Yanmar - How long should it take for oil pressure to come up from a cold start?

Discussion in 'Diesel Engines' started by Frosty, Jul 26, 2009.

  1. wardd
    Joined: Apr 2009
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    wardd Senior Member

    or you can have the oil analyzed
  2. Frosty

    Frosty Previous Member

    Geeex we are getting off topic a but here,-- but thats ok providing my thread does not get misunderstood. I do not have engine wear problems. The engines are sweet when up an running and idle oil pressure requirements are Perfect.

    I am infact talking to Yanmar at the moment. The prob is they just don't know the answer as does no one else, if the oil filters drain then why don't they do it on a Toyota Landcruiser?? you could not get away with this in the motor industry.

    As the prob is filter drain back some how I have hacked apart every one thats been on ,--and thats a lot, maybe a dozen or so in 170 hours of engine life, but for diagnostic reasons,-- to inspect anti drain valves for filter probs.

    I would be devastated if I found even the slightest shimmer of metalic like substances.

    Its possible that the filters drain through the outlet and not necessarily the in side where the anti drain valve is situated.

    To drain back thro the in side would mean getting back through the main oil pressure relief valve on the pump. Now its possible that its draining thro the out side which means its draining thro the crank bearings that will be lower than the filter.

    (For those who cant read, slow oil pressure build up on cold start only, after that we have perfection,--cold start, I mean daily.

    Oil drains overnight, you can spin the filters off,--nothing in there no oil dry!!!!! )

    We are not concerened with guages, could be slow alarm senders?

    Both engines identical, Hmmm,-- 2 slow alarm senders?

    Well No say Australia can not ever have same probs on 2 engines in one boat.

    BUT the speed of the alarm does correlate with gauge readings.

    But why think about it when the filters are empty on every cold start, thats the prob and no one knows why.
  3. Jimbo1490
    Joined: Jun 2005
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    Jimbo1490 Senior Member


    The number one cause of bearing wear is dry starts. This has been well documented in dyno testing. Almost every engine starts dry for some short (usually VERY short) period of time, but as long as this period is kept very short, it's considered acceptable, and not a big enough problem to be worth the complexity and expense of a pre-oil system to deal with it (though that would solve the problem COMPLETELY).

    But your engines with their con rods clanking on for 10 seconds (as you stated) on starting is a big wear problem; it WILL wear the bearings out prematurely.

    If you don't think it's causing any damage, then why are you so worried about it? Is it just the NOISE that bothers you? Then just wear ear plugs, for Christ's sake :D

    But trust me, running dry for 10 seconds on every start IS causing excessive wear!

  4. Frosty

    Frosty Previous Member

    For fcks sake,------Ok one more time.

    The noise rattle is when the engines are turned off. OFF ---OFF--OFF. By that i mean STOPPED, FINISHED WITH,- OFF OFF.

    It is torsional vibration rattling the gearbox clutch plates and is common. I dont like it, and Yanmar should not have it. They are crap like any other. Not the best that you pay for.

    Most motorcycles do it.

    Where the fck did I say con rods Clanking. ( as I stated)

    Dry starts cause wear? you dont say? why do you think I started this thread? why do you think im trying to cure the prob.

    Again for the hard of reading, ---I crank the engines 15 seconds or so before letting them fire.

    Actually for starter motor cruelty sympathizers 2 lots of 6 seconds then let the button go.

    Hey Jimbo Thanks for your help. But no more please.
  5. globaldude
    Joined: Jan 2005
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    Location: Whangarei New Zealand

    globaldude court jester

    Keep ya pants on mate !!, just trying to offer possible causes . Don't know why I bothered as you know it all !. Good luck to you and your family .
  6. Frosty

    Frosty Previous Member

    Globaldude you started Jimbo off on big ends rattling, Who the fck said that I have that???????????

    I have put myself up in a precarious position, throwing stones at Yanmars legal departments windows trying to attract attention, everything I say is 100% true , I don't need some one coming in talking crap about big end bearings rattling.
    Its Ok to speed read fiction, not technical information.

    By all means read my posts on my problems then make a comment.

    I think I know now why Yanmar does'nt come here.

    My Family thanks you for your good wishes!!! what ever.
    Joined: Oct 2002
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    FAST FRED Senior Member

    Every engine will last longer with a Pre Lube before start.

    This does not have to be a pump and motor ($$$$!),

    a simple accumulator with a solenoid valve is cheaper and works for a cold start.

    The solenoid on an oil accumulator is opened , and the engine started.

    After a min or so the engine will have refilled, repressueized the accumulator tank, so the valve is closed.

    Not useful for turboed engines where POST oiling will allow the bearings a better spin down , and cooling.

    But its inexpensive and reliable.

  8. RHP
    Joined: Nov 2005
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    RHP Senior Member

    Frosty's pants came off years ago.... hence his al fresco responses. :D
  9. Frosty

    Frosty Previous Member

    I like you RHP,--dunno why.

    Lovley avatar. Must be your Accent.
  10. RHP
    Joined: Nov 2005
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    Location: Singapore

    RHP Senior Member

    I wish more women would say the same........
  11. Frosty

    Frosty Previous Member

    FF do you have a link or even a name of a manufacturer. That sounds like it could be a cure and not a modification. It would be acceptable by the surveyor as an improvement too.
  12. Bigfoot1
    Joined: Jul 2009
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    Location: British Columbia

    Bigfoot1 Junior Member

    Before you spend the money on a prelube, you should really take the time and plug in a guage into an oil port. As I had mentioned in an earlier post, most electronically controlled guages are damped to purposely give a slow control response to an input to stabilze the needle. So while you are reading the OE guage and it is not up to spec, the engine may be at full oil pressure but the
    OE guage takes time to put the needle up to spec.
    Liquids are incompressible fluids, ie oil does not pressurize like an air compressor ( so that oil pressure does not build slowly ) so in a closed system ( which your engine is not) a single turn on the pump will provide downstream pressure. So if you take a simple bourdon tube guage which gives almost an instantaneous response, plug it into an oil pressurized port downstream of the pump, crank the engine and watch the guage. I would bet that the bourdon guage will read pressure within a few turns while the helm guages lags.

    On the noise issue at shut down
    It is almost impossible to dynamically balance any engine for all rpm ranges so engine designers will design the flywheel balancing profile to fit a general operating rpm, say 2600 on a low speed diesel or some other value.
    They calculate imbalances due to the reciprocating masses of the pistons, con rods, crankshaft, and the effect of the compression as it loads the crank as well as the cylinder pressures/forces at combusion. In addition, a calculation must be made to determine the imbalance that accelerating a piston from bottom to top dead center creates.

    Then the flywheel is balanced and provided enough mass to fit a narrow band width of rpm and load
    This is to minimize vibration at usual working rpm
    But in order for the flywheel mass or balance weights to work properly, they must be turning as the faster they turn the more effect that they have on the balancing process.
    At shut down, this effect is loss as the rpms drop and at say under 500 rpm, probably extremely ineffective.
    So the engine vibrates like heck until it stops,
    Think not?
    If you ever have the opportunity to watch a horizontally opposed piston airplane shut down, at the final 400 or so rpm, they shake so bad that you think the engine is going to come off its mounts. In a boat, it is difficult to get an extremely loose mounting system to absorb this vibration so we see the relatively violent shaking take place.

    So I am putting on the table the cause of the vibration.

    Of course this will manifest itself, in your case, in some extremely load noises from where ever you think that it is coming from. You say it is loud. Until a very recent reply, I think that some members were assuming that it could be the rod ends, which I doubt because the tolerances are too close. So in your case perhaps it is the Clutch I think you mentioned.

    so the reason for the vibration as I see it is the shut off imbalance issue that most engines have, and mainly undamped in boats due to mechanical requirements of the components, which is causing noise.

    For those who are interested
    Comparing straight 4, straight 6, V-6, and V8 engines, a V-8 is the easiest to apply a flywheel balance process to make the engine smooth over a wide rpm range. Inherently the V-8 achieves the smoothest run and widest rpm range, probably followed by the V6 if the crank has offset pins. straight 4's and 6's are the worst. In fact when engines were first developed an eon ago, the 4 cylinder came first then the straight 6. Some manufacturers tried a straight 8 but could not control the vibration. So some genious came up with the idea to put a V into the configuration to smooth out the balance curve and the V-8 came into existence. and upon re reading this, I think that balance curve is not the right terminology, as it looks more like series of concentric circles. memory, who needs it
  13. seamy
    Joined: May 2008
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    Location: Ireland

    seamy Junior Member

    It would appear that frosty,is only happy when he is complaining about something,ive read this, and previous threads and the story is always the same,Last time out it was Arneson surface drives and some ******** about what grows on them,who gives a f***,He will ask peoples opinions and when they reply, he snaps their head off,really dont know why people on the forum tolerate this crap,now he wants a go at yanmar,leave him to it thats what i say,thats just the way some people are:confused:
    1 person likes this.
  14. apex1

    apex1 Guest

    Thank you Bigfoot, a good and valuable post. Until it came to the end. The straight six is the best balanced engine! Not the V8. Due to free forces of the second order! The V6 is the worst. In fact a V6 is not possible without balancing.
    Well, the Boxer is as good, a tiny bit better actually (your airplane engine) but we have no Boxer engines in boats.
    The widest useable range of rpm has the 4 cyl. due to the least internal friction, the V8 is worst.


  15. globaldude
    Joined: Jan 2005
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    Location: Whangarei New Zealand

    globaldude court jester

    What was that about people not reading posts correctly ?.
    Jimbo was off on the rattly big ends on post #24 before I put up any comment. appology acepted [refer below to cheek ]
    [ although I rather suspect it was tounge in cheek -- stop it Jimbo, frostys past the humor stage ]
    People in glass houses !.
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