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The alternator has two likely seals and both just require some care to replace. The most common is the one behind the pulley and there is a kit available from Elreg or even Prevost that just requires the remo0val of the pulley and six small bolts. As long as the bearings are OK the shaft should not move and the seal should deal with any leaks.

The seal at the plate on the rear is easy to replace, but also easy to mess up. It is like a big long skinny O ring that is behind the rear plate and if it moves out of position while tightening the plate oil leaks. Both have nothing to do with Detroit, but are a Delco alternator issue. If I wanted an expert in dealing with them I would go to a shop that works on and rebuilds the 50DN alternators. But the fact Prevost did the work, if it was recent they should try again for free.

Ditto on the oil pan seal. That’s a little more work and should be timed to take place during an oil change, but like the alternator it takes some care to replace it if it is an oil pan seal. That’s a Detroit issue and my guess is a good dealer should be the one to do the replacement unless Prevost is going to stand behind their work.

[Per]

Well, if Prevost can’t get the job done next week, hopefully American Fleet can cure the oil leaks next year.

[Archived]

Do you have the larger vent line installed on your
alternator per service bulletin 14-60-00?

If not it may help.

Check out page 64 of the attached link.

http://www.prevost-stuff.com/Prevost_Training_Reference_Guide.pdf

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Thanks, Tim,

I printed out the info, and will show it to Marcello Monday.

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Tim,

That is a good reference guide, Thanks! I printed it out and will add it to my others.

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I’ve switched to the air cooled alternator after leaks and other issues but my engine itself has been dry; nearing 210,000 miles.

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How heavily do you load your alternator Joel.? With the OTR the 50DN usually doesn’t get heavy loads and that might be a good option.

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Per,

First I don’t have a series 60, however I have built many gasoline engines. One thing that will ruin an engine rebuild is to not follow the bolt tightening sequence. Now I’m not saying that is the problem or not, but if your cover has six bolts in a circular pattern they should be tightened across the circle not consecutively around the circle. On a piece of paper layout six points around the circumference. The number one bolt is at the top of the circumference, snug that bolt (not to torque spec just yet), the next bolt to tighten would be across the diameter of the circle making it the number 4 bolt, snug it also. Then go bac to a bolt next to the #1 bolt, that would be the #2 bolt. Snug it also. Same pattern go across the diameter of the circle to the #5 bolt, snug it. Then the #3 bolt, the next bolt clockwise around the circumference and snug it too. Finally, the #6 bolt also snug tight.

Having done that, go back through the same tightening sequence taking each bolt to half the tourque spec required. Then finally, one more round the pattern taking all bolts to the torque spec required. If you want, a break can be taken between the half torque sequence and the full torque sequence before doing the full torque sequence.

I think following this sequence would be critical when using a rubber O-ring as going to full torque spec the first time around will displace the o-ring resulting in a puckered out place where oil/fluids will leak.

When building an engine there is a manufacturer’s specification of which hed bolt first gets snugged and a sequence from the first to the second and so on. I usually completed the first tightening to snug on al head bolts and would not allow any distractions during the sequence. I took a break after all had been snugged before going back over the sequence to half torque spec and then allowed the bolts 10-15 minutes to “relax.” Then once more a final tightening to required torque and the heads were properly tightened. Of all the engines I built from Chevy sixes, Mopar slant sixes/354/392 Hemi’s, Ford 292/312/390 V-8’s, I never had a head gasket failure. Same goes for tightening the main bolts and rod bolts.

In 2012 I had a leaky sleeve gasket on my “classic” 8V-92 DD. I had no experience with diesels and thought this was not the one for me to learn on, plus I did not have a facility to do this level of repair work. So I left it with a heavy equipment shop for an in chassis rebuild. I went back to pick it up on a Sunday afternoon. I had a deadline to be in SanFrancisco within four days. The work was not finished although the internals of the engine had been buttoned up. One of the techs reached for an overhead bulk oil hose to top off the engine. I asked if that line had been used to fill the engine. Response was we fill all of our engines with this oil. Well it was a multi-grade oil and that is NOT the oil used in the old 2-cycle engines. A straight 40 weight oil is. So now they have to drain the engine, remove and replace the oil filter then refill with the straight 40 weight oil. The 8V-92 takes seven gallons to fill the engine. Where on a Sunday night at 10:00 PM are they going to find the oil? Well, I keep 8 gallons in the underbay and a set of oil and fuel filters, so the change out was made. At 11:30 PM I made a 10 mile road test and all seemed fine. I went home, loaded up on Monday morning and off we went for California. We logged exactly 245 miles since pick up when topping Black Mountain on I-40 I felt a vibration. Quick check of gauges looked OK, went to set the Jake for the downhill run when in the rear view mirro I see armegeddon behind me. OK so I was able to pull over, with the engine still running to make air pressure, got completely off the road then shut the engine down. My Grandson and I got out, went back to the curbside engine bay access door and looked in. There was a BIG oval hole in the side of the block and I could see an empty journal on the crankshaft. Obviously a rod had taken leave from the crank and been ejected out the side of the block. Art Linkletter expression for what was about to be said by the Grandson was “Kids say the darndest things.” Well the Grandson looked at me and said, “Popa, how we going to fix that?”

Most likely/reasonable cause of the failure was tech distraction. That would be either a cell call/meeting/lunch/ or any nuber of other possibilities. When he returned to the job under the engine he thought he had final tightened one of the rods so went to the next rod, never going back over all of the rods to make cretain all were spec tight. The heavy equipment shop did an “autopsy” on the pieces and parts coming to the same conclusion.

So if you have someone working on your engine that is not familiar with the needs of the piece of equipment they are working on, you will most likely encounter problems somewhere on down the road.

That’s a little more than two cents worth but it has served me well in all my engine building years.

[Rick]

Jon: Heaviest load is when I’ve gone all night and all batteries are at 50%. My batts are hooked together so I have 6 8D, 4 31’s, and 2 27’s. OTR load is nothing compared to initial charge of the batts. The alt is 24 volt, and I’d have to look at the calibration on my gauges to be sure, but I’d guess it’s putting out 200-250 amps at startup. No problem with the alt so far (50-75,000 miles) in the desert southwest (ambient often over 115F) but those initial high load start ups are usually in a cooler time of day. I did have a problem with the bolts securing the alt mounting bracket to the engine shortly after initial installation which seems to have been resolved.

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Carol and Will,

You are absolutely right that it is imperative to follow the proper bolt tightening sequence. But when I pay someone a $110 shop rate, I expect them to know that. Unfortunately, sometimes Prevost puts an inexperienced individual on the job. We are back here at Prevost, and hopefully tomorrow we can get at least closer to a leak-free engine.

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Per,

I fully agree you should get quality service for that shop rate, and the only way to justify a rate like that which is often 5 times what the tech actually makes as an hourly rate is that the job is professionally done to the highest standards, and is done more quickly and efficiently due to the skill level. But here in the real world that is not always the case.

Not all shops will tolerate it, but on those rare occasions when I have had others work on my bus I make it a point to ask the dumb hard questions. I am not shy about asking techs to show me if they say something needs to be repaired or replaced. I am not ever going to pass up an opportunity to just stand and watch the tech work. I will also ask the tech for the procedure he will follow and I expect it to be what i have read in a service manual or I know to be the proper procedure like Will’s outline above.

Just being there, observant, and interested seems to get the desired level of craftsmanship.

[victor]

Sitting here at Prevost running the engine to see if their leak fix took. Looks good so far. Raymond and I ordered the breather kit that Tim pointed out, but it won’t be here until tomorrow. Since they have a kit, DD must have had this as an issue that needed attention. We noticed the newer coaches have a better vent setup.

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Sitting here south of Memphis in E-Z Daze campground–very nice campground BTW, and with somewhere around 550 miles sice the work was done, no leaks from the repaired areas so far. We had the kit mentioned by Tim installed. The kit was $168 plus freght–don’t have the bill yet, so can’t tell on labor. Will arrive Tuesday at Jeff’s for brake chamber replacement–with 18 years on these, perhaps it’s time for replacement!

Could add this campground to the list of campgrounds where no Prevost has gone before, but it seems that’s the case just about everywhere we camp. A guy stopped by yesterday and asked if he could take a picture of the coach–that’s happened several times so far. The coach still attract attention, even at 16, but we never have any problems in a campground.

[Bill]

Good morning Per and Margrit,

Yes, E-Z Daze is a nice park. I was there about 2 months ago taking the Liberty out of storage and ran it to give it a little exercise (about 30 miles from storage).

Anyway, when you leave there, you may want to consider taking the 385 by-pass to avoid the 240/40 interchange as there is major construction and very tight lanes to maneuver.

When leaving E-Z Daze, head north on the 55 and take 240 East towards Nashville. After you pass the Mt. Moriah exit you will see the 385 by-pass. It will take you to I-40 east and is a good easy drive to get around the major construction that I mentioned.

Safe travels,

Mark

On Edit: There is also heavy construction at exit 20 (Canada Rd.) on I-40 which is east of the 40/240 major construction project, the 385 by-pass will put you even further east on I-40 to Nashville.

---

2005 XL Thompson Coach

Rarely tow anything behind us.

Sold: 1993 Liberty that we loved for 12 years.

[Per]

Thanks, Mark. We’ll give it a try!