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DN50 replace
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Mike: let me see if I understand your coach. One alternator driven by the Detriot Diesel that charges both your house and chassis batteries.
If that’s the case, you might have an isolator so the chassis batteries can’t back feed into house batteries and Vice versa. That’s what we have on our 99 Liberty with a single alternator that charges both the house and chassis batteries. One comes from the alternator to the isolator. Then separate outputs to the house and chassis batteries.
Our isolator failed. It charged the chassis batteries fine, but nothing for the house batteries. Find the isolator, fire up the DD, check i incoming voltage from the DD alternator and each of the outputs. I suspect one output side is dead. If so, replace the isolator.
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My Bus has two alternators Both 24 VDC. One is the Engine Mounted 50DN, and the second is a pulley driven under the AC Compressor. My Country Coach Build sheet shows a 12V Pulley driven, and my Prevost Build sheet shows the 50DN. I have one vanner, there was originally 2, open space for the missing one, and I do have a 12V Delco Remy Voltage regulator also. The only thinng i have confirmed as of right now is the Pulley driven Alternator is putting out 24 VDC. I am interested in finding a schematic or some document, or someone that has a bus around my vintage showing how my bus should be configured, I also know for a fact I do not have 12 VDC on the 2/0 cable coming into my house Batteries. That wire is labeled and it measure 0VDC with the engine running.
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I am hoping someone out there has a bus similar to mine for comparison.
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Correct me if I’m wrong. It is my understanding that on the 8V92 the 50DN is gear driven and in a difficult location to work on?
If that’s true? I wouldn’t be surprised if a “smarter than the average bear” previous owner did as you describe. 🙁 -
Mike may not help – but another configuration to ponder. Mine is 96 (95 chassis) Marathon OTR A/C coach.
One 24V 50DN for everything. 3 Vanners – 100A above chassis batteries, slightly smaller (60A I think) RH side of rear electrical box, and a third 100A on fwd wall of 1st curbside bay where house and gen start batteries are.
No “isolator” in traditional sense, this has a Kilovac high voltage relay. 2 large terminals, one has main charge cable from 50DN and chassis connection. The other terminal is house connection.
Two small sets of trigger wires, guessing one is signal that alternator is producing power and triggers relay connecting ALT and CHASSIS to HOUSE. The other set likely performs the “jump start” function using same relay.
I do have an isolator between house batteries and gen start batteries which are charged thru house bank.
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Don, The previous Owner had the bus for 18 years and other than Diesel fuel put no more than a nickel into it. I could sense this when I looked at it, and I bought it knowing i had a lot of work to do. I am not complaining, I wanted a Hobby that would give me endless work to keep me busy. I am just trying to get it back to where it was originally.
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Billy, Yes, I think the best thing for me to do at this point is go thru the Prevost 24/12VDC Charging circuit and trace all the wires (as much as i can) and document everything as best as I can. If the 50DN is bad, it needs to come out thru the bedroom floor. I need to pull the access plate to get at the terminals to check voltage when the bus is running, Priority #1. From what I can tell Country Coach had Prevost Install the 50DN and one Vanner for the Prevost 24/12 VDC Country Coach installed a Belt driven 12 VDC Alternator for the Chassis 12 Volts. What the second Vanner did, I have no idea, maybe there were two in series for the Chassis 24/12 VDC? I am going to Quartzsite at the end of the month for a few days to give the Bus a 600 mile shakedown, hopefully there will be some early 90’2 Vintage XL’s there. Thanks for everyone’s input.
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A 50DN on an 8V92 can be removed from beneath the coach. The coach needs to be on a lift.
Unbolt it, use the bell housing as a support until you can get it balanced on your hands and shoulder and lower it down. It helps immensely if someone can raise and lower the bus as needed.
If you opt to take it out from above you literally have to line the coach interior with a lot of plastic drop cloths because a lot of oil is coming out of it.
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Thanks Jon, Let’s hope it still puts out 24VDC and removal won’t be needed. I am going to be investigating and documenting my findings regarding the Chassis and House charging systems from the Detroit side this weekend. All other charging systems work as intended.
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For those of you that have removed your 50DN gear driven Alternator, 1) Have they been driven off the Blower drive or one of the accessory drives? 2) Do you have any pictures of what the drive mechanism looks like?
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It has been too long ago for me to remember details, but I do remember when reinstalling it there was a specific procedure. It should be described in the Detroit Diesel manual.
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Ok so far today, I can confirm my belt driven alternator (below the AC compressor is a 24 VDC Alternator, the red cable runs to the alternator to the starter, then another cable runs up to the Klixon breaker, then onto the disconnect. So it is looking more and more like the previous Owner had an issue with the 50DN and instead of looking at the issue, they swapped out the 12 VDC alternator with a 24 VDC for the Chassis.
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Jon, When i first brought the Bus home, one of the first things I did was pull the oil pan to see what i might find. See the attached picture, This is an accessory drive gear made from Phenolic or Bakelite and is used on the 8V92. I reconstructed the pieces as shown. I wonder if this was from the 50DN drive mechanism, it broke the found it’s way down into the oil pan? Is this the drive gear for the 50DN?
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Next Weekend I am going to remove my Delco Remy 12Volt 50DN Alternator and see if the the fiber coupler is the one i found in the oil pan. My engine is an 8V92, Alternator is mounted above the transmission to the Blower accessory drive. Are there any shops around I can send this alternator to?
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Mike-
Have you reached out to Premiere RV in Oregon?
My understanding is they are in the original Country Coach factory facility, and many of the people working there worked for CC back in the day. They may have records of the builds they did on Prevost conversions.
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