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Cayce Leithauser (207.75.32.215)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 12, 2004 - 11:50 am: | |
I just purchased a 4104. Its at the shop 700 miles away where I bought it and they can't seem to figure out my generator. Where can I get a wiring schemetic for this bus? If someone has a manual for sale for this bus let me know. I could scan it in and put it online so we could all have access to it. Also the electircal components on the passenger side panel by the engine are about as rusted and corroded as I've ever seen. What is the best way to replace these? Are there any more modern, more readily availible parts that will last longer. Also It is a fully converted RV but the prevois owner never switched to a negative ground. How difficult will it be swithcing it to negative ground. Anyone with some good wiring knowlegde would be really helpful right now. Also if anyone knows of any good articles about fixing the electrical components by the engine that would be great too. Thanks, Cayce cayce749@yahoo.com |
Jim-Bob (12.46.52.74)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 12, 2004 - 1:23 pm: | |
Don't sell the old girl short. Get some Corrosion Block or Corrosion X and spray the terminals by the driver, at the rear panel on the pax side & elsewhere.
The bus can be changed to negative ground pretty easily. There have been posts here that you can look up in the archives. I believe the polarity of the batteries has to be changed, the generator "polarized" and the safety/buzzer relay in that driver's panel has to be modified. I modified mine with diodes from Radio Shack in place of the selenium rectifiers, changing polarity at the same time.
There are lots of these buses running around so there are folks here who can help you. You've bought a really fine model of bus.
The gear driven GENERATOR can be replaced with a drive pulley that you can drive a normal car alternator from. Mine was converted that way. |
Marc Bourget (209.142.38.81)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 12, 2004 - 1:30 pm: | |
I think Richard Bowyer had some additional advice on this, but I didn't retain it at the time. I believe I excerpted the original article accurately, but that's all I'll represent. So take the following with a grain of caution. This is offered for discussion, only.
Marc Bourget
Re: pos to neg ground - Why's and Hows
Posted by Marc Bourget on September 15, 1999 at 17:21:07 PST:
In Reply to: pos to neg ground posted by Mark on September 15, 1999 at 09:59:03 PST:
:
: Have a 4104 with pos ground system. am interested in changing over to neg. ground. anybody have this information?
Doug's post questioned why someone would want to do this.
First the Why's. For the most part, all cars have gone to a negative ground. This dictates that all the 12V auto accessories maintain a neg. ground. Attempts to leave the chassis pos. grnd and run the accessories neg. ground (isolation systems. etc.) just lead to fried equipment. Don't go there.
The 4104's and the Flexibles were positive ground as well as others. This post assumes a generator. Alternators can be switched also (Late 4104's 4501's but, while doable, alternators are more complicated.
This procedure is taken, generally, from the FMC Magazine, Aug '85 article "All About Busses" Copies of this series of articles can be obtained from the FMCA central office.
Ground Changeover Procedure.
1st. Verify that the Batteries are grounded from the positive terminal to the chassis. The battery will be marked with a + or Pos. and it's the larger diameter terminal. Disconnect the Battery, positive terminal first (in case you ground your tool - this avoids a short) remove all battery cables and inspect them for condition and verify length suitable to the new hookups. Because the Pos and Neg poles are different diameters the battery clamp hookups with be the same but the end attachments will be reversed. A braided (bare) ground cable will have to be discarded and replaced with at least a 2/0 (two ought) insulated cable. Welding cable is ideal but if its used and has holes in the insulation touch up the holes with silicone, wrap with a double layer of electrical tape and cover the tape with shrink tubing of suitable diameter. The end connections should be bright, clean and in good physical condition.
2d. With the batteries still disconnected, disconnect anything in the coach that might be damaged by reversed polarity, such as the refrigerator, CB radio, etc. If the conversion has not yet been started the CB is the only thing to worry about. Now disconnect the Field lead from the generator where it attaches to the voltage regulator and put it where it can't touch anything (cover it loosely with tape for insurance). The regulator will have four terminals - a ground, a battery terminal, an armature terminal and the field terminal They're usually identified with a single letter or "Bat", "Fld" "Arm" and G or Grd for Ground.
3d. Reconnect the batteries, this time for neg. ground. The battery grounds will usually go to a stud welded (better) sometimes bolted (watch corrosion) to the chassis.
They may go to a stud on the back of the starter in coaches where the batteries are mounted close to the starter (flexibles). The Positive battery leads will go to an insulated stud in the battery compartment of a 4104. or directly to the starter solenoid for the Flexibles.
4th. Repolarizing the Regulator. Take the field wire you protected earlier and touch it to the battery lead on the voltage regulator, holding it there for about 2 seconds. It will make a small spark when you do so. Repeat this 4-5 times at 2 sec. each and then reconnect the Field lead to the regulator terminal from which you removed it.
You are basically done at this point. The charge indicator needle will reverse it's direction but will read accurately. The Oil Pressure will probably read wrong. The Temp guage will be correct. Simply replace the offending units with "off the shelf" Stewart Warner guages and make sure you get the matching guage senders. Electronic Speedometers can usually be corrected by reversing the red and white wires. |
DrivingMissLazy (66.168.175.51)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 12, 2004 - 3:46 pm: | |
I did not retain any of my instructions, but as I recall it is imperative to disconnect a safety shutdown circuit. This is located in the panel on the left side of the drivers seat and contains an old selinium rectifier about 1-1/2 inch square. It should be disconnected until you get a schematic and require it with a diode and in the proper polarity.
Richard |
mel 4104 (170.224.224.123)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 12, 2004 - 7:40 pm: | |
you sound feed up with the dear old lady allready, you have just got a very fine coach that will out last most other buses that are not made by GM. yours is built to last. as to newer parts that will last longer, we i do not know the year of your coach but it has to be at least 43 years old and that is very good for lasting. as to the change over it is easy to do and is the best wiring change that you can do as then you will be staandard wired as the auto and rv industry is today. |
Cayce Leithauser (204.38.22.85)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, October 12, 2004 - 10:03 pm: | |
It really is an awesome bus. I know what a great coach this is, I'm just an imaptient person. And need to live in it, my Toyota isn't as roomy. I will post a picture of it soon. It was designed by an old trucker who put a lot of love into it. His son inlaw got it and let it sit for way too long. It has all his maps of the southwest so in its days as an RV it went a lot of places. I had an idea for all of us that want a manual for a PD4104. If we all chipped in to have someone who ownes a manual scanned in at a copy shop and put onto CD we could make copies for everyone that needed and it could be posted online for everyone to have access too. Anyone that wants to go in on this idea let me know? cayce749@yahoo.com |
FAST FRED (4.247.54.78)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 13, 2004 - 5:10 am: | |
Reproduction manuals are on the shelf , and far better for crawling around the coach than lugging a laptop.
FAST FRED |
Jim-Bob (12.46.52.74)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 13, 2004 - 9:04 am: | |
Marc's description is right on except for the rework of the safety relay as I described. The polarity of the rectifiers is wrong there. This is the relay for the low air pressure/low oil pressure/high engine temp/escape door ajar light & buzzer. (You probably won't need the escape door circuit.)
As for the 4104 maintenance & parts books, It would be better, I think to scan the pages & make them available to download. Each owner can delete the pages that just don't apply (systems removed or updated)& print a more applicable book. It would also serve well that when you add items such as different transmissions, steering boxes, etc, those pubs could be scanned & printed (by the owner)& a very accurate book printed for each bus.
Just my $.02 |
Marc Bourget (209.142.38.81)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 13, 2004 - 10:08 am: | |
Cayce, In case (does that rhyme?)you have a rare alternator, I have different instructions.
It requires disassembly of the alternator and replacement of the diodes. The procedure on disassembly is strict as damage to thingies can occur.
Let me know if you need the instructions. |
Marc Bourget (209.142.38.81)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 13, 2004 - 10:16 am: | |
My further notes on the subject revealed Jim Stacy's comments, including a soldering procedure, from back in 1999, which follow:
"The changeover procedure called for literally rewiring the jumpers in the rectifier (wired with soldered jumpers like an old style bridge rectifier) to allow reuse of the same part. It would be a lot easier to get 4 silicone diodes from Radio Shack, solder the anodes together and hook it up. Anything to avoid the odor of a selenium diode junction that has gone South.
Jim Stacy"
JIm-Bob, your comments are worth much more than $.02! I think the best resource is the Yahoo GM group(s) Did you post this suggestion with them?
Onward and Upward
Marc Bourget |
Cayce Leithauser (24.247.41.234)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 14, 2004 - 1:06 am: | |
Since I have a rare alternator that would require disassemly wouldn't it be easier to just sawp in a modern alternator? Any thoughts on a good candidate for a swap? Also what amp alternator should I be looking for? |
Marc Bourget (209.142.38.81)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 14, 2004 - 5:46 am: | |
It will be hard to find a belt driven replacement with the capacity and longevity of the stock unit.
Apart from the work particulars, it involves switching out 6 Diodes of the opposite polarity.
I'll dig out the procedure, if you wish!
Let me know |
Jim-Bob (12.46.52.74)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 14, 2004 - 10:53 am: | |
If you have a true alternator and not a generator, it is not stock on a 4104. If you really have a huge alternator bolted on the gear drive on the rear of your 6-71 engine, it is a rare find & you should keep it. It will be about 250-300 amps CONTINUOUS rating. It will not have brushes inside and is totally sealed as it is oil cooled.
If it is a generator, it will have brushes and should have a flexible air tube for cooling about 2" in diameter that runs from the rear of the gen up to the intake air housing overhead.
If it is a generator, I would not put any $$ in it. If it is actually an alternator, somebody has upgraded it, and I doubt that it is positive ground.
If it is a generator, you can get a drive pulley assembly that will fit where the generator is mounted. You would then fabricate mounts for an internal regulator (modern) alternator, maybe 150 amps or so. Mine is 140 amps & though it has a two belt pulley, I use one belt with no problems. (Do carry spare belt!)
Mine had been converted with the alternator mounted behind the exhaust manifold (3 o clock position)& I had two alt failures. I then made new brackets to mount the alternator above the engine, (12 o clock) out of the heat flow & have had no further problems. |
Carroll (65.1.235.61)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 14, 2004 - 11:21 am: | |
Jim-Bob
Where can you get the drive pulley assembly that fits where the generator is mounted? Mine still has the old generator and regulator which I had reworked last year with the pos ground. I would like to put an alternator in when I rewire the bus and convert to neg ground.
Carroll 4104 |
Jim-Bob (12.46.52.74)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 14, 2004 - 2:29 pm: | |
Well, you CAN buy the drive from a Detroit Diesel Dealer/Distributer new, (But you're going to have fun getting the parts 'cause they were not originally on your engine. A good DD parts guy will be able to do it.) or you can scrounge one used from a big engine shop if you have time to search one out. There are several pulley drives made to fit in different places on Detroit Diesels so be prepared to describe what & where to the seller. If you take pictures of the drive opening to e-mail to the seller it helps. |
(Unregistered Guest)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 16, 2004 - 6:00 pm: | |
How do I tell if I have a generator and not an alternator? The system is postive ground. I picked the bus up yesterday and drove it back. Not as hard as I would have thought. |
(Unregistered Guest)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 16, 2004 - 6:05 pm: | |
If I do have an alternator what is the procedure for switching out the diodes? |
Marc (Unregistered Guest)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 16, 2004 - 6:51 pm: | |
Re: Alternator pos to neg ground - Why's and Hows
Dear UG!
The "KIAA" here!
If you have the gear driven version alternator, it should have a 1/2 circle shaped rear housing that's about 2-1/2 " deep. There will be one large and one small terminal on top.
1) Remove the oil line(s) from the top right hand side of the rear housing, then, after disconnecting the batteries as with the generator conversion, remove the heavy wire, the small wire next to it (mark it "R" and the other wire near the small wire which you will remove and mark "F". There may also be a ground wire. If so, disconnect it also. Remove the nuts from the mounting studs. Take care, this alternator weighs 80# or so.
Remove the cover plate, or the whole back cover, if no cover plate and the cover has to be removed first, remove the nuts and insulating washers from the large terminal and push down on it to break it loose from the housing, repeat for the small lead through the cover.
Remove the hex head screws holding the rear cover or housing and remove the cover. There are six (very black and oily) diodes. These are "cathode to case" diodes. Remove the leads on each from there termination posts. Note that 3 of the diodes are mounted on little aluminum plates isolated from ground, and the leads of these 3 all go to one of the plates upon which the first 3 diodes are mounted. Unscrew the diodes from their mounting places, Clean up all with mineral spirits.
What you now have are six diodes with either a 3/8" dia. mounting stud, or about one-inch diameter threaded bases. If you have the 3/8" type, simply get six rectifier diodes, "ANODE TO CASE" (note the switch from cathode!) , rated at 70 amps or more and at least 200 volts. If the diodes have the large threaded bases, you will need an adapter, which is available at automotive electric places selling Delco Remy Parts (may be hard to find, I haven't checked) Take along an old diode for a sample. The diodes themselves are available from Universal Coach Parts or a wholesale electronics parts house.
After installing and connecting the new diodes, be very careful that nothing touches the case (it's a tight fit) and re-install the large and small studs in the cover, being sure to reinstall any insulating washers you removed. A small amount of silicone sealant around the hole helps prevent oil leaks.
Carefully reinstall the rear cover or housing, using a little silicone sealant over the original "O" ring. After assembly, check with an ohm-meter for shorts. You should get a low resistance in one direction only. Reversing the probes on the ohm-meter should give an opposite reading if everything is satisfactory. Reinstall the alternator on the engine again, using a small amount of silicone on the gasket. DON'T CONNECT THE BATTERIES YET
Go to the voltage regulator. It's usually about 5x9" with three terminals. Interchange the wires on the Pos and Neg terminals. (Usually the two outside terminals but the will be marked)
Now go revise the battery hookups for Neg Ground. Do not attempt to "polarize" the field of the alternator, like in the generator switch over, It's not required and could damage the alternator.
These instructions came form the Aug 1985 FMCA article on "All about Buses"
Onward and upward,
Marc Bourget |
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