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Pre-oiler Idea

Discussion in 'DIY (Do-It-Yourself)' started by markusmark, Feb 16, 2014.

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    markusmark

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    In looking for comments on a potential (cheapee) pre-oiler idea. Basically, I would install a normally closed/press to open (on-(off)) switch in the console. This switch, when in the "open" position would cut the power to the fuel pump relay. The idea is to press the switch to open the contacts and crank the engine. Once the oil pressure idiot light goes off the switch is released. Releasing the switch sends power to the fuel pump relay and the engine starts.

    Comments/raves/rants are welcome.
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    steven s

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    Interesting.
    This is to allow oil to circulate before starting?
    Curious, is this a problem for cars?
    What year and model?

    Sounds like you answered your own question.
    Cut power to the relay.

    Depending on the car, couldn't you also mess with the EWS to cut fuel?
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    markusmark

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    Steven, it's a 2001 330Ci. Yes, "dry running" - running the engine before oil has reached all parts of the engine - is a known problem. In some circumstances it can account for a large % of engine wear. The dependency is the number of times the engine is started versus the time the engine is run. BTW, many (expensive) emergency vehicles such as fir engines have per-oilers.
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    steven s

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    That's why I often question people that change their oil at very short intervals.
    Starting the car with virtually no oil covering where it's needed the most.

    Even with synthetic, this is a problem?

    What little I know, and it's very little.
    Either cut the power to the fuel pump relay or it might me possible to cut a wire at the EWS to prevent spark and fuel.

    Be cool to have it timed for the relay to be energized. Then you don't need a switch.
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    MGarrison

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    I think that approach would be relatively inexpensive, but I also think it's only partially effective at best and doesn't do much to address the issue. Fuel-relay cutout or not, you're still cranking the engine up "dry", and it's the very start that's the primary problem, to whatever degree it's a problem.

    If it's that much of a concern, an accusump is the solution - and then pray the extra plumbing never fails.

    http://www.improvedracing.com/accum...husen&osCsid=4a7199db1e406f77d55e61743557c91b

    Not sure if your car has the same feature as E30's with on-board computers, but OBC-equipped E30's allowed for entering a 4-digit security "code" which basically disabled the fuel delivery. You could crank all day, but no start due to no fuel delivery until the code was re-entered into the OBC. IF the E46 has the same feature and it works the same way, you wouldn't have to do any more than that - but that won't eliminate dry startup.

    As a practical matter, going to such efforts, consider your long term goals or plans for the car. If all other engine-related maintenance is attended to (fixing leaking gaskets, control valves, anything related to oil circulation & delivery, etc.) it's perfectly plausible the engine in stock form might well run up to 250k-300k miles or more without requiring major teardown. In that amount of time, given all other maintenance issues that are likely to come up after that much usage/driving, you may find it all to add up to more than you ever want to deal with, or various things easily surpassing what the book value of the car would be by then.

    Unless the majority of the engine's life is cold-startups (ie, almost all short-trip city-driving with enough time between startups for the engine to cool and have oil drain-down), I suspect you might be hard pressed to see the difference from having an accusump installed until you reached at least over 250k miles. And, you'd need to be consistently patient to realize the benefits, it takes time for any pre-oiling system to pressurize; hopping in, starting & then going before a pre-oiler has done it's job negates its purpose. Unless it's purely a weekend or fair-weather-use-only driver, I'd think there would be any number of occasions when you need to get going and not have time to wait; that's certainly my usual scenario!

    If you're shooting to put 400k or more on your car, perhaps an accusump might pay for itself by extending out the timeframe when an engine teardown would become necessary - short of that, not sure if you'd realize that much practical benefit.
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    Satch SoSoCalifortified

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    I think I would be analyzing the oil, looking for evidence that I'm scoring the bearings, before I'd worry too much about pre-oiling. The film strength of modern synthetics is supposed to protect things until fresh oil arrives.
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    space gray

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    the oil film stays on parts for a long time, sometimes lifters leak down causing a noise

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