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MAN Compression specs for D2840LE-401

Discussion in 'Engines' started by SeaEric, Jul 23, 2014.

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  1. SeaEric

    SeaEric YF Historian

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    Does anyone know what is the "acceptable" compression test range for an 820 MAN D2840LE-401? One source said "recondition necessary under 24 bar" I wish to confirm this information.
  2. Marmot

    Marmot Senior Member

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    If the question is academic, contact a MAN service shop. If you are concerned about the report of a compression test, the operative question might be "does it start easily when cold?"

    As long as the engine starts easily there is adequate compression. If other factors like injector condition, fuel quality, and cranking speed are not an issue and the engine starts quickly, compression is not something to worry about.
  3. SeaEric

    SeaEric YF Historian

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    They seem to start OK with no block heaters with minimal smoke that clears pretty quickly, but its 90 degrees here on the Chesapeake. The compression tests came back in the 19 bar area with one cyl at 21 bar. A buyer's concern is that if these engines need a major, the cost of doing that is very high.
  4. SomeTexan

    SomeTexan Member

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    I would have a leak down test performed. Don't know MAN specifically, but usually 15% is the max variation allowed between cylinders. You can also do the compression test again, after adding a small amount of oil to the cylinders. If that brings compression up, you have worn rings, if not, valves need some work. Also, too little valve lash (worn seats) can keep valves from closing fully and lowering compression. I would think a good survey would check all of this though?
  5. Marmot

    Marmot Senior Member

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    With that information I would ask how much running the engine(s) have had recently. Have they been sitting for an extended period or have they been in regular use?

    Reason being that if they were sitting for considerable time it is possible one cylinder has some surface rust on the rings or bore. A period of hard running might completely change the readings for the better. As the other poster mentioned, a leak down test will help identify rings or valves as the source of low compression if it does not come up after a good run.

    In any event, a "major" is not necessarily in the cards given the description you provided. You might even get away with doing a single head and valves.
  6. Capt Ralph

    Capt Ralph Senior Member

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    “Engineering S Data S Setting values”

    MAN repair manuals refer to a separate “Engineering * Data * Setting values” manual. Of course I don't have it. When it comes to exact specs, I hit up my MAN support guy, he has it.

    Marmot is correct (if I read it rite), a engine that has been sitting up will not offer reliable readings. Can you fill a filter with marvel oil and make a quick run. Then within a day recheck your readings?

    Consistent readings between all cylinders I think is important. If you're starting up fine with min smoke, you're off to a good start. Your 21Bar reading I'm betting is from a lower (more aft) lung.
    I worked on great running and fast Viking sport with the V-10 mach's. Mosquito control when started on a summers morning. Out of fuel before daylight everyday during her summer runs. Never a problem.



    The manual on the 403;

    D Check valve clearance and adjust, if necessary,
    see page 109
    D Let engine warm up
    D Remove all fuel injectors, see page 40
    D For compression guideline values, see publication
    ”Engineering S Data S Setting values”
    Fig. 1
    Start with 1st cylinder. Insert new seal, screw on
    test connection of compression recorder with union
    nut and tighten with pin spanner.
    Insert test sheet into compression recorder for Diesel
    engines. Screw compression recorder on to
    test connection.
    Turn engine over with starter until needle deflection
    of compression recorder stops, at the same time
    holding adjusting lever of injection pump in stop
    position.
    Connect up compression recorder with test connection
    to the next cylinder, and check all cylinders
    as described above.
    Fig. 2
    Depending on the compression recorder design,
    the engine can also be started directly by the compression
    recorder. For this purpose the electrical
    connections on the starter electromagnetic switch
    (terminals 50 and 30) are to be accordingly
    connected up.
    Fig. 3
    Compare the values measured and remove compression
    recorder and test connection. Apply
    ”Never Seeze” to contact faces on fuel injectors.
    Fig. 4
    Screw in fuel injectors with nozzle and new seal.
    Screw on union nut and tighten to specified torque
    (see “Engineering S Data S Setting values”).
    Connect up injection lines and leakage fuel return lines


    numbers in a few days.
    ,rc
  7. SeaEric

    SeaEric YF Historian

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    Engines have approx 3000 hours on them. There have been 2 separate compression tests by 2 different mechanics with somewhat similar results. Boat has been run at cruise for 4 to 6 hours in between the testing. I'd still like to know what the MAN spec is for minimum acceptable compression.
  8. Capt Ralph

    Capt Ralph Senior Member

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    From the book

    Compression pressures
    (Engine has run before the measurement and is warm to the touch)
    good bar over 18
    permissible bar 16-18
    in need of repair bar under 16
    pressure difference bar max. 4
    (between individual cylinders)


    Think your looking good.
  9. Capt Ralph

    Capt Ralph Senior Member

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    I'm starting to like the MAN engines more and more. So far, I'm lucky just working on the hang on stuff. I'm doing it myself because there is NOT any MAN support here in Jax.
    I'm worried that you had two techs check this out, AND they could not offer any data on their readings.

    My ramblings are trying to make a point. If you're considering a MAN purchase, make darn sure you have a good tech or shop you can count on. Real MAN Techs are far between and hard to find.
  10. Capt J

    Capt J Senior Member

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    I'm not a fan of working on Man's.....They just never fix their design flaws......upside down spring loaded canister oil filters that always make a mess and are a 2 person operation to get on. (I've done it by myself but they're a pain). They have the same **** oil filters on the 1942 U boat that's sitting in the Museum of Science in Chicago.......Threadcerts on iron parts that always come out with the bolts on the oil filter and fuel filter bolts. Never relocating filters to the Aisle.......LOTS of electrical issues which are design flaws yet they never take accountability for and make the owner pay for it. Sensors that go bad far too often and are expensive. The electrical is their real pain or weak knee. Engine controls that they knew would screw up sooner than later, and never warrantied....But the "updated" ones have chrome through the center hole all of the way.......I'm so tired of hearing "It's not covered under warranty, but he have an UPDATED part". Even MTU now uses spin-on oil filters.......OHHHHH and the very best was the high pressure injector line on the old 1050's and 1350's that would break off because of a bad design and the engine harmonics and shoot fuel ALL OVER the entire engine room and dump 100's of gallons in the bilge, the ceilings, the walls, that they knew about for 2 entire years and never recalled nor covered if it made it out of warranty. When one engine blew the high pressure line, the other was going to within 3 months and 50 hours also. But after they waited until their entire inventory of the old ones was depleted, they then redesigned it with an "updated" part. Everyone designs bad parts sometimes, but don't stick it to the customer, take some accountability for your mistakes, especially something as dangerous as a high pressure fuel line.

    They do run quiet and are fuel efficient........
  11. SeaEric

    SeaEric YF Historian

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    These are tests performed by mechanics in business to make repairs and overhaul motors, not surveyors. I have their data. I would prefer to hear analysis from someone who doesn't have a dog in the hunt.
  12. Capt Ralph

    Capt Ralph Senior Member

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    UH? Surveyors have factory data and proper MAN techs do not?
    If I was hunting for your business, You think I would pass service info & data?
  13. SeaEric

    SeaEric YF Historian

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    Ralph, I appreciate your information very much. It is, in fact exactly the information I was looking for. I certainly did not intend for you to infer that my cynicism was directed at you. It was not. If you read my initial post - the information from the mechanic was that under 24 bar was recondition. What you have told me is far different. Again, thank you for your information and please accept my apology.