Usually that’s a gm problem. This is the only mci i have ever worked on with a gear driven alternator. They always have air tensioned belt drive alternators
@@BusGreaseMonkey I was always going to get you a couple of these alternators. I have a gear driven one from an MCI 8v71, and a belt driven one from a Prevost XL series 60. If I ever get down your way, I’ll drop them off. When you were up in Minnesota at Stan’s shop a few years ago I tried to get up there but it didn’t work out.
@@BusGreaseMonkey I took the 50dn off my bus (1995 Prevost xl series 60 Detroit) and replaced it with a duel setup 140 amp 24 volt Bosch and a delco 200 amp 12v for my house batteries. I took all the bus HVAC out except the front defrost and air
The folks that own these buses are really Fortunate to have a company like yours to repair and inspect them. If I owned one of these buses, yours is the only place I would bring it for service. .Keep up the great video's please.
I used to rebuild Delco and Leece-Neville starters and alternators when I was younger in Atlanta. This is a very interesting topic to me. Thanks for letting us watch.
Ah the joys of oil-cooled motors & generators. Great when they are running well, but oh dear me, how messy when they stop, particularly with gear/shaft drives. Last one I worked on suffered a winding failure which seized the machine (at least there was a shear-pin in the drive shaft so the diesel didn't break). We drained the oil and copper filings from the machine before stripping it using filter pads to collect the debris (we did a full failure analysis as there were several similar failures at the same time), then wash the residue out (more bits of copper). Finally located the source of the failure - incorrect taping and balancing of the windings leading to the rotor hitting the stator, the debris caused a bearing to fail and, as they say, the rest was history. A batch of about 80 generators was recalled (or at least those that hadn't destroyed themselves) and all were found to be heading down the road to destruction.
Also you are so correct about that bearing. I had a Jabsco pump on the back of a 4 71 that was missing a little bearin retainer for when it does go bad. The gear drive does not like ball bearings. Not one bit.
found it,was in community section.wife ill and my brain is frazzled.further look at that debris in pan tells me internal damage to driven gear in engine.those are pieces of gear teeth.ruh oh.as said if they arent lined up this happens.now theres your meow mix from engine.memories from my days at domenico tours .
I have overhauled several 50 DN units , on large motor homes. I built a jig for my tester to run it up for testing. It’s an interesting unit, oil cooled high output. I haven’t seen one in a while.
Man that is lucky. Though Scott I hate to go against your thought but I would be extremely hard pressed to be convinced that melted aluminium is the cause of the failure and whatever shorted it out either damaged or welded a ball or 2 in the bearing and came apart. That's all too much damage and fresh looking enough to be coincidence and whatever happened isn't on the hot side of the system. There's a massive ground issue and the oil line became a high current ground
"A bunch of screaming cats" is never a sound you want emanating from your engine bay. It would make sense that the bearing behind the drive gear should be a tapered roller to handle the radial loading force of gear mesh, once the ball cage is deformed and spit out, it's game over.
Aah nice one, yes that might indeed have happened. Arcing digging pits in the ball bearings, grease flowing out and BAM. Why you should never weld broken equipment with bearings still in them.
He was very lucky. Do you think the drive gear on drive train is centred in the housing? Maybe putting side stress on alt gear? The damage at the oil fitting looks like the 24v lug broke off one time, and was bouncing and shorting on case.
I know what happened. The cable rubbed thru, arced, grounded out and deposited a small piece of metal in a small gap somewhere inside the alternator and eventually made its way to thru the bearings and ruined it.
That rebuild alternator looks sus specially with all that red rtv silicone. That is also one lucky bus owner only a inch away from a total catastrophy.
Is there a work around to put a regular belt driven alternator on there to get away from the possible gear train damage or is it even necessary? I assume that style of alternator must be pretty reliable or you wouldn't be putting it back to stock.
Goddamn do I hate that wrestling the alternator through the side door bullshit. Laying on your stomach over the corner of the hatch trying to wrestle that thing back into place. Nah, glad Im done with 2 stroke buses.
I wonder if the electrical current flow due to the short might have caused damage to the bearing. I have seen the same type of things happen on motors that have low insulation resistance, current passes through the rotor back to earth through the bearings and basically ruins the surface of the bearings.
That’s the biggest alternator I’ve ever seen! You deal with these vintage busses all the time. Is it common for owners to ignore routine maintenance? Knowing the age of these busses I would think owners would be more interested in the condition of their investment. Seeing the alternator wiring patched together like that would drive me nuts.
There are so many items to maintain and it’s almost a full time job keeping up. Having that alternator replaced three years ago if should have been good for quite a while.
If I am thinking right a taper roller bearing takes on side thrust way better than a ball bearing. Hopefully that ground up metal is in the filter. Thanks for the upload
Most common in that Location is a Cast Iron Bearing Housing that Bolts onto the Accessory Housing Inside is a Male Gear ⚙ that slips inside a female Gear ⚙ as a Connecter to the Gear train. On the outside is a Double V Pully that Belts run to the Alternator....
To me it looks like a high ampere current flowed through that brass fitting and into the aluminum case, or just the opposite. The brass fitting was better able to handle the heat from that high ampere current so the aluminum around it melted.
The ball barring moving created friction, the will draw energy to it. The wire short pulled the energy to the bearings. They got electric hot. The heat melted the contact location, look for pitting on the alt flange lip. The engine to alt will show ark pitting. Also.
I bet it failed because the tapered roller bearing wasn't on the correct side. I bet that eroding happened because whomever installed it didn't disconnect the batteries before putting a wrench on it and grounded out on the case while hooking the power wire back up. 🤣
Well, the wire looks smooth, not molten. Kind of would expect the heat melting the wire insulation... There is only abrasion marks and no signs of fire. If that starter aluminum housing melts it needs at least 900 Celsius grades. On the other end of the arc would be the wire and its insulation. Anyhow. Everything is possible. But it looks like someone tried to do some repair with something not suitable...
I’m assuming that since my seven has a generator still, I don’t have to worry about this problem. Correct me if I’m wrong. That bus would look a lot better if it had a red, blue stripe and a dog on the side.
@@BusGreaseMonkey Yep mine is belt driven, but I did not know it was in fact a alt. Funny you said in the video that he did not have a not gen light. From what I've understood in the short time I've been a bus guy, is that having a not gen light illuminated is almost "normal" on Mci's of that time frame. Some of the guys on the bus monkey site said just turn on everything electrical you can and most the time it will put it out. Makes me wonder if it's getting an overvoltage. My light cycles on and off for a while then it stays on.
Is there was some sort of early warning situation for this type of failure? Besides just pulling it at 80-100k and having someone rebuild a perfectly good one and possibly screw it up for you? This is one area of concern on my bus I haven’t been able to address.
You said you think there would be a fuse. I’m betting the original red and black wire that was spliced had a fuse link in the wire and burned up previously. My guess anyway.
As for the black and red being flip flopped at some point, some of the early regulators were set up to control the ground side of the field. It may have been switched to a regulator that controlled the positive side. The negative side regulators are not readily available anymore so most set ups have been converted to positive side control.
Looks to me like a very incompetent individual worked on the bus. In fact most likely 2 individuals. One that used a piece of red wire to replace some missing black wire twisted together and black taped and not secured correctly to avoid that short. Another that rebuilt that unit and installed the beerings incorrectly. From the look of the design ball beerings would be a really bad idea in that position even if they're sealed bearings.
The mysterious Arc marks may have been from someone before removing the battery cable and touching it accidentally? Idk what I'm actually looking at. Lol
@@BusGreaseMonkey wow, had to be that shorted wire then! Crazy it wasn't enough to melt all the insulation off the wire. Would adding a fuse right off the ring terminal be benificial? Or just secure the wiring properly?
Hey Lance………… Ah no, not today, it’s now…… Hey Don!!! This is NOT the video I wanted to see right now!! Especially at 3am, cause now there’s absolutely no way I’m gonna get back to sleep at all!! This is the exact same problem I’ve got on my 82 MC9 with the 8V71. Yep, I did get ROOKED by the church, just like I thought. I just bought this bus and the entire day I was there looking it over, I started it 5-6 times and drove it a couple times, walked around it checking all the lights and they were burning good from what I could tell but it was still light out at the time. I did not have any warning lights on the dash for no-Gen, or anything else. The bus was running great, as it should for the engine only having 10k miles since rebuild but that was about ten years ago when it was done. I finalized the transaction and was giving things in the cockpit one more good looking over before I was gonna leave and I noticed the amp gauge on the dash was in the yellow and reading approximately 22amps which is extremely low for a 24 volt system so I said something to the church Deacon that I had been dealing with through out this entire process and I asked him again if they had been having any charging issues cause the amp meter was reading low and he once again stated that no, they had Not had any charging issues, had not had to ever charge the batteries at all unless they had forgotten to shut off the main battery disconnect, which is fairly common on these, but the lights seemed to be burning good, and it had started fine all day giving me no indication that the batteries were not charging and especially the fact that I did not have the “No-Gen” warning light illuminated on the dash panel. At this point, I was thinking that it was completely possible that I had a faulty gauge. I’m a. Old jet engine mechanic from the Air Force and that happened to gauges all the time and nothing e was indicating, without actually putting a meter on it to see what it was producing but since I flew to Florida to look at it , I was limited on what tools I had I made the decision, after being told by both the church Deacon, as well as the pastor himself, numerous times that the bus had just come out of a complete and thorough, top to bottom, inspection to be sure it was road ready and had no issues and was ready for a cross country trip except for the air conditioning. I made it about 40 miles down the road and I lost all lights cause it was apparent by now that I had generator issues. Long story short, I managed to limp her the 500 miles home by having to jump start her each morning, which for jumpstarts for three mornings I accrued $800 in jump fees which I feel like I got raped over but I had to get home. I have not torn into that part yet because I’ve been trying to research it to find ouT what the issue was cause the no-Gen light not being illuminated on the dash was throwing me off but this video pretty much explains it all right now. Scott, when you say this is an engine killer, what do you mean exactly? What other indications do I need to look for that I have bigger issues? I have not driven the bus since I got her home until I could figure out what’s happening. The oil looks good so far and I don’t have any screaming cats back there when I have started it a couple times. Is this simply gonna be a generator change or what am I looking at? I was gonna try and schedule a visit with you guys this summer when you could get me in an I am a patreon member but it sounds like this may be something a bit more critical than being able to wait if I’m in danger of trashing the engine. Please Scott, advise me what to do here brother! This video now has my stomach wrapped up in knots! But at least this explains my situation and what has happened, now I just need to know how to proceed. Thank you Scott for all you Kelli, and Tyler do to help us keep these buses on the road.
The direct gear drive alternator can destroy an engine if they fail. Yours is maybe not gear driven but if it is not belt driven and it’s not working i would recommend finding out what’s wrong and inspecting the alternator. Usually a non working alternator is not to big of a deal to fix or get working.
@@BusGreaseMonkey the one on my engine tho scott is identical looking as the one you pulled off in this video. It is located on the very back left side of the engine and is directly below the access hole in the floor at the very back of the bus. It is not belt driven at all and is huge. I’ll call Luke today to see if he’s got one that matches it. Thanks Scott
Well, from a strictly electrical perspective, the back section of the alternator has the six rectifier diodes that are wired up for a 3-phase AC -> DC conversion. (Visible in this video at 8:05...3 are up on top, going to the output wire; the other 3 bolt directly to the alternator frame.) The problem is that the 50DN alternator is rated for 270A. Rectifier diodes will easily drop 1.2v each (or more, depending on their spec!) at such currents...and due to the 3-phase rectifier method, power is always going through at least 2 diodes (positive and negative output). This means that at full load of 270A * 2.4v loss (1.2v per diode) = a happy 648W of heat dissipation in the back section of the alternator alone. (Yes, to be technical, this does get spread out evenly across the diodes on all 3 phases, so technically each diode has to dissipate ~108W.) I always like to compare heat dissipation to a soldering iron...a 25W soldering iron can melt solder. Imagine a similarly-sized diode being responsible for 4x that power: without oil cooling (or LARGE heatsinks!), these diodes will melt VERY quickly under load!
Where are you fellas located I’d like to start using you for my repairs. I have a 1995 Prevost XL and a 2003 H3-45. Both always need something. If I could acquire a phone number and/or email with location I’d surely appreciate it. I’m worn out with repairing, driving and I just wanna do the singing from now on. Thank you GT
What a dumb design, same level as modern timing belt engines that can destroy the entire thing just from snapping a belt. How about a shear pin?? EDIT, just for some sick lulz, inspect the ball bearing for electrical arcing (pitting).
That’s one lucky bus owner. I did a LOT of those in my day. I only had one drive take out the gear train in 43 + years of working on buses.
Usually that’s a gm problem. This is the only mci i have ever worked on with a gear driven alternator. They always have air tensioned belt drive alternators
@@BusGreaseMonkey I was always going to get you a couple of these alternators. I have a gear driven one from an MCI 8v71, and a belt driven one from a Prevost XL series 60. If I ever get down your way, I’ll drop them off. When you were up in Minnesota at Stan’s shop a few years ago I tried to get up there but it didn’t work out.
@@BusGreaseMonkey I took the 50dn off my bus (1995 Prevost xl series 60 Detroit) and replaced it with a duel setup 140 amp 24 volt Bosch and a delco 200 amp 12v for my house batteries. I took all the bus HVAC out except the front defrost and air
The owner was very lucky
Rest of thing’s looking kinda sketchy
Owner needs to up his game on prevention maintenance maybe
The folks that own these buses are really Fortunate to have a company like yours to repair and inspect them. If I owned one of these buses, yours is the only place I would bring it for service. .Keep up the great video's please.
I used to rebuild Delco and Leece-Neville starters and alternators when I was younger in Atlanta. This is a very interesting topic to me. Thanks for letting us watch.
Ah the joys of oil-cooled motors & generators.
Great when they are running well, but oh dear me, how messy when they stop, particularly with gear/shaft drives. Last one I worked on suffered a winding failure which seized the machine (at least there was a shear-pin in the drive shaft so the diesel didn't break). We drained the oil and copper filings from the machine before stripping it using filter pads to collect the debris (we did a full failure analysis as there were several similar failures at the same time), then wash the residue out (more bits of copper). Finally located the source of the failure - incorrect taping and balancing of the windings leading to the rotor hitting the stator, the debris caused a bearing to fail and, as they say, the rest was history. A batch of about 80 generators was recalled (or at least those that hadn't destroyed themselves) and all were found to be heading down the road to destruction.
Hey Scott, this was a great video that helped me with my 50d generator issue on my MCI. Thanks Scott!!
Also you are so correct about that bearing. I had a Jabsco pump on the back of a 4 71 that was missing a little bearin retainer for when it does go bad. The gear drive does not like ball bearings. Not one bit.
I've never seen THAT before! Good grief... Thank goodness they found BGM! Be well, be safe!
That burn up spot on the alternator was probably caused by the original wires that were replaced with that new red wire
found it,was in community section.wife ill and my brain is frazzled.further look at that debris in pan tells me internal damage to driven gear in engine.those are pieces of gear teeth.ruh oh.as said if they arent lined up this happens.now theres your meow mix from engine.memories from my days at domenico tours .
Wow that alternator looks super heavy duty. I can only imagine what it costs to replace it.
Absolutely love hearing that big 2-stroke sing!
I have overhauled several 50 DN units , on large motor homes. I built a jig for my tester to run it up for testing. It’s an interesting unit, oil cooled high output. I haven’t seen one in a while.
Man that is lucky. Though Scott I hate to go against your thought but I would be extremely hard pressed to be convinced that melted aluminium is the cause of the failure and whatever shorted it out either damaged or welded a ball or 2 in the bearing and came apart. That's all too much damage and fresh looking enough to be coincidence and whatever happened isn't on the hot side of the system. There's a massive ground issue and the oil line became a high current ground
Original wire was probably shorting on spot ware red wire was stuck
"A bunch of screaming cats" is never a sound you want emanating from your engine bay. It would make sense that the bearing behind the drive gear should be a tapered roller to handle the radial loading force of gear mesh, once the ball cage is deformed and spit out, it's game over.
Me-Owwwwwch
If the bearing transmits the short circuit caused by the red wire,it will damage the balls and race,so cause the bearing failure.
Aah nice one, yes that might indeed have happened. Arcing digging pits in the ball bearings, grease flowing out and BAM. Why you should never weld broken equipment with bearings still in them.
@@Wayoutthere Go tell that to those pakistani boys. LOL...
He was very lucky. Do you think the drive gear on drive train is centred in the housing? Maybe putting side stress on alt gear? The damage at the oil fitting looks like the 24v lug broke off one time, and was bouncing and shorting on case.
As always, nice close ups.👏🏻👏🏻👍👍
I have had 24 volts blow the end of a large screw driver. I would not be surprised if it did that to aluminum.
I know what happened. The cable rubbed thru, arced, grounded out and deposited a small piece of metal in a small gap somewhere inside the alternator and eventually made its way to thru the bearings and ruined it.
That rebuild alternator looks sus specially with all that red rtv silicone.
That is also one lucky bus owner only a inch away from a total catastrophy.
Wow. That was a very lucky ball! Hate to think what the repair bill would have been if had not done what it did. Something different thats for sure.
Lucky Dog just being lucky..
what happened to the vid of debris found in the oil pan of this bus,left a comment .but wheres the vid
That bus owner is livin' right. Voof.
Is there a work around to put a regular belt driven alternator on there to get away from the possible gear train damage or is it even necessary? I assume that style of alternator must be pretty reliable or you wouldn't be putting it back to stock.
Goddamn do I hate that wrestling the alternator through the side door bullshit. Laying on your stomach over the corner of the hatch trying to wrestle that thing back into place. Nah, glad Im done with 2 stroke buses.
ABSOLUTELY----> AWESOME!!!!!!!!!!. 🙂
Electrolysis has been rampant
Guy has a couple horses in his back pocket. Thought for sure the mating ring gear was going to be destroyed.
Strange one there. Hilarious part is that something chewed up that aluminum bc it ain't a fantasy. 🚌 💨
Quite peculiar alternator issue 🧐 BGM investigator 🤓☮️
I love the hill climbs
Never seen one before ,I shure appreciate belt driven accessories more
What’s the reasoning behind geared alternator? Are some busses belt drive? Hopefully the wireing gets all sorted when the new alt goes in.
So many McGyver's working on buses.
I wonder if the electrical current flow due to the short might have caused damage to the bearing. I have seen the same type of things happen on motors that have low insulation resistance, current passes through the rotor back to earth through the bearings and basically ruins the surface of the bearings.
Yikes! Wow yeah that coulda even been worse indeed!
I think someone welded that fitting and hit the case with their chipping hammer tryna clean the slag off the weld.
Performance evaluation: Can you climb "Monkey Mountain"?
When you go to reassemble. Are you going to run the output cable. The relay and field wire thru at least a foot of fire sleeve or 1" heater hose.
A bunch of screaming cats in the engine bay - did he leave his wallet back there by mistake?
That’s the biggest alternator I’ve ever seen! You deal with these vintage busses all the time. Is it common for owners to ignore routine maintenance? Knowing the age of these busses I would think owners would be more interested in the condition of their investment. Seeing the alternator wiring patched together like that would drive me nuts.
There are so many items to maintain and it’s almost a full time job keeping up. Having that alternator replaced three years ago if should have been good for quite a while.
keep the clips coming
Yes....a BGM video..
MC-7? Very nice bus.
If I am thinking right a taper roller bearing takes on side thrust way better than a ball bearing. Hopefully that ground up metal is in the filter. Thanks for the upload
Glad this wasn't worse 😅
Propane welding stick?
Good job
Most common in that Location is a Cast Iron Bearing Housing that Bolts onto the Accessory Housing
Inside is a Male Gear ⚙ that slips inside a female Gear ⚙ as a Connecter to the Gear train. On the outside is a Double V Pully that Belts run to the Alternator....
When this bus was converted to an automatic they changed from a belt driven alternator to a gear driven one.
Good place for some loom lol
I'm surprised there's no shear pin anywhere between the engine and the alternator.
Could you please autopsy the rest of that alternator?
My guess is there's nothing beyond what you'd expect from an offset rotor. I'm only asking because it's a bus alternator /for interesting laughs.
To me it looks like a high ampere current flowed through that brass fitting and into the aluminum case, or just the opposite. The brass fitting was better able to handle the heat from that high ampere current so the aluminum around it melted.
What ever happened it’s probably good no one saw it or they might have pooped their pants.
The ball barring moving created friction, the will draw energy to it. The wire short pulled the energy to the bearings. They got electric hot. The heat melted the contact location, look for pitting on the alt flange lip. The engine to alt will show ark pitting. Also.
I bet it failed because the tapered roller bearing wasn't on the correct side.
I bet that eroding happened because whomever installed it didn't disconnect the batteries before putting a wrench on it and grounded out on the case while hooking the power wire back up. 🤣
I have a new one in a box as a spare!
Well, the wire looks smooth, not molten. Kind of would expect the heat melting the wire insulation... There is only abrasion marks and no signs of fire. If that starter aluminum housing melts it needs at least 900 Celsius grades. On the other end of the arc would be the wire and its insulation.
Anyhow. Everything is possible. But it looks like someone tried to do some repair with something not suitable...
Geez, that alternator is the size of a small transmission!
It almost weighs more than a Prius ;)
@@BusGreaseMonkey Actually, a Prius is probably lighter.
Is the battery door missing on the MC7?
It’s inside
I’m assuming that since my seven has a generator still, I don’t have to worry about this problem. Correct me if I’m wrong. That bus would look a lot better if it had a red, blue stripe and a dog on the side.
Even though your book calls it a generator it is in fact a 50dn alternator. But yours is most likely belt driven not direct gear drive.
@@BusGreaseMonkey Yep mine is belt driven, but I did not know it was in fact a alt. Funny you said in the video that he did not have a not gen light. From what I've understood in the short time I've been a bus guy, is that having a not gen light illuminated is almost "normal" on Mci's of that time frame. Some of the guys on the bus monkey site said just turn on everything electrical you can and most the time it will put it out. Makes me wonder if it's getting an overvoltage. My light cycles on and off for a while then it stays on.
Is there was some sort of early warning situation for this type of failure? Besides just pulling it at 80-100k and having someone rebuild a perfectly good one and possibly screw it up for you? This is one area of concern on my bus I haven’t been able to address.
Being it a DUMB design for a start, I'd inspect it for wear (on the bearings). Seems like it's not that hard to remove, just heavy.
Red looked freshly spliced to other wire??
We pulled electrical tape off it to see how if was connected. It was old tape
You said you think there would be a fuse. I’m betting the original red and black wire that was spliced had a fuse link in the wire and burned up previously. My guess anyway.
Yep, must be. 'Those annoying fuses keep blowing on me, gonna remove it.' etc.
As for the black and red being flip flopped at some point, some of the early regulators were set up to control the ground side of the field. It may have been switched to a regulator that controlled the positive side. The negative side regulators are not readily available anymore so most set ups have been converted to positive side control.
Jb weld?
Must have been on a side of the road fix on the wiring
Looks to me like a very incompetent individual worked on the bus.
In fact most likely 2 individuals.
One that used a piece of red wire to replace some missing black wire twisted together and black taped and not secured correctly to avoid that short.
Another that rebuilt that unit and installed the beerings incorrectly.
From the look of the design ball beerings would be a really bad idea in that position even if they're sealed bearings.
The mysterious Arc marks may have been from someone before removing the battery cable and touching it accidentally? Idk what I'm actually looking at. Lol
The bus owner says those melted bits were not like that when the alternator went on.
@@BusGreaseMonkey wow, had to be that shorted wire then! Crazy it wasn't enough to melt all the insulation off the wire. Would adding a fuse right off the ring terminal be benificial? Or just secure the wiring properly?
Hey Lance………… Ah no, not today, it’s now…… Hey Don!!! This is NOT the video I wanted to see right now!! Especially at 3am, cause now there’s absolutely no way I’m gonna get back to sleep at all!! This is the exact same problem I’ve got on my 82 MC9 with the 8V71. Yep, I did get
ROOKED by the church, just like I thought.
I just bought this bus and the entire day I was there looking it over, I started it 5-6 times and drove it a couple times, walked around it checking all the lights and they were burning good from what I could tell but it was still light out at the time. I did not have any warning lights on the dash for no-Gen, or anything else. The bus was running great, as it should for the engine only having 10k miles since rebuild but that was about ten years ago when it was done. I finalized the transaction and was giving things in the cockpit one more good looking over before I was gonna leave and I noticed the amp gauge on the dash was in the yellow and reading approximately 22amps which is extremely low for a 24 volt system so I said something to the church Deacon that I had been dealing with through out this entire process and I asked him again if they had been having any charging issues cause the amp meter was reading low and he once again stated that no, they had
Not had any charging issues, had not had to ever charge the batteries at all unless they had forgotten to shut off the main battery disconnect, which is fairly common on these, but the lights seemed to be burning good, and it had started fine all day giving me no indication that the batteries were not charging and especially the fact that I did not have the “No-Gen” warning light illuminated on the dash panel. At this point, I was thinking that it was completely possible that I had a faulty gauge. I’m a. Old jet engine mechanic from the Air Force and that happened to gauges all the time and nothing e
was indicating, without actually putting a meter on it to see what it was producing but since I flew to Florida to look at it , I was limited on what tools I had
I made the decision, after being told by both the church Deacon, as well as the pastor himself, numerous times that the bus had just come out of a complete and thorough, top to bottom, inspection to be sure it was road ready and had no issues and was ready for a cross country trip except for the air conditioning. I made it about 40 miles down the road and I lost all lights cause it was apparent by now that I had generator issues.
Long story short, I managed to limp her the 500 miles home by having to jump start her each morning, which for jumpstarts for three mornings I accrued $800 in jump fees which I feel like I got raped over but I had to get home. I have not torn into that part yet because I’ve been trying to research it to find ouT what the issue was cause the no-Gen light not being illuminated on the dash was throwing me off but this video pretty much explains it all right now.
Scott, when you say this is an engine killer, what do you mean exactly? What other indications do I need to look for that I have bigger issues? I have not driven the bus since I got her home until I could figure out what’s happening. The oil looks good so far and I don’t have any screaming cats back there when I have started it a couple times. Is this simply gonna be a generator change or what am I looking at? I was gonna try and schedule a visit with you guys this summer when you could get me in an I am a patreon member but it sounds like this may be something a bit more critical than being able to wait if I’m in danger of trashing the engine. Please Scott, advise me what to do here brother! This video now has my stomach wrapped up in knots! But at least this explains my situation and what has happened, now I just need to know how to proceed.
Thank you Scott for all you Kelli, and Tyler do to help us keep these buses on the road.
The direct gear drive alternator can destroy an engine if they fail. Yours is maybe not gear driven but if it is not belt driven and it’s not working i would recommend finding out what’s wrong and inspecting the alternator. Usually a non working alternator is not to big of a deal to fix or get working.
@@BusGreaseMonkey the one on my engine tho scott is identical looking as the one you pulled off in this video. It is located on the very back left side of the engine and is directly below the access hole in the floor at the very back of the bus. It is not belt driven at all and is huge. I’ll call Luke today to see if he’s got one that matches it.
Thanks Scott
I have a brand new 24v 50dn I will sell you at a discount to help you that will work for your girl
Diagnose the issue before buying one. Check the voltage regulator.
@@BusGreaseMonkey I second that. They’re a lot easier to replace and cheaper as well. I’ve got a few.
Why is this alternator oil cooled?
Well, from a strictly electrical perspective, the back section of the alternator has the six rectifier diodes that are wired up for a 3-phase AC -> DC conversion. (Visible in this video at 8:05...3 are up on top, going to the output wire; the other 3 bolt directly to the alternator frame.)
The problem is that the 50DN alternator is rated for 270A. Rectifier diodes will easily drop 1.2v each (or more, depending on their spec!) at such currents...and due to the 3-phase rectifier method, power is always going through at least 2 diodes (positive and negative output). This means that at full load of 270A * 2.4v loss (1.2v per diode) = a happy 648W of heat dissipation in the back section of the alternator alone. (Yes, to be technical, this does get spread out evenly across the diodes on all 3 phases, so technically each diode has to dissipate ~108W.)
I always like to compare heat dissipation to a soldering iron...a 25W soldering iron can melt solder. Imagine a similarly-sized diode being responsible for 4x that power: without oil cooling (or LARGE heatsinks!), these diodes will melt VERY quickly under load!
@@sidlori1592 The man knows his stuff. Believe me.
Where are you fellas located I’d like to start using you for my repairs. I have a 1995 Prevost XL and a 2003 H3-45. Both always need something. If I could acquire a phone number and/or email with location I’d surely appreciate it. I’m worn out with repairing, driving and I just wanna do the singing from now on. Thank you
GT
I’ve got a brand new 24v 50dn alternator for anyone who needs it for a great price to help out
Josh helped us with parts on the eagle Christmas bus job recently. He’s real.
@@BusGreaseMonkey thank you so much brother!
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What a dumb design, same level as modern timing belt engines that can destroy the entire thing just from snapping a belt. How about a shear pin?? EDIT, just for some sick lulz, inspect the ball bearing for electrical arcing (pitting).