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Author Topic: Starting a cold engine.  (Read 5788 times)
johns4104s
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« on: March 12, 2010, 06:33:32 AM »

So when you are ready to start up your engine and its not been started for 12hes/1day/1month.3months etc. Should you start it in a way that it turns over several times first? Then allow it to start? This allowing the oil to pressure up and be present everywhere before it fires and takes off.
The reason I am asking is that my engine starts on the first revolution and I dont know if oil is everywhere on the first revolution or not? Also I am told that the MCI,s were originally set up to have a initial delay before firing just for the reason for pressurizing the oil.
I here of lots of 8v92T,s with crank shaft problems I want to be sure I am doing everything I can to look after my engine.

John
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luvrbus
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« Reply #1 on: March 12, 2010, 06:46:23 AM »

John, the oil galley always has oil in it on a 8v92 it never drains back to the pan and the only time they have a crank problem is when they are overhauled and the line bore is off 2 strokes have a tuff a** crank very ,very seldom will one break crank failure is caused by something else 99% of the time 

good luck
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DaveG
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« Reply #2 on: March 12, 2010, 06:51:20 AM »

I'm sure if you wanted to crank it over without firing/starting until you had oil pressure you could wire in a momentary switch that held the fuel shut-off closed, however at start-up and without load there isn't that much load on the crank bearings.
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« Reply #3 on: March 12, 2010, 07:13:36 AM »

With my situation, a bus friend of mine hypothesized that the broken crank was a result of the bus company's improper use of starting fluid when trying to start up a cold engine. Instead of cranking the engine over a few times so that the starting fluid could be equally distributed across all cylinders, they sprayed once, reaching only once cylinder, which allowed isolated (thus, uneven) combustion. This in turn caused incredible torque to one end of the crank, and not the other.

Hope this helps!
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« Reply #4 on: March 12, 2010, 07:28:13 AM »

2 Strokes, while not having a lot of oil pressure, pumps a massive amount of oil.  I wouldn't worry too much about cold start.  If you'd like, just hold the kill lever on the governor for 5 seconds (if it is a mechanical engine) then release.

More importantly- once the oil pressure is reached, you should then increase the engine rpm up to the fast idle of about 900rpm for warm up.  On any Diesel, idling is the hardest on the engine since that's where the most vibration occurs that is being transmitted through the bearings when the engine has the lowest oil pressure.  Good Luck, TomC
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« Reply #5 on: March 12, 2010, 08:10:32 AM »

I have a pre-oiler on My engine!  When the master switch is turned on power is applied to a timer that activates the pump and when oil pressure is up I start the engine.  The timer is adjustable so there is a shut down delay to provide oil pressure to the turbo for both lubrication and to prevent coking of oil in the bearing housing.  I do not have a turbo so in My case it is a mote point.  All large industrial engines read industrial power plants and large marine diesels have pre-oil pumps!  The timer shuts the pump off after starting the engine.  Not real cheap but will keep bearings floating for initial start up and will save turbo's from early death!  John L
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reelnative
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« Reply #6 on: March 12, 2010, 09:09:13 AM »

if you use a good oil like synthedic rotella you wont have to worry about problems like that
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Sean
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« Reply #7 on: March 12, 2010, 09:29:48 AM »

if you use a good oil like synthedic rotella you wont have to worry about problems like that


Umm, Rotella Synthetic is not available in SAE-40, as required for Detroit two-strokes.  Even Shell's own publications do not recommend anything but their conventional SAE-40 and SAE-50 for these engines.

-Sean
http://OurOdyssey.BlogSpot.com
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reelnative
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« Reply #8 on: March 12, 2010, 09:52:17 AM »

doesnt it come in a 5w-40
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Sean
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« Reply #9 on: March 12, 2010, 10:30:39 AM »

doesnt it come in a 5w-40


5W-40 is not an approved viscosity for Detroit two-strokes.  Only straight 40-weight, per Detroit specifications, available here:

www.detroitdiesel.com/pdf/vocations/Lube-Oil-Fuel-Requirements.pdf


We have discussed this extensively in the past:
http://www.busconversions.com/bbs/index.php?topic=10774.0
http://www.busconversions.com/bbs/index.php?topic=14645.0
http://www.busconversions.com/bbs/index.php?topic=13734.0
http://www.busconversions.com/bbs/index.php?topic=13689.0
http://www.busconversions.com/bbs/index.php?topic=3580.0

...and many more.  My search just on this board turned up pages and pages of results.

I strongly recommend you educate yourself on this topic if you are running one of these engines.  Perhaps more importantly, if you are going to make recommendations here yourself that contravene those of both the engine manufacturer and the lubricant manufacturer, you had better be able to back up the tribology.

-Sean
http://OurOdyssey.BlogSpot.com
 



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reelnative
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« Reply #10 on: March 12, 2010, 11:21:30 AM »

well im sorry that I hit a nerve of yours sean, my comm on oil was just that, and you or anyone elese can run what they want in there rig, I myself have run rotella in all my diesels , cummins, perkins, izuzu, vp maroiti, powerstroke, and a few others im sure I cant rem,ive run rotella in all of them and never have I had an oil related issue, I own 4 dump trucks 1 bobcat 2 backhoes 2 dodge rams with diesels and a jeep liberty with a diesel in it, I have logged in well over 2million miles of driving with rotella and 10s of thousands of eqp hrs with it also, so for me I think ill stick with the rotella
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junkman42
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« Reply #11 on: March 12, 2010, 11:40:16 AM »

I have besides My coach a John Deere 440 with a dd 2-53 and have never run anything but 15-40 rotella in it and it managed to clear 75 acres of heavily wooded property!  It was certainly not big enough for the job and was always over stressed.  It still survives and runs quite well.  The US ARMY runs mil multi grade oil in the Detroit's in the middle east where it is hotter than hell and the units are beat by the operators.  My son has served 3 years in the sand box and maintains heavy equipment including the HEMET which is a large wrecker with a 8V92 and a Allison for power. I am not suggesting running multi grade oil but I wonder about some of the it will kill Your engine experts opinions!  After all sometimes a expert is a drip under pressure , or someone thousands of miles away saying just turn that potentiometer and that will fix it!  I for one am not convinced that single weight is necessary.  The bit about the rod bearings not getting a rest because of the two cycle bit is simply not logical.  Oh well run what You brung guys.  I suffered for years with stuck valves in aircraft engines because of the crappy ancient oil specifications for aircraft oil.  I switched to ordinary car oil and then to Mobil one syn when continental started delivering engines from the factory with the same damm oil in them!  Makes one wonder sometimes about the real truth.  Regards John L
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Happycampersrus
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« Reply #12 on: March 12, 2010, 11:50:22 AM »

In the famous words of Yogi Berra

"This is like deja vu all over again."

 Grin Grin
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Just Dallas
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« Reply #13 on: March 12, 2010, 12:11:12 PM »

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« Last Edit: July 15, 2010, 03:04:21 AM by Now Just Dallas » Logged

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Sean
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« Reply #14 on: March 12, 2010, 12:47:34 PM »

well im sorry that I hit a nerve of yours sean,


You didn't hit any of my nerves.  But lots of people read these forums, and an otherwise neophyte might read your post as if there was something behind it, and they deserve to hear, first, the recommendations of their engine manufacturer.

Quote
my comm on oil was just that, and you or anyone elese can run what they want in there rig,


Well, that's not how it reads, at least to my eye:

"if you use a good oil like synthedic rotella ..."

the implication being that non-synthetic Rotella is a "bad oil" or "not as good" or whatever, even though Shell themselves recommend the non-synthetic product for Detroit two-strokes

"... you wont have to worry about problems like that"

Again, the implication being that Rotella Synthetic, in a viscosity not approved for Detroit two-strokes, will alleviate the concern about journal bearings on a dry crank, and is, therefore, somehow better than the high-quality conventional oils most of us run.

You're certainly entitled to that opinion, but newcomers deserve to hear that it is not the consolidated wisdom of tribologists in general.

Quote
I myself have run rotella in all my diesels , cummins, perkins, izuzu, vp maroiti, powerstroke, and a few others im sure I cant rem,ive run rotella in all of them and never have I had an oil related issue, I own 4 dump trucks 1 bobcat 2 backhoes 2 dodge rams with diesels and a jeep liberty with a diesel in it, I have logged in well over 2million miles of driving with rotella and 10s of thousands of eqp hrs with it also, so for me I think ill stick with the rotella


Well, most of those engines and vehicles are four-strokes, which is not what we were discussing.

I run Rotella myself.  But I use the recommended straight 40-weight, which does not come in synthetic.

The diatribes of anecdotal evidence are unpersuasive -- everyone has stories of things working just great, for them.  There are boats running around the Caribbean even as we speak using distilled water in the coolant loop, rather than anti-freeze.  Anecdotally, they have thousands of hours of experience that says antifreeze is not needed.  That experience becomes meaningless the minute the engine is in freezing conditions -- conditions those operators never experience.

It's quite possible you've been running 15W-40 or whatever else for years without deleterious effects. I don't doubt it.  But Detroit has billions, not millions, of miles of experience with these engines, and they make their recommendations for good reason.  I, for one, will stick with them, notwithstanding anecdotal evidence that the recommendations might be overly cautious.

I'm not telling anyone to follow suit.  I just want any visitors to this thread to hear both sides of the story, from which they can draw their own conclusions.  FWIW.



-Sean
http://OurOdyssey.BlogSpot.com
« Last Edit: March 12, 2010, 12:55:15 PM by Sean » Logged

Full-timing in a 1985 Neoplan Spaceliner since 2004.
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