| Author |
Message |
RichInternational Bus & Parts
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 4:12 pm: | |
Have an MCI customer that is getting an electric fluctuation in his lights in the coach when the engine is running. Changed out the voltage regulator, cleaned & tightened all connections to alternator......Still fluctuates (pulses) in the interior lights in the coach. When engine is off, all is calm. Anyone run into this & what did you do????
Thanks
Rich
800-468-5287 |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 4:31 pm: | |
my Eagle does the same thing...ask him to turn his headlights on...& see if that stops it |
Tim Strommen (Tim_strommen)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 5:28 pm: | |
Is this at idle or at speed? Also, what's the specific gravity of the batteries? |
Jim Ashworth (Jimnh)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 7:12 pm: | |
Rich- Frequently, this is caused by a bad diode or two in the alternator. Accessible on an MCI thru the side door to check if it is an air cooled unit. Oil cooled.... whole 'nuther ball game.
Jim |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, September 30, 2005 - 9:56 pm: | |
Rich, our impression is that it is normal if there is a big generator with not enough load.
Fast Fred has come up with an interesting fix for this symptom. He set his regulator down to around 13.4 volts, with the result that the batteries will absorb those surges because they are not quite topped off.
IIRC, he figures on the batteries getting topped off when he's hooked to shore power or running the genny.
Your customer should use double the voltage if his system is 24 volts.
For what it's worth.
Tom Caffrey PD4106-2576
Suncatcher |
John Jewett (Jayjay)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 01, 2005 - 2:37 am: | |
Rich, the last time I was in your shop we discussed my 4905 doing the same thing, except it's the headlights (the always-on-low-beam daylight setting) There may be a diode in the drivers control panel too. As above set the voltage regulator a little lower, say about 26.5 instead of the 27.6 to 28.2 volts that the manual recommends. Cheers...JJ |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 01, 2005 - 5:31 am: | |
I think Jim nailed this one , get a set of diodes installed.
FAST FRED |
John Jewett (Jayjay)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, October 01, 2005 - 9:55 pm: | |
Nope- tain't the diodes, 'cuz diodes don't go intermittent. Kinda like being pregnant-either you are or you aren't, ain't no almost or maybe. If the lights are working then the diodes(s) is (are) OK, and don't need replaced. Check for a bad coil in the voltage regulator, or a leaking end-of-line resistor in a lighting circuit. If the voltage regulator has a capacitor (to reduce point arcing) it may be breaking down also. Resistors and capacitors (and transformers) have a habit of getting hot under load, then the internals "open" (breaks the circuit) and voltage ceases to flow, then it cools down and "closes" (makes the circuit). This make/break, on/off if occuring fast enough can cause the apparent flicker. Cheers...JJ |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 02, 2005 - 5:24 am: | |
"'cuz diodes don't go intermittent"
True but for smooth rectifying all 6 diodes are required.
IF 1, 2 or 3 are shot the alternator will still have an output ,
but bulb brightness will "Bounce" as described.
BTDT
FAST FRED |
Jim Ashworth (Jimnh)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, October 02, 2005 - 8:02 am: | |
The alternator is a 3 phase device. Thats why there are 6 diodes. If one of those phases is not putting out, the lights will flicker.
Jim |
Gary Stadler (Boogiethecat)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, October 03, 2005 - 2:13 am: | |
...and beleive it or not, diodes can and do go intermittent. Not often but it happens. The bonding wires to the diode chip sometimes are not manufactured correctly and years later they can get loose to the point that cold they will connect, hot they will disconnect, or the other way around. I've seen a few do it, although it is admittedly rare. |
james dean boggs (Jd_boggs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 05, 2005 - 12:52 am: | |
Can the diodes be replaced on an alternator from a 6V92 engine without pulling it altogether?
I have the same problem. I replaced the voltage regulator, shunt and a corroded jumper. It is getting better but still flickers the lights. |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 05, 2005 - 7:20 am: | |
If its the style on most coaches the alt can be left in place only the plate carring the diodes comes off , and you install new diodes in your old plate , or just stick on a replacement.
At least thats what happens on an 06 with an 8V71 with the stock alt.
You might consult Da Book for fill instructions.
LUKE at Us Coach or IBP should have any parts you need.
FAST FRED |
Jim Bob
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, October 05, 2005 - 11:18 am: | |
The oil cooled alternator doesn't get filled. It is supplied engine oil by a hose & returns the oil to the oil pan. |
Dick Bell (Richardkan)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, October 06, 2005 - 11:28 pm: | |
One of the smartest guys I know re vehicle electrical and voltage problems is Chris Rochester. He is in the starter and alternator business back in one of the Carolinas I believe. I think he contributed to this board regularly when he was converting his magnificent Eagle. I talked to him at a rally about the very problem all of you are describing and that I too was having.
His answer is that there is a bad relay in the charging circuit. Then he went to the back of my Eagle and pointed it out. It's a small ,four post, Delco-remy relay that is connected to the voltage regulator leads. He said "Change that out and your problem will go away."
Another Eagle owner having the exact same problem and I went down to the local auto supply store and bought relays and put them in. About $20.00 each as I remember. Sure enough, the fix worked for both of us.
I took the old one apart for an autopsy and discovered the contacts were severely corroded due to the relay being around all that moisture in the rear for many, many years. Even was some rusty material halfway holding open the armature(?) of the relay.
I would not hesitate to recommend his expertise any time you're trying to track down a bug in your system. |
Richard Bowyer (Drivingmisslazy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 07, 2005 - 8:13 am: | |
I believe that may have been Gene Rochester. Sure sounds like a good description of him.
Richard |
niles steckbauer (Niles500)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 07, 2005 - 3:34 pm: | |
Yep - its Gene - in Walhalla SC - there is none better - Niles |
Dick Bell (Richardkan)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, October 07, 2005 - 8:07 pm: | |
As the kids say "My Bad". You're right, it is Gene. |