As in how to do both! Thomas and I both seem to have a similar problem, oil leaking from the back of the engine, mine is an 8V71 MCI. With Cliffords advice from the other thread in mind I pulled the inspection hatch and from what I see the big connecting hose from the blower to the rear engine cover is there, looks newish (blower is Reliabilt from 2004, replaced at the Detroit dealer in Toronto) with new spring loaded bands to clamp the ends. The little 1/4" pipe mentioned is there with no signs of weeping at all. There is a cross-over tube underneath the large blower hose that looks to be a vent from the heads back down into the valley, not sure what that is about. There is pooling of oil at the base of the blower. The RH valve cover seems very wet (drivers side if I got RH wrong) while the LH is completely dry (I did have it off and cleaned it up 500 miles ago when I was checking injector timing and valve lash and such). I wonder if the valve cover gasket is leaking, I will check that. This after noon I am going to fire it up and observe from the hatch while it's running to see what I see.
So the question is - after you check those blower hose and pipe connections, what are the next most common points of leakage? Particularly that would cause pooling of oil at the base of the blower?
Thanks, Brian
crank case pressure can push oil past seals..take off and clean the ones on both valve covers (vents that is ) easy to pinch gasket on valve covers when reinstalling valve cover gasket.(I've done it) also easy to overtighten ,this leads to smash valve cover gaskets..any hose carrying oil under pressure or not is suspect(or tube)..have found lines to air comp & alt with small leaks..just some I have experienced...Bob
I know when I bought my bus (MC-9), the top of the 8V71 and the drivers side was wet with oil and was leaking pretty bad. It looked like it leaked out a quart of oil while the engine was idling at the fuel island. The passengers side was dry as could be. The PO had 2 of his mechanic climb up in there with a flashlight while I was there. The first mechanic said he could not tell where the oil was coming from but the second mechanic took a shot and guessed it was coming from where the big DN50 Alternator was mounted on to the engine. They pulled the DN50 and replaced the gasket between the alternator and the block and no more leak. It took them a couple hours but it was well worth the wait.
Thanks for that tip. I do suspect the accessory drive where the belt drive pulley for my alternator comes out. All part of the inspection process!
Brian
The more i read about this particular oil leak, and the more people i talk to about it, i begin to suspect the head to block o-rings. What have been other peoples experiences with this type of leak? Are the head o-rings a common problem? or am i barking up the wrong tree?
Only if they were not installed right and 99% of the time they leak at the bottom not the top
Quote from: luvrbus on September 10, 2010, 08:06:19 AM
Only if they were not installed right and 99% of the time they leak at the bottom not the top
well that makes me feel better. there is definitely large amounts of oil leaking at the top somewhere, so I will check on the things previously mentioned and see what can be found. Be doing this right now and report back what i find.
Reading posts about similar trials on other boards, one person had a leak at the accessory drive location for the alternator, his was a gear driven alternator, and another person had loose blower mounting bolts letting the base gasket leak.
Brian
Quote from: bevans6 on September 10, 2010, 12:10:04 PM
Reading posts about similar trials on other boards, one person had a leak at the accessory drive location for the alternator, his was a gear driven alternator, and another person had loose blower mounting bolts letting the base gasket leak.
Brian
Mine was where the gear driven DN50 alternator adapter plate was bolted onto the engine. It was leaking very bad and running down the drivers side of the engine. Once they pulled the alternator and replaced the gasket, the leak stopped.
I believe the MCI 8 alternators are belt driven not gear driven , when checking for leaks on a 2 stroke clean the engine good first and always run the engine at about 1000 RPMs most of the time it will not show up at idle not enough oil pressure or flow
good luck
my 8 was gear driven off flywheel end on top of motor 8V 71 78 mci 8 Bob
Bob my 8 was belt driven had 4 -3/8 in wide belts and was air cooled not oil cooled located on the drivers side.50 D gear driven have to be driven off the camshaft where are talking at the top is the blower drive they do have a auxiliary pulley you can belt drive from there but never saw a 50D gear driven mounted there.
Fwiw DD uses a special cam for the gear driven 50D and they brake lol just sent Don Fairchild one to replace a broken drive cam for a MCI.
A gear driven alternator if it was mine on a 2 stroke would be the 1st to go
good luck
don't know history of my 8 so it could have been changed...Bob (was one of the last 8's built)or could have had a engine swap before I got it.
well here's what i found...the 1/4" oil tube at the back of the blower was very evident it was leaking. there is an adapter on the back of the blower (3/8" x 1/4" ??). when i put a wrench on the 1/4" tube the adapter spun pretty easy. backed off the nut a little then tightened the adapter and tightened the nut back up. the hydraulic pump bolts were not as tight as they could be, there was evidence of leakage there, so all those bolts got tightened up. the plate on the back and front of the blower got tightened up, those bolts were loose. there is a cover plate on the back of the top of the motor with evidence of leakage and loose bolts, so that got tightened up. the starter bolts were about to fall out, all three bolts went about 3 turns or more just by hand. that one next to the block was a little bugger but i had an old distributor wrench that worked perfectly. at the front of the blower are two little hoses about 1 1/4" or so in diameter. one side had hose clamps, the other had little plastic clips on it that were broken, so i took those off and used bug heavy zip ties for now. (I am parked in the forest far away from any auto parts store, so this will get me to where i can get some hose clamps.) the bolts on the front plate and governor got tightened. there is some kind of motor looking thing under the governor plate that was loose. the left side (standing at the back of the bus) valve cover is leaking, and the oil sending unit is leaking really bad.
there are two oil sending units on the oil manifold attached to the frame rail. one is very large, the other one small. both have one wire attached. the one that is leaking is the smaller one. can i get this at a napa or other box store? anyone have a part number that will cross to a box store part or is this a DD order item?
Derick, you probably still have a leak on the supply tube it has rubber compression seals on each end and that tube slides to remove the blower no flares just a straight pipe you do need to replace those seals if you get close to a DD dealer they are about a buck for both.
good luck
update: the beast is now leaking about a gallon in 200 miles. The 1/4" tube does not seem to be leaking anymore, but just to be sure I am going to the Detroit dealer this week and picking up new o-rings. I will also replace the oil sensor switch and valve cover gasket at the same time. Then i will pressure wash the engine and see if I can find more leaks. Leaking really bad now. :'( :'(
Try driving 50 miles a gal low to see if the leaks slow down or if it uses anymore oil it maybe over full,let it set for 30 minutes and then check the oil those old engine hold a bunch of oil up top and takes a while to drain back
good luck
Quote from: luvrbus on September 10, 2010, 02:03:23 PM
Bob my 8 was belt driven had 4 -3/8 in wide belts and was air cooled not oil cooled located on the drivers side.50 D gear driven have to be driven off the camshaft where are talking at the top is the blower drive they do have a auxiliary pulley you can belt drive from there but never saw a 50D gear driven mounted there.
Fwiw DD uses a special cam for the gear driven 50D and they brake lol just sent Don Fairchild one to replace a broken drive cam for a MCI.
A gear driven alternator if it was mine on a 2 stroke would be the 1st to go
good luck
Our original 8V71 in our MC-8 had the gear driven Alternator. The replacement engine that we installed had the pulley adapter installed where the gear driven alternator had been installed on the original. Since all lighting (interior and exterior) is now 12 volt, we do not need much 24 volt output, a small belt driven truck alternator is adequate. Jack
I found a leak on mine, the vent line on the top of the DD50 was loose to the point of almost coming off, so I tightened it down and we'll see if it makes a difference. If I think about it, that vent would probably only leak much when the oil was hot and less viscous, and when the alternator was spinning at high speed - highway travel. The leak would be very misty - hence it got all over everything. I hope it helps, I'm tired of washing the car every single time I stop.
Brian
If you have a gear driven alternator I would recommend buying and installing a support bracket to revent future leaks as well and I found that my most serious leak was the air compressor and they can leak internally and externally.
The unloader was leaking oil into the motor which would find it's way out through the spitter tubes and some got burned as well (don't ask me how) and all over the rear passenger side of the block.
If your compressor is cycling alot and struggling to get up yo pressure you might want to consider a rebuild as mine was leaking alot.
I can sit in a parking lot running and have a single drop of oil in 10 minutes and that is coming from my home made spitter box catchcans,man does that feel good.
I am winning the war for the time being but I have to remind my wife and myself, we never actually win the war against two strokes leaking we just have brief moments when we aren't losing. ;D
Rick
BTW you may be burning some or most of the missing oil as well... just a thought
Derrick, check and see if you have a tach drive on the back of the blower if you do they are bad about the bolt coming loose and the strap falling off that much oil if a external leak should not be hard to find.
Do you have the cast valve covers or the stamped metal ,if you have the old stamped metal style stop on the way back and I'll give you a set of the cast for a 8v71 without Jake Brakes I don't have the ones for Jakes
good luck
Clifford, I have been running it about a gallon low. I always check the oil after sitting for a while, usually in the morning after sitting over night. I verified the dip stick was reading the correct level after I changed the oil. Oh, and that 1/4" tube...is that supposed to be a hard tube or a flexible tube? Mine is a flexible tube that has a loop in it. When you said it slides that got me wondering. Also, no tach drive I don't think. I have no tach anyway. There really is no oil to speak of on the back of the bell housing, none of the accessories are leaking. I can't seem to find clamps narrow enough for the hoses at the front of the blower, only find the wider ones. Does DD have the clamps or just the plastic clips? Oh, and I beleive I have the cast valve covers but I will double check that to be sure.
RickB, I have a belt driven air cooled alt, and I am sure the DD is leaking most if not all of the oil being lost and not burning it. I can pull in and park for 2 minutes and have huge puddles. My white pickup is completely black and nasty. it looks like a big square on the ground under the engine, you can see where it is dropping off of the engine. The air compressor will only cycle maybe twice an hour rolling down the highway, and that is mostly due to a believed faulty/leaking front leveler valve. I don't believe the slobber tubes are leaking much if any at all, the sides of the engine are covered in oil from the heads down, and the front is coated from the blower down. The rear is pooled from the top of the block under the rear of the blower and down the sides of the bell housing. No danger of this thing EVER rusting. I'm hoping I don't end up with starter problems, that thing gets soaked pretty good.
Brian, as mentioned above I have a belt driven air cooled alternator. No oil hose going to it. Only oil hoses at the back of the engine go to the blower and there is one around the back of the bell housing that looks to be in a really bad spot if it ever needs fixed/replaced.
I am going to fix the few items mentioned in my previous post, and wash the engine off again and see what else I can find. I have thought about loosening the blower shaft tube and rotating it 180 deg so the bottom is now on the top, so I can see if that is leaking or possibly cracked on the bottom. It does not look like it from what I can see, but may be better to actually turn it over and get a good look at it.
And a note to every one that has taken the time to post their ideas and thoughts here...A BIG HUGE THANK YOU TO YOU ALL!!!! I am a tent evangelist, this bus is our home and we appreciate your help. For obvious reasons I can't afford to take it to a shop every time something pops up.
Derrick, you have the wrong tube it should 4 inches long straight and made of steel not copper,DD should have both style clamps the plastic will hold for about 5 years
good luck
Quote from: luvrbus on September 13, 2010, 07:28:11 AM
Derrick, you have the wrong tube it should 4 inches long straight and made of steel not copper,DD should have both style clamps the plastic will hold for about 5 years
good luck
Clifford, it is not copper it is braided high pressure stainless steel. same hose as found in other locations on the engine, such as the oil pressure switch manifold. Does not look like a scab job, looks like it belongs there, I'd have never guessed it wasn't original. the tag on the motor says it's a 1981 if that makes a difference. BTW, the valve covers are the cast ones.
They, do not use a hose somebody just didn't know how to install the tube and tried a easy wayout that you are paying for now it has to have the wrong fitting to make a hose work ,those are special fitting send me a shipping address and I will ship you the correct tube and fittings for the blower and end plate, but I don't have the 2 seals.
They have 2 different fitting for the blower end just tell me if the fitting is screwed into the blower plate or has 1/2 inch shoulder and the fitting goes past the plate and then screws into the blower
good luck
Quote from: luvrbus on September 13, 2010, 10:23:38 AM
They, do not use a hose somebody just didn't know how to install the tube and tried a easy wayout that you are paying for now it has to have the wrong fitting to make a hose work
good luck
It does not appear to be leaking, but that doesn't mean it's not. Is this something that should be replaced back to oem anyway just for good measure? I don't want to just blindly throw money at it, but I also don't want to overlook something so simple that may come back to haunt me later. What would you do if it were yours?
On my 6v92 I had a leak . It seamed to come from behind the alt. I kept tightening it up but got worse. The oil ran down the back of the engine. and under the blower and all over the trans.
Removed the alt and replaced all gaskets. Made it worse.
Finally removed the alt and checked the adapter and found a almost invisable crack that got bigger when tightened down. new adapter cured the problem.
uncle ned
Man that is a LOT of oil, I sure hope you get it figured out. I am certainly no expert on DD, but when you say its leaking from the heads down, it really sounds like rocker covers (valve covers). The upper head rocker cover could dump an awful amount of oil onto the blower, and the rear head would ooze down the back and blow all over everything else. I think even if you dont suspect them, I would change them anyway, just to check it off the list. In fact, I would change any gaskets I could reach, starting with the easiest ones. Sometimes air turbulence can blow oil around and make it look like its coming from somewhere else. But when an engine is completely covered with oil from the top down, you gotta believe its coming from up high. Ive had many engines with loose rocker covers, and the amount of oil they can throw is amazing.
I have 2 valve cover gaskets on will call to pick up. The oil switch I am told the DD dealer does not have a listing for them and i need to get it from MCI as it was installed by them and not a DD item. I will order the switch and just put in a 1/4" plug for now. I am guessing the switch completes a ground to shut down the engine? With the wire disconnected the engine still runs.
You are running straight 40 wt conventional (non-synthetic) oil right? A buddy was running 10/40 rotella in his 6v92 and it was leaking/burning like mad and he switched to what most folks here run (straight 40 weight) and he started driving it more and voila! no more leaks and no more burning oil either. I have heard that synthetic is considerablt more leak prone than conventional oil.
Rick
One other thought... any chance some of this oil is coming from the squirrel cage gearbox? Other than the obvious stuff that has already been suggested it was all I could think of. And you're sure it's not fuel correct?
Rick
it is most definitely oil, and it is most definitely coming out of the engine. I run Delo 100 40wt. it had delo 400 40wt when i got it. I changed it out and drove 1800 miles since then and it's leaking more now then ever before.
You have got yourself one gremlin of an oil leak. You will have to keep us informed as to how it turns out.
Inquiring minds want to know... ya know!
Sorry i couldn't help more
Rick
If you wanna fix it once and for all and quit throwing $ at it I'd suggest you make a trip over Clifford's way and let the master find, & show you the problem and help you fix it RIGHT!
In my opinion ain't nobody closer or better!
FWIW JMHO!
;D BK ;D
Quote from: Busted Knuckle on September 14, 2010, 04:49:23 PM
If you wanna fix it once and for all and quit throwing $ at it I'd suggest you make a trip over Clifford's way and let the master find, & show you the problem and help you fix it RIGHT!
In my opinion ain't nobody closer or better!
FWIW JMHO!
;D BK ;D
that is probably just what I am going to do. I will go ahead and fix the obvious leakers that I can see, and beyond that I will certainly accept the help. I don't have the money to just throw at it. I have ordered parts for and plan to replace the 1/4" tube and accompanying connectors at the back of the blower, replace the broken/missing 1" tube clips at the front of the blower, replace the oil switch that is literally dumping out oil, and replace the valve cover gaskets that are also dumping oil down the sides of the heads. Those are blatantly obvious, beyond that I am not playing guessing games anymore.
Quote from: thomasinnv on September 14, 2010, 06:13:48 PM
I don't have the money to just throw at it. I plan to replace the oil switch that is literally dumping out oil, and replace the valve cover gaskets that are also dumping oil down the sides of the heads. Those are blatantly obvious.
Obvious oil leaks leak the most oil. I have a feeling that once those items are correct your gonna be okay.
A few days ago when i parked the bus i soaked the engine down with oil eater and sprayed it down really good. (that stuff is awesome!) it was so clean you could eat off of it. anyway, today i had to move a few hundred feet to where we are setting up the tent getting ready for our revival to start tomorrow. With it running in high idle i checked all around the motor and found that 2 of the air box covers are leaking pretty bad. There is nothing at all coming out of the slobber tubes, so I am assuming they are plugged. Do the tubes generally plug up? or the elbow at the top? or somewhere inside under the covers? or a combination of all of the above? what am I looking for? I will probably dive in tomorrow based on what you all have to say on here. a little guidance???
I tried to get some new gaskets for the covers but the best I could find was 2 weeks out. I need to be rolling before then. what would be the best way to seal these things up in the interim? what kind of sealer/gasket material etc. can I use here? or am i just out of luck?
Two weeks? for gaskets for an 8-71 ? Wow, thats almost scarey.
Slobber tubes: fast idle might be too fast. It might be enough pressure to close the check valves. On regular idle, feel with your hand for air coming out of the tubes.
For the gaskets, I would cut some out of cork material you can buy at any auto parts store, and put them on with gasket maker for added peace of mind.
JC
Derrick, the gaskets for the cast valve covers are designed to be used more than once that is why they are hard to get, if you have a piece tore or missing just use a good silicone I use Ultra Black made by Permatex put it on the damaged areas and let set for about 30-45 minutes before installing the covers.
Buy a tube and use a chalking gun it is lot cheaper than buying the stuff in the small tubes
While you have the covers off take the breathers apart and clean those wish I could help more but it is hard to tell what is causing your problem over the net I am beginning to think now you may have a problem up top also check the exhaust system and be sure the inside of the muffler hasn't come apart
good luck
Clifford you may be more on the $ than me, but I thought he was talking about the air box covers and drains on the side of the block. FWIW
Thomas what part of the country are in now? Maybe there is a bus nut close who would have better access to parts for you.
;D BK ;D
I just remember him saying he was ordering valve cover gaskets I can send all the air box cover gaskets he needs or wants a 83 model 8v71 should be the same as a 8v92- 2 singles and 1 double on each side but the Ultra Black will hold there also and you were right BK
good luck
BK, I am in Fallon NV. About an hour from Reno.
Clifford, in The last post I was talking about air box covers. If the check valve were to close at high idle then I suppose the leakage would be expected considering the gaskets are in sad shape? When looking around for leaks last week I noticed the airbox covers were extremely loose, most nuts barely hand tight and one nut missing. I replaced the missing nut and snugged the rest of them. The gaskets were oozing with heavy amounts of rtv from a previous poorly done job by the po, so may have squeezed the gasket out when I snugged the cover. I did notice the oil leakage got worse after tightening some loose objects, so I suspect trying to tighten things up actually made it worse.
The valve covers are very tight and gaskets are leaking, so I just assumed new gaskets would be in order. Learn something every day.
As for the airbox covers, I will try removing them and clean up the gaskets if possible and use a thin layer of black rtv and re-assemble. If this proves to be of no success then I will be contacting you about the possibility of getting some gaskets from you. Oh, and that tube on the back of the blower....I managed to find all the pieces but one nut for just a few dollars. I can't find the one that goes on the bell housing side. part #5144478. wouldn't happen to have one laying around would ya?
Derrick, sent you a PM ;)
Derrick
Try loosening the valve covers and move them around see if they drop into place there is (on mine anyway) a lip that fits inside I drove from IL to FL and back used over 7 gallons of oil. As I was pulling the I felt it drop into place felt like a fool. LOL could of fixer on the road anytime
Rick 74 MC-8
Rick, tried your suggestion. No luck.
As to the leaking airbox cover, I dove in today with the intent of pulling it off and cleaning it and re-sealing/re-assembling. Found that one nut was completely stripped. Replaced the nut, (had to remove the washers to get enough good threads on the stud to hold the nut) and tightened her up. No more leaking cover. Also checked the slobber tubes at idle to make sure they weren't plugged, got air coming out both at idle with no oil. Yay! (I think) the blower bolts were a little soft again so snugged them up a little more. Do they require lock-tite? Or should I just re-torque them a few more times after running it some more?
In the next few days I will be replacing the valve cover gaskets. While I am in there, should I re-torque the head bolts or is there any other kind of maintenance that should be done while the covers are off? Or just don't touch nothin'? any thing specific to look for upon visual inspection? any preventative maintenance items?
Derrick, you chasing the wrong place for a oil leak on the air box covers if you are getting a lot of oil from those sorry to tell you but there is a problem elsewhere.
Just plan on stopping by if you are coming back this way I am going to give you a class 101 on the engine you and your oil leaks are starting to give me gray hair LOL just joking but I will help you FWIW the cast valve covers have no lip they are centered on the head
good luck