Delco 50DN to twin Bosch alternator conversion

[joelselman]

Last March, Prevost replaced my non-charging and heavily leaking 50DN with a reman at about 125000 miles. 15000 miles later, current alternator is now leaking from the drive end seal. It appears I have the latest 1-piece drive end on my alternator.

I'm going to have Prevost change out unit/replace seal as I'm still under warranty. However, at the time the alt was replaced, comments were made about converting to the twin (I assume 24volt) Bosch air-cooled alt setup used on a later XL2. Anybody on here have any experience/comments on this issue?

[Jon Wehrenberg]

Joel,

Have you tightened the hex head bolts behind the pulley?

The pulley needs to come off but with the right size socket and an impact wrench that is easy. On mine all the bolts needed to be tightened. I did not have a leak in the sense oil was dripping, but I was getting a film around the plate.

I tend to think the 50DN leaks more from the return oil fitting at the bottom than anywhere. I've used thread sealant and I still get oil dripping from there and I don't dare tighten too much.

[AprilWhine]

I found this very interesting, and had I not just bought a new Aquahot system, I might have given it a try.


http://cgi.ebay.com/ebaymotors/400-AMP-NIEHOFF-ALTERNATOR-/220714671061?pt=Military_Vehicles&hash=item33639e9bd5

Jim

[Denny]

When I was at Elite Coach, Ephrata, PA, having my ac system repaired, Nelson, their shop foreman, told me about this system and showed me several of their buses that they had converted because of prior problems with the existing alternator. He spoke very highly of it and they had not experienced any problems with it. This is one of several upgrades that are available for our buses rather than just replacing the original one.

Another upgrade is with dash air conditioning system. My compressor went out this summer and I went to Elite Coach for the necessary repairs since I was in Eastern Pennsylvania. Nelson showed me the upgrade for the dash air system and I was very impressed with it and had my original system replaced with the new one. The new system has a 50% increase in cooling over the original one. I believe the original is rated at 2 tons and the new is a 3 ton system. I think those were the ratings, but I am sure of the 50% increase figure. I have been very satisfied with it and it does a much better job of cooling than the old one.

[joelselman]

Thanks, Denny.

Jon, my 50DN installed 3-10 has the new design one piece drive end designed to stop leaks. It has a radial seal only driven into the end and I wish it were seeping. The info on this update is on the site in Canada to which, I believe, you have referred us. "50DN Oil Seal Improvement Update 2009.08.19"

[Kevin Erion]

Joel,
I also changed out my 50DN to the latesed greatest model with the pressed in seal. Did you contact the mfg to see what they will do?
Kevin

[joelselman]

Hi Kevin: As you can see, I finally let go of 100 clams and joined POG! I HAVE the latest and greatest (It appears to be the 1-piece drive end) and I believe the entire leaky mess will be replaced under warranty Thursday. My thinking of converting comes from an apparent degeneration of 50DN quality. The 50DN on my 8V92 was the original when I sold the coach @285,000; the oem 50DN on my current coach went only 125,000; the replacement reman went 15,000. Current coach does have road air, placing a heavier charge burden on the alt, BUT???

[Kevin Erion]

Joel, glad to read your post! You made me think, I bought a brand new one from the mfg direct, not a reman. so far I have only run about 5000 miles so time will tell.
Kevin

[pwf252]

Denny,
Not to get off the subject but as my dash air could be stronger do you mind giving an approximate on your costs? And was it worth the cost?

[Denny]

Patrick,
I believe the total cost was around $4000. This is a whole rebuild of the dash air - parts and labor. It included a heavy duty compressor, new larger condensor, new valves, hoses, dryer and anything else I don't recall that is part of the ac system. It was a lot more than just replacing the compressor which would have repaired the system. Now this was on a 2003 Royale that I had just purchased and was on the maiden voyage when this happened. I traded my old coach (99 CC) on this Royale and just before delivering it to the dealer the dash air went out. Turned out it was a broken hose but is still cost about $200 and I replaced the hose myself. On my old coach the compressor was replaced prior to this and now a broken hose so I was interested in going to the better, newer system on the 2003 Royale to help eliminate future problems. Since I had rebuilt the OTR system on the CC in addition to dash air items just mentioned I was about burned out on ac problems and want the newest, greatest system. After the repair, we were in 95 degree heat and high humity and by running the dash air and one roof unit the bus was very comportable. If you ask my wife it was cold. Now several months later and playing Monday morning quarterback, I am very satisfied with the upgrade and do not regret it.

[BenC]

The twin Bosch alternator setup was not used, to my knowledge, and ANY motorhome conversion units, but was used by Prevost on their seated bus units. The biggest issue with the Bosch alternators is that the voltage regulators are NON-ADJUSTABLE, so if your coach is equipped with either Gel or AGM batteries, and you drive more than 4-6 hours at a time, the batteries will end up OVERCHARGED, resulting in premature failure. There are a several alternator options that exist, which are also easier changes than the invasive bracket and pully system change as well, that you really should consider first. C E Niehoff offers a 350amp/24volt and a 500amp/24volt alternator that fit right in the existing Saddle Mount, and there is a company called Penn Tex, model PX-833, which is basically a reengineered 50dn, that has been converted to air cooling, had the diode pack replaced with higher efficiency heat sink, and the overall resulting product is rated at 330amps/24volt. Personally, I am partial to the C E Niehoff alternators, with which I have had experience, however industrial customers who have used the PennTex product speak very highly of them as well. Both of these options offer newer technology brushless design, and unlike the Prevost Twin Bosch changeout, they both use the existing pully, bracket, and belt system with few modifications being needed, and also, and MOST IMPORTANTLY, offer adjustable voltage regulators to prevent House Battery damage. Hope this information helps.

PennTex Alternator: http://www.penntexusa.com/PX-8a.htm

C E Niehoff: http://www.ceniehoff.com/product.asp_Q_catID_E_145

Sincerely,
Ben @ Coach Worx

[truk4u]

Good Post Ben!

[Jon Wehrenberg]

With increased output, if a change is made make sure the existing wiring and cables are sized to carry the potential load.

I can envision a 350 or 500 amp alternator being asked to run a couple of AC units, the normal house stuff such as the fridge and TVs plus charge batteries that were drained from dry camping all night. The alternator output may prove more than adequate, but the wires and cables may not be.

[jack14r]

Ben,You brought up a great point about overcharging AGM or gels with the coach alternator,what voltage would you think would be a happy medium to charge the lead acid coach batteries and the AGM house batteries?

[joelselman]

Thanks, Ben...that's EXACTLY the kind of info I was looking for.