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Author Topic: updated oil mods for ohv 17 -Important!!!  (Read 1011 times)
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Honey Badger
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« on: April 10, 2013, 08:56:34 PM »

While tearing my oil pan off to replace a blown sump gasket, I discovered that the epoxy used by someone to seal the oil supply hole in balance shaft journal had come loose!.  The epoxy came out as a formed casting to how it hardened, and was not sealing anything at all.  This epoxy is subjected not only to heat and thermal expansion (which the epoxy will have a different expansion rate than aluminum or any other material you put it in) but also oil pressure as well.  These factors all help to loosen and then remove the epoxy rendering your oil pressure next to nil.  After finding this, I pulled the rod and took the crank out, to find the main journals heavily grooved and the rod bearing looking pitted and all in all bad.  Luckily I happened to stumble upon this before the engine blew. 

The fix, aside from getting another block and crank, is to take the star torx bolt out of the oil supply hole that has been drilled in the block casting for this balance shaft.  The thread is 1/4" 28 pitch (fine thread).  I took a quality tap (the cheap ones have less thread cutting length on them) and tapped all the way into the journal of the balance shaft. You do not need to tap all the way to the other side, just the side the bolt plug was blocking off.  I used threaded rod from fastenal (like $4) and bought some ALL METAL locking nuts.  Applying some locktite to the threaded rod, I put it in all the way so that it traveled across the bore into the oil supply side from the upper main, threading it into that untapped hole about 2 or 3 turnes.  Then use your nut to lock the threaded rod even more.  Be sure to blow out the hole (spraying from the upper crank main) towards the balance shaft to remove the chunks of metal that result as you send the rod into the untapped part of the oil supply hole.  This mod is best done with the crank out of the block if you intend on threading the 2 or 3 turns into the untapped side. 
Also, the tap will not have enough threaded portion to give you a clean threaded hole all the way through, but the good quality tap will have a nice fluted base that will eat away the threads as it passes further into the block. This is not really what the tap is designed for but actually works out well.  I have done this and it seems to work wonderful.  Good luck!
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Alex Stella
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« Reply #1 on: April 10, 2013, 09:01:10 PM »

What type of epoxy was it, do you know?
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Ed King
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2nstoys
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« Reply #2 on: April 11, 2013, 07:59:58 AM »

JB Weld. Clean and scuffed area also.In fact it filled the hole completly to the crank journal.
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Glenn VanEpps
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« Reply #2 on: April 11, 2013, 07:59:58 AM »

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« Reply #3 on: April 11, 2013, 08:38:00 AM »

Was just the drilled oil passage filled/plugged, or was the entire balance shaft bore sealed off as well?
I use the JB weld "stick" 2 part epoxy. I mash it into the balance shaft bore, so that it expands out into the oil passage. Once it hardens, I stake the edge of the balance shaft bore over. I have not had any issues, and I check it every time one of the engines is apart. Maybe I have been lucky.
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Ed King
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« Reply #4 on: April 11, 2013, 07:20:05 PM »

For the most part, it was just the oil passage.  A small amount around a portion of the radius of the bore was there.  I wasn't present during the initial sealing, so I don't know if it was sealed as you did yours Ed, but judging by the shape (intact) of the hardened material that came out, it was only the oil passage with a small amount around a portion of the radius next to the passage. 
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Alex Stella
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2011 rookie of the year MILMRA   2012 most improved driver MILMRA   2nd in points national CP
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« Reply #5 on: April 11, 2013, 08:16:46 PM »

That may be the difference?
After I pack the epoxy onto the bore, I actually take the old balance shaft and set the entire thing in a press and lightly put some pressure on it to "squeeze" it into the oil gallery. Then I stake the bore over the top of the epoxy. Hasn't failed me yet.
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Ed King
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« Reply #6 on: April 12, 2013, 08:16:39 AM »

Thanks for the tip. I run a 17.5 ohv. I'll check it next it's apart!!
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