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DN50 replace
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My Engine configuration looks like this:
Mounting Locations:
A= 50 DN
B= Tu-flo 750 Compressor
C= Vickers power steering pump
D= Blower accessory drive (unused)
E= Accessory Drive (unused)
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Today is the day. 50DN removal day.
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Good luck! Please post pictures of the operation…
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Yes, for sure i have pictures coming, I have everything disconnected, I will be removing the mounting nuts next. Soaking with PB Blaster since last night. I did discover the two bottom nuts were missing! Either they vibrated off or were not installed.
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Well, That wasn’t nearly as bad as I thought it was going to be. the 50DN is out!
Here is what i did.
1) All the work was done thru the access hole next to the bed.
2) Spray with PB Blaster
3) I scraped and cleaned as much as I could to minimize the debris
4) I disconnected the oil feed line
5) I shut off all the house batteries, and removed the field wire, power wire to the VR, and both Positive Battery Cables.
6) Using a 3/4″ socket I cracked the mounting bolts
7) I next put a strap around the alternator and shimmed up a board to take the weight off the bolts
8) removed the bolts
9) lifted the alternator out
10) walked it out the front door and placed it on the work table.
Now I see how the 50DN is driven. I have seen this gear drive before, just trying to figure out why this Behemoth didn’t put out 12 Volts. Easy Peasy.
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Now i need to make a temporary plastic cover to go over the hole so I can clean this area all up. I also wanted to mention, there six bolts holding the alternator on, 5 of them are 1/2″-13, there is one at 6:00 that is 3/8″-16. This one was rounded over, and one of the 1/2″-13 nuts was missing. I started to notice oil was getting on the side of the transmission, not enough to hit the ground. This is why. Once I get everything cleaned up i will make an aluminum cover and a gasket.
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Great info Mike. Thanks for sharing.
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I also need to plug the oil lubrication line, will do that tomorrow.
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Great job, glad all went well. Thanks for the pics.
2005 XL Thompson Coach
Rarely tow anything behind us.
Sold: 1993 Liberty that we loved for 12 years. -
Thank you, after going thru this process, it’s not really that bad of a job. The alternator is heavy, but with a little planning was very doable. I do have a couple comments that were questions of mine before I started. One was this notion of requiring a special tool to install a 50DN. I was unable to locate any information on this, and after looking at how the 50DN interfaces with the cam gear and flywheel housing on the back of the engine, I am not sure why you would need a tool or what it does. The 50DN has a large locating ring that centers the alternator with the cam gear. The other comment i had regarding a term i have seen around online and which Prevost corrected me on is “oil cooled”. Prevost told me the Alternator in my bus is air cooled, Oil lubricated, now that may have changed on the newer models, but mine was oil lubricated. To lubricate the Alternator there is a very small line that comes from the engine block, (oil filter housing area) that lubricates the 2 sets of tapered roller bearings internally. This oil is engine oil and it feeds in the top, runs into the roller bearings, and gravity takes it out the front to lubricate the drive gear, then back to the oil pan. I now have more room to work in this area if the need arises, and will be installing a belt driven alternator to charge my house batteries in the near future.
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Here is my cover setup, drawing and installation fitment. I had a piece of 1/2″ thick blanchard ground, hard anodized 6061-T6 aluminum plate i could use. I need to pick up (5) 1/2″-13 hex head bolts and make the gasket.
2005 XL Thompson Coach
Rarely tow anything behind us.
Sold: 1993 Liberty that we loved for 12 years. -
Gasket is done, need to get my bolts, I ordered 2″ long in stainless, they will be here tomorrow.
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I had an thought yesterday as i installed the cover where the 50DN was, that oil that used to run out of the 50DN and back into the engine, that was not used for any engine lubrication on it’s return to the pan was it?
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Mike, It seems unlikely that they would use an accessory that may or may not be needed for the application as a path for critical engine lubrication. Just a hunch that i would not rely on.
I was in the pit yesterday trying to squeeze my body into the needed position to remove the 50dn. I may have to remove the cross member to get at the top bolts as i see no access from the bedroom.. It looks like it will be doable if things go ok. The photos and info in this thread have been very helpful to me. Thanks again.
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That is what I thought too Jeff, Just a thought I had as I was sealing up and torqueing the bolts. I could take my cover and drill and tap it for a fitting to let the oil flow again if needed, I left the braided line there and plugged the end just in case. I will take a couple more pictures today before i close the hole up. Reach out anytime.
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