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Author Topic: fuel in engine oil  (Read 373 times)
Larry B
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« on: July 04, 2015, 06:45:41 PM »

   Hello everyone--- I recently did the yearly engine oil change , grease, filter , general check over, etc.  I sent an oil sample away just as a precaution and for my own satisfaction.  It came back with 2-3% fuel in oil. was not what I was expecting.  Glad I sent the sample away. Need a little guidance what to do now and as usual have several questions. Oil had 140 hours on it since last change-year and half since change.  Is this considered a high reading?  The first place for a leak one thinks of is the injector tubing lines. Are there other ways of fuel to be getting in the oil?  To remove the valve cover on dr. side I need to remove exhaust crossover to get the high cover out--jakes. So when I do this I would like to check all ways of intrustion  of diesel fuel. If I leave the covers off and start engine would I see the diesel fuel leaking/ or leaving a "wash" trail in the oil?  I do not let my engine Idle and when I start it I get only a few drops of oil from the air box drains.  I have done nothing about this issue yet, looking for a little guidance before I start. 
    Could a defective injector cause this?  How would the diesel get past the rings?
        thanks Larry B
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1977 MCI-5B---
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Scott Bennett
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« Reply #1 on: July 04, 2015, 07:21:10 PM »

Subscribed. Will be interested in what others say.


Sent from my iPhone using Tapatalk
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Scott & Heather
1984 MCI 9 6V92-turbo with 9 inch roof raise & conversion in progress (home)
1992 MCI 102C3 8v92-turbo with 8 inch roof raise & conversion in progress
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5B Steve
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« Reply #2 on: July 04, 2015, 07:44:05 PM »



   Several years ago I had fuel in my oil also, the local Detroit shop could not find the leak, I call the next day and ask how to find it,

   they told me to remove the fuel return line in the head and put a 3/8 barb in and put 10 LB of air pressure in the line and listen for the

  hissing sound and that will tell you if you have a broken  crossover line which I did.  If you have this problem you will save several

 dollars by doing this.  Hope this will be of some help. Good luck!

Steve 5B.........
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luvrbus
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« Reply #3 on: July 04, 2015, 07:53:00 PM »

Which fuel jumper tubes do have o-ring or flared and a injector can leak at the o-ring where the tube screws on to the body
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Brassman
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« Reply #4 on: July 04, 2015, 11:42:53 PM »

Don't the '71's have a copper tube in the head that the injectors sit in. IIRC, if those crack they can lead to fuel dilution.
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luvrbus
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« Reply #5 on: Today at 05:20:18 AM »

Don't the '71's have a copper tube in the head that the injectors sit in. IIRC, if those crack they can lead to fuel dilution.


All the 2 strokes have the injector tubes in the heads when they go bad you water in engine
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bevans6
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« Reply #6 on: Today at 07:47:07 AM »

When I had that, the fuel stand pipes at the back of the heads that the jumper tubes attach to had to be torqued down.  If you have the O-ring type jumpers, the O-rings are 3/16" size 008.  If you have the flare nut type, the flares are strictly speaking single use deals, from an engineering perspective they seal the first time they are torqued by stretching the flare, after that one time they are work hardened and start to be prone to cracking in the flare area.

Brian
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« Reply #7 on: Today at 08:24:29 AM »

What did the oil sample people say?  Blackstone usually comments.  Does it smoke at all when its running?  I mean more than normal....idle, deceleration, etc. 
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luvrbus
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« Reply #8 on: Today at 08:46:17 AM »

Since no one answered he probably does not have a fuel leak about all the old 2 strokes will come back in his range anything below 2.5 is ok for fuel in the oil.

I just ran a sample on my 60 series it came back 1.3 well below the 2.5 warning limit DD says is ok what puzzles me I never saw a report that says 2 to 3 % they are usually more accurate with the % readings 
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bevans6
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« Reply #9 on: Today at 09:01:46 AM »

Yeah, my leak came back at 15% fuel...   Shocked
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Scott Bennett
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« Reply #10 on: Today at 04:31:15 PM »

Whistle


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Scott & Heather
1984 MCI 9 6V92-turbo with 9 inch roof raise & conversion in progress (home)
1992 MCI 102C3 8v92-turbo with 8 inch roof raise & conversion in progress
Click link for 900 photos of our conversion progress:
https://plus.google.com/photos/112938923773048709099/albums/566295393808374
Larry B
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« Reply #11 on: Today at 07:23:15 PM »

Thank-you for all the replies. Sorry guys, I hit the wrong button when typing. The post should have said 2.3% not 2-3%.  The oil lab people recommend changing the oil and identify the source of leak. 
   Clifford--- my jumper tubes are flare type and they are used
   Brian---When I bought my jakes the jumper lines came with -used- and I have  them off at least once  That makes them a min of three time use. The stand pipes on my engine have a soft metal washer under them and I did torque at time of rebuild.   
   Opus--my engine does not smoke at any of the times you mention
    As a note I had a leak on the rear crossover line between heads. I could not get it to stop leaking so i took it out and plugged heads with pipe plugs.  Now each my heads have own supply and return at front (rear of bus). Still not real convenient to tighten but doable with comb wrench and crowfoot
    From the replies can I assume that 2.3% is not an amount to get REAL alarmed about. Would I be wise to do as Dave suggests and use air to check and see if one (or more) of the USED injector lines might have developed a crack. On my previous  oil sample I had no recordable fuel in oil and there was more hours on that change.
    Clifford ---if the O ring between the tube and body leaks is there any way of telling this while injector is still in postion in head?
    Thanks for all your replies -  Larry B     
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luvrbus
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« Reply #12 on: Today at 07:37:35 PM »

Tap on each line with a wrench if it rings the connection is good if no ring that line is bad remove the Jake rubber connector between the lines if you have one or they won't ring that's my method for finding a leak on the the flared lines.If the injector is leaking it will be clean around the leaking injector where it sets in the head   
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