My MCI 8V92 oil leak

viking1 · November 27, 2015, 01:02:50 PM

Ok, so from my last post regarding my oil leak I got a lot of good advice. I steamed the motor and fired her up. I found that on both sides of the motor there is what looks like a breather or relief tube that comes of the block on both sides of the motor. Both of them have oil dripping fairly heavily. What can I do. Do I have internal motor problems? Can I cap them, any ideas?

Iceni John · November 27, 2015, 01:06:03 PM

Are they your airbox drains?

John

viking1 · November 27, 2015, 01:15:08 PM

Maybe, not sure. There is one on each side on the block. They connect to a drain tube that vacates under the motor. Tried to attach a pic but file was to big

MB LeMirage · November 27, 2015, 01:30:00 PM

Those are your airbox drains. I remember reading about either putting check valves or catch cans on them but have no direct experiance with either.
They do tend to dribble a little on most engines, but should not be heavy.
Ryan.

viking1 · November 27, 2015, 02:07:46 PM

Mine are excessive, covers the back of the bus with oil and leaves a trail wherever I go. I'm using a gallon every 250 miles and I think most of it is on the back of the bus. What will happen if I cap them?

Hi yo silver · November 27, 2015, 02:17:25 PM

Maybe you just have too much oil in the crankcase. My 8V71 didn't like to be all the way to the full mark on the dipstick. It held just fine when it was about a gallon low on the stick. Catch basins fashioned from plastic jugs just in case, but they stayed relatively empty. HiYoSilver!

MB LeMirage · November 27, 2015, 02:19:14 PM

Somebody with more knowledge than I have could probably explain this better than I can, but they are needed and capping them would lead to severe damage. My knowledge is more in modern Detroits, though I am learning on the oldies. Hopefully someone like Don Fairchild or Clifford could tell you (and me) the exact purpose.
Ryan.

Iceni John · November 27, 2015, 04:00:04 PM

At the very least, disconnect the airbox drains' valves (they have a 1/4" FPT on the input and a 3/8" barb on the output), clean them in kerosene and make sure the spring-loaded valve inside works freely and seals shut at a few PSI, then reinstall them pointing slightly down and towards the back of the bus. Buy some more 3/8" plastic tubing so you can run them into a catch can - I use a 1 gallon plastic jug inside my rear bumper, easy to see inside and to empty if/when it gets full.

This way you can easily see how much is slobbering (sorry, Geoff) out of your airboxes, and you won't leave an embarrassing trail of black drips behind you. My valves are open at Low Idle (600 RPM) but close at Fast Idle (1100 RPM).

John

luvrbus · November 28, 2015, 01:27:11 AM

Check your oil level first the 8v92 holds 7 gals of oil did this engine just started pumping oil? if it is not overfilled then check the cold side (compressor) of the turbo to see if it is wet the top mounted turbos are a pain to check fwiw while there check the blower for leaking seals on each end.Using much oil it should be smoke and don't cap the drains the oil will be come fuel and your engine will runaway into no mans land fwiw

viking1 · November 28, 2015, 04:22:33 PM

Thanks for all the advice, I have gotten most of the oil leaks taken care of. Put the slobber hoses into a couple of bottles and I have ordered a kit that mounts under the engine and both slobber hoses run into it. Cost me 85 bucks, not bad. I also found a pin hole in a cooper line, I think it's lubrication for the alternator/generator. The only leak left is coming from the exchaust side of the turbo. Oil is leaking out from the clamp that holds the exchaust together, dripping straight down on the valve cover on the left hand side. Is it normal for the exchaust to be wet at that point.

luvrbus · November 28, 2015, 11:16:09 PM

How much do idle the engine ? wet exhaust are not the norm

bevans6 · November 28, 2015, 11:38:34 PM

Wet exhaust is usually black, sooty unburnt fuel. Can come from excessive idling loading things up. On the air box drains, the check valves that were mentioned are supposed to close with around 5 psi of positive pressure in the airbox, which happens around 1000 rpm. That should mean that there would be no leakage there when running on the road, just when idling. Like the exhaust the black stuff leaking out may be mostly unburnt sooty fuel. There will only be oil in the airbox if the turbo seals, blower seals or or the oil rings on the piston are shot.

Brian

luvrbus · November 29, 2015, 12:03:38 AM

I think he may a problem also Brian,the Walker catch can he bought is not going to solve his problem either IMO

bevans6 · November 29, 2015, 08:32:31 AM

Well Clifford, you know I had the same problem, and it was an easy fix. New engine... My old engine blew liquid stuff out the exhaust, the air box drains, the blower, and every other place... It had been run without oil in the air filter for 40K miles and had a 1/4 of dusty sludge lining the inside of the airbox. I got $125 a ton for it.

Brian

Detroitenginespecialist · December 01, 2015, 02:17:54 AM

Viking 1

Brian here from American Fleet. We specialize in re-manufactured Detroit bus engines. We build 4-6 Detroit 2 cycle engines like your 8V92 every month. While our main business is now more of the Series 60 Detroit, we are very well versed in the 2 cycles as well. If you would like to call and get another opinion from our Tech Dept, please do. Ask for Danny, and if it turns out you might need a new engine Danny will turn you over to me.