I hate those alternators just a picture of a small amount of damage one can cause,this one is going to need some serious TLC and money,any one have a 8v92 take out from a MCI that is rebuildable for sale ?
A little to late for Denture adhesive now I guess, what a shame. :'(
Contact Interstate Power in Butler WI. They bought a few dozen used DD 2-stroke engines year before last. Not sure if they were for parts or to resell.
Quote from: richard5933 on January 09, 2021, 11:18:36 AM
Contact Interstate Power in Butler WI. They bought a few dozen used DD 2-stroke engines year before last. Not sure if they were for parts or to resell.
Thanks but I do not want a military surplus engine I have those too
Can you still get the gear that goes on the alternator?
Quote from: chessie4905 on January 09, 2021, 04:32:27 PM
Can you still get the gear that goes on the alternator?
They should still be around have you tried Kirks in Detroit MI
FYI A place up my way still does full rebuilds on the 12 or 24 50DN's. ;) ;)
Thanks, I'll try them. I found a nos cup gear.
Bet that bent a few valves. How are the cylinders?
And this is why I switched to a small belt driven 24v unit. No more sleepless nights.
I swear Clifford owns the shop that rebuilds and sells these things. Have you ever wondered why he seems to be the only one that always ends up with broken engines due to the 50dn?
I replaced my 50dn before I knew the dangers of keeping the gear driven.
I figure if it grenades I'll try and stuff a series 50 in the MC9.
What's the catastrophic failure rate on these things? I've heard of them occasionally causing big trouble, but I always figured that was a pretty small minority of them. Any warning signs to watch out for or things to check?
Quote from: Nova Eona on January 11, 2021, 11:33:39 PM
What's the catastrophic failure rate on these things? I've heard of them occasionally causing big trouble, but I always figured that was a pretty small minority of them. Any warning signs to watch out for or things to check?
I was told by one of the techs at one of the suppliers for commercial fleets that these alternators are considered a regular maintenance item, and that commercial operator pull & rebuild them at regular intervals (Not sure of my memory, but I think he said every 100,000).
It would seem that if a person is converting a coach which has lots of miles on it, replacing the 50DN at the start of the process would be a good idea if the mileage on it is unknown. If it's known that it was replaced/rebuilt recently, then the remaining miles on it are likely more than will be driven for a long time for most of us.
I guess it comes down exactly what is failing. My guess would be the front bearing. Since AC Delco upgraded the oiling and bearing assembly on it, I would say that was the reason for failures. If so, then thats what needs done to end the issues. After all, they were used on tens of thousands of busses and coaches.
I think there was an AC Delco service bulletin that directed any owners to go to Clifford for repairs.😁
This dark cloud has suddenly appeared over the gear drive 50dn.
There's 20 years worth of busnut internet history available for research, some here, most of it over on BNO, which historically involved way more industry knowledgeable people and engineers.
Nobody talked about this. Nobody.
Same old song, however. If you don't do your proper maintenance, if you don't install things according to the manuals, if you don't trust the former owner to have done any of the above...
Before the panic, can you wait for me to set-up a little business building over priced, ill fitting brackets to convert to pulley?
Happy coaching!
Buswarrior
They have always been a problem a bus engine is the only applications you will find one,they are a high amp, high rpm (3 x's the engine speed) and trying to cool with 200* plus engine oil is not a good recipe.The air cooled Niehooff 200 amp the military uses driven from the blower never gives a problem lol I do get my share of the 50D that went off, you may drive your bus for miles and never have a problem with the 50d but some are not that lucky like Mike,I never understood why people would want a alternator that takes 5 to 7 hp to operate.The 50D years back would break the cam Detroit had to start making a different cam just to drive the thing
That overpriced poorly fitting bracket does sound like a proper fix. If I had a 2 stroke you could sign me up! ;D
Jim
Quote from: luvrbus on January 12, 2021, 06:25:07 AM
I never understood why people would want a alternator that takes 5 to 7 hp to operate.
Are you saying a converted bus may not need so much power while running down the road? A smaller alternator would work to run headlights, running lights, charge the battery? There isn't much else pulling electrical power.
If that is the case and it is a real concern, then removing the gear driven 50DN and adding a 3rd party to run off the main crank pulley would be simple and pretty cheap, especially compared to the cost of fixing a blown up engine.
Wouldn't the HP consumed by the 50DN be in direct relationship with the load on it? I understand that spinning an idle alternator takes some power, but certainly not 5-7 HP. I just ran some numbers through an online amps-to-hp converter and it came up with 7 HP to make approx. 270 amps @ 24v.
Whether someone 'needs' the 50DN really depends on a few things, like are they running the OTR heat or a/c. With the OTR a/c it's pretty much necessary to have that large of an alternator. You also have to ask what other demands are being placed on the system, like charging a large house battery bank, running a mini-split or large inverter, etc.
The other consideration is how much fab work someone is comfortable/capable of doing, since there really isn't a plug-n-play option for replacing the 50DN. Depending on how you mount the replacement, there will be need for new brackets, belts, etc. plus some wiring changes.
If I ever get a second bus and it's unknown how long since the 50DN has been serviced, it will be on my list of first-round items to be serviced/replaced.
Quote from: richard5933 on January 13, 2021, 04:30:29 AM
Wouldn't the HP consumed by the 50DN be in direct relationship with the load on it? I understand that spinning an idle alternator takes some power, but certainly not 5-7 HP. I just ran some numbers through an online amps-to-hp converter and it came up with 7 HP to make approx. 270 amps @ 24v.
Whether someone 'needs' the 50DN really depends on a few things, like are they running the OTR heat or a/c. With the OTR a/c it's pretty much necessary to have that large of an alternator. You also have to ask what other demands are being placed on the system, like charging a large house battery bank, running a mini-split or large inverter, etc.
The other consideration is how much fab work someone is comfortable/capable of doing, since there really isn't a plug-n-play option for replacing the 50DN. Depending on how you mount the replacement, there will be need for new brackets, belts, etc. plus some wiring changes.
If I ever get a second bus and it's unknown how long since the 50DN has been serviced, it will be on my list of first-round items to be serviced/replaced.
The v drives in buses are the toughest to convert to a belt drive something is always in the way and are limited with out replacing the drive for the 50D ,Richard my Delco manual says the draw is 5 hp at idle your 7 hp at 270 amps at 24v is spot on with the manual for the oil cooled 50D,anybody with a belt drive 50D on a MCI can hear the engine change when a 50D kicks in at idle
When we finally abandoned our air cooled 160A pos. grnd. generator. We revamped its carcass (housing) as an accessory drive for the new air cooled two belt drive 200A alternator. It has performed flawlessly for a few years now.
If you have an isolater charging 8 8d lifelines and otr ac a 50dn is pretty much a necessity- fwiw
I certainly treat mine with like a baby, as I could not imagine having to remove the damn thing. It weighs more than I do.
if you have most of the original equipment then you likely need the same power as the original so 7hp is 7hp. My point is with all that gone. no OTR AC, no seating with overhead lights, no 8D batteries. Really not much to power except headlights and charging the battery which are standard group 31 that charge up almost as fast as a regular car battery.
I don't plan on doing it but, it would be fairly simple to get a read of amps being pulled with the stuff on. With the OTR AC gone, there is a free spot on the pulley and the brackets could be easily adapted for a much smaller alternator.
I know them things weight a ton but it would be easiest to unbolt it and take a look at it's condition. oh yeah - just like the maintenance states. lol
I can say with certainty, the alternator does not use the same HP all the time. Go ahead and adjust the voltage and you'll hear the engine unload. Then on the other side when my Two ACs turn on and the inverters kicks in I can hear the engine load up some more.
I know it uses power, my best MPG was always spring trips when AC wasn't required. I just don't buy it robbing 7HP just spinning the armature.
Sometimes my solar takes over and I get the nogen light.
Quote from: neoneddy on January 14, 2021, 07:36:04 AM
I can say with certainty, the alternator does not use the same HP all the time. Go ahead and adjust the voltage and you'll hear the engine unload. Then on the other side when my Two ACs turn on and the inverters kicks in I can hear the engine load up some more.
I know it uses power, my best MPG was always spring trips when AC wasn't required. I just don't buy it robbing 7HP just spinning the armature.
Sometimes my solar takes over and I get the nogen light.
Any gear driven assertories takes HP you guys would faint if knew how much HP a blower on the 2 strokes uses up
Right, any friction / load of any kind takes HP. My point was the parasitic HP draw is not always 7 HP. I'd buy it being 7HP at the top or middle ground, but if the batteries are full I'd suspect the load is closer to spinning the armature alone.
Set it up to not charge on grades to lessen draw when the hp is crucial.
Set it up to not charge on grades to lessen draw when the hp is crucial.
I've thought about wiring a remote potentiometer up to the drivers area to do exactly that. Sometimes I get situations where my solar system will not kick in because the mighty 50DN can keep voltage above float while pulling in 4000 watts to the domestic side. I could turn down the juice for a bit to get the solar chargers to start trying to get to absorb, and save fuel. In this why I consider my bus to be a hybrid vehicle.
Maybe a heat sensor in the exhaust or a an adjustable map sensor in intake with some delay before re-engaging to take into account short power demands. I'm sure something could be worked out.
on the MCI at the start batteries I put a latching solenoid in that I could turn off so that the engine alternator could not charge the house batteries . worked great
dave
This might be overly simplistic, but why not keep the engine and house systems separate? The power distribution system maintains my house bank 24/7 so I don't see a need to mess with the engine system.
Quote from: daddysgirl on January 15, 2021, 06:51:18 AM
This might be overly simplistic, but why not keep the engine and house systems separate? The power distribution system maintains my house bank 24/7 so I don't see a need to mess with the engine system.
I'm not sure on your setup for power distribution.
I don't like to run my generator while driving. Although with my new to me diesel, I may run it to help keep engine temps in check.
I'm all about redundancy, I could lose solar and generator and still have house power. I could lose my alternator (as long as it doesn't seize and kill the engine ) and get home on solar or generator.
We have chassis & house banks separated but can literally swap them, combine them or use either of them. Each have their dedicated solar inputs. We like redundancy as all our appliances/utilities are redundant also.
When we first got our MC8 and installed the inverter we had an 8V71 with a belt drive 50D and the first time I turned on the roof top AC it scrambled the four belt set. I bought a set of 8 to replace the four and keep a spare set. Now that I have the L10 and a 300 amp 24 volt alternator driven by a serpentine belt it is no longer an issue and I have the alternator connected to the house battery bank. As daddysgirl said keep it simple. I have switch by the dash that connects the house bank to the start bank and connect the two to keep the start batteries charged. That much charging is not necessary to keep the diesel running down the road it is only required for all the extra stuff that draws electric for lights and such. Just like Scott says a small 24 volt alternator will keep up just fine for the motor systems. I like the big alternator for my 4024 inverter and AC while traveling.
Melbo
Man I really like the big 24v 50dn I have but I did not realize it can blow up like that.
The plan is to charge a 500ah Lithium bank which will put stress on it. I figured the stress it was under supporting the 4905 AC it came from is similar.
Would adding the external oil line would be a good preventative?
Quote from: fortyniner on January 16, 2021, 03:39:25 PM
Man I really like the big 24v 50dn I have but I did not realize it can blow up like that.
The plan is to charge a 500ah Lithium bank which will put stress on it. I figured the stress it was under supporting the 4905 AC it came from is similar.
Would adding the external oil line would be a good preventative?
I believe you have to pull the alternator to install the kit for the extra oil line. Someone can correct me if I'm wrong on that, but if you do need to pull the alternator it makes sense to just put in a newly rebuilt one and not have to worry about it for another 100,000 miles. Only way it makes sense to install the kit is if your alternator is fairly new, but if it were fairly new it would likely already have the second oil line.
The drive end bearing was updated also. Pretty sure the gear failure was caused by drive end bearing failure causing enough radial play to strip, break and cause gear failure. Better bearing plus more oil. That alternator was used on thousands of city busses also. There is an adjustable mounting spacer between alternator and engine rear housing. The spacer has small screws to ensure the gear mesh between cup drive gear on engine and driven gear on alternator is concentric. There is a procedure to ensure this is aligned properly in service manual.
I should have included the bearing tech sheet with my earlier post. Here it is. I think this is what chessie4905 is talking about.
The gear drive 50D was just used on the V drive engines till the late 70's before they were used on T drives maybe they like being tilted better,they have 3 different drives for those also the step down drive is the worst of the 3
Quote from: neoneddy on January 15, 2021, 07:02:38 AM
I'm all about redundancy, I could lose solar and generator and still have house power. I could lose my alternator (as long as it doesn't seize and kill the engine ) and get home on solar or generator.
In the last 60 miles when I was first getting my bus home, I had to throw a small generator and 24v battery charger to supply power to the batteries. I ran this to get the bus home as the air system was freezing causing the charging system to stop working.
At the time I was not thinking of any catastrophic alternator failure taking out my engine. I did not even know if charging the batteries this way would start the damn thing of fire or not. All I knew was that it was about 40 below, about 11:00 at night and I was not going to pay for a tow truck.
All worked out in the end. The generator ran out of gas just outside my shop door.
Where there's a will there is a way... :^
Quote from: luvrbus on January 17, 2021, 06:51:20 AM
The gear drive 50D was just used on the V drive engines till the late 70's before they were used on T drives maybe they like being tilted better,they have 3 different drives for those also the step down drive is the worst of the 3
The V drive engines had three different alternator drives? What is the step down drive exactly?
One of the different drive ratios may have been for the 6v-71 or some other application. I have two alternator gears that have 3 less teeth on them.
I still have the OTR AC, so we retained the 8D's with the 50D on the engine side.
For the house, I have a 90A converter charger that has AC, DC and three charging levels to keep the batteries charged.
For whatever reason, we never connected the house bank to the engine bank, but I could run a transfer switch easily enough if I needed to.
I wonder if the higher amperage alternators fail more often. I think mine is 270amps but Ive seen them as small as 240 amps and as large as 500. That said I have had three 4106 and the according to records the alternators on two of them were repaired due to low output. No actual gear failures and one bus had over 900k on the clock.
Quote from: fortyniner on January 24, 2021, 03:34:45 AM
I wonder if the higher amperage alternators fail more often. I think mine is 270amps but Ive seen them as small as 240 amps and as large as 500. That said I have had three 4106 and the according to records the alternators on two of them were repaired due to low output. No actual gear failures and one bus had over 900k on the clock.
I spoke with a tech at https://www.elreg.com/ (https://www.elreg.com/) about the 50DN alternators recently. Part of the discussion was about the newer high-output versions of the 50DN which are being used in some newer coaches due to the amount of load being placed on them. He told me that while a 270-amp version can last 100,000 miles or more without service/rebuild, the high-output versions will require service much sooner. My guess is that the higher output results in higher temps, and higher temps are not good.
When your alternator was repaired, do your records show exactly what was done? If the bearings were not replaced over 900K miles, that would be something I'd be doing pretty soon.
I believe it said "rebuilt alternator" and cost over $600 (1990). I pulled it and the gear looks nearly new.
.
Subsequently I replaced it with one from a 4905 for 24v conversion. That one has no records but gear looks very good condition at least.
Still I think Ill snag a new one just for peace of mind before running around this summer.
It's not the gear in the alternator that's the main culprit from what I understand. It's the bearings failing and causing the alternator to seize up, thus causing destruction of the gears in the engine which drive the alternator. Or destruction further down the line in the engine if the gears hold out for a moment or two before failing. Someone with more direct experience can hopefully spell out exactly how these things fail, but the bearings are a main piece of the equation and that's why they added the second oil port in them at some point.
The new Prevost H3-45 coaches have 2 24V at 150A or 250A alternators. MCI J4500 have 2 24V at 250A. All belt driven. They power all the usual stuff, plus the electric fans on the radiators these last few years.
Look carefully in a Prevost, some have 3 alternators hung all over the Volvo powerplant.
There were add-on small "get home" alternators being retrofit by some fleets, on the electronic coaches with only the single big one.
It would keep the drivetrain functional, in the case of a traditional alternator failure.
That voltage in the batteries slips to that magic point... better have a warm coat, hat and boots...
Happy coaching!
Buswarrior
Sometimes it is difficult to mount one belt driven alternator on a GM V-drive. Can't imagine trying to mount 2 or 3.
Hmmm. for the high output alternators adding a little power steering cooler in the oil supply line might help. Kind of hard to cool with 180 degree oil. Is hot oil one of the issue with the bearing or just lack of reliable lubrication (old style alternator).
Delco found issues with life of old design over time and upgraded it, including extra oil line. Conjecture here now, but fast idle with heavy charging mode and lower oil pressure and less oil cooling was probably causing more bearing wear. More robust bearing design plus oil line added to that new design setup took care of the issue. If you check their site, the new 450 amp belt driven version uses that same additional oil line.
They do list service intervals for that alternator in their manuals.
Bearing starts wearing out like a front wheel bearing, gets sloppy. Allows excess slop at gear and cup drive to the point some teeth break and catastrophic failure. The basic design of the overdriven gear unit is fine. Been used in millions of automatic transmissions for decades with great reliability. Only important item is to be sure the alignment procedure is correct. The instructions are in the shop manual.
I had one 50d the casnio owned in a MCI 12 their mechanic installed from a rebuilder the rebuilder didn't punch lock the nut on the drive gear on the 50D and the mechanic didn't either, the nut came off and fell into the gear train I all got to use was the block .alignment is very touchy and take times to get it right if not it's going to break something
sort of like of tune up on the engine and not following factory directions.
Reading this thread has me worried. Anyone know if a 1996 mci 102dl3 with a 12.7 series 60 has a belt or gear driven 50d? I would go out to my storage lot where it's parked but it's buried under 13 feet of snow and it's -20 degrees wind chill today?
Most likely same as mine it's a 99
I never saw a gear drive 50D on the series 60 all were belt drive oil cooled.they have enough problems with the bull gear to start with
I dont think the 60 series has many locations for any gear drive accessories.
Quote from: chessie4905 on February 09, 2021, 04:16:28 PM
I dont think the 60 series has many locations for any gear drive accessories.
The series 60 only has 2 locations,nothing drives from the rear only the front ,with belt drives the accessories are endless not like gear drive
So for the 50D with a belt I don't have to worry about it destroying my engine if it quits?
Quote from: luvrbus on February 10, 2021, 03:37:18 AM
The series 60 only has 2 locations,nothing drives from the rear only the front ,with belt drives the accessories are endless not like gear drive
Quote from: Jcparmley on February 12, 2021, 12:03:13 PM
So for the 50D with a belt I don't have to worry about it destroying my engine if it quits?
Nope all it will cost you is a belt
No problem with belt drive, but you have the bull gear to worry about instead.😲
Quote from: chessie4905 on February 12, 2021, 03:38:24 PM
No problem with belt drive, but you have the bull gear to worry about instead.😲
Only at around 750,000 miles Chessie 8)
Well I'm at 450k I'm wondering how long the b500 will last but I'm not worried besides that
Quote from: 6805eagleguy on February 12, 2021, 05:31:29 PM
Well I'm at 450k I'm wondering how long the b500 will last but I'm not worried besides that
B500's will last if you stay off the retarder mine had a retarder that was never used I used only the Jake brakes
Well looks like I'm fine then I don't have a retarder jakes are just fine for me ;)
Quote from: 6805eagleguy on February 12, 2021, 08:32:42 PM
Well looks like I'm fine then I don't have a retarder jakes are just fine for me ;)
Stock pile some drop boxes for the Eagle or have the series 60 reprogramed for less torque in 1st and 2nd gear they will do a number on a drop box,the C-15 Cat is even worse I have pallet of drop boxes from Mel's (rip) Eagle
Yes, that may be a need, it's set at 430hp 1600tq which is more torque then most busses I see...
Feels nice on hills tho :D
Although it is the base engine with the small turbo and injectors
We have a crane at work with the 11.1 it makes 350 hp 1800tq... that's a lot of torque! :o