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Thread: Slow oil pressure 406 / 419

  1. #1
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    Default Slow oil pressure 406 / 419

    On my FLU419 the oil pressure takes about 11 seconds to register on the gage. This is consistent every time the engine is started after sitting overnight. It occurs to me now that I haven't confirmed how long it lags after a few minutes off with the engine warm, but not long. As you might imagine I'm reluctant to start the engine and find out. I can't confirm with the documents I have where (or whether there is) a check valve or anti backflow system in the oil filter filtration but I suspect there is and that's what needs attention. Any input from those more familiar with the OM352?

    Edit:
    The pressure rises quickly ( 0.5 sec ) after the lag and is strong in the 70psi range at idle.

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    I have three 406 mogs with OM-352 engines. They all take many seconds to show gauge pressure. 11 seconds seems like longer than mine though, but that time is dependent on idle speed. I think you are seeing normal operation. I have 70's model 406's so you need comparisons to later model SEEs.

    When the engines sit for a while, like days, the oil pan level increases indicting the oil has drained out of the engine/ That might be true especially on the newer model OM352 engines with upside down oil filters (like the SEEs?). Oil remains in the bearings though (tight Mercedes tolerances) and lubrication has not been a problem. That's why oil level should be checked just after shutdown.

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    The slow reaction of the gauge is normal, unfortunately. Never did get around to check if there's an actual lack of pressure, or just a delayed gauge. It doesn't sound like they're running without pressure...to me anyway.

    Oh, and the filter on a FLU is positioned correctly, tennmogger, so that's probably not the reason for the "eternal" wait. I hate it, but keeping the rpm low until the gauge registers full pressure is about all I can do.

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    Copy those responses. Thank you. I did check today by cranking the engine with the throttle off until pressure registered, that took a while, but as soon as I open the throttle and started the engine the pressure rose immediately. The take-home is the engine is definitely tight, there’s no low oil pressure, it just takes a while to build which made me think maybe the filter or pump was draining as that’s happened in other engines I’ve worked on. Also, if you shut down for 2min or 2hrs the pressure rises more or less immediately when starting it back up.

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