The fuel is a little dark in the filter. I am working on the car on Friday so I will check the tank strainer then.

Anybody have an answer as to this?



I will have to check the glow plugs tonight and see if any are out.

I am more than willing to do some more videos as well.

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'78 300D 85,000 original miles drive her daily

need to remove a variable in the tea kettle test. block the vent. the condition of the vent tube and everything down range will make it different on everyones engine.

-just a suggestion

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'82 Euro MB 300 D Turbo Silver/Blue - Fixed
Adding W115 Intake and Intercooler

1986 Chevy Camaro Cp 400HP For Sale
Engineer
Tuscaloosa, AL

The shutoff diaphragm on the IP is vented to the crankcase from the inside. When pressure builds in the crankcase, the shutoff diaphragm moves in similar fashion to applying vacuum to the outside and fully closes the rack.

BTW, this test is not recommended due to the rather high crankcase pressure...........and the possibility of blowing out the crankshaft seals.

Furthermore, why concern yourself with blowby? You cannot do anything to improve it without spending thousands of dollars and it has no real impact on the day to day operation of the engine.

That is the darn truth!

I have 2 MB's that have almost no blow by, but on a 616/617 engine that is 20 plus years old, that is really rare.

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1981 300D 147k
1998 VW Jetta Tdi 320k
2001 Dodge Ram 2500 141k
1979 300D 234k (sold)
1984 300D "Astor" 262k(sold)
Mercedes How-To and Repair Pictorials
I love the smell of diesel smoke in my hair

Excellent point about the blowby I suppose. I will keep everyone updated about the tank screener. I will be testing this tomorrow.

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'78 300D 85,000 original miles drive her daily

That bubble is to big. Are small air bubbles coming from the tank? Time to replace the hoses.

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http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

Thanks, Brian. Is that venting deliberate on the part of M-B's designers? (I need to learn more about diesel injection pumps.)

I would not think that the pressure would be high enough to blow out a seal. Nonetheless, I will be careful. And yes, you are correct that blowby can't be fixed by buying (as Click and Clack are fond of saying) a can of something that says "Miracle" on the label.

Anyway, my engine doesn't use any oil between changes and starts easily so I won't worry.

Jeremy

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Can't say the intentions of the Germans.........they're a pretty secretive bunch.

I wouldn't want to lay any odds on that. You might be correct........but........what if you're not?

Too much time spent discussing blowby. It provides some indication of the condition of the rings and helps to make a decision on keeping the vehicle for the duration. But, in the short term, there's nothing you can do to improve the situation............

DG: thanks for the useful video, cant wait to go home and check it.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

On the blow-by test:

I notice some have those cheap plastic oil fill caps and some of us have the OEM heavier metal ones. I would think the plastic caps would bounce around a lot more since they are much lighter than the metal ones. I happen to have both types and I didn't like the plastic one because it still leaked. I purchased new gaskets for the metal one and adjusted it so that it fits tightly.

With this test.....is it required to use the plastic cap? I just ask because the results with the two different caps would surely be different.

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2008 Jeep Grand Cherokee 3.0 CRD (OM642)

Compared to other 617's that I've seen that started and ran fine, you have no blowby. I looked at one that chugged like a steam locomotive out the oil fill hole when warm but had no detectable problems. There is a device for measuring blowby but I've never seen one. I think the smother test is largely irrelevant because the time it takes to shut down the engine is entirely dependent on the quality of the seals in the engine. (not to mention the altitude at which you perform the test) A slight seal leak somewhere, even in the oil fill cap, would increase the shut down time.
Put some diesel in a soda bottle and run a fuel line from it directly to your primary fuel filter and see if this shortens cranking time. If so, it would show you have a problem between the tank and the filter.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13

I loosened my oil filler cap but it didn't rattle around at all. Didn't even move. Engine was hot, cap is the OEM heavy metal one. If I plugged the breather hose, there might be enough pressure to make it bounce a little, I'll have to try that.

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"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

I think the movies are great...I really enjoyed the clickity-clack of the old Mercedes diesels.

I think your problem is a worn out engine. I once had a 240D with that kind of blowby and spent thousands rebuilding the top and bottom. In the long run it wasn't worth it, but my brother and I spent a lot of quality time together. If the body of the car is really nice, it may be worth it for you.

In my opinion, the first clue for me was that the engine just cranks too fast to have enough compression to make it start quickly. Also, I think when you close off the breather tube, it's building so much crankcase pressure that it is stalling the engine.

I would get the compression tested and also perform a leak-down test. I think you'll find low compression due to worn rings.

If it starts and runs well enough for your needs, keep driving it.

2005 Mitsubishi Galant
1989 260E
1987 300D Turbo
1986 BMW 325E
1994 Dodge Ram 250 Van (yech!)

Sounds like your wife or someone was helping out on this one....LOL.

I like on the last one where you yell at her...."OKAY......turn it off!"

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2008 Jeep Grand Cherokee 3.0 CRD (OM642)

Well not my wife, my girlfriend. She's pretty good about helping when I need it. I agree with most here that blow-by is a good reference point but for the daily driver one is better off to get it all tuned up to spec and then drive and enjoy your classic benz. Thanks to everyone for the insight and I hopefully can create some more helpful videos.

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'78 300D 85,000 original miles drive her daily