Question on the 8V71 Blower Drain Tubes

[MCIGenes]

   I am trying to eliminate a leak from the Blower left side drain tube. I want to make a collection container to catch any drippings. There was a hose that was cracked and I replaced it with a new one about a month ago. But, I still have a leak someware that does not go into the catch container. I compaired the right and left sides and they are plumbed differently. The right seems to just have an elbow that is connected to the tube. the left has an 1/8" to 1/4" adapter into the block and then a 1/4" female coupler, then a 1/4" short nipple and then an elbow. Connected to the elbow before it goes into the tubing there seems to be a device like a check valve. It this normal? I took all the fittings apart and bead blasted them and the devise that looks like a check Valve has the following stamped into it.
"AC SPARK PLUG 15042692"
^ TO CRANK CASE^
The funny thing is the devise is installed with the up arrows facing away from the crankcase. My parts manual does not show and devise like this.
Are these drains just supposed to be straight through without any restriction? Or is the Check valve device I found in mine supposed to be there?
Thanks for any help you can give me.

Gene     
 

[luvrbus]

The 8v71 with the 1/8th fitting in the block were not equipped with the check valve from the factory that has been added should have 1 on each side they only open at idle should be on 60 degree angle not a 90 does it work it should rattle when shaken and those do not come apart brake cleaner will clean one nothing wrong with adding the check valves air flows out so the arrow should be away from the block

If you  have a large amount of oil coming from 1 side you have other problems a 8v71 in good shape does not drip a lot of oil from those tubes excess idling for long periods of time is a huge problem even on high idle causing excessive oil dripping 

Geoff will  be happy someone called those air box drains and tubes lol

good luck

[Geoff]

 

--Geoff

Like Cliff says, it is not normal to have excessive oil coming out the air box drains.  Your choice is to fix the problem, or put your makeshift catch containers.  The check valves that close above idle are only forcing the excessive oil to get sucked into your intake liner ports. 

[MCIGenes]

Thanks for the infromation. I just wanted to confirm that someone did not put something in that did not belong in the system. The check valve does rattle when shaken so the parts are not froze up inside.
I have more oil coming out of the left side and hardly any out of the right. From that information can you give me any ideas as to what might be wrong? I want to build an engine stand and pull the engine this winter. I have a rebuilt blower from a friend of my that sold his bus. Again any help will be appreciated.

Thanks.
Gene   MC5B 1975

[wg4t50]

I like the check valve arrangement, but there is another setup I have seen, the drain lines were ruted back into the oil sump, no joke, I would not want that oil going back into my oil sump, but there it was.  Maybe someone else has seen it too, as I can not recall where it was., But it did eliminate the oil drip.
Dave M

[luvrbus]

Dave that was required for buses in CA piss poor setup cost DD a lot of engines DD sent out a service bulletin telling owners to disconnect that setup and use the Walker Can sad but true you still see that sometimes to this very day on GM and transit buses with the old DD laying on it's side

Red Ryder had the ones dumping into his oil pan on his newly purchased engine and he wasn't going to leave my shop with it so he gave in and removed it

[bevans6]

The oil that comes out is not really oil to speak of, it's going to be a combination of condensation, oil from blower seals, oil bypassing the oil control rings and unburnt fuel.  Not much oil from the crankcase should get it past the oil rings since the air box is under constant positive pressure from the blower compared to the crank case, which is vented to atmosphere.  Where you tend to see more oil on one side is a sign that those pistons have compression ring issues, I found.

If you build a stand, here is an idea - I stripped off the oil cooler and starter motor off my engine and built stands that bolted to the sides of the block.  On each side of the block are rows of 3/8" NC tapped holes for attaching stuff to the block.  I bolted on 1/4" steel plates, two on each side, with 2 foot long steel legs welded on in a slightly tapered out configuration.  Cost little, strong and stable, and easy to carry around once you take them off.  Here is a pic, albeit out of focus...

Brian

[bevans6]

Here is the dolly I built.  I ran out of orange paint     Strategic picture of the nasty old engine and the bright new dolly, with the engine just pulled out of the bus.  Buswarrior has the stands and the dolly now.

Brian

[luvrbus]

Now days with a new 5500 lbs pallet jacks costing 350 bucks it's almost not worth the trouble to build a dolly,Doyle used a pallet jack for his Eagle engine it worked like a charm 

Brian has a good theory but a 8v71 will pump a steady stream of oil from the tubes with broken oil rings, bad wrist pin seals and bad valve seals also 

good luck

[Scott & Heather]

I have a can for my slobber....err I mean airbox drains (wink Geoff) and as nice as it is to have one, the dumb motor leaks every other kind of fluid from other places. So I kinda don't see the point. At the moment I just noticed red fluid belching from somewhere. Have to find out if its a tranny leak or power steering. Oh joy.


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[wg4t50]

I have rebuilt a few 71 & 92 series, they do not leak (not talking air box drains) with the new DDC/MTN seals & gaskets, if installed correctly,  Even the 12V-71 would
run 3000 miles only needing 2 quarts oil.
My rebuilds were not a paint job, and every plug removed steam cleaned and reassembled correctly, put washer in oil regulator etc.
They do not have to be a leaker unless your happy with older engines or sloppy rebuilds.
My rebuilds did not include painting, so it was easy to see the rust building, who ever heard of a Detroit Diesel rusting ?.  I did not go for the show, just the get-r-done and smile while calling "Here kitty kitty".
Dave M

[sledhead]

Had my 6v92 rebuild in 2010 and no drips yet! So if it ain't leaking does that mean it ain't runnin       dave

[Fredward]

My 8V71 drips an occaisional drop out of the curb side tube if its cold and i make it idle too much. I've really gotten to the point that I just start it up, build air and then start driving. Cautiously at first, but once its over 150 degrees I drive it like I stole it. Never thought I would say this; but I love the sound of that damn 871.

Its got other leaks elsewhere that I can focus on.

Fred