in either direction, but while running & crossover pipe removed, saw it stop a few times @ idle, would start spinning @ higher rpms.
this is a little suspect to me.

also, when I revved it up & placed my hand over EGR pipe, I did not feel more than a slight pressure increase.

same white smoke comes out of breather as well.

smoke smells neither of fuel nor coolant, & hangs in the air quite a while.

it is entirely possible that this car experienced overheating prior to my brief ownership as crank pulley/balancer were not in place @ time of purchase.

smoking aside, the motor runs great above 1500 rpm, idle is smooth, starts right up, but misses from time to time off idle to 1500.
missing seems to be improving each time I run it.

fresh synthetic oil, fuel filters, injector nozzles, return lines, IP lines

I have spent hours researching the archives & have come up with turbo seals, head gasket, valve stem seals or some combination of the three as being the likely culprits.

any gurus want to weigh in on this?

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1991 300D

I'm not sure why you would expect a pressure increase at the EGR valve, EGR is closed under load. But no matter.

To measure turbo boost you need a pressure gauge or boost gauge. Look at the left side of your intake manifold. You will see a large electrical sensor. Directly below that is a fitting with a small hose leading off. Unplug the hose and temporarily install your gauge on the fitting. Goose the engine and see what you're getting. Should peak at around 1 bar.

I'm having a similar problem with my 190DT, and it's had me baffled. My turbo is freshly rebuilt, so it's not that. It seems to be sucking oil in through the breather tube. I recently took apart the air cleaner and cleared nearly thirty years of accumulated gunk out of the air flap, and also replaced the air filter. The problem is better, but not cured. I'm interested in hearing what you find.

turbo impeller sometimes stops @ idle when egr flap closes, spins when flap is held open/engine revved.

it is pushing oil and making some small grindy noise, suspect it is time for a rebuild.

I do have the parts for the wastegate actuator swap

mxfrank: perhaps I was unclear. I was putting my palm over where the crossover pipe would be. also I didn't check to see if the egr flap was open or closed when I did this.

will look into checking boost pressure.


blow-by out of valve cover seems excessive, but not entirely unexpected given the mileage/history.

interestingly, when I put my thumb over the hose outlet, the engine came to a stop after a bit. I don't think I will do this again.

additionally: there is a steady drip of coolant coming from a bolt head in the block located aft of the new water pump, south of the sensor, very tight access with the alternator in place. I could just get a 10mm wrench on it to turn it a little. tightening it some made no difference & am afraid/unable to try to sock it down without being able to see what I'm doing.

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1991 300D

What's your oil consumption? Fairly common with these engines at this mileage for the head gasket to fail allowing oil into the #1 combustion chamber. Remove the #1 injector and crank the engine with a finger on the stop lever. Does oil puff out of the open prechamber?

Sixto
MB-less

sixto: haven't actually driven this car yet, so consumption is unknown.

will draft wife for cranking duty this weekend to check #1

I am beginning to think I'd be better served by just keeping this a parts car & finding one that runs/drives.

pulling the head opens up all sorts of while-i'm-in-there stuff, & I'm not prepared (wintertime, gravel driveway, no money) at this point.

got laid-off a couple weeks ago

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1991 300D

FWIW similar symptoms to my failed head gasket on the 92 I had.

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14 E250 Bluetec 4Matic "Sinclair", Palladium Silver on Black, 154k miles
06 E320 CDI "Rutherford", Black on Tan, 172k mi, Stage 1 tune, tuned TCU
91 300D "Otis", Smoke Silver on Tan, 142k mi, wastegate conversion, ALDA delete

19 Honda CR-V EX 61k mi
Fourteen other MB's owned and sold
1961 Very Tolerant Wife

I'd be happy if it were only a head gasket as well..

sort of between a rock and hard place with this one, might need a turbo too...

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1991 300D

I had a failed head gasket last spring lots of white smoke and rough running while cold once warmed up seemed to run great. I ended up changing the gasket number 5 showed signs of coolant leakage and number 1 had oil evidence. It is now all good and basically the cost of the gasket and coolant.

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92 e300d2.5t
01 e320
05 cdi
85 chev c10

x2 what dieselbenz1 said. Any inline engine 124 is going to need a head gasket as the miles pile on. Fix this one or clear space for a lot of parts cars

Sixto
MB-less

The head gasket & turbo kits + related tools are do-able on my limited budget. I've been reviewing a lot of threads on this topic, startekinfo & GSXR's site.

Maybe I should collect some part #'s for Santa

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1991 300D

To do the turbo you will need the heaviest duty snap ring pliers you can find...I used a 16" pliers to disassemble mine, and it was still tough. If the case hasn't been apart, there's a good chance that the bolts are rusted solid. I ended up snapping all four. In the end, I threw it in a bag and brought it to be professionally rebuilt. In addition to all of the above, the compressor wheel turned out to be damaged. I never would have been able to balance it, either. Some jobs just aren't doable at home.

some small progress:

alternator & carrier removed to gain access to coolant leak.
will check VR. all these parts are absolutely covered with oily grime. fun times ahead cleaning everything up.

found that in order to remove bolt on front of carrier, the harmonic dampener needs to be rotated to one of the 2 divots machined into it.

removed water pump housing & water pump together as it was not clear where the drip was. now suspect lower pump bolt as source, dripping onto carrier bolt. oh well. so I need 2 gaskets now. passageways were clean, oil free, but a little white scale here & there.

removed egr & pipe

basted all the fasteners on exhaust with special sauce & was able to remove the nine nuts/studs present on the manifold with little fuss. stud on #1 missing, probably broken off inside head. we'll see.

will tackle the turbo & related plumbing today.

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1991 300D

If you pull and Injector and look down inside of the Prechamber it should all be coated with a thin coating of Dry Carbon. If the Carbon is wet and shiny you are getting Oil up in there.

I think the newer tyes if Coolant may not have the same smell as the older Green Coolant has.

A Compression Test or a Leak Back Test might show a Head Gasket leak.

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84 300D, 82 Volvo 244Gl Diesel

I'm fairly certain that pre-chamber was wet @ #1, possibly others. When I had the intake manifold off everything was completely covered in thick oily residue.

My revised plan of attack, scaled back from just doing the head gasket and everything else from the get-go, is to address the external coolant leak, inspect the turbo for internal damage maybe install the waste gate mod.

Dependent on my slender finances I may able to do a pressure test, & compression check before proceeding with the tear-down.

I am attempting to minimize the number of times I remove and reinstall various engine components.

A variety of flavors/colors of coolant have been run through at this point with no change in exhaust smell. No oil residue has been found in any of the inspected cooling system parts I have examined so far.

from my previous w124 experience, I know what fuel smells like coming out the back. Also, having had 3 other cars that have been strong runners, I know what exhaust is supposed to smell like

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1991 300D

turbo looks ok, just an internal leak.
wastegate moved when I put a vaccuum to it. starts opening with just a little, I can see why the pressure mod is desirable.
spins freely but with a little more drag than I would have thought.
Its my first time touching turbo innards

time to clean everything

never a better time to change out that motor mount

anyone handy with the EPC can get me the pn for water pump housing gasket in exchange for fist-bump?

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1991 300D