| Author |
Message |
Michael 4905
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 02, 2005 - 9:07 pm: | |
Hello!
The starter of a1977 GMC 4905 w/ 8V71 N that I'm converting won't crank. I've checked to everything back to the starter and find all is in order. I get 24 volts back to the solenoid, and pushing the start button triggers the switch at the engine compartment panel and sends 24 volts to that other connection at the back of the starter solenoid, but there's no reaction or any sound from the solenoid or starter when this is done. I manually applied 24 volts to the starter solenoid by shorting across those two connections at the back of the starter solenoid that (as I understand it) should cause the starter to crank over, but still get nothing. Unless someone has something else I can do to troubleshoot this problem (that I have not yet tried) I've reached a stage where I am ready to remove and replace the starter/solenoid. Therein lies the problem.
Under the subject of "Starter Replacement" the GMC manual essentially (simply) states "remove the starter and put in the new one". When I look through the access panel under the rear seat area into the depths of that 4905 engine compartment I have to wonder if there are not some kind of tricks or some special tools involved to make the job a little easier (or even possible).
I guess for starters (pun intended) I need to find a helper with (at least) very long arms.
Seriously, though I understand the procedure as described in the book, and I can see how to get the manifold off and even remove two of three bolts securing the starter, I don't yet have any idea how I'm gonna get at the third starter bolt let alone how to get it back on and together.
What am I missing here? Is there anybody out there that's done it before that can offer some hint for me? Any help will be appreciated. I've got air tools and a compressor, but will I need to find (or make) a 1/2 inch drive extension that is two feet long, or what? How do you get a bolt started in the threads at these distances?
Until now I was convinced these GMC's were at least among the best engineered coaches around. Though I still feel this way, I am equally convinced that the engineers that designed the 4905 was never called upon to perform any service on them (least of all replace the starter).
Thanks for helping.
Michael |
Don/TX
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 02, 2005 - 9:20 pm: | |
I only did it on a 4905 twice, but it is not nearly as bad as it looks. It CAN be done by not even opening the hole in the passenger compartment. You are right, long arms do help. Two things NOT to forget if getting a replacement, it is for a CCW engine rotation, and a wet bell housing (gotta have that seal in there on the starter) |
mel 4104
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 02, 2005 - 9:35 pm: | |
before you go to the trouble of taking the starter out you might like to check the ground that goes from the engine block to the back bulk head. clean them real good as bad grounds are the cause of starter failure in most cases. you can check the grd. by taking a heacy battery jumper cable and go from the starter to the grd. side of the battery and try turning the starter over be sure that it is out of gear and the brakes are on. bad grd. over the years have caused a lot of to change a lot ot things that did not need changing and we have spent a lot of money finding out check the grounds... |
Vin (Billybonz)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 02, 2005 - 9:38 pm: | |
Michael, what book do you have? I have the Maintenance manual for my bus and the engine section is really lacking information. I know there is an engine manual that I don't have yet. I was just looking for fuel pump info and there isn't even an actual picture of it in the maintenance manual.
There may be more info in the Engine Series 71 Maintenance Manual. I will be getting one soon I got a feeling.
Bones
1973 T6H4523 |
Michael 4905
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 02, 2005 - 9:54 pm: | |
Hi!
Thanks Mel. Yes I did check that. At least I think I did. To be extra certain I'll check it again, but the 4905 batteries are at the right front end of the coach so I'll have to find a good ground at the rear to try your method with the jumper cables.
Hello Vin!
The manual I have is "X-7564" entitled "GMC COACHES MAINTENECE MANUAL" foe intercity models P8M-4108A and P8M-4905A. I understand that it's out of print, but got one from Luke at U. S. Coach in Berlin N. J. I'll bet you can get one from them too (and anything else you might need for your coach). I havn't seen the engine manual yet (need to get one soon). Give Luke (or Mike in parts) a call at 888-262-2434. They're good people.
Michael |
Norm Edlebeck (Bandleader)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 02, 2005 - 10:25 pm: | |
Hi!
I had a 1970 - 4905 w/DD 8V71 and my good friend who owns a truck garage in No. Wis. looked through DA BOOK & it said to REMOVE the engine to take off the starter. What we did was put a little mechanic (he had working for him at the time) up and over the top of the engine and down between engine and firewall. WORKED PERFECTLY!!! Good Luck!!!
Norm |
Michael 4905
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 02, 2005 - 10:33 pm: | |
Hey!
What's his name and telephone number?
Michael |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Wednesday, March 02, 2005 - 11:33 pm: | |
wait !!!! this is going to piss alot of people off....(AGAIN)....but get out there & tap it with a hammer while somebody up front is repetedly hitting the starter button ...TAP on the solinoid...(and...ALSO ....IT might be JUST the soliniod that needs replaceing...(and)......starter rebuilds....are usualy around 400.00 |
John Jewett (Jayjay)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 12:58 am: | |
Michael, stand on the right side of the coach with your head in the transmission side door and look at the end of the starter. It has a round cap (about 1 1/2 in. in diameter). This should be aluminum (unless painted) and will have a screwdriver slot in it , perhaps even another at 90 deg. to make a cross. Unscrew this cap and take a rod and manually force the solenoid arm into electrical contact. You will be pushing toward the left side of the coach. If the ignition is on when you push here (push hard), the starter will spin. No spin=bad starter becasuse you are bypassing the electrical solenoid. If it spins then the solenoid is bad.
Jack the body very high to give room to work and use a l-o-n-g extension and with care you won't have to take the manifold off. Use heavy grease in the socket to hold the bolt in when you go to replace it. Only one tough one, so don't give up. Put a rope around the starter so it doesn't fall and get wedged in. Same rope to help lift it back up for replacement. GET HELP, or have insurance to repair the hernia, 'cuz this critter weighs around 70 lbs. The rope may save you from loosing a finger if it slips. Good Luck and Cheers...JJ |
CARL GULLETT
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 2:18 am: | |
MAN I HURT FORE YOU I HAI THIS HAPPIN TO ME I USED ALL THE TRICKS THAT HAS BEN MENTIONED AND A COPLE MORE FIRST BYE A BOX END RANCH CUT IT IN HALF THAY ARE TO LONG OUTHER WISE THE STARTE BOLTS TO GIDE IT ON AND OFF I PULED THE THANG 4 TIMES AND HAID IT REBUILT 2 TIEM HAID IT CHECKED WAS GOOD HAID NEW BAT FROM SEARS 8-D IT WOULD START THE BUS MABY 4 TIMES AND THEN CHECK AS GOOD BUT AFTER I TAKIN IT BACK TO SAERS AND GOT A NUTHER ONE STARTER WORKED FORE A NUTHER YEAR BAT WOULD NOT HOLD CHARG
BUT STARTER CAN BE TAKIN OF FROM INSID BUS AND I USED 2 NYLON ROPS TO HOLD IT UP AND ALSO TO GIDE IT BACK IN BUT TO I CUT THE INSPECTION HOLE LARGER TO DO THIS AND THEN REPATCHED IT GOOD LUCK AND DOUBLE CHECK THE BATERY CARL |
Vin (Billybonz)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 7:54 am: | |
Michael, I will be pulling my starter soon. It seems that one of the caps that covers the brushes has fallen out....a long time ago from the looks of it. The starter began acting up back in November. I shot some penetrating oil in the hole and beat the crap outta it to get it spinning. All I can say is check yer caps.
Bones |
Frank Allen
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 10:27 am: | |
I can tell you how i do mine on the 06, i crawl under it, there is a hole in the bulkhead about midway, remove the breather, use a long ext and socket witha ratchet to remove all the conections and mounting bolts, then i reach through the hols and work the starter back through the hole, i can sit up under there which makes it better, if the 4905 is the same thats one way to do it, before you do it check every ground from the batt to the starter, remove and clean , they will fool you
Frank Allen
4106 |
Buswarrior (Buswarrior)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 10:53 am: | |
Hello Michael.
And be sure to look very closely at your cabling.
The corrosion that can hide under that nice heat shrink, and appear perfectly good, will haunt you at the worst time.
With cables the age of many of ours, it might be better to cut off that heat shrink over the lug and cable end for better inspection and then tape it up or add the electric goop of your choice to seal it, if you want. You might be "pleasantly" surprised at what you find in there, and in a few minutes of cut, strip and crimp, have improved your electrical reliability immeasurably.
Good preventative maintenance practice suggests a periodic disassembly and cleaning of all the major electrical connections, hot and ground. Short list: Starter, Alternator, engine to frame, batteries, junction boxes.
Fleets that spend the time keeping the electrical connections clean and corrosion free spend less time dealing with no starts and electrical related break downs.
happy coaching!
buswarrior |
Brian Brown (Fishbowlbrian)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 11:34 am: | |
I'm printing off this thread to keep in a binder in my '06 under a tab for "starter and electrical" issues.
There's some real golden advice here, folks, and it's much appreciated!
Brian Brown
Longmont, CO
PD4106-1175
Bus Photos |
Brian (Bigbusguy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 1:09 pm: | |
On my 4905 With the muffler out you can sit where the muffler was and reach the starter I tightened all the bolts when I was rebuilding my muffler . You just need a pit or a hole under the bus to get the muff out.
Brian 4905 Klamath Falls Oregon |
R. Steve Nichol (N4rsn)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 2:26 pm: | |
When you are a hefty guy, as I am, you learn to improvise.!!
On my 4106, if I remove the inside valve cover, or the starter, or anything else that I need to be back there, I remove the air intake tube, and what ever else is needed, remove the 2 bolts that hold the rear of the engine frame up. Be careful not to brake of bind any of the wires, hoses, and cables. Don't forget to put a jack under the cradle, and let it down just enough to accese the starter.
This is a good way if you are in the middle of nowhere, and no outside air, and of course you can't get air from the engine to get the bus up on the air bags.
Just a thought
Steve N4RSN |
Michael/MD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 5:09 pm: | |
Hi!
Lots of good advice here.
Thanks Don from Texas. It would be like me to get a clockwise starter without a seal.
Hey Twodogs. You know, now that you mention it that's the one thing I haven't tried yet. Gonna get out there soon as I can get some help to move the starter switch while I bash the solenoid with a hammer.
Mel, I got out there this afternoon with a set of jumper cables. Hooked one end up to the ground stud at the back of the starter and found a ground for the other end (that I also double checked with my meter just to make sure I really had made a good ground connection) where I clamped on to the bulkhead. Sorry to say no joy was found, but it was a good idea anyway. thanks for the tip.
Jayjay had a good idea to manually trip or make the solenoid electrical connection that I will also follow-up on. Sure would be cheaper to replace only the solenoid if it turns out I get that lucky here.
Dropping the muffler and or finding a pit isn't an option, because the coach is sitting on a level area at the top of a very steep driveway. In any case it would need to be towed were it to be moved. That's not an acceptable alternative except as the very last resort.
I've been thinking this thing through a little more and I think I'd be a good idea prepare the way in advance by prepping those rusty nuts and washers securing the manifold by beginning to soak them every day with a rust penatrater of some kind.
Then I'll get in there with a still wire brush to loosen up and remove an accumulation of rust, dirt, hardened grease, or whatever else that accumulated crap is around and over the manifold so that when it's removed it's less likely to fall into the open engine exhaust ports.
Also I think I'll try in advance to work out what will be a workable means to be able to support and remove as well as replace that heavy starter/solenoid. That might not be as easy as it seems at first sight. I noticed that the opening above the starter does not get you quite far enough over to be able directly suspend a strap or sling under the starter. Working from an angle may make it much more difficult to replace then to get out.
I hope to anticipate as many as possible of the potential problems I may encounter and avoid them if possible, or find solutions to get around any problems before it creeps up to bite me in the behind when I'm looking the other way.
I appreciate the effort and all the good advice coming my way. I just hope I have the chance to return the favor.
Michael |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 6:10 pm: | |
I have no experience with 4905 starters but lots of experience with MCI 8V71 starters. From your posts I think you say that the solenoid doesn't pull in and if you short across the big bolts on the solenoid the starter doesn't spin.
That means that the solenoid must be bad and ALSO the starter must be bad. It would be very unusual for both to fail at the same time. This situation is usually a voltage problem. Before you take anything apart do a thorough electrical diagnosis. With your meter negative lead connected to the starter ground terminal (not the case) and the positive lead to the battery connection on the solenoid use a jumper wire to put battery voltage to the solenoid coil (small terminal).
If the voltage stays up on the meter but the solenoid doen't pull in then put the meter positive lead to the solenoid coil terminal and see if the proper voltage is there. I think on one or both of these tests the voltage will drop to very low value indicating a high resistance in the battery cable system. It could be anywhere from the lugs on the battery posts to the connection on the solenoid. As mel pointed out it could also be in the ground system. Again it could be anywhere from the negative lug on the battery post to the connections on the chassis. If it is like an MCI the battery is grounded to the chassis and then the starter is grounded to the chassis so you have losts of possible bad connections. Unlike most starters on cars, the starter frame is not electrical ground. You have to ground to the starter ground terminal.
The starter is the only high current draw on the bus that will drop the voltage across a high resistance connection while everything else works fine.
This may seem like a lot of work, but a lot less than changing a starter. the initial test will only take five minutes but you can spend hours finding the bad connection. However, if this is your problem, you will still have to do it after you change the starter because a new starter won't work either. |
Jerry Liebler
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 7:52 pm: | |
On My 4107 which I think is very much the same it was easy through the access panel under what had been the rear seat. The trick I used was take off the exaust manifold. Once the manifold's out of the way access to the starter is easy. Well worth the price of manifold gaskets. I replaced my starter wires too as the insulation was long gone that was more of a challenge than the starter.
Regards
Jerry 4107 1120 |
Jim C
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, March 03, 2005 - 9:56 pm: | |
One thing that I can add,
I was lucky when I replaced the starter on my 4106, the previous owner had the foresight to lengthen the bottom bolt. He welded a heavy (1/2) rod to the bolt, and another bolt head to the rod, that way the head that you loosen and tighten sat at the rear end of the starter in plain view.
I did remove the exhaust manifold, it made it very easy to see what I was doing, I then slid the starter out over the transmissin and out the side door rather than try and pick it up and out the hatch.
Good luck
JIm 4106
Wisconsin |
Stephen Fessenden (Sffess)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 04, 2005 - 1:35 am: | |
I pulled a starter in a 4905 and it was OK. The problem was a blown battery cable. Don't forget that you can measuere 24 volts from a cable that is too corroded to cary starting current.
Plan on using a block and tackle to lift the starter out. You do not need to take loose any manifold if you do it from the inside. Tie a rope around it before it is loose so you have control. The starter weighs about 85 lbs and that is what ruptured a disc in my back, so take weight seriously. You will be is an awkward position for lifting.
HERE IS THE BIG TIP: you need a 3/8" drive cutback socket for the bolts, the kind that is wider at the end than where the socket wrench attaches to it. I spent several days trying to get the last bolt loose then a mechanic friend loaned me the proper wrench and it took 15 minutes. The body of the starter prevents a normal short socket from going on the bolt straight. You can make your own cut back socket at a grinder instead of looking for one. Just grind off enough so that the socket seats over the bolt head straight. If you have the right 3/8 inch drive cut back socket, you will not need the special box end wrenches. |
Michael/MD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 04, 2005 - 6:42 pm: | |
Hello again!
In a previous post Sffess raised an issue about which I have questions that I hope someone can answer for me. When checking #0000 cables how does one determine short of cleaning the connections and, or visually examining them that it can let alone will and is in fact carrying the levels of 24 volt current that is required (for example) to drive a starter. Using a meter I can measure the volts and determine a circuit is continuous, but in this case that clearly isn't enough. A good example may be the ground cable from starter to chassis grounded at the engine bulkhead. It's a continuous circuit, but as I understand what's been said here it's possible (due to internal corrosion for instance) that it's not providing an adequate ground that otherwise would allow the starter to function properly. How can I definitively determine that a connection is not only is made, but that it will indeed fully carry a current draw placed upon it?
By the way, I want to say thanks again to all for so graciously helping. I fell very frustrated by the problems I am currently suffering. I really hate it when I flip that switch and what was intended to occur doesn't. However, I sure am learning a lot in this process and I must say there is no small amount of satisfaction in that.
I guess that's the silver lining to this cloud?
Michael |
Jack Conrad (Jackconrad)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 04, 2005 - 7:27 pm: | |
Any poor connection/conductor will have resistance Resistance=Heat. Check wires and connections with a non contact temp gun, during or immediately after cranking. (This will only work if some electrical energy is flowing through wires and connections) An open circuit will not generate any heat. Hope this helps, Jack |
Jim Stacy
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 04, 2005 - 9:02 pm: | |
Also check where + voltage goes from solenoid and enters the starter body. This is a 3/4" nut like the solenoid terminals on my 6V92 (which has the starter on the rear side of the block where you can work on it like a gentleman). This starter body connection has corroded on two different GM starters. Solenoid clicks but starter doesn't crank. HTH.
Jim Stacy |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 04, 2005 - 9:04 pm: | |
Unless you have a load bank to draw high current the starter can be used as a load. If you start with 24 volts at the battery then you should have close to 24 volts on the starter when it is cranking. There will be very little voltage drop on 0000 cable and good batteries will not drop much cranking a warm engine (above 32 F).
If you don't have 24 volts at the starter solenoid bolt and starter ground bolt then you need to do voltage tests.These tests are best done with the negative meter lead connected right to the negative post of the battery (make sure it is clean and tight) with a long clip lead, then measure the voltage at the battery while someone holds down the starter button long enough for you to read the meter. If you have 24 volts at the battery, go to the next connection (or joint) and measure there. When you find a lower voltage, you have found a bad joint. Fix that one and continue on until you have 24 volts at the starter.
Now the tricky part of checking the ground. When you have 24 volts at the starter you need to connect the positive meter lead to the battery positive post and measure the voltage at the ground point of the battery (again while someone holds down the startter button). If you measure 24 volts at the ground point then measure to the chasis. If it is OK then go to the engine and measure both ends of the cable connecting the starter to ground. At this point the engine should be cranking if everything is good. If not short across the solenoid bolts to see if the starter spins and the solenoid is bad. If the solenoid is good it will pull in but a bad starter may not turn. The only other connection to check is the copper strap connecting the solenoid to the starter. Just make sure the nuts are tight.
Certainly the most common fault is that you measure 24 volts at the starter when your meter is connected to the battery negative but not when connected to the starter ground bolt and this indicates a bad connection somewhere in the battery negative sircuit through chassis ground and then to the starter ground.
You check the battery connections ths same way, by putting the meter leads directly to the post and then to the lug. Any drop in voltage shows a bad connection. Incidentally, a big drop at the battery post when cranking, shows a bad battery or a discharged battery.
Always use care when working with a 24 volts system. It can weld or melt things in a big hurry |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 04, 2005 - 9:10 pm: | |
got a question..is the battery cable hot after an attemted start ?? |
Michael/MD
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 04, 2005 - 10:18 pm: | |
3/4/05
You know, some of what I read here over the last few posts causes me to think about something that seemed sort of strange at the time, but I didn't know what to make of it. Accidentally in the past I drooped a metal tool across both the negative and positive terminals of a 12 volt battery. The result was impressive. In an attempt to test the starter and solenoid I used a heavy duty set of jumper cables. I attached one red end to the lug at the back of the solenoid where a #10 wire that comes from a switch in the engine compartment apparatus panel that's energized when the engine start switch in the drivers position is flipped and held. I attached one black cable end directly to the battery cable lug at the bulkhead where the two heavy cables that go to the other large lug at the back of the solenoid. I then touched the other ends of the jumper cables together to see if I COULD GET ANY response at all from either the starter or the solenoid. I didn't get any sound to indicate that anything happened when touched the cable ends together. I did this because, finding it difficult to reach the lugs at the back of the solenoid under the manifold, while trying to short across the two connectors I was uncertain that I got no response because it wasn't working or because I simply wasn't actually shorting it across both lugs. However, it did strike me as somewhat strange that the sparking I got when I caused the short by touching the copper teeth of the cable clamps together was not as active as I anticipated they would be. They did cause spark when brought together, but were smaller and much quieter then I had expected. It's sort of silly to say this now, but until this moment it had not occurred to me to take those cables and attach them directly to the batteries to see what kind or quality of sparking I get, but having said that I'm gonna go do that right now. Interesting. I don't know why I didn't think about this before.
I'll post again after I do it.
Michael |
Brian (Bigbusguy)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, March 04, 2005 - 11:16 pm: | |
I dont know if you checked. There is a bulkhead cable connector for the main battery on the other side of the starter on the other side of the bulkhead. It is very hard to get to if you have the muffler under the rear seat area . But you may want to check that connection as the one on the starter side.
Brian 4905 Klamath Falls OregOn |
TWODOGS (Twodogs)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 05, 2005 - 6:09 am: | |
sounds like you were not hooking up the jumper cables correctly... |
Stan
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, March 05, 2005 - 9:09 am: | |
Michael/MD: The amount of spark you get is determined by the resistance in the circuit. If you short out the terminals with a jumper cable that is minimum resistance (maximum load). If you don't get a big spark it is because there is still a high resistance between the point you are checking and the battery. If you have trouble understanding my previous posts I will try and expand it. I have written numerous technical manuals but it is difficult when the reader has no basic knowledge of troubleshooting elecrical and electronic systems.
Two Dogs: Michael 4905's battery cable will not get hot because the resistance in the circuit is so high (very little current flow) that enen the solenoid will not pull in.
The other solution is to use the rather typical mechanic method and replace the starter, then the battery, then the starter a second time and then check the cables. Remember the old joke - jack up the hood ornament and put a new car under it. Just a joke but sometimes cheaper if you are paying $75.00/hour plus parts. |