Hi everyone,
My 8V71 has a problem. The bus has been sitting for about a month. I drove it 400 miles round trip while towing my car trailer, it ran perfectly the entire trip. When I parked the bus it was running fine.... oil pressure good, antifreeze normal level, no noises, nothing notable.
Today I went to move the bus. The engine cranked over a bit slower than normal but I expected that since it's been sitting for a month. After about 10 seconds of cranking, the engine stopped hard. The starter would only clunk after that. From the rear controls I hit the starter switch a few times and by watching the clutch I determined the engine was coming up hard against something and stopping.
I used a pry bar to turn the engine back a few degrees and try to start it again. The engine stopped in the same spot. I turned the engine back about 20 degrees and tried the starter again. This time the engine cranked for a few seconds and started, but it made a horrible crunching noise, irregular, enough to cause the engine to shutter and shake. I shut the engine off within 10 seconds.
I pulled the Vickers pump and the coupler. Both were fine, the coupler was perfect and the pump turned smoothly. I started the engine again, this time without the Vickers pump. I had a friend depress the clutch in an effort to rule out transmission noise. The engine started right up, oil pressure was 65 psi, but the engine made the same irregular crunching, chunking noises, shaking and bogging when it crunched. I shut it down after about 15 seconds.
It seemed that the noises were louder at the back cover. There was no smoke at all from the exhaust.
I'm looking for suggestions as to what is wrong. It seems something is bind up in the accessory drive gears, but if it was metal wouldn't the engine just stop? Or just break gears and stop running? What should I remove next?
This timing of this sucks, of course. I'm in the middle of an expensive generator engine and alternator rebuild.
Thanks,
Mark
Did you get a rodent in your blower?
Quote from: mung on October 20, 2014, 06:42:11 PM
Did you get a rodent in your blower?
I will check but I know the metal screen above the blower is in place.
If the alternator is still gear driven that is where I would start 1st then on to the air compressor
good luck on this one Mark
Thanks for replying, Clifford. Yes, the alternator is still gear driven. I put my hand on it when the engine was running and it didn't *feel* as if the crunching was coming from it. I didn't put my hand on the compressor. I'll remove both and hope for the best.
Darn good thing you were not on the road somewhere far from home. It's hard to imagine an accessory creating the hard stop as you described it but something stuck in the blower lobes seems like it might.
I'm following this thread with interest because if it can happen to Mark, who takes good care of his coach, it could happen to others as well.
-Tom P.
Bearings going bad in a accessory drive will lock one down, any blower problems they break the blower drive for safety, the compressor is keyed to shear if it seizes, a rod that come loose in a compressor they don't always shear the key
When you are building the engine you put a rag in the cam gears to lock it up, and then put around 400 ft lbs of torque on the crank pulley bolt. It doesn't take much to lock an engine. If it runs you know the gear train is still there, the cams and the blower are still spinning. Be interesting to see what it turns out to be.
Brian
Update: No solution yet but I've ruled out a couple of things and saw one very disturbing thing.....
It's not the blower. I took the intake horn off and it looks fine.
It's not the Vickers pump. I determined that yesterday
It's not the transmission fluid pump. The fiber disc is in perfect condition. There are no pieces of metal in the bottom portion of the trans pump gear housing. I used my finger to feel around and felt nothing.
I cranked the engine over with the fuel shut off. The engine spun over like it always does, no binding at all. I started the engine and it made the same crunching noise for about 15 to 20 seconds then it went away. Here's the disturbing part, SPARKS shot out of the tranny pump hole! I sh*t you not. Sparks.
After the sparks shot out, the engine ran perfectly smooth. I did not rev it up since the Vickers and tranny pump are out. I used a good light to look into the blower housing and both pump housings. I saw nothing out of the ordinary.
So..... something metal has fallen off and managed to get into the gears. I'll pull the generator off and look at the bearings, as well as the compressor. Right now the engine starts fine and sounds smooth.
One thing I noticed when I got this engine from the NYC Transit Authority. The engine was a rebuild with a new factory block, but when I took the engine apart I noticed a cracked lock washer on the left cam gear. It was cracked in half and the nut wasn't tight. I removed the washer and torqued the nut down since the manual didn't show a lock washer on the cams. I found the other half when I swapped rear engine covers. After that I was super careful to inspect everything, as well as retorque every nut and bolt I could find.
Ugh! I really don't want to pull the tranny and rear engine cover to find this problem!
Really strange that it would happen from sitting though.
Stranger things have happen ;D
Things usually don't happen from sitting, they happen when the engine stops, and then they just wait to jump out and bite you. Cam gear nuts are supposed to have a locking plate that bolts on to the gear and fits over the nut, you can see them in this picture. These pulleys don't have accessory drives bolted on to them.
That this point I would drop the oil and stick a magnet on a stick thingy in to fish around and see if I could find a few bits of whatever the gears ate. Then I would probably drop the pan and fish out the parts to see if any of them were gear teeth looking bits. Then I would probably take the back cover off to see how many gear teeth I lost.
Note to self - never try to spin a locked up engine, it's usually locked up for a good reason...
Brian
Yep the backlash when you shut a DD down works on the gears it does on a all large diesel engines the bull gear is a weak point on the series 60 also.
Could be he just lost a pilot bearing or the throw out bearing I hope it's not a gear train problem for him
Mine looks like this....
(https://lh3.googleusercontent.com/Y2PpmTt11mzhRhsXjvBgcji4wxR5oS5mwVmPIAvbby0=w756-h567)
and ......
(https://lh6.googleusercontent.com/-774Y6VBMmc4/VEaHJQGRzrI/AAAAAAAACn8/I2e7hF7O5Hg/w756-h567-no/DSC01010.JPG)
um, errrr... and to Brian's point, I found this photo of the original engine...... You can clearly see the star shaped lock washer on the left cam gear nut....... uh oh.
Time to pull the compressor.
(https://lh5.googleusercontent.com/-pBJjetf_qZA/VEaJrOot2rI/AAAAAAAACoI/EjI3S_gL9Nk/w756-h567-no/DSC00905.JPG)
I went and found my manual - left hand rotation engines, which yours is, use a bolt and washer on the right hand pulley instead of the nut and lock plate. They only use the nut and lock plate on the left hand cam pulley, as your picture shows.
Edit: torque on the nut on the left hand (compressor drive) cam nut is 300 - 325 ft lbs. Torque on the 9/16" 18 tpi bolt is 180 - 190 ft lbs with assembly lube on the threads and under the bolt head, so they torque it kind of like a rod bolt, stretching the bolt to lock it in place.
Brian
It's diamond shape on the gear but the actual lock is a circle with adjustment holes that takes 2 allen head bolts.
DD had so many problems with the 50D trashing the engines they developed a special locking system and cam for the 50D If I could post a photo here I could show the set up to you
The planetary gear for the alternator diffidently uses a lock system that is not on yours I am going to try a PM you a photo
Mark photo sent
Quote from: luvrbus on October 21, 2014, 10:34:18 AM
Mark photo sent
Got the photo, Clifford. Big thank you!
I got the air compressor and alternator off... trying to get my SD card reader slot on my PC to work. As soon as it is I'll upload the pictures.
Okay, thank goodness I didn't forget the locking washer for the left cam nut.....
(https://lh5.googleusercontent.com/HzpIs7W4eRZoktt5dTNxDIqXXL4F5Muksd2bbD_zc4o=w756-h567)
Everything looks normal. I can turn the alternator and air compressor by hand, neither feel crunchy in any way.
(https://lh3.googleusercontent.com/fBwx634sEGnJ70a9croIA6HCSKYYrXUsVpGESLb9F_Q=w756-h567-no)
(https://lh3.googleusercontent.com/mHjfk0cvnv826UP4jKlmWWMYFUyYEVR6klUe1lyv0yo=w756-h567-no)
Take a screw driver and see if the planetary moves that is scary no lock on the planetary gear cam
Due to the fact that it all happened I'm wondering if you lost a tooth on the flywheel or the starter and it got stuck for awhile in the bell housing. Easy enough to check. And if it is, it won't take many starts before you land on that missing tooth. It also may account for the sparks you saw. Hard to believe you would have visible sparks coming from inside the motor.
RB
Is that an optical illusion... that ear on top doesn't look right...
(https://lh3.googleusercontent.com/mHjfk0cvnv826UP4jKlmWWMYFUyYEVR6klUe1lyv0yo=w756-h567-no)
Pull the starter; the bendix may have broken internally or a tooth came off the drive.
I HATE pulling the starter off this engine! The flywheel and starter are on the transmission side of the rear cover. The cam gears are on the inside. This problem is definitely on the inside.
Clifford, what is supposed to be on the planetary gear for a lock? IIRC, this is what I took off both engines. I think there was only the bolt holding the planetary gear to the right cam.
RB, I absolutely hear you. If I didn't see a spark shoot out of the tranny pump hole myself I'd say "no way" too. But it happened. The question is what got into the teeth of the gears and how much, if any, damage was done.
I suppose I have to figure out how far I'm going into this engine. I can't pull the engine pan down because of the way I built my hitch, but I can loosen it and drop it a couple inches, enough to fish around in it with a magnet.
All I can say is I don't ever want to have to see that far into my engine.
Quote from: eagle19952 on October 21, 2014, 02:01:03 PM
Is that an optical illusion... that ear on top doesn't look right...
(https://lh3.googleusercontent.com/mHjfk0cvnv826UP4jKlmWWMYFUyYEVR6klUe1lyv0yo=w756-h567-no)
Donald, yes, optical illusion. The ear is there and fine, the camera is at the perfect angle to make it look like it's missing.
Mark in the photo I sent you notice you cannot the see the diamond shape on the gear the lock goes over the bolt head on the cam covers the diamond shape and is locked in place with the the 2 screws in the photo the lock is not on your engine
Quote from: mung on October 21, 2014, 06:44:14 PM
All I can say is I don't ever want to have to see that far into my engine.
Well, I honestly thought that I'd never have to see these parts of my engine again! I was so super careful when I put this engine together. Maybe you get what you pay for.... I paid $2500 for the engine and figured it was worth it since it had a new factory block. I ended up using most of the engine because the blower and heads were Reliabuilt units and looked absolutely like new.
The question I have is what is in there that can break off?????
Quote from: luvrbus on October 21, 2014, 06:56:07 PM
Mark in the photo I sent you notice you cannot the see the diamond shape on the gear the lock goes over the bolt head on the cam covers the diamond shape and is locked in place with the the 2 screws in the photo the lock is not on your engine
Ack! Neither my original engine or the NYC transit engine had that locking plate! Time to call the DD dealer and see if they can find a part number and order it.
Is the bolt with the missing lock plate loose?
I do hope it is a simple fix Mark have you ruled out the cam followers rollers and push rods ?
Quote from: luvrbus on October 21, 2014, 08:16:19 PM
I do hope it is a simple fix Mark have you ruled out the cam followers and push rods ?
I didn't pull the valve covers off. Right now it seems that whatever it was is now out of the gear train and hopefully in the oil pan. The engine starts and runs smoothly. I'll keep going till I find out what it was, even if I have to remove the tranny and the the rear engine cover. It may seem odd, but I get some level of peace of mind that my bus is in excellent mechanical condition and is capable of going 5000 miles, if needed, at a moments notice. I can't ever imagine needing to do that, but IF I needed to, I want it in perfect condition. Ok, I'll settle for 'very good to excellent' condition, 'perfect' might be a bit out of my budget.
Thinking on this, I would hazard my guess that one of the 3/8" bolts that hold the engine plate to the block came loose, was sitting on a gear and got jammed in a tooth, backing the engine up 20 degrees made it slip out and get jammed between the gear and the back plate or the engine cover so that the engine would run, but with loud noises and sparks (had to be ferrous for the sparks), and then got spit out so that now the engine runs normally.
As far as the locking plate on the right hand cam bolt is concerned, my January 1978 Detroit manual specifically says that no locking plate is used. You just torque the bolt and have the special thick washer underneath. Bolt pre-load stretch keeps it locked. Now, I have no idea about locks for the bolts that hold the generator drive gear on. The book doesn't show anything to lock those bolts.
Brian
Good Morning,
Just a little curious. When did you purchase engine from NYC Transit Authority? To my knowledge we ran very few.
- Seaton
Brian, 1978 is a old manual if you were the original owner DD would send all the releases and updates for manual mine has all up to 1998 then DD stopped supporting it, mine has something like 143 releases each one contains as many as 20 new service bulletins
yep, that's why I said the date! I have no doubt there are updates in the past 36 years! ;D Just thinking that if that engine is circa 1980's it just may not have had a locking plate so no need to feel bad for leaving one off.
Did the aftercooler come back yet?
Brian
No it hasn't Brian I have a call in to Fedx to see where it is at lol those people are getting as bad as our USPS here in the US, I got a notice it was to be here Friday and today is Wed no package yet
Quote from: bevans6 on October 22, 2014, 05:15:06 AM
Thinking on this, I would hazard my guess that one of the 3/8" bolts that hold the engine plate to the block came loose, was sitting on a gear and got jammed in a tooth, backing the engine up 20 degrees made it slip out and get jammed between the gear and the back plate or the engine cover so that the engine would run, but with loud noises and sparks (had to be ferrous for the sparks), and then got spit out so that now the engine runs normally.
Brian
Sounds plausible to me. I'm going to try and fish it out of the oil pan but if I recall the oil pan has baffles in it so I don't think I can get to the end of pan with a magnet.
Quote from: seaton@mta on October 22, 2014, 05:54:11 AM
Good Morning,
Just a little curious. When did you purchase engine from NYC Transit Authority? To my knowledge we ran very few.
- Seaton
The engine can from Nimco who purchased it from NY when the last of the 2 strokes were replaced. My friend works for the company that owns Nimco and told me about this engine after a conversation he had with Jim (at Nimco). Nimco purchased about 200 buses, most were shipped to central America, the best running had the drive trains removed and the bodies scrapped.
Here's the update;
Today the Nor'Easter storm blew thru so the weather was good enough to work on the bus. I borrowed this very handy tool which worked great!
(https://lh3.googleusercontent.com/GKjgeAeUVPKp7yBCeK_dyy0dXV0CFketklG1swG2u8k=w756-h567-no)
Inside this hole I found a bent lock washer and a bunch of metal shavings. I remove a 3/4 JIC pipe fitting and used a magnet to pull out the washer. I don't believe that hole goes into the rear gear cover, but someone will certainly know what it's purpose is. This engine had an automatic connected to it and I assumed that this fitting had tranny fluid in it. If so, maybe the bolt fell out of the clutch area and into this part of the rear cover.
(https://lh3.googleusercontent.com/Goz3R8NOjLwmNBFBNrQHTlQxbOrIw0asT88-eaNAYOM=w756-h567-no)
I used the inspection camera and looked at all the gear teeth. They all look fine. Inside the clutch housing I found this....
(https://lh5.googleusercontent.com/zyr_bEy98fEwIwpLv1p50i0Wa6EBB1kTIk7Hz1ufAYM=w756-h567-no)
(https://lh6.googleusercontent.com/hdNDE2ygupxVacp1BnOxQ_QQIzhGP0hHdqo7uYWsVqw=w756-h567-no)
(https://lh4.googleusercontent.com/72tkKe3b2cyTwfwEZoopUvpshGmlYvBV5en6G-nh_cc=w756-h567-no)
I have used the inspection camera and looked at every single nut and bolt on the or in the clutch housing. I can't find one missing. None of the ones I could reach were loose.
Good news is the accessory gears are fine and the problem doesn't appear to be in that part of the engine! Bad news is the tranny needs to come out to be certain the clutch isn't falling apart.
(https://lh4.googleusercontent.com/430CKqkuPxDrMdDWa0LaAzHG5_ZJ3BvIdfG-WcIXLN8=w756-h567-no)
Would those parts be from the clutch disc?? or pressure plate?
Quote from: Ralph7 on October 23, 2014, 06:15:01 PM
Would those parts be from the clutch disc?? or pressure plate?
At this point I don't know where the bolt came from. All of the bolts that hold the pressure plate to the flywheel are in place. But 'm pretty sure it's a bolt since I found a washer (although it wasn't found near the other part. The bolt isn't much of a bolt anymore, and it certainly wasn't a "fresh kill". That thing has been banging around for a while.
Does any know what that fitting went to and what was goes in the hole?
Now that I've looked at some engine build photos, I suspect this is the bolt that fell out. If it loosened up enough it looks like the ring gear teeth can contact the head, wear through that, then the bolt shoulder can hit the ring gear teeth. The flywheel spins clockwise which would turn the bolt counter-clockwise, effectively backing out what's left of the bolt from it's threaded hole.
(https://lh5.googleusercontent.com/-2ilC3w08ycY/VEmz_Woia7I/AAAAAAAACqg/SEEVk9_owOY/w681-h567-no/DSC00906a.jpg)
The piece of the bolt has a flat spot worn into it, I'm assuming from the ring gear.
Now what? Pull the transmission, clutch and flywheel to replace this 3/8" bolt and lock washer? Or????
There shouldn't be a lock washer on the bell housing all those are copper or flat steel washers on a aluminum bell housing that fitting is used where the spacer goes between the bell housing and the V730 a return line
Quote from: luvrbus on October 23, 2014, 07:33:19 PM
There shouldn't be a lock washer on the bell housing all those are copper or flat steel washers on a aluminum bell housing that fitting is used where the spacer goes between the bell housing and the V730 a return line
Thanks Clifford! I put back what I removed, hence the lock washers. I'm pretty sure I used blue loctite on those three bolts, but I must have not tightened that one down. Hard to believe I could make a mistake like that. I even used a paint pen to mark the bolts after I torqued them.
I feel better now that I've likely found the problem. I'll rent the garage and pull the tranny this winter to fix these issues.
Thanks guys!