From: David Cole (DavidCole@tk7.net)
Date: Mon Sep 22 2003 - 10:46:53 PDT
FWIW, the really big generator sets that Caterpillar makes also have
prelube pumps on them. They start up the prelubers and let the oil
pressure come up before the engines are cranked. This are the big 1
megawatt plus gensets that come in a container the size of a semi trailer.
I was told that was to avoid bearing failure during startup. Of course the
cranks on those engines weight tons, literally.
When you think about it: What would be best - start and engine with no oil
pressure vs start and engine with full oil pressure. I think it becomes
obvious which is best.
It is normal to prelube newly assembled engines - especially race engines
by attaching a drill motor to the oil pump drive and spinning oil pump
until it reaches full pressure.
Why aren't they more popular - I have no idea. My guess is that people are
ok with getting 140K miles out of their cars and they aren't willing to pay
more so they can go 250K miles.
But what would it take to make up a preluber; a small hydraulic gear pump,
a simple DC electric motor, a check valve, a switch, and a little bit of
plumbing and wiring.
Dave
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
On Mon, 22 Sep 2003 05:19:03 -0400, James Shanks <n1vbn@bit-net.com> wrote:
> The reason for the electric oil pumps on railroad Diesels is to provide
> a supply of oil to the bearings on the Turbocharger to cool the bearings
> down for twenty minutes after shutdown when the oil pump would
> automatically shutdown. This feature was usually negated when the
> personal shutting down the engine would then immediately open the battery
> switch thereby shutting down the oil pump.
>
>
> This is on GE and GM Railroad Diesels.
>
>
> Jim
>
>
>
>
> At 12:33 AM 9/22/2003 -0500, Adam Suess wrote:
>> I've read some where that a high % of engine where occurs at start up.
>> Something like 70% or 80%. the way I understand it is that during normal
>> engine operation the bearings and other parts ride on a thin film of oil
>> and should not normally directly contact the two metal faces. when a
>> engine sits for a bit much of the oil drains down and upon start up no
>> film is present to prevent metal on metal contact. In the case of the
>> multi fuel and other engines the oil also drains back out of the filters
>> and when started the pump must fill them up again before oil goes to the
>> moving parts. The difference in engine noise is some more rattling and
>> also internal engine friction until the oil reaches it. I use to work on
>> the rail road and got this info from one of there diesel mechanics after
>> inquiring how they got there big diesels to last so many hrs. Also
>> there is some issues of oil break down during operation due to high oil
>> temps or over lugging the engine exceeding the pressures the oil can
>> protect at. All second hand info to me but seems to make since. The
>> Rail Road ran straight 50wt and the engine had oil pressure "electric
>> pumps" before even cranking it to start they rarely shut it off any way.
>> I switched to semi synthetic oil myself because it is suppose to hold to
>> the parts better after shut down. Also tolerates higher temps and
>> pressures or so they advertise. I did note a significant drop in full
>> load oil temp switching from Shell Rotella T to Cenex Maxtron DEO in my
>> tractors as well as easier cranking. Lighter engine loads I saw little
>> or no change in oil temp. The Mack engine in my M54A1 takes quite a
>> while to get pressure and sounds much different once it does also.
>>
>> Adam Suess
>>
>>
>>
>>> From: Marc Strangfeld <curlyjoe98@yahoo.com>
>>> To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
>>> Subject: Re: [MV] M35 dry start issue
>>> Date: Sun, 21 Sep 2003 07:50:35 -0700 (PDT)
>>>
>>> Don't forget...oil pressure is needed to lube more
>>> than just the turbo. I don't rev it up either. Can
>>> anyone else notice a change in engine sound once oil
>>> pressure is restored? I'll look into the preluber
>>> idea. However maybe Jon is right in saying I don't
>>> need to worry. What does everyone else think? I
>>> sense an interesting tech article in Military Vehicles
>>> Magazine...Bjorn?
>>>
>>>
>>> Marc
>>>
>>>
>>>
>>> --- Jon Shoop <shoop19@brick.net> wrote:
>>> > I dont think think is a problem.....I know the turbo
>>> > has a pocket for oil to
>>> > rest after shutdown......just dont rev it up...wait
>>> > the 10 seconds for oip
>>> > pressure to come up.........
>>> >
>>> > Jon
>>> > ----- Original Message -----
>>> > From: "Marc Strangfeld" <curlyjoe98@yahoo.com>
>>> > To: "Military Vehicles Mailing List"
>>> > <mil-veh@mil-veh.org>
>>> > Sent: Sunday, September 21, 2003 1:43 AM
>>> > Subject: [MV] M35 dry start issue
>>> >
>>> >
>>> > > I'm wondering what other's thoughts are on the
>>> > long
>>> > > delay in getting oil pressure on the multifuel
>>> > engine.
>>> > > I crank my engine with the fuel shut off for a
>>> > few
>>> > > seconds thinking it may help. Am I worrying for
>>> > no
>>> > > reason and/or burning up my starter? Does anyone
>>> > know
>>> > > of a way to prelube the engine or change the
>>> > filter
>>> > > configuration to keep them from draining?
>>> > >
>>> > > Thanks
>>> > >
>>> > > Marc
>>> > >
>>> > >
>>> > >
>>> > >
>>> > > __________________________________
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>>>
>>>
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>>
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>
> James Shanks
> n1vbn@bit-net.com
> 1998 IMZ 8.103
> 1984 H-D FLHT-C
>
>
>
> ===Mil-Veh is a member-supported mailing list===
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> To reach a human, contact <ack@mil-veh.org>
>
-- Dave
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