| Author | Message | ||
| Buddy Tennison (Buddyten)
Registered Member Username: Buddyten Post Number: 21 Registered: 7-2005 Posted From: 207.68.235.83 Rating: N/A |
Well guys, here I am again, probably wasting your time(s) with some question, but I need the help. We have an 80 Eagle, 8V71. A few months back, among some other problems, we had a few instances where when you depress the starter button, the solenoid (or something back there) would click but it would not engage the starter. Since we were scheduling to have the engine rebuilt anyway, while the mechanic was doing that, he installed a new solenoid. Now, after all that has been done, we still are having the same problem, only not all the time. Sometimes, you can get in it, depress the button, and it starts immediately. Sometimes, you have to keep depressing the button over and over and it will start. Last week, we noticed that the cabling was getting old, and at least one of the cable ends seemed loose. Since they were old, we elected to have all new cables made up, with soldered ends. Now we are not experiencing the same problem as much, but sporadically. I had one of the other guys attempt to start it while I sat back by the starter. It seems that the solenoid is not kicking in really hard enough to spin the starter. Also, from the electrical panel above the engine, you can hear what appears to be an air switch of some kind engaging. One more than one occassion, when the starter switch was depressed, all the bus power shut off momentarily (interior lights, etc). Any suggestions on what we might look for to alleviate the problem? It has not left us stranded, and eventually starts up, but I much prefer to "hear her purr" when I hit the starter button. | ||
| Ron Crabtree (Ron_c)
Registered Member Username: Ron_c Post Number: 5 Registered: 1-2006 Posted From: 70.56.17.238 Rating: N/A |
Hi from OR, I have a 1980 Eagle 6v92 all though the wireing should be simaler,I had the same promblem and I found that by cleaning all the grounds and pulling out the small starter cube relay and cleaning the contacts ,checking the wires,that the relay plugs into I have not had that problem since. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 162 Registered: 8-2006 Posted From: 207.231.80.150 Rating: N/A |
Buddy, You are not wasting our time, and here is the answer. Also, you have made it easy, because you have done an excellent job of describing the problem(s). I feel strongly that the entire problem is going to be corrosion under the battery ground cable where it bolts to the frame. If not there, look closely at all of the cable connections between the batteries, etc. It is also possible that you have a high resistance connection in the feed from the batteries to the master switch. The air switch you are talking about is the "Skinner Valve" which controls the air to the shutdown plunger. When the coil on this valve is ENERGIZED, it stops air flow to the shutdown plunger. So, when you shut off the master, it lets air into the shutdown cylinder and pushes the shutdown lever. The start relay energizes the start solenoid, which engages the starter drive, when the drive is all the way engaged, it closes the high current contacts, and the starter operates. Whew, but with a good ear, if it will misbehave while you are back there, you can figure out which component isn't working. Loud clunk=bad starter brushes or contacts. Small click=bad relay or loose small wires, or open solenoid coil. No click=open relay coil, or open circuit from the front. I don't want to get into the starter protection relay circuit yet... Please note that Ron said "clean the grounds" also. HTH, George | ||
| Paul Lawry (Dreamscape)
Registered Member Username: Dreamscape Post Number: 2 Registered: 5-2007 Posted From: 64.40.223.242 Rating: N/A |
I agree with all that has been said. It does sound like a bad ground, loose wire. You have to have a strong ground otherwise you will loose lights etc. like you mentioned. Check all grounds, especially to frame. Paul | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 733 Registered: 11-2004 Posted From: 24.129.157.205 Rating: N/A |
Buddy - nothing wrong with what's been posted - but in addition, you did not specify the number, age and type of batteries - It is a good idea when your out and about the next time to stop in at a battery place like Interstate and have them "load tested" - HTH | ||
| Bill 340 (Bill_340)
Registered Member Username: Bill_340 Post Number: 35 Registered: 7-2006 Posted From: 75.203.117.172 Rating: N/A |
Buddy what makes this board great is all the opinions, and trial and error. As an ex eagle owner with the exact same problem, I was told by a retired bus mechanic, Common problem on older eagles, you can scrape the ground contacts all day, some times it helps and sometimes not,. NOW for the no fault fix. Take a NEW ground cable FROM EACH battery to the starter. DO NOT tie them together and run them there, one cable from each battery directly to the starter, and problem will be solved, as eagles and all others rust away the continuity of the metal weakens, and even cleaned poor conductivity is made, try this on any older coach and you will see, We had spent aprox $900 trying to solve that problem when at a bus rally, this gentelman. HOWARD BEST walked up ask the problem and never hesitated for a second. AND he was correct. never ever had the problem again, Standard problem Simple soloutiom. Good luck Bill 340 BUT PLEASE let us know how it turns out, thats all any of us ask. | ||
| Buddy Tennison (Buddyten)
Registered Member Username: Buddyten Post Number: 22 Registered: 7-2005 Posted From: 207.68.235.83 Rating: N/A |
Guys: Thanks for all the good advice!! From what you all have indicated, it appears that we have started on the right track at least, by replacing all our old cabling and ends. Incidentally, when I say we replaced them all, we actually have replaced the cable to the alternator, the one that feeds the main power panel back above the engine, & the positive cable from the batteries to the main switch. We did not replace the feed from the main switch to the starter, as it appeared to be in fairly good condition. The batteries were replaced last year, (3) 12V, but am not sure what "series" they were. We just took the old ones to the battery dealer, and got replacements for them. At that time, we did install new cable ends on all the "tie together" cables between the batteries. You all seem to agree about the ground from the batteries to the frame. We have not been able to break loose the bolt that affixes it to the frame. We even put a small impact wrench to it, and it won't budge. Should I just disconnect/cut that one loose, and run another new cable to somewhere on the frame and affix it? It appears this is about a 2/0 cable. Should we go with a bigger cable? All the new cables we ran that we mentioned above were (I think) 4/0. If we should run a new ground cable, any suggestions on the best place to make a new frame attachment? George, you explained the "skinner valve". I have noticed recently that when we cut the key off to shut down the engine, a lot of times it is not an immediate shutdown (like a second or two delay before the shutdown). Does this mean that this valve is going bad? What does this valve look like and where is it located? Is there a lubricating process we should try (I am assuming that if it has actuating plungers, there might be the need for some lubricant). Also, about a year or so ago, we ran during some very cold weather. On a couple of occasions, when we cut the key off, the engine would not shut down at all, and finally had to kill the engine by lugging it down in high gear. The mechanic installed some new switch then. Was this the skinner valve? Is this a generic type part common to most diesel engines? Can we go to the local truck parts dealer and pick up such an item? Bill, you talked about running new ground cables from each battery and the problem would be fixed. What size should these cables be? I did forget to mention something. We have just had an out of frame rebuild on our engine. Prior to that, we had only had the conditions we mentioned occur on a couple of occasions. Is it possible that with the engine removal and reinstallation, the skinner valve was not set properly, or is this an "adjustable" item? Any other suggestions along this line? I plan to spend the next few days removing, cleaning, and reinstalling all the electrical connections that I can. We have never done this, and although we don't see any visual corrosion, I'm sure there is some there. Is there some type of lubricant or treatment that should be put on all the electrical connections after they are cleaned that would minimize any future corrosion? You guys have been a great help!! Off to the shop tomorrow to start scraping and clenaing. If the problem is not corrected after that, then we will start with other suggestions you have and will make. Thanks!! | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 164 Registered: 8-2006 Posted From: 207.231.81.59 Rating: N/A |
Buddy, Cut the old ground bolt off, and install a new one. The skinner valve is not adjustable, you can find it by following the small air hose from the shutdown cylinder in the middle of the Vee at the back, up to the bulkhead. The valve will have two hoses, and probably two wires. This part is common to all mechanically injected 71 and 92 series bus engines. (Non DDEC) I hate to say this, BUT, if a bus frame is so rusted it can't carry starter current, its in imminent danger of collapsing! The guy that put in two ground cables to the starter uses a sledgehammer to swat flies. Sure it fixed the problem, but one strap between the engine and the frame (bypasses the motor mounts) would have done the same thing. I'm willing to bet he didn't clean and tighten his connections first. | ||
| niles steckbauer (Niles500)
Registered Member Username: Niles500 Post Number: 734 Registered: 11-2004 Posted From: 72.91.107.56 Rating: N/A |
If your going to all that trouble - be sure and buy a tube of dielectric grease and treat your terminals and connections accordingly - FWIW | ||
| Jim Wilke (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 142 Registered: 2-2001 Posted From: 69.77.144.142 Rating: N/A |
Buddy, I agree with all of the above. (1980 Model 15) I have had the same problem and I found I had to replace the battery cut off switch. It was not passing proper voltage through it. I got going several times by switching it on & off about 10 times, kind of "wiping the contacts". When I replaced it, I noticed that the new switch was not loose but had a very firm action as you switch it. As for your engine not shutting off, could it be that when that happens, the bus has not run long enough to build up much air? They need air pressure to push the shut off piston. Jim-Bob | ||
| Paul Lawry (Dreamscape)
Registered Member Username: Dreamscape Post Number: 4 Registered: 5-2007 Posted From: 64.40.223.242 Rating: N/A |
I had the same problem with the shutdown skinner valve cylinder, it would not extend the full length, therefore not touching the linkage to shut down the 8v71. Replaced the cylinder, works everytime now. You should have two small cylinders on top of engine, one for shutdown, other for high idle. Get a new cylinder, that should fix the shutdown issue. Understand which one does what by reading up on them in your manual. Paul (Message edited by dreamscape on May 25, 2007) | ||
| H3-40 (Ace)
Registered Member Username: Ace Post Number: 530 Registered: 10-2004 Posted From: 216.9.250.6 Rating: N/A |
Buddy a lot of good advice has been handed to you. Eagles are KNOWN for having bad grounds. The ground connection you speak of that you can't remove could be a sign of past grounding problems. Maybe te guy welded it to the frame or maybe your trying to undo a welded nut where the actuall bolt on the other side can be loosened! I have also heard of seperate grounds from each battery. That way if one is bad, there are backups! Another tip was the switch. Anywhere there are connections, there CAN be a problem! Good luck and keep us informed of what you find! Ace | ||
| Bill 340 (Bill_340)
Registered Member Username: Bill_340 Post Number: 36 Registered: 7-2006 Posted From: 70.222.212.42 Rating: N/A |
Well George. I dont know you but I am also sure dont care to. seems you have an MCI not an eagle. so you are doing what you probably do best and that is run down someone elses opinion. I typed what worked for us with the same problem and it solved ours. not the eternal fix you would have I am sure,And as far as the frame being that rusted that it would colapse, PLEASE dont park next to me at a rally, cause I never want to be in aperfect world, I have never Blasted anyone on this or other board. so for you to basicly type your response insuating I dont know what I am talking about is wrong, and why some of us dont normally post, By the sound of it you do more bussin on the board than in your coach, go ahead and blast me for I will not respond again, Maybe never, actual facts are my response not guesses or therorys. dont get me wrong there are a lot of great folks on this board and they deserve some respect, | ||
| Jeffrey Smith (Greenhornet)
Registered Member Username: Greenhornet Post Number: 31 Registered: 12-2006 Posted From: 198.136.32.74 Rating: N/A |
For the ground cable you should use the thickest cable you can get. NAPA can make them up for you with lugs and all that. I used one size smaller than welding cable. 00 I think. And you should run from the batteries to as close to the starter as possible. From what I was told it will increase the energy to the starter that way. I have had automotive sarters that had spring problems and would stick in place. The solinoid would click but no action in the starter itself. I have had the starters gears stick in the sarting ring wheel before that way. I had to remove the starter and rebuild it, or replace it if cheaper. | ||
| larry currier (Larryc)
Registered Member Username: Larryc Post Number: 107 Registered: 2-2007 Posted From: 64.12.116.203 Rating: N/A |
I did mine like Bill stated, it permanently addreses the issue. I also purchased a start button, mounted it in the engine bay and connected it to the hot battery post on the starter solenoid and the start post on the starter solenoid, gives me a reference point and an emergency option. If the electrical smokes, I can always go home. | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1092 Registered: 5-2001 Posted From: 65.74.65.197 Rating: N/A |
Buddy, don't just connect the battery ground cable near the starter. There's a big ground post right on the starter for just that purpose. Since all the loads in the coach are smaller than the starter and generator, your batteries should be connected directly to them. You can take the ground for your engine and chassis right from the starter. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 166 Registered: 8-2006 Posted From: 207.231.81.59 Rating: |
Bill 340, From reading your second post, you left something out. You should have said, "I have never blasted (your term) anyone until now." I have a lot to discuss here and now, which will explain to you, why I said what I said. First off, I read the entire thread carefully, before I post anything. Secondly, I only post in areas where I am qualified. Believe it or not, MCIs came with a frame, batteries and cables, and a Detroit with a starter and relays too. Mine is 38 years old. The only difference in the high current portion of the starter circuit between an MCI and an Eagle, is that the batteries are wired in series on an MCI, and in parallel on an Eagle. I hold California Electrical Contractors License #624299, issued August 6, 1991, and I have an Associate degree in industrial electronics from Pasadena City College, given in June, 1972. I also have a current Class A Commercial Driver's license, with double trailer and tank endorsements. I mention all of the above only because of your comment: "You do more bussin on the board than in your bus." Now, there are TEN other people who have posted to this thread, NINE of them discuss cleaning grounds, and the same symptoms, and one of them had to replace a battery switch. What if your bus had been the one with the bad battery switch, and you replaced all the ground cables in yours because somebody else did it in theirs, and it didn't fix the problem? That's embarrassing! Now, I was going to ask you to consider the ground portion of the high-current starter circuit, and what doing what you did would cause, but Tom beat me to it, (Run a ground cable between the starter and the chassis.) I feel special, because you "Blasted" me for differing, but not him! Running NEW cables between the battery negative terminals and the starter ground lug REPLACED BOTH BATTERY NEGATIVE TERMINALS, ALL THE BATTERY CABLE(S) AND ALL THE CONNECTIONS BETWEEN THE BATTERIES AND THE ENGINE! Sure, you threw parts at it, and fixed the instant problem, but you STILL don't know what the actual problem was? What would you have done if THAT didn't fix it? The reason I wouldn't, and still won't do it that way, is that it DOESN'T DO A THING ABOUT CLEARING UP THE ORIGINAL CHASSIS GROUND PROBLEM! What are you going to do when your headlights go dim, run wires from each of them to the starter? What about the house batteries that are grounded to the frame? Run wires to the starter from them? The voltage regulator uses voltage between a hot wire from the master switch, and chassis ground to determine proper alternator output. It's mounted on the chassis, if the problem was between the engine and the frame, your charging voltage would have been all over the place! I won't even ask you to think about what a high resistance ground will do to the low voltage protection circuit in an inverter! There is a 50% chance that the original problem was between the batteries and the frame ground, and 50% that the problem was between the engine/starter, and the chassis. Look again at Tom's post: "You can take the ground for the engine and chassis right from the starter." Your frame/chassis STILL has to carry ALL of the current from EVERYTHING else except the starter, whether you like it or not. What this means is that if all of your electrical problems went away, with what you did, then the problem was a high resistance in the ground cables, terminals, and/or frame connection, which would have been easy to find with an ohmmeter, and cheap to fix. YOU DIDN'T post anything about a "new cable between the starter and the frame also," so we can only assume you didn't install one? That would have left the bus you no longer own, open to a myriad of problems down the line. I know you don't want to hear this either, but I thought about every thing I have posted here, BEFORE I made my first post. I don't like "throwing parts at things" hoping for a fix. Your electrical problem could have been easily located with an ohmmeter, and quickly repaired with nothing more than a new battery terminal or ground lug, sandpaper, AND John and Niles and Paul and Jim and Ron and Aces' and my FREE advice: "Sand hell out of the connections, use dielectric grease... I had the same problem.. it sounds like a loose ground... I can't get the ground bolt off, maybe the previous owner had grounding problems... " I hope I didn't leave out any of the other CORRECT (ALL OF THE OTHER) posters, If I did, I'm sorry, it was unintentional. This is the way INSINUATING is spelled, BASICALLY. I'm also quite certain you are sitting in your bus, calling me a derogatory body part over this, but you said what you said. The difference between us, is that I will put out the considerable effort to explain it, every time, and WITHOUT PERSONAL COMMENTS. George | ||
| John MC9 (John_mc9)
Registered Member Username: John_mc9 Post Number: 338 Registered: 7-2006 Posted From: 66.217.107.132 Rating: |
Another opinion? Actually George, Bill's suggestion is a good one, and he was only relaying that suggestion from someone else. A poor engine to chassis ground will keep the starter from doing a first rate job, but may not always interfere with the lights, or charging circuits. In Buddy's situation, all the lights and all electronics were involved at one point (during starting), clearly indicating a problem common to all circuits. A poor positive connection could as well be the cause, as much as a poor ground. With these old buses, and all the years of "tinkering" and "hob-cobbing" that every pressured mechanic may have done to keep the cash-cow rolling, there's no telling what's been changed, or simply not serviced; Sometimes only the process of elimination will find the cure to a problem. Bill's suggestion to isolate and remove the single "starting problem" (by running dual grounds directly from the battery to the starter) is a good suggestion. It eliminates that one possible problem, and for good; it is part of the "process of elimination". The lights could have dimmed, from the drain of power by the starter, attempting to pull power through a deficient ground circuit. These forum fights usually start from a simple misunderstanding of the intention of the ones posting. No-one's ego should be held to the fire.... there's really no need for it. We are all here to learn from other's experiences.... It doesn't matter if a guy (or gal) has some sort of "special" accreditation, or is just a normal, everyday common human being. Let the one looking for a solution pick the most sensible sounding solution. That's always worked well for me! (but that's only -my- opinion) Cheers! | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 169 Registered: 8-2006 Posted From: 207.231.81.59 Rating: N/A |
John, You are right, both in your first suggestion to fix the problem, and now, as well. "Sand hell out of the connections" just couldn't be more correct! The only problem with the "dual cable" suggestion, is that it was put in Bill's bus by someone who had absolutely NO idea what the actual problem was. Then Bill recommends it to someone else as gospel, without having a clue to what the actual problem is in that bus, and gets upset when something else is suggested? Now, as you just said, "What if the problem is in the positive side?" Obviously, new dual cables, and all new connectors, and their cost wouldn't fix it, and what would he say then? (Not to mention that there is another post in this thread about a bad battery switch.) So, someone gets out an ohmmeter, finds it and fixes it quickly and easily, without throwing expensive parts at it that may not fix it! Bottom line? Again John, your suggestions on repairs are/were correct, and I appreciate the reinforcement, also the peacemaking effort. As I said, I won't make personal remarks, so its no big deal on my end. I do appreciate your effort to keep peace, I didn't post credentials to impress anyone, only to prevent a response of "what do you know?" THX, George | ||
| Buddy Tennison (Buddyten)
Registered Member Username: Buddyten Post Number: 23 Registered: 7-2005 Posted From: 207.68.235.83 Rating: N/A |
Guys: I cannot tell you how much great info we have gotten from this board. Like every other situation (not just on our "money pits"), there are more than just one solution(s). While we restrict our questions and postings to a minimum, when I post, it is usually because our mechanic has not experienced such situations before. While we use one of the best diesel mechanics in our area, he is not extremely experienced in busses. We depend on him to keep the basic mechanics of our bus going. As we have learned, bussing is a whole different animal. We only try to ask questions about things that we have not been able to solve with obvious fixes. I have learned that you guys are all, in your own areas, very experienced with just about all situations, and I heavily value your thoughts and suggestion. NOT JUST ON THIS THREAD, BUT I HATE TO SEE PEOPLE ARGUE AND GET THEIR PANTIES IN A WAD ABOUT POSTINGS. IT SERVES NO PURPOSE OTHER THAN TO TIGHTEN THE WADS OF THE PANTIES!! Each posting to a thread, constitutes an opinion!! And as the old saying goes, everybody has one!! Having preached my sermon, lets get back to my situation. Just to reiterate, I want to clarify the wiring on my bus. I have (3) 12V batteries that power the bus. They are less than one year old. The "tie together" cables were replaced at the same time, with soldered cable ends, and they are 2/0 in size. I have one ground cable that goes from the negative post on one battery to the frame, just inside the battery compartment door. It appears to be slightly larger than the others (maybe a 3/0 or 4/0). This is the one that we have not yet been able to get loose and may end up having to re-route. From the positive side of the batteries, I have a lead (which is also new and is a 2/0) that goes to one side of my kill switch. To that same post on the kill switch there is a heavy lead (looks to be about a 4/0) and goes to the starter. There is another lead (I think a 4/0) off the starter that goes over and bolts to the engine block. On the other post of the kill switch, there are two heavy leads (look to be about 4/0), one of which goes up to the panel above the engine to feed other electrical requirements, and the other which runs to the alternator/generator (these are new as well). Having said all that, I have the following questions: 1. Is this the proper routing and connection of these cables? If not, what should the proper routing be? 2. Are these cables sized correctly? I have started with my trusty sandpaper, disconnecting, cleaning, and reconnecting ALL cable ends and connections. 1. Is there ANYTHING else that I need to do as I am going through this process. Also, I am installing new leads from the skinner valve to the starter solenoid. Don't know if it needs it, but just trying to cover all the bases. 1. What size wire should this be? I am making an assumption here (which we all know is probably a mistake). When I get all the connections cleaned and done, I am going to put a voltmeter on each of them to make sure that the current is traveling as it should be. My assumption is that I should be reading 12V across all these. IS THIS CORRECT, AND IF NOT, WHAT SHOULD I BE READING? Thanks again for all your help. You guys are so knowlegable about these money pits. HAVE A GREAT MEMORIAL DAY!! GOD BLESS OUR TROOPS AND THOSE WHO HAVE SERVED!! | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 170 Registered: 8-2006 Posted From: 207.231.81.59 Rating: N/A |
Happy Memorial Day, Buddy, From the way you describe it, sounds like the starter is not being disconnected by the battery switch. It is possible that someone did this in order to eliminate their starting problem. Obviously it didn't work. Normally, the battery switch kills everything, (cable from the batts the only thing on one terminal, everything else on the other, or spliced to the large cable downstream.) Once in a great while, a starter solenoid will weld closed, keeping the starter engaged, and you want a way to stop it, other than hunting a wrench, and undoing 3 batt terminals! Also that will let you work on the starter without having to disconnect 3 battery terminals. Most of us (including your mechanic)would also figure the batt sw would kill the whole bus, and its a nasty surprise when a wrench touches a hot lug. The mech is going to check your starter for the problem above, pulls the switch, and when he drops the hot cable which he thinks is dead, WAHOO! Standard Electric Code terminology, a switch has a 'line' side, and a 'load' side. Line came from power lines obviously, in this case, its the batts, and the load side explains itself. So, batt cable on the line side, everything else on the load side. Your cables are all big enough. I would use #12 stranded wire to the skinner valve, its a little big for the current it will carry, but that gives some physical strength also. Remember that a loose wire/open circuit to the skinner valve will cause the engine to STOP, if the air pressure is up. You will read voltage ACROSS an open (off) switch, and ESSENTIALLY no voltage across a closed (on) switch. You will read voltage from HOT to GROUND on an energized circuit. You must have a good multi-meter to troubleshoot a bus. You need OHMS (resistance, indicated as an upside-down horseshoe) DC Volts, and AC volts, minimum. Be careful, DON'T have the meter on OHMS, and touch an energized circuit! The meter should have an internal fuse, but your testing day will be over until you get a new fuse at best. The trick is looking for voltage DROP ACROSS connections. Sounds crazy, but, go to DC volts, and touch one probe to the frame, (push hard, make a hole in the rust/paint, a good contact) and one probe on the round metal end of the cable terminal. IF there is NO voltage showing, the connection is good, if two or three TENTHS (or more)of a volt show up, you just found your problem! There must be a fair amount of current flowing to get a reading, so turn on the high beams with a dead engine, and look across every connection, on both hot and ground. That includes line to load on the closed batt switch. You could do it by attaching a 40 foot wire to the battery ground terminal, and measuring the difference as you go away from the batts, 12.5 at the batts, and when you find 12.3 on the other side of a connection, its sandpaper and grease time. I would do it the first way. Third way, and on par with the first, is to disconnect all the battery hots, go to the OHMS scale, maybe R X 1, and look for resistance across each connection, as described in #1. It MUST read OHMS, not Kohms, or MEGohms. If you find more that 1/10 of an ohm across a connection, there is a problem. Touch the meter leads together first, to see what the reading is on the leads, it may show one or two tenths, you have to subtract that from your bus reading. If you find half an ohm across the closed battery switch, and can't reduce it to a tenth or so by cleaning, throw it out. I'm being easy with your money, but you do want the bus to start. Disconnect the house batteries before you do resistance testing also. All of the lights going out momentarily indicates the problem is in one of the main connections, Ace may have the answer in that someone welded a nut or bolt to the frame, or it may have welded itself due to the heat caused by high current and resistance. Check that main battery/ground connection first! Its drudgery, but you WILL clear the problem! Enjoy the rest of your Memorial Day, A little electrical info. Apms (current) equals volts (pressure) divided by resistance (ohms.) So, in your 12 Volt bus, a resistance of 12 Ohms, will only allow ONE amp to flow. Now there are three starting batteries for a reason. A 12 Volt starter will probably draw 600-800 Amps on a cold morning, so you can see what a little resistance will do to your starting circuit. George | ||
| Jim Wilke (Pd41044039)
Registered Member Username: Pd41044039 Post Number: 145 Registered: 2-2001 Posted From: 69.77.144.142 Rating: N/A |
Buddy, on our Eagle the cut off switch in the rear terminal/relay panel kills the low amp "control" power but does not disconnect the starter cable, nor the cable to the alternator output. This is OEM, it was never changed. (1988 Model 15) Jim-Bob | ||
| Chris Peters (Chris_85_rts)
Registered Member Username: Chris_85_rts Post Number: 21 Registered: 11-2006 Posted From: 66.194.150.45 Rating: N/A |
Buddy said "There is another lead (I think a 4/0) off the starter that goes over and bolts to the engine block." Shouldn't this lead bolt to the engine cradle? Bolting this lead from the starter case the engine block is redundant since the starter is already bolted to the engine block. Seems to me the starter ground lead should bolt to the engine cradle. Then, there should also be a ground strap from the engine cradle the chassis. | ||
| Tom Caffrey (Pvcces)
Registered Member Username: Pvcces Post Number: 1095 Registered: 5-2001 Posted From: 65.74.65.197 Rating: N/A |
Chris, if I get your meaning, you think that the ground from bolting the starter to the block would be sufficient. If there was an internal ground to the starter frame, that would be true. There isn't. The negative lead in the starter motor is only connected to the ground stud in it's end plate. In our GMs, the alternator is not a floating ground; it grounds to the block. The big lead between the starter and the block is there to carry 200-300 amps from the alternator. This is so that we don't fry u-joints and wheel bearings. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher Ketchikan, Alaska | ||
| Gus Causbie (Gusc)
Registered Member Username: Gusc Post Number: 363 Registered: 11-2005 Posted From: 63.97.117.18 Rating: N/A |
Buddy, Along with all the other advice I would advise using a battery shutoff switche on each battery. This eliminates all the doubts and questions of the bus battery shutoff. I have a green knob shutoff switch on every battery on the bus so I can have any combination of batteries I choose. These switches are not expensive, look at your local farm store. |
