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Author Topic: fast idle/jake switch oil leak on gov. 8v71-MCI5B  (Read 546 times)
Larry B
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« on: January 26, 2013, 08:51:52 PM »

I have not posted in a long time but I have been reading along as others try to find answers to their problems. I have done a lot of finishing things on the interior of the bus and I desided to get my hands dirty and try fixing oil leak on govenor. This is the only leak I have and it would be nice to fix. As you can see it has made a mess in the last 5000 miles. Where the plunger from the fast idle cylinder/ jake switch passes through the governor housing there is an O ring. (Item 3 as shown in parts list) When I installed these pieces last summer I used an o ring from a kit I had, but as the picture shows that didn't work well. I went to a couple diesel shops and an auto supply house looking for a different size o ring. They basiclly said on an o ring that small they carry the same size as in my o ring kit. They all wished me good luck. The plunger shaft passing through the gov housing does not have a wear spot where o ring sits. Maybe other out there driving an old 8v71 and had same oil leak can give a heads up to were they bought correct size o ring.           
           Thanks Larry B
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1977 MCI-5B---
8V71- 4speed man
Larry B
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« Reply #1 on: January 26, 2013, 08:55:39 PM »

More pictures-- The last time I tryed sending this post I sent too many pictures and it deleted itself. I I NOT good at tying.
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1977 MCI-5B---
8V71- 4speed man
stevet903
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« Reply #2 on: January 27, 2013, 12:26:41 PM »

Check here in the Jake Parts manual:

http://www.jacobsvehiclesystems.com/files/support/docs-pdfs/015803B.pdf

Looks like it is part number 2017, a .176 x .07 o-ring.  Should be able to get it at a Detroit Dealer...

Steve
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bevans6
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1980 MCI MC-5C




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« Reply #3 on: January 27, 2013, 12:44:22 PM »

Your kit will have that as a 008 size o-ring, nominal size 3/16" OD by 1/16" thick, actual size .176" by .070".  http://www.marcorubber.com/sizingchart.htm

I just bought a pack of 50 to put in all of my injector fuel pipes.  I got them at a bearing supply place.

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
Larry B
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« Reply #4 on: January 27, 2013, 06:21:25 PM »

Thanks guys. Start of a new week tomorrow,people should be back to work, I will make a couple of phone calls. A question out of curiosity came came to me today. The oil inside the govenor works on an overflow system and I assume is flying everywhere from the spinning weights. If your engine runs at 60psi oil pressure when driving down the road would it be likely that there is a positive pressure within the govenor housing above the oil level say 5 to 10 psi?
          Thanks Larry B
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1977 MCI-5B---
8V71- 4speed man
bevans6
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« Reply #5 on: January 28, 2013, 03:12:39 AM »

The interior of the governor is at no pressure - remember that it is connected to the valve cover area with those two control rod tubes and the valve covers are vented to atmosphere.  All you have inside there is splash.  I would take the top off the governor and inspect the little spring deal at the end of the buffer screw - if oil is getting in, it's getting past that.  I would also check that the filters on the valve cover vents are clean.  I'll confess that I don't remember an o-ring on mine at all when I had it apart, but I'm not taking it to bits to go look at this point!

Brian
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1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Spicer 8844 4 speed Zen meditation device
Vintage race cars -
1978 Lola T440 Formula Ford
1972 NTM MK-4 B/SR
Larry B
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« Reply #6 on: January 28, 2013, 06:12:59 PM »

        You are absolutely right Brian, I totally forgot about about the injector control rods. I sure missed on that one on my thinking. Checked buffer spring and breathers on valve covers. they are OK. Put all together today with fresh O ring from kit and started engine. It started right up after sitting for three months, but I still have a leak. Enough fooling around I went to Detroit dealer and ordered rings and washers as listed in Jacobs parts list. They must be something special those little rings and washers are $3.50 each. Coming from Kentucky, will be here in a week or so. In mean time will change oil, filters,  grease,brakes, etc. and get ready for summer holidays. Thanks again for eveyones help.
           Larry B
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1977 MCI-5B---
8V71- 4speed man
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