| Author | Message | ||
| Nick Morris (Nick3751) (65.117.139.135)
Rating: N/A |
Alright I'm baffeled ya'll tell me what's going on with this 671. As you know I just got my 3751 the first of the year. I bought it with one new bat and one old one. I had heard some "wives tails" about reviving old bats and wasn't in a hurry to go anywhere or spend the money to replace the old one much less both. I played with the bats and low and behold I've got them both puttin out 13-15 volts. So here's the thing, a few weeks ago I got her fired up and started to take her out. In the process the gear shift broke off in my hand (very mad busnut at that point). It was real cold at the time and she didn't want to start without the charger since it took a few tries to keep her running. Anyway I put her back in the shed and changed the oil and fuel filters. I didn't have any fuel here so I thought I'd see if the engine would prime the filters, no go, but the engine turned over very well. I ended up with the charger on it but only after several 12-15 sec starting sessions. I got some fuel the next day and filled the filters up walked to the front to crank her and of all things I had left the master switch on for two days and the voltmeter read about 10 so I bumped the started just to assure myself it wasn't going to crank and put the trickle charger on it. I checked it this morning and I had between 13 and 15 again bump started and it just kinda rolled over one slow time so I went to work. Came home this afternoon and it was reading around 15 hit the button same thing a slow turn one time. So what's the deal? I checked the connections checked the voltage at the bats and at the starter(the exact same BTW), cleaned the only terminal that looked a little bad, tightened everything I could find to tighten. Any ideas, thoughts, related stories, or anything else that might in some way help me figure this deal out. | ||
| Jimmci9 (209.240.205.68) Rating: N/A |
depending on how mechanically inclined you are...... you can use 24 volts to spin the starter... just to start the bus!!!!... if you make/install a remote start switch.... you'll need to UNWIRE everything else from the starter... go straight to the starter with good/new battery cables... and its a positive ground unless things have been updated....this way you'll spin the stater faster.. it won't hurt anything....we do it all the time in thetruck shop...but remember to UNWIRE everything so you won't damage the generator, lights. etc....mark the wires as you take them off....i did this to satrt the "man show"... its a '54 tdh5105....thats has been sitting for 6-7 yrs..... | ||
| Luke Bonagura (Lukeatuscoach) (12.75.172.55)
Rating: N/A |
Hi Nick: Your frustration comes through Loud & Clear. It is not the battery voltage but the cranking amps available in your batteries that will turn over your 671. There was just another dicussion recently, either here or perhaps on another Board I read. The owner took his batterys to a battery shop, they did an amp draw test on them and guess what!!! Plenty of volts, but no amps!!!! He replaced his batteries and the bus STARTS!!!! Get your batteries checked for amps, cut down on your frustration, replace 1 or 2 as needed, then have fun with your CLASSIC!!!! I Hope this HELPS!!! Happy & SAFE Bussin to all!!! LUKE at US COACH | ||
| Nick Morris (Nick3751) (65.117.139.135)
Rating: N/A |
I can do that Jim, the thing is, and I don't mean to sound ungreatfull, I want to fix it so it doesn't leave me stranded somewhere. I don't have a real need just to get it started, although it would be pretty cool, but I do want to get the problem fixed. It has been updated to a negitive ground system. Unlike the bus my folks had years ago, it did the same thing. Hit the button nothing, come back 10 minutes later hit the button and bang she'll fire up. So what causes the problem. | ||
| ED-NJ (67.85.226.217) Rating: N/A |
You may have the volts but not the cranking amps. If that confused you try reading this--http://www.amasci.com/elect/vwatt1.html | ||
| Nick Morris (Nick3751) (65.117.139.135)
Rating: N/A |
So what caused it to crank so well sat? | ||
| ED-NJ (67.85.226.217) Rating: N/A |
Luke it looks as if you are a faster typer than I.LOL ED-NJ | ||
| Luke Bonagura (Lukeatuscoach) (12.75.172.55)
Rating: N/A |
Hey Ed: It doesn't matter who answers first, it is that Nick, hopefully, gets the help he needs, but that is why we both posted!!!! And, if he gets the same answer twice, maybe we are correct???? It was good to see you in Arcadia, but why the HECK!!! did we come back to N.J., with the winter we have had??? If it were not for liking a roof over my head and food in the frig., I would still be there. Don't you get jealous of the guys & gals we meet who are retired???? Oh Well!!, One lives in HOPE that some day that could be us!!! LUKE at US COACH | ||
| jrgers (24.161.195.43) Rating: N/A |
Hi Nick.Glad to see another 3751 owner out there.I read previous posts about your problem.I agree with having batts load tested.My question is what size batteries are you useing? I put 2 8D batts w/1200 cranking amps each in our 3751 and she whrills quite nicely.Just my 2 cents worth.Good luck Joe | ||
| Stan (24.67.45.35) Rating: N/A |
When you check the voltage at the starter make sure that you are measuring right on the starter and not just to chassis ground. DD starters do not ground through the frame. Put one volt meter lead on the starter terminal that is connected to the solenoid and the the other lead on the terminal that has a cable going to the frame. If you have over 12 volts when the starter solenoid is energized then the starter has to turn. There are only teo possibilities if it doesn't turn. Either the starter is faulty or the mechanical load (seized or too cold an engine) exceeds the power rating of the starter motor. If you test this way, I expect you will find that you do not have 12 volts on the starter motor, caused by high resistance in the solenoid or in the ground cable. I suggest that you connect the battery ground cable directly to the starter ground and go to the engine cradle and bus chassis from that point. If you are able to hold 12 volts across a low resistance (the starter motor) and not have current flow you have just defied the most basic laws of electricity. | ||
| John Rigby (24.174.233.93)
Rating: N/A |
Nick Probably a bad cell in one of the batteries. Start of right get two new 8d,s from sams $100 each. ALWAYS diconnect the batteries when you are not using the bus( there are always some drain someware old baggage door lights etc. ) Get a couple of trickle chargers from harbor frieght $17 each keep them on the batteries AT ALL times. Change the batteries out every 2 years and you will never be stuck with battery problems. John | ||
| BrianMCI96A3 (206.107.222.206) Rating: N/A |
Nick, one battery on the brink can easily go bad and take the other with it... it sounds like you were doing some sustained cranking, it is possible that one OR the other battery shorted internally and then took the other battery down. For my money I'd say if you want to get by for now a new pair of group 31's should work just fine, and if you wish, you can add two more later. John, right now Harbor Freight has 12v float chargers on sale for $7.49 at their online store, use two, one each battery and if they are any good the batteries will stay that way for a looooog long time Brian | ||
| Larry (208.18.102.161) Rating: N/A |
I use a three stag convertor charger which moniters the battery and keeps it where it should be all the time and stops the boil over. I leave it connected all the time. My problems went away. | ||
| John Feld (Deacon) (150.199.209.41)
Rating: N/A |
Nick, Next time you change the filters and don't have any easy supply of diesel, just use ATF oil to fill the filters, its good for the system too. Heres a little story from years back. I had my first Detroit motor, ran out of fuel overnight at a truck stop (guage malfuntion). OK, prime the system, fill the filters, hit the starter, ran a minute and quit, re-fill the filters and same thing. It would not pull the fuel so a driver next to me used his airline to presure the fuel tank and we cracked the line to fill to secondary filter, hit the switch, same thing. Now I'm getting short of time for my pick-up at a steel mill so gotta get this thing going. Another driver offered to pull start me. We went around that parking lot several times and no luck. An older driver came over and asked what RPM I was useing while being pulled, I think it was around 8 or 900. Well he says, "try getting it over 1100 RPM and see what happens". Away we go again, tis time in a higher gear, 1100 RPM it sputters, 1200 RPM it springs to life. Now I don't know for a fact, but I have done it since and for others and it always works. The old driver claimed that a detroit fuel pump needs to go 1100 RPM or more to pull fuel. FWIW, your mileage may vary. John 4104 & 4106 | ||
| Nick Morris (Nick3751) (65.40.77.246)
Rating: N/A |
Sounds like you had fun John. So am I going to have to pull this thing off now that I've turned it over and didn't get any fire or will just filling the filters since it didn't run out get me started once I fix my starting trouble? I sure hope it will crank cause pulling it off where it is is not an option, unless I can get a chopper pick it up and put it on the road first.  | ||
| Nick Morris (Nick3751) (65.40.77.246)
Rating: N/A |
I got another question for you guys now. Brain said a pair of group 31's would get me buy for the time being(a good idea on my budget). So how much juice does this thing need to turn over? I can get 8d's at the local Detroit place for $70 but they're 700 CA. How much do the 31's put out compared to cost(didn't ask about them, brain not in gear) and if the 8d's are cheaper will they crank her? | ||
| John Rigby (24.174.233.93)
Rating: N/A |
Nick Go with the tried and try BIG 8D,s and you will not go wrong. Beliveve me in 17 years I am convinced, ever two years replace. John | ||
| Phil Dumpster (24.16.189.48) Rating: N/A |
Oh boy, here we go again... It sounds like you just want to start the engine and maybe move the bus on your property, but not drive it on a regular basis. Hell, in that case, a pair of group 24s from Costco should allow you to do that. If you plan to drive it on a regular basis, or you plan to drive it in cold climates, and you want the thing to be reliable, use the correct size battery the engineers who designed your bus specified. If that means 8d batteries, then use those. If you bus was designed to take group 31s, use those. If your bus is designed to use group 8d batteries, and you put in smaller batteries, and your bus doesn't restart 100 miles in the middle of nowhere and you don't have a generator on board to jump start the bus, well, there's an old saying about lying in the bed you make. Now, about your current batteries. They're probably shot. Starting batteries really hate deep discharges, and a terminal voltage of 10 volts is a deep discharge. You may be able to slowly charge the batteries back up to the point where they will start the bus, but it's going to take a long time, and they may not have enough capacity to start the engine when it is cold. Chances are, if they've been on a charger for a week and they still won't start the bus they probably never will again. I've dealt with batteries before that would gas out whatever water was added rather than hold a charge. The local battery supplier was more than happy to take them off my hands in trade when I replaced them. Since you probably don't have a load tester capable of drawing a few hundred amps, you can try this assuming you have a stout set of jumper cables (0 or 2 gauge at least, don't do this with anything lighter) and a piece of 1/2 inch rebar about 12 inches long with clean ends. Connect one end to your battery bank, hook your voltmeter to your battery bank, and clamp the other end of the cables to the ends of the rebar. Watch the voltmeter - you should have at least 9.6 volts and the rebar should get red hot within seconds. If your fully charged batteries can't maintain 9.6 volts when doing that, they aren't going to reliably start your bus. Don't go by just the fact that they can melt a piece of rebar. They need to hold at least 9.6 volts at the battery terminals while throwing 400 to 500 amps. Below that voltage the starter solenoid will just chatter away. If you don't want to try melting low grade steel with your batteries as a test of their stamina, the local Detroit dealer should have a load tester in his shop. $70 for a group 8d battery is a good price provided it has good warranty support. Personally, I would save up my money and get the group 8d batteries if there's room in the battery tray for them. You can never have too much battery capacity, especially with a 2 cycle Detroit and cold weather. | ||
| BrianMCI96A3 (206.107.222.206) Rating: N/A |
Nick, if you want to do a little reading look down about a hundred topics to "Can I run my MC-8 with regular 12V batteries" The first post was around the end of January. You might find it interesting. Cold Cranking Amps, and to a lesser extent, Reserve Capacity are the best ways to determine the most starter battery for the money. Cold Cranking Amps: How many amps a battery will deliver at 0 degrees farenheit for 30 seconds. Reserve Capacity: How long a battery can deliver 25 or 75 amps before full discharge. Reserve capacity is intended to give you an idea of how long your vehicle can run on it's battery bank if the alternator fails. A rough rule of thumb for any diesel engine is cold cranking amps should be at least equal to three times the displacement of the engine. Your 6-71 has a displacement of 426 cubic inches. 3 X 426 = 1278 The minimum CCA for your engine then, is 1278. SO, you could buy two inexpensive 650 CCA group 31 batteries and have enough cold cranking amps to whirl your 6-71 over for 30 seconds at zero degrees! More than enough to get you by for now, AND you could later add a third inexpensive 650 CCA group 31 and have extra reserve. Battery technology has advanced so far from the time your coach was built, and I seriously doubt that 8D's even existed then, but there are companies out there making the old lead top style batteries for correctly restored vehicles of that period, THEN you'd have what the engineers called for. (smile) Brian | ||
| Nick Morris (Nick3751) (65.40.77.246)
Rating: N/A |
To calm your frustration a little Phil I was hoping to get a couple of deep cycle bats a little cheaper now to start it and drive back and forth from the house to work(where my tools and a shop are) and later use them as part of my house bat bank. I'm hoping that for around the cost of one 8D I could get a pair of deep cycles that will get me by and that way I won't just be throwing the money away I can use them later as well. I really appreciate all the info guys I think I'm going to try the deep cells and see what I get for now. It's really getting agrevating not being able to move her when I want to, not that I have anywhere I need to go nor do I have the funds to get anything done now but just knowing I CAN go start it and take off will help calm my feble little brain. | ||
| Phil Dumpster (24.16.243.37) Rating: N/A |
There are some more considerations you should make before buying batteries. Deep cycle batteries can be damaged by heavy loads like starting. One damaged battery in the bank can kill the rest of the batteries. There are so-called "marine deep cycle" batteries out there which supposedly are designed for combination starting and deep cycle service but most folks I've talked to don't recommend them. They don't have the CCA of starting batteries and cannot handle repeated deep discharges like a real deep cycle battery. They are a combination that works in a recreational power boat but not much else. While trying to economize on starting batteries generally isn't a good idea, I think your best bet would be to get one of the group 8d batteries from your Detroit dealer for $70. One 8d will usually start a 6-71. Disconnect it from the bus when not in use and keep it on a float charger. Also understand that with a single 8d your bus may need help starting in real cold weather. | ||
| BrianMCI96A3 (65.173.86.232) Rating: N/A |
True deep cycle wet cell batteries have much heavier solid lead plates which are actually more tolerant of rapid discharge than wet cell starting batteries and can easily withstand the discharge of starting a 6V71. What they can't do is provide the same cranking amps as a regular starting battery of similar size. If you want to use deep cycle batteries for the time being, you should either oversize them or buy three instead of two. Brian |