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-   -   Compression testing a D (http://www.peachparts.com/shopforum/tech-help/7794-compression-testing-d.html)

Dusty4 06-05-2000 04:00 AM

Time to show my ignorance re diesels- took the project car out for a burn, 150 miles, 1qt oil. To do a compression test, do I use injector holes? Does pump need to be removed? Time to see a pro? This car has 206k, has sat for a year or more-- should I just drive it for a while and see what happens first? Thanks, Dusty


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82 240D



LarryBible 06-05-2000 08:10 AM

Dusty,

Do you know if this car used a lot of oil before it sat up for the year?



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Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles

Dusty4 06-05-2000 11:51 AM

No history at all, Larry. Can say engine has surprising zip, but someone following me noted some blue smoke from exhaust when going down steep hills. I have a hard time imagining this engine being so peppy if its low on compression, but seems like a natural place to start looking. Thanks, Dusty

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82 240D



Harvey Sutlive 06-05-2000 01:42 PM

Could this be the oil scraper rings not doing their thing? Somebody recently said they had success with an engine cleaner additive - I think it was an STP product.
At any rate it might be worth putting some more miles on the motor and observing for leaks before assuming bad compression.

Harvey

fz500sel 06-05-2000 08:34 PM

Dusty,

You said "150 miles, 1 qt. oil" Do you think it leaked the oil (did you see any leaks)? Did it burn it? I realize that you stated that a guy following saw the smoke, but it's not uncommon for our diesels to burn a little.

If you could be a little more specific, it may help us diagnose or suggest some things to look for.

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FrankieZ
84 500SEL EURO 87K
85 300D 267K (and still goin' strong)

Dusty4 06-05-2000 08:59 PM

I find no oil puddle under the car, and haven't caught it smoking, so at this point I don't know where the oil is going. At that level of consumption, you would think I could get a good smoke screen going. Although I am skeptical of miracles in a bottle, I have seen piston rings stuck in thier grooves in engines that sat too long. Might try some.

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82 240D



LarryBible 06-06-2000 09:12 AM

Dusty,

Remember, a diesel engine runs on oil, however thin diesel fuel is, it's still oil. If motor oil finds its way into combustion it's just more fuel. Agreed, oil is about $5.00 per gallon fuel, but it's just fuel.

Try some frequent, hot oil changes. If that doesn't work, you may have to soak the rings with solvent. If you resort to this, make sure you never try to start the engine with liquid in the cylinders.

Good luck,

------------------
Larry Bible
'84 Euro 240D, 523K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in
Mercedes automobiles


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