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Author Topic: Re-introduction with questions  (Read 199 times)

Blacksmith

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Re-introduction with questions
« on: October 01, 2017, 03:53:49 AM »
Hi all,
My name is Peter. I was a member here several years ago. I have been running ST3's to power my blacksmithing shop for about 8 yeas now. Wow, 8 years... I didn't think it has been that long... Anyway about a month ago I was running the gen set and it started to smoke and loose power. On inspection I noticed the oil was very thin. When I smelled it smelled of Diesel. I seem to have a memory of some discussion about how diesel could get in the oil. Seemed like it was a fairly easy fix if my memory can be trusted... Has anyone had this problem and been able to solve it? Anything I should check right off? The compression seems good still.

On another note, These engines have become the back bone of my business and I think I'd better have a spare. I have an ST3 that I took out of service several years ago because of brass in the oil. Is anyone rebuilding these motors? I live in Eastern Oregon.

Thanks for any and all help-
Peter

starfire

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Re: Re-introduction with questions
« Reply #1 on: October 01, 2017, 09:30:39 AM »
"Making oil "can be caused either by excessive blowby, or poor combustion. The former implies worn rings, the latter implies low fuel pressure, partially blocked injector, or worn injector pump.

AdeV

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Re: Re-introduction with questions
« Reply #2 on: October 01, 2017, 12:41:34 PM »
This link should be interesting to you: http://www.marineengine.co.uk/LubricatingOilDilution.pdf

It's almost certainly a leak somewhere in the system, which is contaminating the lube oil.

Fortunately, these being Listers, nothing need be wasted... simply drain off the contaminated oil, find & rectify the leak, refill with fresh oil and off you go. The contaminated oil may be recycled without issue as the fuel supply, after suitable filtration of course.
Cheers!
Ade.
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dieselgman

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Re: Re-introduction with questions
« Reply #3 on: October 01, 2017, 03:21:30 PM »
We build the ST engines in Kansas. Plenty of parts stocks available as well. Fuel in oil will be an internal fuel supply leak. Likely culprits: fuel lift pump, injector lines, delivery valve seals.

dieselgman
Ford Powerstroke, Caterpillar 3304, Cummins M11, Too many Listers to count...

Blacksmith

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Re: Re-introduction with questions
« Reply #4 on: October 01, 2017, 05:14:54 PM »
Thank you all for the replies! AdeV thanks for the link on Oil dilution. I will be using it when I trouble shoot the problem. dieselgman, I can't afford one of your refurbished units right now (I looked at your website).  If I sent parts to you for machining, is something you would do? Thinking Block, crank, cam and piston assembly fitting.
Thanks again-

cujet

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Re: Re-introduction with questions
« Reply #5 on: October 01, 2017, 10:36:35 PM »
Worn rings will absolutely cause fuel dilution of the oil in a diesel engine. Combustion is slightly delayed, some fuel gets by the rings on each power stroke, and oil level rises. Some time later, as oil dilution progresses, and the level is high enough, the engine may not shut off. As sufficient quantities of the fuel/oil dilution is then carried into the combustion chamber past the rings, during fuel rack shutdown. The engine continues to run on. Sometimes at very low idle, sometimes at very high speed depending on the engine and situation. The only way to stop it then is to block the airflow.

From what you've said, I'd guess worn rings as your situation got worse during operation. But just a guess.
I give up

ronmar

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Re: Re-introduction with questions
« Reply #6 on: October 03, 2017, 03:40:09 PM »
I would look at the injector spray pattern first.  Flip the injector over so it points up, purge out all the air and crank it up as fast as you can and drop the start lever.  You are looking for a good even spray pattern of very fine droplets. 

Low Fuel pressure or an injector spray issue could be delivering fuel that isn't as atomised as it should be.  What you are looking for are large drops or straight streams which will cause large quantities of fuel to stick to the cylinder walls and pass the rings.  Running at reduced load and even more importantly reduced temperature can contribute to this also...
PS 6/1 - ST-5.